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Heat stress, resulting from elevated heat and absolute humidity associated with climate change, will increasingly occur in the tropics and parts of the mid-latitudes and could threaten the liveability and viability of many regions. Concomitant with predictions of increased heat stress in northern Australia, the Australian Government seeks to boost the population in northern Australia substantially. This paper assesses the heat stress-related wet-bulb temperatures the largest northern centres could experience under Representative Concentration Pathways 4.5 and 8.5 by 2080. The paper finds that substantial population growth could place significant future urban populations at risk from heat stress-related health issues. [ABSTRACT FROM AUTHOR]

The Forest Fire Danger Index (FFDI) is the main measure used in Australia for estimating fire risk. Recent work by the authors showed that the FFDI forms stable state regimes, nominated as fire climate regimes. These regimes shifted to greater intensity in southern and eastern Australia around the year 2000 and, a decade later, further north. Reductions in atmospheric moisture were the primary contributor. These changes have not been fully incorporated into future projections. This paper compares the recent regime shifts with the most recent national projections of FFDI, published in 2015. They show that for most states and regions, the 2030 upper limit is approached or exceeded by the recent shift, except for two states with large arid zones, South Australia and Western Australia. Methods for attributing past changes, constructing projections, and the inability of climate models to reproduce the recent decreases in atmospheric moisture, all contribute to these underestimates. To address these shortcomings, we make some suggestions to modify efforts aiming to develop seamless predictions and projections of future fire risk. [ABSTRACT FROM AUTHOR]

Recently, global epidemic models that use climatological factors have been proposed to explain influenza activities for both temperate and tropical regions. In this paper, these global models were extended by including interactions of climatological factors. This study was aimed to estimate the relative benefits of such interactions in explaining the global influenza epidemics. The effects of four climatological factors on laboratory-confirmed influenza cases were investigated, i.e., weekly temperature, precipitation, absolute humidity and relative humidity. It was found that countries in Europe and Australia have higher forecast skill, indicating the stronger relationship of influenza with climatological factors, than regions in other continents. The influenza activities of 47 (83%) countries can be explained with a closer match using multi-factor interactions along with original factors than only using the original factors. The temperate countries are characterized by the interaction of factors of temperature and absolute/relative humidity. In contrast, the interaction of factors of precipitation and absolute/relative humidity are dominant in tropical countries. [ABSTRACT FROM AUTHOR]

The harsh Australian environment makes the use of steel reinforcement in concrete structures problematic on account of corrosion. The probability of corrosion damage will significantly increase in the years to come and will become a major problem not only in coastal regions but also in inland parts of Australia due to increasing carbon dioxide concentration, temperature, and relative humidity as a consequence of climate change. In the last two decades, glass fiber-reinforced polymer (GFRP) composite bars have become an alternative to steel reinforcement for reinforcing concrete structures exposed to harsh environments. The reinforcing material is noncorrodible, nonmagnetic, lightweight, and has high tensile strength, thus making it a viable reinforcing material for concrete structures. This paper provides the state-of-the-practice in the research, development, and application of GFRP bars, with the aim of properly informing the engineering community about this alternative, noncorrodible reinforcing technology. The paper also presents a strategy toward the development of fiber-reinforced polymer bar material specifications with the aim to ensure quality use and application of the GFRP material in a wide range of applications in Australia in the years to come. Moreover, the best practices and data presented in this paper will be very useful in the development of unified international standards and specifications for GFRP bars. [ABSTRACT FROM AUTHOR]

The optimal provision of thermal comfort and energy efficiency for residential housing in the hot and humid tropics presents challenges and opportunities for housing and subdivision designs. Climatic challenges come in the form of high ambient temperature and humidity, especially during the wet season and transition periods. On the other hand, climatic advantages come in the form of breezes coupled with relatively dry air during the dry season, enabling thermal comfort attainment through natural ventilation that employs prevailing breezes. This paper discusses existing design practices for housing and subdivisions in the hot and humid tropics with particular reference to the city of Darwin in Australia’s Northern Territory. This includes several research issues and gaps that have been identified and need to be addressed. The paper also critically assesses how air speed, air temperature and humidity – three of the thermal comfort parameters – play a key role in housing and subdivision design consideration in the hot and humid tropics. In doing so, the paper sheds light on the inadequacy of the current residential energy rating methodology as a tool for assessing tropical housing performance and proposes a new direction for future research to ameliorate these issues for the tropics. [ABSTRACT FROM AUTHOR]

Various human heat stress indices have been developed to relate atmospheric measures of extreme heat to human health impacts, but the usefulness of different indices across various health impacts and in different populations is poorly understood. This paper determines which heat stress indices best fit hospital admissions for sets of cardiovascular, respiratory, and renal diseases across five Australian cities. We hypothesized that the best indices would be largely dependent on location. We fit parent models to these counts in the summers (November-March) between 2001 and 2013 using negative binomial regression. We then added 15 heat stress indices to these models, ranking their goodness of fit using the Akaike information criterion. Admissions for each health outcome were nearly always higher in hot or humid conditions. Contrary to our hypothesis that location would determine the best-fitting heat stress index, we found that the best indices were related largely by health outcome of interest, rather than location as hypothesized. In particular, heatwave and temperature indices had the best fit to cardiovascular admissions, humidity indices had the best fit to respiratory admissions, and combined heat-humidity indices had the best fit to renal admissions. With a few exceptions, the results were similar across all five cities. The best-fitting heat stress indices appear to be useful across several Australian cities with differing climates, but they may have varying usefulness depending on the outcome of interest. These findings suggest that future research on heat and health impacts, and in particular hospital demand modeling, could better reflect reality if it avoided “all-cause” health outcomes and used heat stress indices appropriate to specific diseases and disease groups. [ABSTRACT FROM AUTHOR]

Exposure to weather extremes, such as heatwaves, can cause discomfort, harm, or death in grazing cattle in pastures. While the Australian Bureau of Meteorology issues sheep graziers alerts when there is an exposure risk to chill for livestock, there is no equivalent alert for heat stress for Australian cattle. Before any such alert system can be developed, a robust assessment and comparison of relevant cattle thermal stress indices is required. This study evaluates and compares the multiyear climatology of three cattle thermal heat stress indices across Australia in the warm season months (October–March). The same indices are then used to assess historical Australian heat events where cattle died from heat exposure. These events are based off official records and survey responses from northern Australian graziers. In the seven historical heat events studied, high relative humidity combined with low wind speeds, or high solar exposure combined with high surface temperatures, exacerbated the impact of heat stress on cattle. In the two historic events where multiple compounding weather factors combined (e.g., high humidity, low winds, and high solar exposure), the cattle mortality levels were significantly high. These events were characterized by rainy conditions followed by a rapid warming, meaning cattle were likely unable to acclimatize to such dramatic temperature changes. This study highlights the need for using more than one thermal stress index when verifying cattle heat stress events and, importantly, calls for further research on standardizing the risk classifications of these thermal indices for cattle in Australia's variable climate. Significance Statement: Cattle across Australia's northern tropical and semiarid regions often experience extreme hot and humid conditions in the summer months, which increases the risk of heat stress. This is the first study of its kind to evaluate observations of cattle heat stress across Australia using indices that describe the combined effects of solar exposure, wind speed, relative humidity, and surface temperatures. These cattle heat stress indices can be used to evaluate historical cattle mortality events in feedlots and in grazed pastures. This study lays the groundwork for the development of Australian-wide cattle heat stress forecast products on the 7-day to multiweek time scales. [ABSTRACT FROM AUTHOR]

The energy efficiency performance requirements of the Australian National Construction Code have been regularly enhanced since 2003 to reduce greenhouse gas emissions. Since 2010 research has increasingly raised a concern about high air moisture content, moisture accumulation and mould growth. Coincidently, in Australia, asthma is the leading cause of disease in children aged 0–14 years, accounting for 17.9% of the total burden in boys and 18.6% in girls. Many researchers have supported a connection between damp housing and childhood respiratory symptoms. The contemporary code compliant houses in Australia may have inadvertently created ideal interior environments that promote mould growth. If the built environment is promoting mould growth, leading to sick building syndrome, it is a matter of serious concern, resulting from the design or technical flaws in the building fabric. This paper attempts to bridge the gap between architectural and medical science perspectives in this area of study. [ABSTRACT FROM AUTHOR]

The Murray dairy region produces approximately 1.85 billion litres of milk each year, representing about 20 % of Australia's total annual milk production. An ongoing production challenge in this region is the management of the impacts of heat stress during spring and summer. An increase in the frequency and severity of extreme temperature events due to climate change may result in additional heat stress and production losses. This paper assesses the changing nature of heat stress now, and into the future, using historical data and climate change projections for the region using the temperature humidity index (THI). Projected temperature and relative humidity changes from two global climate models (GCMs), CSIRO MK3.5 and CCR-MIROC-H, have been used to calculate THI values for 2025 and 2050, and summarized as mean occurrence of, and mean length of consecutive high heat stress periods. The future climate scenarios explored show that by 2025 an additional 12-15 days (compared to 1971 to 2000 baseline data) of moderate to severe heat stress are likely across much of the study region. By 2050, larger increases in severity and occurrence of heat stress are likely (i.e. an additional 31-42 moderate to severe heat stress days compared with baseline data). This increasing trend will have a negative impact on milk production among dairy cattle in the region. The results from this study provide useful insights on the trends in THI in the region. Dairy farmers and the dairy industry could use these results to devise and prioritise adaptation options to deal with projected increases in heat stress frequency and severity. [ABSTRACT FROM AUTHOR]

The gas-induced swelling behavior of coal is important when considering CO2 sequestration into coal seams or enhanced coalbed methane applications, but coals may also swell in the presence of moisture, or shrink on drying. In this paper we examine the moisture-swelling properties of coals from Australia and elsewhere. Results on the moisture uptake and corresponding swelling measurements are presented for 15 coals of various ranks (sub-bituminous and bituminous) at 22°C and atmospheric pressure. Measurements were made by exposing sample blocks of coal (nominally 30 × 10 × 10 mm) to relative humidities ranging from 0% to 97%. A selection of coals was also fully saturated in water. Moisture uptake at 97% relative humidity (RH) ranged from about 2.5% to more than 16% db. Maximum linear strain associated with the moisture sorption (measured at 97% RH) varied from about 0.2% to 1.3%, with lower rank coals showing the most swelling. In all cases, swelling was greater in the direction perpendicular to the bedding plane. These results correspond to volumetric swelling of about 0.5% to around 5%. Although exhibiting significant expansion, all of the samples returned to their original dimensions upon drying. Volumetric moisture sorption and the amount of swelling induced were found to be strongly correlated by a single linear expression that held for all of the coals examined. It was further found that the volume of the water adsorbed was linearly related to the pore space within the coal, however, at 97% relative humidity, only about 60% of the available pore space is occupied by water. Exposure to liquid water allowed the pores to completely fill; although for the lowest rank coals, the volume of water absorbed appeared to be slightly more than the corresponding pore volume. Despite the additional water uptake, immersion in water did not produce further swelling beyond that induced at 97% relative humidity. [ABSTRACT FROM AUTHOR]

The Class A pan evaporation rates at many Australian observing stations have reportedly decreased between 1970 and 2002. That pan evaporation rates have decreased at the same time that temperatures have increased has become known as the “pan evaporation paradox.” Pan evaporation is primarily dependant on relative humidity, solar radiation, and wind. In this paper, trends in observed pan evaporation in Australia during the period 1975–2004 were attributed to changes in other climate variables using a Penman-style pan evaporation model. Trends in daily average wind speed (termed wind run) were found to be an important cause of trends in pan evaporation. This result is a significant step toward resolving the pan evaporation paradox for Australia. Data inspection and interstation comparison revealed that some of the significant wind run trends were discontinuous or spatially uncorrelated. These analyses raised the possibility that some of the changes in observed wind run, and by implication some of the significant changes in pan evaporation, may represent changes in the local environment surrounding the observing stations. Daily pressure gradients and NCEP–NCAR reanalysis wind surfaces were analyzed in an attempt to identify any climatological wind run trends associated with large-scale changes in atmospheric circulations. Unfortunately, the trends from the two data sources were not consistent, and the challenge remains to conclusively identify the cause or causes of the changes in observed station wind run in Australia. [ABSTRACT FROM AUTHOR]

Background: There is scant guidance in the literature on the most appropriate Australian measures of, and thresholds for, extreme heat regarding giving advice on safe sports participation in hot weather. The purpose of this paper is to present a process for investigating two common measures of heat (air temperature, wet bulb globe temperature (WGBT)) in one state in Australia (South Australia), regarding their usefulness in making decisions regarding sports participation in the heat.Method: Commonly reported measures and thresholds of extreme heat were identified from a systematic review of guidelines regarding sports participation in hot weather. Dry air temperature (threshold of 35 degrees C), and WBGT index (threshold of 28 degrees C) were highlighted. Repeated daily measures of dry air temperature by the Bureau of Meteorology (BoM) and WBGT index from 12 meteorological recording sites in South Australia (SA) for four consecutive summer periods (2000-2004) were analysed using these thresholds to investigate the prevalence of extremely hot temperatures in SA during these periods. The extremely hot hours-per-day data were standardised using a denominator of per-day-month across the 12 SA recording regions.Results: Across the four summer seasons of data in SA, there were similar standardised numbers of hours-per-day of extremely hot dry air temperature and WBGT index. There was a high correlation between these hours of hot weather measures, highlighting the congruence between hot air and humidity measures. Three distinct regional site groupings were identified, in which there was a different prevalence of extremely hot weather conditions.Conclusion: In SA, dry air temperature is an appropriate and robust measure of extreme heat related to sports participation, this measure providing as much information as WBGT in identifying extremely hot periods of weather. Dry air temperature can be readily measured by sports participants or officials irrespective of the geographical location in SA. Three SA regions demonstrated distinct differences in prevalence of extremely hot conditions, suggesting the need for site-specific interpretation of heat participation guidelines to ensure sports safety in hot weather. Other states in Australia could use the approach outlined in this paper to identify the most appropriate measure of extreme heat relevant to local conditions, and to assist in interpreting heat limit guidelines in a local context. [ABSTRACT FROM AUTHOR]

This paper evaluates convective boundary layer (CBL) budget methods as a tool for estimating regionally averaged sensible and latent heat fluxes for the study region used in OASIS (Observations at Several Interacting Scales). This is an agricultural region of mixed cropping and grazing extending about 100 km west of the town of Wagga Wagga, NSW, Australia. The analysis proceeds in three stages: first, a simple one-dimensional model of the well-mixed layer (the CBL slab model), forced with measurements of the surface heat and evaporation fluxes, is evaluated by comparing measured and modelled CBL temperature, humidity and depths. A comparison of several entrainment schemes shows that a simple model, where the entrainment kinetic energy is parameterised as a fraction (α3) of the surface sensible heat flux, works well if α is set to 0.5. Second, the slab model is coupled to a Penman–Monteith model of surface evaporation to predict regional scale evaporation and thence heat fluxes. Finally, the integral CBL budget approach, which is an inverse method using the one-dimensional slab model, is used to infer regional heat and evaporation fluxes from measured time series of CBL temperature and humidity. We find that the simple CBL slab model works reasonably well for predicting CBL depth and very well for CBL temperature, especially if approximate estimates of subsidence velocity and warming due to advection are included. Regional sensible heat fluxes estimated from the integral CBL method match those measured, although the method is very sensitive to measurement errors. Measurement-model differences were larger for short integration times, because the well-mixed assumptions are violated at particular times of the day. The corollary is that `whole-day' (0530–1530 h) estimates are in reasonable agreement with measured values. Integral methods could not be used to infer the regional evaporation flux directly because CBL humidity profiles were complex and often not well mixed until mid-afternoon. We recommend that regional evaporation fluxes be predicted either from a coupled Penman–Monteith – CBL slab model, or inferred as a residual term from estimates of the regionally averaged available energy and sensible heat flux. Furthermore, we show that inferring fluxes via integral methods will always be difficult when the scalar concentrations have either a large surface source and free atmosphere sink (in the case of water vapour and methane), or a large surface sink and upper level source (in the case of CO2). [ABSTRACT FROM AUTHOR]

The incidence of pyro-cumulonimbus (pyroCb) caused by extreme wildfires has increased markedly in Australia over the last several decades. This increase can be associated with a dangerous escalation of wildfire risk and severe stratospheric pollution events. Atmospheric and fuel conditions are important influences on pyroCb occurrence, but the exact causal relationships are still not well understood. We used the Continuous Haines Index (C-Haines) to represent atmospheric instability and the Fuel Moisture Index (FMI) to represent fuel moisture to provide better insight into the effects of atmospheric and fuel conditions on pyroCb occurrence over southeast Australia. C-Haines and FMI were related to the probability of pyroCb occurrence by employing a logistic regression on data gathered between 1980 and 2020. Emphasis is placed on investigating the independent effects and combined effects of FMI and C-Haines, as well as assessing their potential to predict whether a pyroCb develops over a fire. The main findings of this study are: (1) high C-Haines and low FMI values are representative of favorable conditions for pyroCb occurrence, but C-Haines can offset the effect of FMI—the addition of C-Haines to the logistic model muted the significance of FMI; (2) among the components of C-Haines, air temperature lapse rate (CA) is a better predictor of pyroCb occurrence than the dryness component (CB); (3) there are important regional differences in the effect of C-Haines and FMI on pyroCb occurrence, as they have better predictive potential in New South Wales than in Victoria. [ABSTRACT FROM AUTHOR]

To move to holistic indoor environmental quality (IEQ) assessment methods of residential building performance in Australia, a relevant evidence base on the comfort behaviour and preferences of contemporary households is needed. A lack of information on the environmental conditions, behaviour and preferences relevant to dwellings in Australia’s hot humid climates has been revealed as an area of ongoing policy and research interest. This paper explores the cooling practices of households living in predominantly naturally ventilated dwellings in Darwin, the Northern Territory through a survey of behaviour, preferences and dwelling construction (n = 102) and a 12-month longitudinal thermal comfort study in 20 houses (n = 2535). The results show that these households employ a range of adaptive behaviours in response to warm and hot conditions. The houses were almost always naturally ventilated, with the assistance of ceiling fans for approximately 50% of the time. The limited use of air-conditioning in these houses is more strongly associated with indoor humidity levels than temperature. These patterns of comfort behaviour provide a basis for the enhancement of building simulation models for the performance assessment of dwellings in naturally ventilated mode in hot humid climates in Australia. [ABSTRACT FROM AUTHOR]

Navua sedge (Cyperus aromaticus (Ridley) Mattf. & Kukenth) is a significant agricultural and environmental weed found in tropical island countries including north Queensland, Australia. It is a prolific seed producer and consequently forms a high-density seedbank, and therefore understanding the longevity and persistence of the seeds can provide critical information required for the management of this species. A laboratory-controlled artificial ageing experiment was conducted where the seeds were exposed to a temperature of 45 °C and 60% relative humidity for 125 days. Seeds were removed at various times (1, 2, 5, 9, 20, 30, 50, 75, 100 and 125 days) and their viability determined through standard germination tests. It took 20 days in the artificial ageing environment for the seeds to decline to 50% viability which indicates that Navua sedge has relatively short-lived persistent seeds. These findings will assist in developing a better understanding of the seedbank dynamics of this invasive species, allowing managers to tactically implement control strategies and prepare budgets for ongoing treatments, and have implications for the duration and success of management programs. [ABSTRACT FROM AUTHOR]

Recent work attributing decadal regime changes in temperature to radiative forcing is extended to atmospheric moisture. Temperature, and specific and relative humidity (T, q, RH) from the HadISDH data set were analyzed for regime shifts using the bivariate test. Most shifts in q and T for global and northern hemisphere (NH), and tropical land occurred within a year of each other. Only one shift of q was recorded in the southern hemisphere (SH). RH increased in the NH in 1990–91 and decreased in a series of shifts from the late 1990s, while in the SH decreased from 2001. The tropics have remained neutral, shifting negative over land and positive over the ocean. The global decreases in 2001 and 2011 was −0.56%. Global RH from 32 climate models from the CMIP5 RCP4.5 archive all contained regime shifts but only 4 reached or exceeded the observed decreases by 2100, the earliest in 2056. Regime shifts in RH and fire danger over Australia are consistent with the SH decreases in RH, shifting within one year of global fire season length in 2002, showing that impacts are also being underestimated by current analyses. Methods for nonlinear attribution and the contributing processes for nonlinear change are discussed. These results show that developing a better understanding of nonlinear change in moisture-related climate risk is an urgent task. [ABSTRACT FROM AUTHOR]

O'Connor, FK, Doering, TM, Minett, GM, Reaburn, PR, Bartlett, JD and Coffey, VG. Effect of divergent solar radiation exposure with outdoor versus indoor training in the heat: implications for performance. J Strength Cond Res 36(6): 1622–1628, 2022—The aim of this study was to determine physiological and perceptual responses and performance outcomes when completing high-intensity exercise in outdoor and indoor hot environments with contrasting solar radiation exposure. Seven cyclists and 9 Australian Football League (AFL) players undertook cycling trials in hot conditions (≥30 °C) outdoors and indoors. Cyclists completed 5 × 4 minutes intervals (∼80% peak power output [PPO]) with 2 minutes recovery (∼40% PPO) before a 20-km self-paced ride. Australian Football League players completed a standardized 20 minutes warm-up (∼65% mean 4-minute power output) then 5 × 2 minutes maximal effort intervals. Heart rate (HR), PO, ratings of perceived exertion (RPE), thermal comfort (TC), and thermal sensation (TS) were recorded. Core (Tc) and skin temperature (Tsk) were monitored in cyclists alone. In both studies, ambient temperature, relative humidity, and solar radiation were monitored outdoors and matched for ambient temperature and relative humidity indoors, generating different wet bulb globe temperature (WBGT) for cyclists, but the similar WBGT for AFL players through higher relative humidity indoors. The statistical significance was set at p ≤ 0.05. Cyclists' HR (p = 0.05), Tc (p = 0.03), and Tsk (p = 0.03) were higher outdoors with variable effects for increased RPE, TS, and TC (d = 0.2–1.3). Power output during intervals was not different between trials, but there were small-moderate improvements in cyclists' PO and 20-km time indoors (d = 0.3–0.6). There was a small effect (d = 0.2) for AFL players' mean PO to increase outdoors for interval 4 alone (p = 0.04); however, overall there were small-moderate effects for lower RPE and TS indoors (d = 0.2–0.5). Indoor training in hot conditions without solar radiation may promote modest reductions in physiological strain and improve performance capacity in well-trained athletes. [ABSTRACT FROM AUTHOR]

Reconstructed weather datasets, such as reanalyses based on model output with data assimilation, often show systematic biases in magnitude when compared with observations. Postprocessing approaches can help adjust the distribution so that the reconstructed data resemble the observed data as closely as possible. In this study, we have compared various statistical bias-correction approaches based on quantile–quantile matching to correct the data from the Twentieth Century Reanalysis, version 2c (20CRv2c), with observation-based data. Methods included in the comparison utilize a suite of different approaches: a linear model, a median-based approach, a nonparametric linear method, a spline-based method, and approaches that are based on the lognormal and Weibull distributions. These methods were applied to daily data in the Australian region for rainfall, maximum temperature, relative humidity, and wind speed. Note that these are the variables required to compute the forest fire danger index (FFDI), widely used in Australia to examine dangerous fire weather conditions. We have compared the relative errors and performances of each method across various locations in Australia and applied the approach with the lowest mean-absolute error across multiple variables to produce a reliable long-term bias-corrected FFDI dataset across Australia. The spline-based data correction was found to have some benefits relative to the other methods in better representing the mean FFDI values and the extremes from the observed records for many of the cases examined here. It is intended that this statistical bias-correction approach applied to long-term reanalysis data will help enable new insight on climatological variations in hazardous phenomena, including dangerous wildfires in Australia extending over the past century. [ABSTRACT FROM AUTHOR]

Drought is projected to become more severe and widespread as global warming continues in the twenty-first century, but hydroclimatic changes and their drivers are not well examined in the latest projections from phase 6 of the Coupled Model Intercomparison Project (CMIP6). Here, precipitation (P), evapotranspiration (E), soil moisture (SM), and runoff (R) from 25 CMIP6 models, together with self-calibrated Palmer drought severity index with Penman–Monteith potential evapotranspiration (scPDSIpm), are analyzed to quantify hydroclimatic and drought changes in the twenty-first century and the underlying causes. Results confirm consistent drying in these hydroclimatic metrics across most of the Americas (including the Amazon), Europe and the Mediterranean region, southern Africa, and Australia, although the drying magnitude differs, with the drying being more severe and widespread in surface SM than in total SM. Global drought frequency based on surface SM and scPDSIpm increases by ∼25%–100% (50%–200%) under the SSP2-4.5 (SSP5-8.5) scenario in the twenty-first century together with large increases in drought duration and areas, which result from a decrease in the mean and flattening of the probability distribution functions of SM and scPDSIpm, while the R-based drought changes are relatively small. Changes in both P and E contribute to the SM change, whereas scPDSIpm decreases result from ubiquitous PET increases and P decreases over subtropical areas. The R changes are determined primarily by P changes, while the PET change explains most of the E increase. Intermodel spreads in surface SM and R changes are large, leading to large uncertainties in the drought projections. SIGNIFICANCE STATEMENT: Drought may become more severe and widespread under greenhouse gas (GHG)-induced global warming in the twenty-first century based on model projections. However, there are still large uncertainties in projected future drought changes, especially regarding the extent to which drought changes depend on drought indices and the future emissions scenarios analyzed. The latest projections from CMIP6 models reaffirm the widespread drying and increases in agricultural drought by up to 200% over most of the Americas (including the Amazon), Europe and the Mediterranean region, southern Africa, Southeast Asia, and Australia under moderate-to-high emissions scenarios in the twenty-first century, despite large uncertainties in individual projections partly due to internal variability. Ubiquitous increases in atmospheric demand for moisture under rising temperatures and precipitation decreases over many subtropical regions are the main driver of the projected drying and drought increases. [ABSTRACT FROM AUTHOR]

Aims: Flower blights (grey mould, green mould and dry flower) are important diseases of macadamia. Lack of information on pathogen biology and disease epidemiology in macadamia has hampered control options. Effects of climatic variables including temperature, relative humidity (RH) and vapour pressure deficit (VPD) on the abundance, germination and growth of conidia of four fungal pathogens that cause various flower blights in macadamia were studied. Methods and Results: Mycelial growth, sporulation, conidial germination and germ tube growth for five isolates each of Botrytis cinerea, Cladosporium cladosporioides, Pestalotiopsis macadamiae and Neopestalotiopsis macadamiae, at eight temperatures, seven RH and the corresponding VPD regimes were determined in vitro. The optimal climatic range of each of the four pathogens was validated during macadamia flowering periods in the 2019 and 2020 seasons by conidia detected and quantified using quantitative PCR. Several growth models were fitted to the data with high significance; predicted optima from these models ranged from 0.9 to 1.1 kPa VPD for P. macadamiae and N. macadamiae and <0.6 kPa VPD for B. cinerea and C. cladosporioides. Conclusions: This study showed that VPD, as a determinant of the fecundity and growth of the four fungal pathogens, was predictive of flower blight incidence in macadamia. The importance of temperature, RH and, thus, VPD for defining the conditions for infection and flower blight epidemics was established. Significance and Impact of the Study: This information provides a firm basis for the development of prediction tools for flower blights in macadamia. [ABSTRACT FROM AUTHOR]

Abstract: This research aims to find a scientific rating scheme for roof system for the warm humid tropics. The overall air-to-air thermal transmittance (U-value) or thermal resistance (R-value) of roof are most widely used properties, but these are based on steady-state heat conduction and do not respond to changing conditions of climate, design and comfort needs. The paper presents a new thermal performance index, which is based on thermal comfort and actual thermal performance of a roof design option. It provides a basis for identifying the optimum roof design for unconditioned and acclimatised regimes. A review of the acceptable limits of ceiling surface temperature is presented. The mathematical modelling for predicting performance of roof based on admittance procedure and derivation of thermal performance index is described. In the proposed scheme the galvanized iron roof is given 0% rating and the roof satisfying the comfort needs for the given climate is rated as 100%. Illustrative examples of built roofs or design options are taken from India and Australia. It clearly shows that the roofs with the highest thermal resistance are not necessarily optimum solutions. [Copyright &y& Elsevier]

Studies were undertaken to determine the combined environmental effects of two temperature regimes (14/11 ℃, 17/14 ℃ day/night) and duration of postinoculation high humidity on progression of white leaf spot, caused by Neopseudocercosporella capsellae, in rapeseed (Brassica napus) at each of two different plant growth stages. Overall, percentage disease indices were significantly affected by temperature, high humidity duration, plant growth stage, and host cultivar (all p < 0.001). There were significant two‐way interactions of temperature regime with plant age (p < 0.001) and with host cultivar (p < 0.01), and significant three‐way interactions of high humidity duration with growth stage and host cultivar (p = 0.01) and with temperature and host cultivar (p = 0.03). At cotyledon stage, mean percentage cotyledon disease index was 38.2 at 17/14 ℃ day/night, and 33.1 at 14/11 ℃. At fourth leaf stage, mean percentage leaf disease index was 32.0 at 14/11 ℃ but 17.5 at 17/14 ℃. Disease severity increased with increasing duration of high humidity. Results explain why this disease is more prevalent and severe in Australia following longer durations of high humidity; why disease at cotyledon stage is largely independent of temperature if seasonal temperature ranges between 11 and 17 ℃; and why more severe leaf infection (e.g., at fourth leaf stage) can be attributed to cooling winter conditions between autumn and winter. Studies suggest current/predicted climate changes across southern Australia of increasingly warmer autumn‐winter temperatures and decreasing growing‐season (May–August) precipitation will lessen severity of future epidemics. [ABSTRACT FROM AUTHOR]

This study uses sea surface salinity (SSS) as an additional precursor for improving the prediction of summer [December–February (DJF)] rainfall over northeastern Australia. From a singular value decomposition between SSS of prior seasons and DJF rainfall, we note that SSS of the Indo-Pacific warm pool region [SSSP (150°E–165°W and 10°S–10°N) and SSSI (50°–95°E and 10°S–10°N)] covaries with Australian rainfall, particularly in the northeast region. Composite analysis that is based on high or low SSS events in the SSSP and SSSI regions is performed to understand the physical links between the SSS and the atmospheric moisture originating from the regions of anomalously high or low, respectively, SSS and precipitation over Australia. The composites show the signature of co-occurring La Niña and negative Indian Ocean dipole with anomalously wet conditions over Australia and conversely show the signature of co-occurring El Niño and positive Indian Ocean dipole with anomalously dry conditions there. During the high SSS events of the SSSP and SSSI regions, the convergence of incoming moisture flux results in anomalously wet conditions over Australia with a positive soil moisture anomaly. Conversely, during the low SSS events of the SSSP and SSSI regions, the divergence of incoming moisture flux results in anomalously dry conditions over Australia with a negative soil moisture anomaly. We show from the random-forest regression analysis that the local soil moisture, El Niño–Southern Oscillation (ENSO), and SSSP are the most important precursors for the northeast Australian rainfall whereas for the Brisbane region ENSO, SSSP, and the Indian Ocean dipole are the most important. The prediction of Australian rainfall using random-forest regression shows an improvement by including SSS from the prior season. This evidence suggests that sustained observations of SSS can improve the monitoring of the Australian regional hydrological cycle. [ABSTRACT FROM AUTHOR]

In recent months, the world has experienced the outbreak and spread of a new infectious disease, COVID-19. The spread of this disease has been so severe, and even many developed countries have struggled to manage this situation. However, some countries, such as China and Australia, have shown success in taking effective steps towards tackling the crisis. So far, some preventive measures to contain the spread of infection have emerged. Numerous studies have been undertaken worldwide in parallel in order to develop strategies to contain the virus, as well as to determine climatic or atmospheric conditions favoring COVID-19 spread. In this research, an artificial intelligence (AI) system has been adopted to assess the effective role of various environmental conditions in the spread of COVID-19. Temperature, relative humidity (RH), and UV index (UVI) of some affected countries were considered as input parameters while the total number of infected people is taken as the output variable. After plotting all available data as linguistic variables, a relationship is established between temperature, RH, UVI, and the number of infected people. From the surface graph, it can be stated that in addition to UVI, temperature and RH have a significant impact on the number of affected people. The maximum and minimum temperatures as well as other parameters are considered on the basis of mean values. [ABSTRACT FROM AUTHOR]

Projection of extreme rainfall under climate change remains an area of considerable uncertainty. In the absence of geographically consistent simulations of extreme rainfall for the future, alternatives relying on physical relationships between a warmer atmosphere and its moisture carrying capacity are projected, scaling with a known atmospheric covariate. The most common atmospheric covariate adopted is surface air temperature, as it exhibits great consistency across climate model simulations into the future and, as per the Clausius‐Clapeyron relationship, has a well‐established link to atmospheric moisture capacity. However, empirical assessments of this relationship show that it varies with latitude, surface temperature, atmospheric temperature, and other factors, suggesting there may be more stable "global" atmospheric covariates that could be used instead. We argue that a better‐suited covariate would be one that captures the relationship between extreme rainfall and temperature but exhibits greater consistency in the relationship across regions as well as climatic zones. Our analysis identifies plausible atmospheric indicators of changes to future extreme rainfall, which now proliferate literature and compare their suitability based on the variability they exhibit across multiple geographical, topographic, and climatic zones within Australia. It is shown that surface air temperature exhibits a regionally inconsistent relationship with extreme rainfall and hence is not suitable for projecting to future conditions. The study identified integrated water vapor and surface dew point temperature as promising alternatives, with the former showing greater consistency in space but at the cost of reduced temporal coverage. Plain Language Summary: Studies of extreme rainfall sensitivity to temperature (termed scaling) improve our understanding of how extreme rainfall can be expected to change under global warming. The widespread and intuitive use of surface air temperature in rainfall scaling studies is likely the result of its observational availability and its apparent physical relationship with extreme rainfall. This study investigates the reliability of surface air temperature, integrated water vapor, surface dew point temperature, and 850 hPa atmospheric temperature as possible covariates for rainfall projection. Consistent with observed increases in extreme rainfall, a covariate that exhibits consistency across varying climatic conditions will result in more robust projections of future extreme rainfall. Here, we investigate the susceptibility of each covariate to varying conditions exhibited by the broad climates found across Australia. Integrated water vapor, retrieved from satellites, is found to be the most suitable scaling covariate for extreme rainfall projection. Key Points: Extreme rainfall does not scale consistently with surface air temperatureIntegrated water vapor is the most stable covariate when correlated to rainfallIt is suggested integrated water be used as a covariate for rainfall projection [ABSTRACT FROM AUTHOR]

An investigation of Tropical Cyclone (TC) Kelvin in February 2018 over northeast Australia was conducted to understand the mechanisms of the brown ocean effect (BOE) and to develop a comprehensive analysis framework for landfalling TCs in the process. NASA's Land Information System (LIS) coupled to the NASA Unified WRF (NU-WRF) system was employed as the numerical model framework for 12 land/soil moisture perturbation experiments. Impacts of soil moisture and surface enthalpy flux conditions on TC Kelvin were investigated by closely evaluating simulated track and intensity, midlevel atmospheric thermodynamic properties, vertical wind shear, total precipitable water (TPW), and surface moisture flux. The results suggest that there were recognized differentiations among the sensitivity simulations as a result of land surface (e.g., soil moisture and texture) conditions. However, the intensification of TC Kelvin over land was more strongly related to atmospheric moisture advection and the diurnal cycle of solar radiation (i.e., radiative cooling) than to overall soil moisture conditions or surface fluxes. The analysis framework employed here for TC Kelvin can serve as a foundation to specifically quantify the factors governing the BOE. It also demonstrates that the BOE is not a binary influence (i.e., all or nothing), but instead operates in a continuum from largely to minimally influential such that it could be utilized to help improve prediction of inland effects for all landfalling TCs. [ABSTRACT FROM AUTHOR]

Objective: To determine the proportion of the national childhood asthma burden associated with exposure to dampness and gas stoves in Australian homes.Design: Comparative risk assessment modelling study. Setting, participants: Australian children aged 14 years or less, 2011.Main Outcome Measures: The population attributable fractions (PAFs) and number of disability-adjusted life years (DALYs) for childhood asthma associated with exposure to damp housing and gas stoves.Results: 26.1% of Australian homes have dampness problems and 38.2% have natural gas as the main energy source for cooktop stoves. The PAF for childhood asthma attributable to damp housing was 7.9% (95% CI, 3.2-12.6%), causing 1760 disability-adjusted life years (DALYs; 95% CI, 416-3104 DALYs), or 42 DALYs/100 000 children. The PAF associated with gas stoves was 12.3% (95% CI, 8.9-15.8%), corresponding to 2756 DALYs (95% CI, 1271-4242), or 67 DALYs/100 000 children. If all homes with gas stoves were fitted with high efficiency range hoods to vent gas combustion products outdoors, the PAF and burden estimates were reduced to 3.4% (95% CI, 2.2-4.6%) and 761 DALYs (95% CI, 322-1199).Conclusions: Exposure to damp housing and gas stoves is common in Australia, and is associated with a considerable proportion of the childhood asthma burden. Strategies for reducing exposure to indoor dampness and gas combustion products should be communicated to parents of children with or at risk of asthma. [ABSTRACT FROM AUTHOR]

Most of the life and property losses due to bushfires in south-eastern Australia occur under extreme fire weather conditions - strong winds, high temperatures, low relative humidity (RH) and extended drought. However, what constitutes extreme, and the values of the weather ingredients and their variability, differs regionally. Using a gridded dataset to identify the highest 10 fire weather days from1972 to 2012, as defined by McArthur's Forest FireDanger Index (FFDI), for 24 sites acrossVictoria and nearby, we analyse the extent and variability of these highest 10 FFDI days, and of the contributing temperature, RH, wind speed, wind direction and drought indices. We document the occurrence of these events by time of day, month of occurrence and inter-annual variability. We find there is considerable variability among regions in the highest FFDI days and also the contributingweather and drought parameters, with some regional groupings apparent. Many major fire events occurred on these highest 10 fire weather days; however there are also days in which extreme fire weather occurred yet no known major fires are recorded. The results from this study will be an additional valuable resource to fire agencies in fire risk planning by basing fire management decisions on site-specific extreme fire weather conditions. [ABSTRACT FROM AUTHOR]

Quantifying reference evapotranspiration (ET) is essential in water resources management. Although, many methods have been developed with different level of accuracy, in this study, two new equations were developed and optimized for estimating ET using Honey-Bee Mating Optimization (HBMO) algorithm. The first eq. estimates ET from extraterrestrial radiation (R), relative humidity (RH) and mean daily temperature (T), while the second uses the same parameters except that mean daily temperatures is replaced with maximum daily air temperature (T). Both equations were developed using climatic data from eight weather stations in Western Australia and subsequently verified using data from ten sites across Australia. The estimated ET values from both equations versus the FAO56-Penman-Monteith have a coefficient of determination, R, of larger than 0.96. Moreover, the performance of six commonly used methods of estimating ET including Hargreaves-Samani, Thornthwaith, Hamon, Mc Guinness-Bordne, Irmak and Jensen-Haise were assessed and the Hargreaves-Samani method performed better than others. An attempt was made to calibrate the Hargreaves-Samani equation; however, its overall performance did not improved and the two newly proposed equations are suggested to be used in Australia. [ABSTRACT FROM AUTHOR]

Background:Tonsillectomy is a common procedure, with potentially life-threatening complications. Previous investigations into post-tonsillectomy secondary haemorrhage rates suggest an influence of climactic and atmospheric conditions on haemorrhage rate, particularly temperature and water vapour pressure. With a single emergency department and a large variance in atmospheric conditions, Darwin, Australia, is ideal for investigating the effects of local climate on rates of post-operative haemorrhage.Methods:A five-year retrospective review was conducted of all tonsillectomy procedures performed between 2008 and 2013. Effects of atmospheric variables were examined using Pearson's correlation coefficient and analysis of variance.Results:A total of 941 patients underwent tonsillectomy in the study period. The bleeding rate was 7.7 per cent. No variation was found between wet and dry season tonsillectomies (p = 0.4). Temperature (p = 0.74), water vapour pressure (p = 0.94) and humidity (p = 0.66) had no effect on bleeding.Conclusion:The findings revealed no correlation between humidity, season, water vapour pressure and haemorrhage rates. Further research should use multi-site data to investigate the effect of air conditioning, humidification and climactic conditions between different regions in Australia. [ABSTRACT FROM PUBLISHER]

Ignition probability of litter of dry-eucalypt forest by standard flaming and glowing firebrand samples was tested in a wind tunnel. Standard flaming firebrands were sections of bamboo sate stick 50 mm long, and flamed for ~ 9 s in still air. Standard glowing samples were sections of shed bark of Eucalyptus globulus 50 mm long, 15 mm wide and ~2 mm in thickness. These were burnt at their terminal velocities and at deposition had a mean mass of 0.2 g and would remain glowing for 2.5 min in wind. Ignition was tested using air speeds of zero, 1 and 2 m s-1, and oven-dried fuel moisture contents between 4 and 21%. For flaming samples, ignition probability was insensitive to variation in fuel and airflow characteristics and was a function of wind (no wind or wind) and fuel moisture content. For glowing samples, ignition probability was a function of fuel moisture content and wind speed. The models confirm the dominating influence of fuel moisture, are consistent with expert observations in the field and provide a practical measure of ignition likelihood by firebrands. It is argued that airflow turbulence and relative humidity are potentially significant for ignition by glowing firebrands. [ABSTRACT FROM AUTHOR]

We present a new well dated Holocene record of environmental change from Little Llangothlin Lagoon in eastern Australia derived from aquatic plant macrofossils, macroscopic charcoal flux, and sediment stratigraphy from multiple cores. Little Llangothlin was an ephemeral freshwater wetland exhibiting frequent dry phases between 9800 and 9300 calendar years before present (cal. yr BP). There was a switch to a more positive water balance after 9300 cal. yr BP, and by 8000 cal. yr BP, there was a lake that persisted until 6100 cal. yr BP. The period between 6100 and 1000 cal. yr BP was much drier, and there is no evidence for a permanent lake during this period. The Little Llangothlin record provides evidence for a wet phase during the Early to Middle Holocene (9000–6000 cal. yr BP) from the boundary region between temperate and tropical influences in eastern Australia. We propose that generally enhanced circulation after 9000 cal. yr BP explains the pattern of increasing moisture at the site at this time. The later Holocene climate at the site is consistent with other sites in south east Australia with a switch to generally drier conditions after 6000 cal. yr BP. [ABSTRACT FROM AUTHOR]

Precipitation is influenced by multiple large-scale natural processes. Many of these large-scale precipitation 'drivers' are not independent of one another, which complicates attribution. Moreover, it is unclear whether natural interannual drivers alone can explain the observed longer-term precipitation trends or account for projected precipitation changes with global warming seen in climate models. Separating the main interannual drivers from processes that may prevail on longer time scales, such as a poleward circulation shift or increased specific humidity, is essential for an improved understanding of precipitation variability and for making longer-term predictions. In this study, an objective approach to disentangle multiple sources of large-scale variability is applied to Australian precipitation. This approach uses a multivariate linear independence model, involving multiple linear regressions to produce a partial correlation matrix, which directly links variables using significance thresholds to avoid overfitting. This is applied to regional winter precipitation in Australia as a test case, using the ECMWF Interim Re-Analysis (ERA-Interim) and Australian Water Availability Project datasets. Traditional drivers and several drivers associated with the width of the tropics are assessed. The results show that the web of interactions implied by correlations can be simplified using this multivariate linear independence model approach: the total number of apparent precipitation drivers was reduced in each region studied, compared to correlations meeting the same statistical significance. Results show that the edge of the tropics directly influences regional precipitation in Australia and also has an indirect influence, through the interaction of the subtropical ridge and atmospheric blocking. These results provide observational evidence that changes associated with an expansion of the tropics reduce precipitation in subtropical Australia. [ABSTRACT FROM AUTHOR]

Thermal comfort is quantified in 15 regions using the wet-bulb globe temperature (WBGT), examining past and future rates of thresholds exceedance corresponding to moderate, high, and extreme heat (28, 32, and 35 °C, respectively). As recent changes to thermal comfort appear to be dominated by temperature and humidity, a WBGT approximation based only on these is used. A new homogenised dataset from 1973 to 2003 is developed which provides WBGT daily means, daily maximums averaged over 5-day periods, and the highest extreme for each 5-day period; recent trends are positive for all regions except northeast USA and northeast Australia. A simple model for predicting summertime threshold exceedance rates, with a fixed distribution of anomalies about the seasonal mean, is found to adequately predict changes for the above quantities given seasonal mean values. This model is used to predict the impact of regional 1-5 °C temperature increases on WBGT exceedance rates with no change in relative humidity. Results show that heat events may worsen as much, or more, in humid tropical and mid-latitude regions even if they warm less than the global average, due to greater absolute humidity increases. A further 2 °C warming from the present is sufficient to push peak WBGT above 35 °C, an extreme heat event, in all regions except the UK. An ensemble of HadCM3 climate model simulations is used to investigate likely regional changes in mean summertime temperature, relative humidity and WBGT under an A1B scenario for the 2020s and 2050s. Unsurprisingly, simulated regional changes often depart significantly from the global average, and the impact of regional changes in relative humidity is not always negligible. Increases in WBGT are nonetheless expected in all regions, and are more predictable than increases in temperature at least in mid-latitude regions owing to the compensating effects of humidity. © 2010 Royal Meteorological Society and Crown Copyright [ABSTRACT FROM AUTHOR]

A number of different methodologies are developed for examining the sensitivities of an index. These methodologies are applied to examine the characteristics of the Canadian Fire Weather Index FWI and the McArthur Forest Fire Danger Index FFDI using 8 years of gridded data throughout Australia. Percentile changes in input conditions show that the indices are similar to each other in that they are both most sensitive to wind speed, then secondly to relative humidity and thirdly to temperature. On a finer scale, a combination of the relationship between the indices and their partial derivatives shows that the FFDI is relatively less sensitive to wind speed and rainfall, and more sensitive to temperature and relative humidity, than the FWI. A method based on equilibrium values of the indices shows that the FFDI has a temperature threshold set by recent rainfall above which its sensitivity increases, resulting in some nonlinearity in its relationship with the FWI. The sensitivity differences between the indices mean that the indices are complementary in that they each respond to a somewhat different set of conditions, as is shown by examining a number of recent fire events. The fire events also reveal that index values associated with dangerous fire behaviour can vary greatly between different regions. Methods to reduce the consequences of this variation are examined, including the use of index percentiles. Copyright © 2009 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Simulations from general circulation models are now being used for a variety of studies and purposes. With up to 23 different GCMs now available, it is desirable to determine whether a specific variable from a particular model is representative of the ensemble mean, which is often assumed to indicate the likely state of that variable in the future. The answers are important for decision makers and researchers using selective model outputs for follow-on studies such as statistical downscaling, which currently assume all model outputs are simulated with equal reliability. A skill score, termed the variable convergence score (VCS), has been derived that can be used to rank variables based on the coefficient of variation of the ensemble. The key benefit is the development of a simple methodology that allows for a quantitative assessment between different hydroclimatic variables. The VCS methodology has been applied to the outputs of nine GCMs for eight different variables and two emission scenarios to provide a relative ranking of the variables averaged across Australia and over different climatic regions of the country. The methodology, however, would be applicable for any region or any variable of interest from GCMs. It was found that the surface variables with the highest scores are pressure, temperature, and humidity. Regionally in Australia, models again show the best agreement in the surface pressure projections. The tropical and southwestern temperate zones show the overall highest variable convergence when all variables are considered. The desert zone shows relatively low model agreement, particularly in the projections of precipitation and specific humidity. [ABSTRACT FROM AUTHOR]

Background and Aims: The understanding of the links between weather and wine quality is fragmented and often qualitative. This study quantified and integrated key weather variables during ripening, and their influence in red wine quality in the Hunter Valley, Margaret River, Coonawarra and Barossa Valley. Methods and Results: Long-term records of published vintage scores were used as an indicator of wine quality. A χ2 analysis was used to compare good (top 25%) versus poor (bottom 25%) vintages in relation to the frequency of defined weather conditions. Using maximum temperature as an example, better quality was associated with temperatures above 34°C throughout most of ripening in the Hunter, below 28°C in early January in the Margaret River, 28–33.9°C towards harvest in Coonawarra, and below 21.9°C in late January and early February and 28–30.9°C towards harvest in the Barossa. Conclusion: Our quantitative assessment allows for the timing and magnitude of weather influences on wine quality on a regional basis. Significance of the Study: The improved specificity of the links between weather and wine quality will help in the development of a risk analysis framework for wine quality across Australia. [ABSTRACT FROM AUTHOR]

Peronospora cristata, causing downy mildew, has become an economically important pathogen of oilseed poppy ( Papaver somniferum) since its first record in Tasmania in 1996. DOWNCAST, originally developed for downy mildew of onion, was evaluated for its ability to predict sporulation and infection of poppy by P. cristata. To assess the influence of the parameters within DOWNCAST, two modifications (POPCAST1 and POPCAST2) of the standard DOWNCAST model were also developed and tested. Initial accuracy of determination of sporulation events by DOWNCAST was 75%, while POPCAST1 (but not POPCAST2) was a significantly more accurate predictor of sporulation events (86%) than DOWNCAST (χ2 = 5.74, P = 0.025). This increase in accuracy was attributed to increasing both the rainfall threshold inhibitory to sporulation from 0.2 to 3.0 mm, and the relative humidity threshold for induction and development of sporulation from 95% to 96%. While DOWNCAST, POPCAST1 and POPCAST2 had accuracies of infection determination of 65%, 80% and 75%, respectively, chi-squared analysis indicated no significant difference between models. Preliminary field evaluation indicated that POPCAST1 and POPCAST2 were more sensitive in detecting early infection events than DOWNCAST. Field observations indicated that conditions are frequently conducive for downy mildew spread, therefore the ability to predict early season infection events would allow growers to reduce initial infection rates, and thus inoculum loads later in the season. POPCAST1 and POPCAST2 represent a significant step towards the development of a predictive model for downy mildew in poppy crops. [ABSTRACT FROM AUTHOR]

1. A strong relationship between the oxygen isotope composition (expressed as δ18O) of body water and relative humidity has been demonstrated for a number of mammalian herbivores with low drinking water requirements, including kangaroos. Consequently, it has been suggested that the oxygen isotope composition of preserved mammal remains may be used to reconstruct past relative humidity. Other physiological, environmental and ecological factors may also influence mammalian δ18O, thereby confounding the climatic signal, yet these factors have been rigorously examined in few taxa. 2. We examined sources of variation in the δ18O of tooth enamel, assumed to reflect δ18O of body water, of kangaroos ( Macropus spp.) collected throughout Australia. 3. Relative humidity explained a large proportion of the variation in enamel δ18O, a finding that is consistent with previous studies. However, we also found a previously unreported interaction between mean annual temperature and relative humidity. At lower temperatures, the relationship between enamel δ18O and relative humidity was much steeper than at higher temperatures. 4. This may be a consequence of the Peclét effect in plant leaves, whereby high transpiration rates diminish the 18O enrichment of bulk leaf water. It is likely that this interaction is also present in other herbivores with low drinking water requirements. 5. We found little evidence that δ18O varied consistently between molars, suggesting that a ‘weaning effect’ is either absent or swamped by seasonal variation in precipitation δ18O. 6. We suggest that the oxygen isotope composition of preserved kangaroo remains cannot be used to reconstruct relative humidity unless ambient air temperature can be reliably estimated. [ABSTRACT FROM AUTHOR]

A season of operational cell and track data from Darwin, Australia, has been analyzed to explore the statistical characteristics of the convective cell heights. The statistics for the monsoon and break regimes are significantly different with the break season cells being higher for a given reflectivity threshold. The monsoon cells produce more rain, but there are fewer intense cells and there is a much larger contribution from stratiform rain. The monsoon cells are also slightly larger, but shorter lived than the breaks. The shorter lifetime may reflect a more rapid transition to a longer-lived stratiform character. The monsoon regime is shown to be associated with large-scale ascent and higher humidity that may lead to more frequent, but weaker cells. Within regimes, the subset of intense cells generally reach near the tropopause or overshoot. However, there is little evidence in the data for a multimodal distribution of cell heights, except perhaps for the intense monsoon cases. Instead, the picture is a continuous distribution of cell heights with the peak of the distribution shifting to higher values as the distributions are conditioned on higher reflectivity. [ABSTRACT FROM AUTHOR]

Hygrothermal modelling is increasingly used to inform building envelope design. A key input for these calculations is the material's vapour diffusion properties. Respecting a growing international concern, this research has questioned the appropriateness of the current test method to establish construction material for vapour diffusion properties. This article reports on the empirical measurement of the vapour diffusion properties of two vapour-permeable building membranes commonly used in Australia residential systems when subjected to variable relative humidity conditions. The method involved completing dry cup and wet cup standard tests as specified in ISO 12572, (23 °C and 50% relative humidity RH). Further tests were then conducted as temperature remained at 23 °C but the relative humidity changed to 35%, 65% and 80%, respectively, in order to know if the diffusion properties are the same or change with varying relative humidity. The results from the wet cup and dry cup tests under different relative humidity conditions were non-linear and different. These results indicate vapour-permeable membranes behave differently when exposed to different relative humidity conditions. In conclusion, this research demonstrates that the current vapour resistivity test method is inadequate, hence the need to establish more detailed diffusion resistivity properties in different humidity ranges that represent conditions experienced within a building's external envelope. [ABSTRACT FROM AUTHOR]

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