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Monitoring of ambient volatile organic compounds (VOCs) was conducted within typical residential-commercial area in the city of Xi'an in northwest China during typical ozone (O3) episodes, to investigate the major contributors to the characteristic of ambient VOCs and their impact on O3 production. In the residential-commercial area, diurnal variation of VOCs was highly impacted by vehicle exhaust, fuel evaporation, and local solvent use. Relative higher contributions (up to 60%) of VOCs from solvent use to the ozone formation potential were found. The present findings highlight the urgent need for restrictions on the emission of VOCs from solvent use and non-vehicle-traffic-related sources, such as oil storage.

Flux observations are important for understanding the basic processes of carbon and water cycling in an ecosystem. In 2020 (1 January 2020 to 31 December 2020), we continuously monitored the surface energy fluxes of a shrub ecosystem using an eddy covariance system. Additionally, meteorological variables, such as temperature and rainfall, were measured. The study site was located in Chunhua of China, which is a gully region of the Chinese Loess Plateau. The diurnal and seasonal dynamic changes in the energy balance of this region were analysed, Bowen and energy balance ratios were calculated, and environmental factors affecting the variations in latent (LE) and sensible heat fluxes (H) were explored. The results showed that the annual net radiation (Rn), LE, H, and soil heat flux (G) were 2385.6, 1059.1, 787.6, and - 48.3 MJ/m2, respectively, with 490.58 MJ/m2 energy remaining undetected. The main part of the annual energy of the shrub ecosystem was latent heat, accounting for 44.4% of Rn. A seasonal variation in each energy component was evident, and the diurnal variation showed a single peak curve. LE in the growing season was dominant, and the proportion of LE and H in the net radiation in the non-growing season showed little difference. The Bowen ratio changed monthly and significantly fluctuated from 0.2 in July to 4.0 in December. It was high in winter and low in summer, with little fluctuation. The annual energy balance ratio was 0.8. The energy balance closure in the non-growing season was greater than that in the growing season. Both H and LE were significantly correlated with net radiation, and H was negatively correlated with rainfall, soil moisture, and soil temperature. Unlike H, LE was significantly positively correlated with soil temperature. In addition, LE was positively correlated with air humidity gradient and water vapour pressure difference.

This paper examines the hydration behaviour of polymer enhanced geosynthetic clay liners (GCLs) under both isothermal conditions and diurnal cyclical temperatures as recorded at a Melbourne landfill site. The diurnal temperature cycles introduced thermal gradients, which induced water movement downwards into the subgrade. It was found that the bulk of the thermal and hydraulic effects occurred within the upper 50 mm of the subgrade layer. Compared to isothermal conditions, diurnal temperature cycling's main effect was to suppress GCL hydration. Thermal gradients induced capillary breaks, and GCL hydration was thus limited to vapour phase hydration from the subgrade, which restricted the gravimetric water content of the GCLs to

Climate change is increasing the incidence of extreme weather events which have a significant impact on public health. Cardiovascular diseases (CVDs) are the number one cause of death globally (40%). Apparent temperature (AT) and diurnal temperature range (DTR) have been extensively used to evaluate the effects of temperature on cardiovascular disease (CVD). However, the relevant information is quite limited from analysis and comparison of effects and differing pathogenesis of DTR and AT on CVD especially in less-developed, rural areas of China. This is the first attempt to analyze different effects between AT and DTR on CVD using distributed lag nonlinear modeling (DLNM) in rural area. Data on CVD hospital admission in Qingyang (Northwest China) in 2014-2017 originated from the New Rural Cooperative Medical System (NRCMS) of Gansu Province, and meteorological variables were provided by the Meteorological Science Data Sharing Service. Both AT and DTR had significant nonlinear and delayed impacts on hospital admissions for CVD. DTR had a stronger and more persistent effect on CVD incidence than AT. Females were more affected by high AT and low DTR than were males, while males were more vulnerable to low AT and high DTR. Temperature effects were not significantly different between people above and below 65 years of age. These findings provide local public health authorities with reference concerning sensitive temperature indices for susceptible populations with a view to improve CVD preventive strategies in rural areas.

There are significant differences in the way that researchers have defined “Etesian wind days”. An attempt is made here to establish common definitions of the various types of Etesian winds from the weather forecaster’s viewpoint. These definitions are based on objective criteria adopted from the frequency of atmospheric circulation features associated with the occurrence of the Etesian winds and their physical characteristics. The presence of fairly constant northerly winds over the Greek Seas in summer are called Etesian winds. When a new spell of Etesian winds is established with no diurnal variation of the wind direction for consecutive days (maximum of seven), these winds are called “type B” Etesian winds or “Etesian outbursts”. The atmospheric circulations associated with the occurrence, origin and evolution of the type B Etesian winds and the accompanying weather are revealed utilizing data for the period 1975-2015 and focusing on two case studies on July 21-22, 1983 and July 3-4, 2017. The presence of the Subtropical Jet Stream (SJS) over the Greek territory and its interaction with the Polar Jet Stream (PJS) are dominant factors. Large-scale atmospheric circulations are studied to identify simultaneous direct links to the Indian Summer Monsoon (ISM), El Niño-Southern Oscillation (ENSO), Madden-Julian Oscillation (JMO), deep convective activity in the Hadley circulation in the tropics, and West Africa Monsoon (WAM)

This study examined the effect of time of day (TOD) on physical performance, and physiological and perceptual responses to a 10-km cycling time trial (TT

The cerebral pressure-flow relationship has directional sensitivity, meaning the augmentation in cerebral blood flow is attenuated when mean arterial pressure (MAP) increases vs MAP decreases. We employed repeated squat-stands (RSS) to quantify it using a novel metric. However, its within-day reproducibility and the impacts of diurnal variation and biological sex are unknown. Study aims were to evaluate this metric for: 1) within-day reproducibility and diurnal variation in middle (MCA; ∆MCAvT/∆MAPT) and posterior cerebral arteries (PCA; ∆PCAvT/∆MAPT); 2) sex differences. ∆MCAvT/∆MAPT and ∆PCAvT/∆MAPT were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv or PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Relative metric values were also calculated (%MCAvT/%MAPT, %PCAvT/%MAPT). Intraclass correlation coefficient (ICC) evaluated reproducibility, which was good (0.75-0.90) to excellent (>0.90). Time-of-day impacted ∆MCAvT/∆MAPT (0.05 Hz: p = 0.002; 0.10 Hz: p = 0.001), %MCAvT/%MAPT (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.009), and ∆PCAvT/∆MAPT (0.05 Hz: p = 0.024), albeit with small/negligible effect sizes. MAP direction impacted both arteries' metric at 0.10 Hz (all p < 0.024). Sex differences in the MCA only (p = 0.003) vanished when reported in relative terms. These findings demonstrate this metric is reproducible throughout the day in the MCA and PCA and is not impacted by biological sex.

The present study focuses on the investigation of both near-surface and vertical variability of carbon monoxide (CO) concentrations and their potential sources obtained from both in situ and satellite Measurements of Pollution in the Troposphere (MOPITT) over a semiarid region (Anantapur, India) from January 2016 to December 2017. The diurnal variation of CO shows sharp morning (07:00-09:00 LT) and evening (07:00-09:00 LT) peaks associated to local anthropogenic activities as well as the impact of the mixed layer height, and low concentrations during daytime (12:00-15:00 LT). The low levels during afternoon hours may be due to the increase of the mixed layer height and the decrease of anthropogenic sources. The seasonal mean CO showed no obvious variation, with highest levels observed in winter (329 ± 52 ppbv), followed by the pre-monsoon (327 ± 57 ppbv), post-monsoon (234 ± 36 ppbv) and monsoon (192 ± 22 ppbv). The high levels of CO during the winter are attributed to increased emissions from anthropogenic sources and a shallow mixed layer height. The vertical distribution of CO showed secondary peaks at high-pressure levels (300-200 hPa) during winter, pre-monsoon, and post-monsoon, which indicates CO transport from different source regions. These findings are reasonably confirmed through the air mass Concentrated Weighted Trajectory (CWT) analysis obtained from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. This study suggests that except for the monsoon, air masses transported from Indo-Gangetic Basin region also contribute to the enhancement of CO concentrations at the receptor site

Recent studies reported that the diurnal variation of the geomagnetic field exhibited anomalous characteristics several months before earthquakes (EQs). However, the statistical significance of such anomalies detected using the diurnal variation range ratio (DVRR) method still requires verification as only a limited number of EQs occurring in certain seismoactive zones were included. In this study, the DVRR method was employed in conjunction with the superposed epoch analysis (SEA) to perform a large-scale study. A total of 157 EQs that occurred between 2000 and 2019 were investigated using vast geomagnetic field data collected from 92 ground-based magnetometer stations spread across multiple global regions. The case study conducted on the May 13, 2011, M6.1 Honshu (Japan) EQ showed that the diurnal variation of the vertical geomagnetic component disappeared around a week before the EQ. The case study also demonstrated the effectiveness of the DVRR method in minimizing solar disturbance influences, further proving that the observed anomalies were not caused by the Sun. The subsequent SEA revealed statistically significant increases in anomaly counts before the occurrence of EQs for all three geomagnetic components. The number of anomalies gradually increased approaching the day of EQs with temporal lags between the components. Furthermore, a control group analysis confirmed the findings by demonstrating that the increases were not coincidental and several explanations have been suggested, focusing primarily on the emergence and generation mechanisms of the anomalies. Results from this study showed that the anomalies were significant and were potentially precursors to the succeeding EQs.

Background Dysregulation of the circadian rhythm is linked to immune response deficiencies. Diurnal temperature variation—a surrogate for the circadian rhythm, exists in humans, yet its preservation during illness is not well understood. Materials and Methods Temperatures measured within one-half hour of 8 am , 12 pm , 4 pm , 8 pm , 12 am , and 4 am from 16,245 hospitalized patients were statistically analyzed. Results Although we found a diurnal pattern when analyzing the ensemble of temperatures from all patients, stratified by measurement site, the trough-to-peak difference was only 0.2°F, while that for healthy volunteers had been in the 0.5°F to 1.9°F range. The peaks occurred at 8 pm for all patients, regardless of age or sex, which is similar to healthy people. However, the troughs were shifted to later times compared with the 6 am in healthy people–for young patients (age 20-30 years) the trough was at 8 am and for elderly patients (age 70-80 years), at 12 pm , again regardless of patients’ sex. Analysis of individual patients showed that less than 20% of patients exhibited diurnal variation and among those showing variation, the trend was present only on the minority of hospitalization days. The presence or absence of an infectious process or fever did not influence the proportion of patients showing diurnal variation. Conclusions Hospitalization is associated with disruption in the circadian rhythm as reflected by patients’ body temperature. Since abnormality in body temperature is known to affect patient outcomes, an understanding of the diurnal cycle during hospitalization is the first step towards devising approaches to re-establish the circadian rhythm.

The planetary boundary layer (PBL) height (PBLH) is a key physical parameter of the PBL affected by numerous physical processes within the boundary layer. Specifically, the PBLH over land exhibits large spatial and temporal variation across different geographical regions. In this study, the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) radio occultation (RO) profiles and high-resolution radiosonde profiles from 2007 to 2013 were analyzed to estimate the diurnal cycle of the PBLH over the Southern Great Plains (SGP) in the United States. Large variations in PBLH derived from radiosonde temperature, moisture, and refractivity are observed on seasonal scales. COSMIC RO is capable of observing diurnal and seasonal variations in the terrestrial PBLH over the SGP region. Annual mean diurnal amplitude of approximately 250 m in the terrestrial PBLH was observed, with maxima occurring at around 1500 local solar time (LST) in both the collocated radiosondes and COSMIC RO profiles. Seasonal changes in the PBLH diurnal cycles ranging from approximately 100 to 400 m were also observed. Such PBL diurnal and seasonal changes can be further incorporated into PBL parameterizations to help improve weather and climate model prediction. Significance Statement The atmospheric planetary boundary layer (PBL) and its height (PBLH) control many atmospheric processes that affect our everyday lives. Observations of the PBL are usually limited to radiosondes at limited time intervals. GNSS radio occultation (RO) provide high-vertical-resolution atmospheric observations that are ideal for PBL study. This study demonstrates that the GNSS RO is capable of capturing the diurnal and seasonal variations of the PBLH over the southern Great Plains (SGP) well as compared to the collocated radiosonde observations.

The complexity of estuaries allows for the establishment of diverse communities composed of species with different survival strategies. The vertical migration of animals in the sediment is linked to competition, escape from predators and adaptations to diurnal physio-chemical changes related to variations in water levels. The present study aimed to evaluate niche overlap and amplitude, as well as the composition and structure, of communities of polychaetes and molluscs between sediment aliquots during the day and at night. Data sampling was performed in the Tubarão River estuary. The highest individual occurrence was registered during the diurnal period. Communities of polychaetes varied significantly between sediment aliquots during the day and at night, while molluscs did not show diurnal variation. Niche overlap results for polychaetes showed higher values between aliquots during the night, while molluscs showed greater overlap during the day. This indicates that polychaetes and molluscs have different mechanisms of coexistence. This may be related to different attributes of species allowing for the division of resources among individuals. Examination of niche overlap provides insights into coexistence of mechanisms within benthic macroinvertebrate communities.

Background Recent studies have suggested that neuropathic pain exhibits a daily diurnal pattern, with peak levels usually occurring in the late afternoon to evening and the trough in the morning hours, although literature on this topic has been sparse. This scoping review examines current evidence on the chronobiology of neuropathic pain both in animal models and in humans with neuropathic pain. Methods A literature search was conducted in major medical databases for relevant articles on the chronobiology of neuropathic pain both in animal models and in humans with neuropathic pain. Data extracted included details of specific animal models or specific neuropathic pain conditions in humans, methods and timing of assessing pain severity, and specific findings of diurnal variation in pain intensity or its surrogate markers. Results Thirteen animal and eight human studies published between 1976 and 2020 were included in the analysis. Seven of the 13 animal studies reported specific diurnal variation in pain intensity, with five of the seven studies reporting a trend toward increased sensitivity to mechanical allodynia or thermal hyperalgesia in the late light to dark phase. All eight studies in human subjects reported a diurnal variation in the intensity of neuropathic pain, where there was an increase in pain intensity through the day with peaks in the late evening and early night hours. Conclusions Studies included in this review demonstrated a diurnal variation in the pattern of neuropathic pain that is distinct from the pattern for nociceptive pain. These findings have implications for potential therapeutic strategies for neuropathic pain.

Climate change leads to a more frequent occurrence of hot days (HDs) and hot nights (HNs). The consecutive occurrence of HDs and HNs (COHs) is often used as a measure of the persistence of an extremely hot spell. Nonetheless, the combined effect of air temperature and relative humidity on the changing COHs has never been studied. In this paper, we use an ensemble of global climate models and multiple thermal indices to robustly examine the combined effect of air temperature and relative humidity on COHs globally on an hourly basis. Our findings reveal that COHs show an increasing trend in the future and a strong latitudinal gradient increasing from high latitudes to the equator. Compared to COHs based on air temperature, the frequency of COHs based on perceived temperature is amplified by the combined effects of high temperature and humidity for both boreal and austral summers. To investigate the underlying mechanisms, we examine two different diurnal temperature ranges (DTRs), derived from air temperature and perceived temperature, for their corresponding types of COHs. Both DTRs are projected to increase in the future relative to the historical period from 1980 to 2004, but the DTR changes derived from perceived temperature are consistently larger than those derived from air temperature. Due to the nonlinearity in thermal indices, the perceived temperature in HDs and HNs rising faster than air temperature leads to a larger increase in perceived COHs. The COHs are further amplified by the increasing number of HNs and HDs that occur consecutively under wet conditions.

BackgroundThe transition to pulmonary respiration and the termination of foetal cardiovascular shunts is expected to commence immediately after birth. Subsequently, alveolar ventilation and tissue perfusion must be established, despite the challenge of extra-uterine environmental conditions, which could be quite demanding, even to the adult animals. The current study evaluated neonatal adjustment and diurnally induced changes in respiratory and pulse rates in kids of Red Sokoto, Sahel and West African Dwarf (WAD) goats in a tropical climate.ResultsMorning and afternoon respiratory rates started decreasing (P P P P P P P ConclusionIt was concluded that the afternoon rise in ambient temperature induced the establishment of a clear diurnal variation in respiratory rate 24 h postnatal, while the diurnal variation in pulse rate was weak and irregular. The tropical climate may be quite challenging to the attainment of physiological stability in respiratory and cardiovascular functions of neonatal goat kids, especially during the hot season.

Interpreting the similarities and dissimilarities in spatiotemporal variations and various controls between surface and canopy urban heat islands (UHIs) is critical for a better understanding of their vertical structure. Preceding comparisons of the surface UHI (SUHI) and canopy UHI (CUHI), however, remain mostly restricted either in a single city or over a few cities within limited background climates; therefore, the associated similarities and dissimilarities between the SUHI and CUHI under different climates, especially at a global scale, remain largely unknown. Based on both satellite and in situ data, we simultaneously investigated the spatiotemporal patterns of the SUHI intensity (SUHII) and CUHI intensity (SUHII) of 366 global cities within various background climates. We further investigated the different impacts of several controls (e.g., vegetation coverage, population size, precipitation) on SUHII and CUHII. Our results indicate the following: (1) For the selected 366 cities, the annual mean SUHII is higher than CUHII by 1.1 ± 1.9 °C (mean ± Std) during the day and 0.3 ± 1.5 °C (mean ± Std) at night. The SUHII and CUHII in the equatorial, warm temperate, and snow climates are generally consistent with the above characteristics (i.e., SUHII > CUHII), however, in arid regions SUHII is lower than CUHII by 0.8 °C during the day. (2) The annual mean day–night difference in SUHII is positive (i.e., 0.6 ± 1.8 °C (mean ± Std)), while the difference in CUHII becomes negative (i.e., −0.2 ± 1.6 °C (mean ± Std)), indicating that urbanization increases the diurnal temperature range (DTR) based on land surface temperature, but it decreases the DTR based on surface air temperature. (3) Despite the high correlation between vegetation coverage and impervious surface percentage (ISP), their impacts on SUHII and CUHII were not consistent. The urban–rural difference in ISP exerts an insignificant impact on both SUHII and CUHII during the day and a greater impact on CUHII than on SUHII at night, whereas the urban–rural difference in vegetation coverage has a greater impact on SUHII than on CUHII during the day, while the opposite occurs at night. The impacts of population size on SUHII and CUHII are much greater during the night than on the day in which their impacts can be minimal. The relationship between annual mean precipitation and SUHII is positive during the day but negative at night, while for CUHII, their relationship is insignificantly negative both during the day and at night. These results can improve our understanding of the spatiotemporal patterns and controls of these two types of UHIs under various climates.

The biophysical effects of vegetation changes are important in determining future climate changes using climate model. However, compared to observations, model has biases in energy exchange between vegetation and the lower atmosphere modulated by leaf area index and albedo. In this study, land-use induced anthropogenic influences, estimated as the differences between present land-use and idealized natural vegetation, on near-surface temperature were investigated using a regional climate model. Results show that present land-use transitions over China brings a cooler summer and winter accompanied by reduced diurnal temperature ranges by 0.11 °C and 0.25 °C respectively, which are mainly determined by the overwhelming increased evaporation and latent heat flux in summer and reduced net radiation in winter. Three vegetation pairs (i.e., forest and cropland, grassland and cropland, grassland and forest) were selected using observational datasets to evaluate vegetation induced climatic impact without atmospheric feedbacks across various climatic regimes. Albedo led absorbed radiation plays a dominate role in middle to north region while both LAI and albedo are significant below 30° N for latitudinal temperature changes between cropland and forest transitions. Model results have inconsistencies with observations on temperature trends caused by vegetation pairs, indicating summer cropland and forest over southern China is the most sensitive to the atmosphere conditions and forest and grassland pair is the least. These findings demonstrate the heterogeneous biophysical effect of vegetation in different climate zones and imply that a region-oriented parameterization of vegetation types should be applied in the land surface model to reduce uncertainties in future climate prediction.

The rise in the frequency and magnitude of extreme temperature phenomena across the globe has led to the recurrent incidence of global climate hazards, which have had severe effects on socioeconomic development. The daily maximum and minimum temperature datasets of 27 sites in Bangladesh were used to detect spatiotemporal trends of temperature extremes over Bangladesh during 1980–2017 based on ten temperature extreme indices using multi-statistical modeling namely linear regression, Pearson correlation coefficient, and factor analyses. Besides, mutation analyses based on the Mann-Kendall test, Sen’s slope estimator, and Pettit test were employed to show the changing trend in extreme temperature. Results show that except for warmest days, the warm indices showed an increasing trend, mainly since the 2000s, while the growth rate was faster, and the response to global climate warming was sensitive. The cold indices were demonstrated a reverse trend since the 2010s. Diurnal temperature range (DTR) and summer days (SU) increased faster, implying that the rising speed of daily max temperature was higher than of daily min-temperature in Bangladesh. The de-trended fluctuation analysis (DFA) revealed a continuous increase in temperature extreme in the future except for cold days. The probability distribution functions (PDF) analysis revealed an evident variation of the curves in recent decades compared to the past three decades. Besides the warm night, DTR and SU primarily control the general warming trend of temperature extremes over Bangladesh during the study period. The mutation of the warm indices occurred before the cold index, indicating that the warm indices were more sensitive to global climate warming. The temperature extremes recognized in our research suggest that elevated warm temperature extremes due to global climate warming may have huge implications on the sustainable development of Bangladesh in the forthcoming period.

False negative tests for SARS-CoV-2 are common and have important public health and medical implications. We tested the hypothesis of diurnal variation in viral shedding by assessing the proportion of positive versus negative SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) tests and cycle time (Ct) values among positive samples by the time of day. Among 86,342 clinical tests performed among symptomatic and asymptomatic patients in a regional health care network in the southeastern United States from March to August 2020, we found evidence for diurnal variation in the proportion of positive SARS-CoV-2 tests, with a peak around 1400 h and 1.7-fold variation over the day after adjustment for age, sex, race, testing location, month, and day of week and lower Ct values during the day for positive samples. These findings have important implications for public health testing and vaccination strategies.

Under the variant climate conditions in the transitional regions between tropics and subtropics, the impacts of climate factors on influenza subtypes have rarely been evaluated. With the available influenza A (Flu-A) and influenza B (Flu-B) outbreak data in Shenzhen, China, which is an excellent example of a transitional marine climate, the associations of multiple climate variables with these outbreaks were explored in this study. Daily laboratory-confirmed influenza virus and climate data were collected from 2009 to 2015. Potential impacts of daily mean/maximum/minimum temperatures (T/Tmax/Tmin), relative humidity (RH), wind velocity (V), and diurnal temperature range (DTR) were analyzed using the distributed lag nonlinear model (DLNM) and generalized additive model (GAM). Under its local climate partitions, Flu-A mainly prevailed in summer months (May to June), and a second peak appeared in early winter (December to January). Flu-B outbreaks usually occurred in transitional seasons, especially in autumn. Although low temperature caused an instant increase in both Flu-A and Flu-B risks, its effect could persist for up to 10 days for Flu-B and peak at 17 C (relative risk (RR) = 14.16, 95% CI: 7.46–26.88). For both subtypes, moderate–high temperature (28 C) had a significant but delayed effect on influenza, especially for Flu-A (RR = 26.20, 95% CI: 13.22–51.20). The Flu-A virus was sensitive to RH higher than 76%, while higher Flu-B risks were observed at both low ( 83%) humidity. Flu-A was active for a short term after exposure to large DTR (e.g., DTR = 10 C, RR = 12.45, 95% CI: 6.50–23.87), whereas Flu-B mainly circulated under stable temperatures. Although the overall wind speed in Shenzhen was low, moderate wind (2–3 m/s) was found to favor the outbreaks of both subtypes. This study revealed the thresholds of various climatic variables promoting influenza outbreaks, as well as the distinctions between the flu subtypes. These data can be helpful in predicting seasonal influenza outbreaks and minimizing the impacts, based on integrated forecast systems coupled with short-term climate models. Supplementary Information The online version contains supplementary material available at 10.1007/s00484-021-02204-y.

The NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension (WACCM-X) v2.1 has been extended to include the neutral and ion–molecule chemistry and dynamics of three metals (Mg, Na, and Fe), which are injected into the upper mesosphere–lower thermosphere by meteoric ablation. Here we focus on the self-consistent electrodynamical transport of metallic ions in both the E and F regions. The model with full ion transport significantly improves the simulation of global distribution and seasonal variations of Mg+, although the peak density is slightly lower (about 35 % lower in peak density) compared with the SCIAMACHY measurements. Near the magnetic equator, the diurnal variation in upward and downward transport of Mg+ is generally consistent with the “ionosphere fountain effect”. The thermospheric distribution of Fe is shown to be closely coupled to the transport of Fe+. The effect of ion mass on ion transport is also examined: the lighter ions (Mg+ and Na+) are transported above 150 km more easily than the heavy Fe+. We also examine the impact of the transport of major molecular ions, NO+ and O2+, on the distribution of metallic ions.

This article presents the Schumann resonance (SR) variations, obtained in the extreme low frequency (ELF) signal observatory of Sierra de Filabres belonging to the University of Almeria Spain, in operation since 2011. This station has two large and sensitive orthogonal sensors operating between 1 and 100 Hz. A 24 bit low-noise, high-resolution system processes the signal. The Sierra de Filabres ELF station is operating to offer valuable information on SRs’ activity in this area. This system allows us to have a broader range of comparison patterns to study correlations with other phenomena. The information presented in this work deals with the diurnal and seasonal variations of the first six modes of the SRs in 2016 and 2017. The graphs have been obtained through Lorentzian functions. We explain the diurnal variation based on the position and distance to the most important lightning hotspots and demonstrate its relation with the first mode captured in our observatory. We introduce a new yearly evolution method based on the resonance frequency through the most representative lightning activity hours in one year. This article is supported by the comparison between our signals and the global thunderstorm center’s activity.

Temperature has been studied in relation to many health outcomes. However, few studies have explored its effect on the risk of hospital admission for rheumatoid arthritis (RA). A distributed lag non-linear model (DLNM) was used to analyze associations between mean temperature, diurnal temperature range (DTR), temperature change between neighboring days (TCN), and daily admissions for RA from 2015 to 2019 in Anqing, China. Subgroup analyses based on age, gender, rheumatoid factors, and admission route were performed. In total, 1456 patients with RA were hospitalized. Regarding the cumulative-lag effects of extreme cold temperature (5th percentile = 3℃), the risks of admissions for RA were increased and highest at lag 0–11 (RR = 2.68, 95% CI: 1.23–5.86). Exposing to low (5th percentile = 1.9℃) and high (95th percentile = 14.2℃) DTRs both had increased risks of RA admission, with highest RRs of 1.40 (95% CI: 1.03–1.91) and 1.24 (95% CI: 1.0–1.53) at lag 0 day, respectively. As for TCN, the marginal risk of admission in RA patients was found when exposed to high TCN (95th percentile = 2.9℃) with the largest single-day effect at lag 10 (RR = 1.11, 95% CI: 1.01–1.23). In subgroup analyses, females were more susceptible to extreme cold temperature, low and high DTRs, and high TCN. In regard to extreme cold temperature, significant risk of hospital admission in females only appeared at lag 2 (RR = 1.48, 95% CI: 1.02–2.15) and lag 0–2 (RR = 2.35, 95% CI: 1.11–4.95). It is clear that RA patients exposed to changing temperature may increase risks of admission. Supplementary Information The online version contains supplementary material available at 10.1007/s00484-021-02207-9.

This study examined the characteristics of the diurnal variations of heavy rainfall (⩾110 mm in 12 hours) in Korea and the related atmospheric circulation for July from 1980–2020. During the analysis period, two dominant pattens of diurnal variation of the heavy rainfall emerged: all-day heavy rainfall (AD) and morning only heavy rainfall (MO) types. For the AD-type, the heavy rainfall is caused by abundant moisture content in conjunction with active convection in the morning (0000–1200, LST; LST = UTC + 9) and the afternoon hours (1200–2400 LST). These systems are related to the enhanced moisture inflow and upward motion induced by the strengthening of the western North Pacific subtropical high and upper-tropospheric jet. For the MO-type, heavy rainfall occurs mostly in the morning hours; the associated atmospheric patterns are similar to the climatology. We find that the atmospheric pattern related to severe heavy rainfalls in 2020 corresponds to a typical AD-type and resembles the 1991 heavy-rainfall system in its overall synoptic/mesoscale circulations. The present results imply that extremely heavy rainfall episodes in Korea during the 2020 summer may occur again in the future associated with the recurring atmospheric phenomenon related to the heavy rainfall.

Differences in vertical and horizontal structures of the atmospheric wind circulation and its diurnal variation between wet and dry spells over West Africa are studied. CHIRPS products are used to detect the wet and dry spells and Era-Interim reanalysis data to characterize the synoptic conditions during wet and dry spells. The analysis of the zonal wind shows a stronger monsoon flux over the Northern Sahel and the Guinea region during wet spells than that during dry spells, which coincides with a weaker (stronger) and northward (southward) displaced African easterly jet (AEJ) during wet (dry) spells. This strengthening of the monsoon is consistent with the intensification of the Saharan heat low (SHL) observed during wet spells. The vertical velocity analysis also shows an intensification of the southern updraft core associated with deep convection during wet spells than during dry spells. At higher levels, the TEJ intensity is stronger (weaker) during wet (dry) spells. The analysis also showed that the activity of the African easterly waves (AEWs) and the relative humidity are stronger during wet spells than those during dry spells, suggesting that the monsoon flux brings enough moisture to promote the convective activity during wet sequences. This finding is consistent with the weakening of the low-level geopotential height during wet spells over the Sahel region. The diurnal variation analysis shows that the monsoon flux magnitude strongly intensifies during the nighttime and reaches its maximum value at 06:00 during both spells. When considering the difference between the spells, the monsoon flow is stronger (weaker) over the Gulf of Guinea and the Northern Sahel for all synoptic hours during wet (dry) spells. At mid-levels, the AEJ strongly decreases over the Sahel region at 18:00 and 00:00 in both spells. This jet is stronger and southward during dry spells. As for the TEJ, its intensity increases during nighttime and reaches its maximum at 00:00 during both periods. However, the upper levels’ jet magnitude is stronger during wet spells than that during dry spells, especially at 00:00 and 12:00. The analysis of the activity of 3–5-day AEWs shows a more vigorous activity over the Western Sahel at 00:00 during both spells, especially during wet spells.

The seasonal and diurnal variations of cloud systems are profoundly affected by the large-scale and local environments. In this study, a one-year-long simulation was conducted using a two-dimensional cloud-resolving model over the Eastern Tibetan Plateau (ETP) and two subregions of Eastern China: Southern East China and Central East China. Deep convective clouds (DCCs) rarely occur in the cold season over ETP, whereas DCCs appear in Eastern China throughout the year, and the ETP DCCs are approximately 20%–30% shallower than those over Eastern China. Most strong rainfall events (precipitation intensity, PI> 2.5 mm h−1) in Eastern China are related to warm-season DCCs with ice cloud processes. Because of the high elevation of the ETP, the warm-season freezing level is lower than in Eastern China, providing favorable conditions for ice cloud processes. DCCs are responsible for the diurnal variations of warm-season rainfall in all three regions. Warm-season DCCs over the ETP have the greatest total cloud water content and frequency in the afternoon, resulting in an afternoon rainfall peak. In addition, rainfall events in the ETP also exhibit a nocturnal peak in spring, summer, and autumn due to DCCs. Strong surface heat fluxes around noon can trigger or promote DCCs in spring, summer, and autumn over the ETP but produce only cumulus clouds in winter due to the cold and dry environment.

The headwater region of the upper Blue Nile is the main source of the Nile water for the three Eastern Nile countries, namely Ethiopia, Sudan, and Egypt. Climate-related studies for the region is thus paramount. However, previous studies for the region used non-homogenous data, and did not remove all the significant autocorrelations in trend analysis. Therefore, this study analyzed the trend using gap-filled and homogenized meteorological data over the period 1980 − 2017. Using the non-parametric Mann–Kendall test adjusted by effective sample size, the influence of all significant positive and negative autocorrelations on the trend was removed. Sen’s slope was used to determine the magnitude of trends. The tests were applied to minimum and maximum temperatures, mean temperature, diurnal temperature range (DTR), and total precipitation as well as seasonal and annual extreme climate indices. In general, the climate in the study region has become wetter and warmer. As for extreme temperature, the hot ends of the daily temperature distribution have altered more rapidly than the cold ends. Accordingly, the DTR exhibited a consistent increasing trend across the stations. The rainfall showed increases in maximum 1 − day precipitation amount, maximum 5 − day precipitation amount, number of heavy precipitation days, total annual rainfall, and extremely wet days. As trend magnitudes of the homogenized series differed from those of the original series, the results that emerged from the previous hydroclimate-related studies for the region using non-homogenized data should be revised. This study has significant implications for water use efficiency and adaptation to climate risk in the three riparian countries, given the recently commenced water resources projects.

This study presents the SALBEC – Soil ALBEdo Calculator – a Python library and Graphical User Interface designed to predict the diurnal variation of the clear-sky albedo based on the soil surface properties. Such predictions are becoming more and more necessary with the increasing role of remote measurements. The software uses the following input parameters: the soil spectrum, soil roughness, day of the year (DOY) and sample location. It returns the diurnal albedo variation and, as a unique feature, optimal observation time in the form of tables and graphs as outputs. Models created with the SALBEC were compared with the data acquired under near clear-sky conditions. The comparison shows that the differences between the models and measured data do not exceed the variation of input parameters. The software is directed towards scientists and professionals who require precise estimations of the albedo of soils for different field observation times. Our software is issued as free and open source software (FOSS) and is publicly available at https://github.com/jarekj71/salbec.

Introduction Diurnal variations in physical performance can affect athletes' success in competitive sports depending on whether the time of peak performance concurs with the time of competition. The purpose of this systematic review was to investigate the diurnal variation in maximum endurance and strength performance. Methods The databases PubMed, EMBASE, and Web-of-Science were searched from inception to November 2020. The search string was externally reviewed according to PRESS guidelines, the review was conducted in accordance to PRISMA guidelines, and registered beforehand on PROSPERO. Eligibility criteria were that [1] the studies included humans, [2] any kind of maximum endurance or maximum strength test was performed at [3] a minimum of three different times of the day. There were no restrictions regarding study design, participants' sex, age or fitness levels. Results From 10,460 screened articles 63 articles met all three inclusion criteria. Meta-analysis on the harmonizable 29 studies provided evidence for diurnal variations in physical performance. In detail, the overall effect sizes (95% confidence intervals) were 0.23 (0.05; 0.40), 0.73 (0.37; 1.09), 0.39 (0.18; 0.60), and 0.79 (0.28, 1.30) for endurance exercise tests, maximum power output in Wingate-test, handgrip strength, and jump height all in favor of higher performance in the evening. The overall risk of bias in individual studies was moderately high. Conclusions There is strong evidence that anaerobic power as well as jump height are maximal between 13:00 and 19:00. There is some evidence that handgrip strength peaks between 13:00 and 21:00, but only little evidence that there is a time of peak performance in maximum endurance.

Along with climate change, unstable weather patterns are becoming more frequent. However, the temporal trend associated with the effect of temperature variation on schizophrenia (SCZ) is not clear. Daily time-series data on SCZ and meteorological factors for 15-year between January 1, 2005 and December 31, 2019 were collected. And we used the Poisson regression model combined with the time-varying distribution lag nonlinear model (DLNM) to explore the temporal trend of the association between three temperature variation indicators (diurnal temperature range, DTR; temperature variability, TV; temperature change between neighboring days, TCN) and SCZ hospitalizations, respectively. Meanwhile, we also explore the temporal trend of the interaction between temperature and temperature variation. Stratified analyses were performed in different gender, age, and season. Across the whole population, we found a decreasing trend in the risk of SCZ hospitalizations associated with high DTR (from 1.721 to 1.029), TCN (from 1.642 to 1.066), and TV (TV0-1, from 1.034 to 0.994; TV0-2, from 1.041 to 0.994, TV0-3, from 1.044 to 0.992, TV0-4, from 1.049 to 0.992, TV0-5, from 1.055 to 0.993, TV0-6, from 1.059 to 0.991, TV0-7, from 1.059 to 0.990), but an increasing trend in low DTR (from 0.589 to 0.752). Subgroup analysis results further revealed different susceptible groups. Besides, the interactive effect suggests that temperature variation may cause greater harm under low-temperature conditions. There was a synergy between TCN and temperature on the addition and multiplication scales, which were 1.068 (1.007, 1.133) and 0.067 (0.009, 0.122), respectively. Our findings highlight public health interventions to mitigate temperature variation effects needed to focus not only on high temperature variations but also moderately low temperature variations. Future hospitalizations for SCZ associated with temperature variation may be more severely affected by temperature variability from low temperature environments. The temporal trend is associated with the effect of temperature variation on schizophrenia (SCZ).

Iran is a semi-arid and arid country in Western Asia and is exposed to numerous local and trans-regional dust systems due to its location in the global dust belt. The present study sought to investigate the change-point detection (CPD) and trend of the number of dusty hours (NDH) in Iran over a long-term period (1980–2015). The station dust frequency (SDF) of 81 synoptic stations was first hourly obtained and then processed. Furthermore, the dust aerosol optical depth (DOD) was obtained hourly from the Monitoring Atmospheric Composition and Climate (MACC). The results indicated the maximum dust frequency with 21.28 days at 12 GMT due to surface heating and the occurrence of local dry instabilities. The minimum dust also occurred with 7.76 days at 00 GMT in Iran. SDF and DOD had a direct relationship, but they had inverse significant relationships with altitude and latitude in Iran. The maximum average trend of the whole of Iran at 21 GMT with a value of Z 1.83 was significant at a 90% level, indicating an increase in nocturnal dust in Iran. The southwest of Iran, especially Bostan, Omidiyeh, and Masjed-Soleyman stations, had maximum numbers of dusty days so that NDHs of Omidiyeh station were increasing at 18 GMT (2.84 years−1 days). The year 2000 was, on area-averaged, the dust CPD in the across Iran, but 2007 and 2008 were the most frequent CPD of NDHs. None of the hours had lower amounts of dust after the CPD than before the CPD, indicating a significant increase in the dust of Iran.

Satellite retrieval-based precipitation data with high spatial and temporal resolutions give an opportunity for precipitation research in regions with coarse networks of precipitation measuring instruments. This study evaluates the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) data in Bangladesh and surrounding regions and then examines the diurnal variation of precipitation in these regions using the cyclostationary empirical orthogonal function (CSEOF) analysis method. The IMERG data capture the overall patterns of the diurnal variation of precipitation well, except for the overestimation of the degree of diurnal variability in the pre-monsoon season. The spatial distribution of precipitation is also captured well, except for the drastic horizontal change in precipitation within the northeastern region of Bangladesh. These encourage the use of the IMERG data for studying precipitation characteristics in Bangladesh and surrounding regions. Through the CSEOF analysis, the pre-monsoonal precipitation is characterized by the enhanced precipitation in the northern region of Bangladesh and the Meghalaya Plateau region in the late night to early morning. The monsoonal precipitation consists of two contrasting CSEOF modes. One shows enhanced precipitation in the northern region of the Bay of Bengal during 0600–1500 LST, related to the strong westerly moisture transport over the Bay of Bengal. The other shows enhanced precipitation in the southern slopes of the Meghalaya Plateau and Himalayan Foothills during 0000–0600 LST, associated with the strong southwesterly moisture transport toward these slopes that is neither blocked nor deflected by the Arakan Mountains.

The effects of daily mean temperature on health outcomes have been discussed in many previous studies, but few have considered the adverse impacts due to variance of temperature in one day. Diurnal temperature range (DTR) was a novel indicator calculated as maximum temperature minus minimum temperature in the same day. In this study, generalized additive model (GAM) with quasi-Poisson distribution was used to investigate the association between DTR and the number of daily outpatient visits for upper respiratory tract infection (URTI) among college students. Data about meteorological factors and air pollutants were provided by Hubei Meteorological Bureau and Wuhan Environmental Protection Bureau, respectively. Outpatient visits data were provided by the Hospital of Wuhan University from January 1, 2016 to November 31, 2018. Short-term exposure to DTR was associated with the increased risk of outpatient for URTI among all college students. Per 1 ℃ increased in DTR was associated with 0.89% (95%CI: 0.40, 1.38) increased in outpatient visits of all college students for URTI at lag 0 day. The greatest effect values were observed in males [1.83% (95%CI: 0.81, 2.86)], and in females [1.44% (95%CI: 0.51, 2.38)] at lag 0–6 days. DTR had more adverse health impact in the warm season than that in the cold season. Public health departments should consider the negative effect of DTR to formulate more effective preventive and control measures for protecting vulnerable people.