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This article provides the discussion on the evaluation of existing rock excavatability of tropical weathered rocks of granite and quartz type in Malaysia. To do this, a case study was conducted in Nilai, Negeri Sembilan, Malaysia. The rock mass at this site was divided into several subzones which had the same lithology and weathering grade. A scanline survey was conducted to obtain rock mass characteristics like type of discontinuity, dip, dip direction, persistence, nature of filling, surface roughness, surface shape, joint roughness, spacing, and water flow. Collected samples were determined for their moisture content, petrographic analysis, and slake durability. The existing excavatability assessment was made and critically reviewed. Performance for excavatability of rock mass was obtained by performing trial excavation on-site using available machinery. A trial excavation was carried out using an excavator EX200 and EX400. The excavation method was compared with rock mass classifications like rock mass rating (RMR) and Q system and other existing excavatability classification systems. The existing classification system was compared with the production rate of excavation methods used in surface excavation work at road construction sites. This paper presents findings from field work and laboratory tests to obtain rock mass and rock material properties in quartz and granite areas. Next, the parameters are compared to the existing excavatability assessment method, and the results are also presented. There is also an urgent need for an excavatability classification system that considers different rock types according to the geological parameters that are significant to surface excavation in tropical regions. [ABSTRACT FROM AUTHOR]

Using measurements from a ground‐based magnetometer and an in‐house developed quasi‐two‐dimensional theoretical ionospheric model (QTD), the differential response of D and E regions of the equatorial ionosphere to the solar flare events which occurred on 20 February 2002 (M1.5 class), and 24 September 2011 (X1.9 class) has been investigated. The ground‐based magnetometer at Tirunelveli (8.71°N, 77.75°E, 2.9°S dip latitude) was used to monitor variations in the magnetic field (ΔH) during the two events. An abrupt increase in ΔH [positive Solar Flare Effect (SFE)] was noted during both the flare events, a signature of the prompt response to the flare. The ΔH, however, was seen to get weakened (reversed SFE) on 20 February 2002 at a time delay of about 10 min post flare peak. The weakening in ΔH happened during local noon (∼11:30 LT), a period when there was no sign of the counter electrojet (CEJ). The QTD model was used to simulate the ratio of field line integrated Hall to Pedersen conductivity and variations in the east–west currents during the flare events. Model simulations show differential response in the conductivity ratio at the D and E‐regions of the ionosphere during the period when the ionospheric current system was undergoing alternations manifesting as ΔH variations in the ground‐based magnetometer observations. We show that in addition to the changes in conductivity during a solar flare, the electric field variations also modulate ionospheric currents to produce differential footprints in ΔH as positive/negative SFE, SFE*, or reversed SFE. Plain Language Summary: The response of equatorial ionospheric current systems to the solar flare events has been studied using a ground‐based magnetometer and an in‐house developed ionospheric model. During an X1.9 class flare event which occurred on 24 September 2011, magnetic field variations (ΔH) showed an enhancement (positive crochet/Solar flare effect, SFE), whereas during an M1.5 class flare on 20 February 2002, in addition to an enhancement, a reduction in ΔH (reversed SFE) with a time delay was also observed. Using model calculations, we show that the integrated Hall to Pedersen conductivity ratio in the D and E‐regions of the ionosphere plays a key role in controlling flare response. We note that the ratio had a reduction at 105 km while it was enhanced at 90 km. Any change in the conductivity modulates, the east–west electric field, which, in turn, leads to modifications in the ionospheric current systems and gets imprinted in ΔH as observed by ground‐based magnetometers. We show that modifications observed in ionospheric currents during solar flare events depend not only on the changes in conductivity but also on the variations in the zonal electric field. Key Points: This paper discusses an unusual and delayed weakening of magnetic field over the geomagnetic equator, during an M‐class flareDifferential response is observed in the Hall to Pedersen conductivity ratio at the D and E‐regionsAnalysis revealed that during a solar flare, both the conductivity and the east‐west electric field modulate the ionosphere [ABSTRACT FROM AUTHOR]

The circulation of the stratosphere transports important trace gases, including ozone, and can be thought of as having a fast horizontal mixing component and a slow meridional overturning component. Measuring the strength of the circulation directly is not possible, and so it must be inferred from tracer measurements. Long‐lived trace gases can be related to the idealized tracer age of air, which describes how long an air parcel has been in the stratosphere. In this paper, we derive a quantitative relationship between the vertical gradient of age and the horizontal mixing between the tropics and the extratropics using a "leaky pipe" framework in isentropic coordinates. Mixing rates of air into and out of the tropics are related to the vertical gradient of age in the tropics and in the extratropics, respectively. The derivation is repeated with the hemispheres separated so that the vertical structure of the mixing in the two hemispheres can be compared directly. These theories are applied to output from an idealized model of the stratosphere and from a realistic chemistry‐climate model to test our assumptions and calculate the mixing rates in the models. We then perform a quantitative comparison of the mixing rates in the Northern and Southern hemispheres along with an examination of where such a separation is valid. Finally, we perform a very preliminary calculation of mixing efficiency with satellite data to demonstrate the use of the mixing metric to compare mixing in models and data. Key Points: A new metric for adiabatic mixing in the stratosphere is developed from the age of air tracerWe examine hemispheric asymmetry and discuss the slow time evolution of the flowWe calculate this metric to perform a preliminary comparison between models and satellite data [ABSTRACT FROM AUTHOR]

Climatic and anthropogenic changes cause the deprivation of distinct ecosystems in Costa Rica, transforming climatic, ecological, and geomorphic conditions. The high tropical biodiversity of Costa Rica and the tropics is suitable to improve the understanding of hydrogeomorphic process dynamics and to produce baseline data on past disasters in scarce-data regions. The principal motivation to connect natural hazards and dendrochronology on tropics is the desire to create methods that can reduce its exposure and vulnerability. The principal research aim of this study is to give reference data that can improve the understanding of hydrogeomorphic processes and to explore the potential of tropical trees in dendrochronological applications. This paper combines remote sensing, meteorological assessments, and dendrochronology analyses, hydraulic modelling, and risk assessments. This innovative research describes the reduced understanding in treering analysis in Costa Rica related with past disasters and their linkage to climate. This study will likely contribute to the implementation of new methodologies in disaster risk research, and it will promote future adaptation strategies in the most biodiverse region of the world. [ABSTRACT FROM AUTHOR]

This experimental study aims to investigate and analyze the performance of a Water-Air Heat Exchanger that functions as passive cooling in a building ventilation system in the tropics. Before being blown into the room, the high-temperature outdoor air will be passively cooled by the lower-temperature water. Air driven by an Inline Duct Fan with a constant mass flow rate of 4.68 cubic meters per minute flows through a PVC hose as a heat exchanger inserted into a full water reservoir with a diameter of 100 cm and a height of 110 cm. A heat exchanger hose with a diameter of 6.35 cm and a length of 4130 cm is installed in a spiral-circular manner with a total of 16 coils with a diameter of 80 cm to increase the heat transfer effectiveness between water and air. The passive cooling effectiveness is analyzed by decreasing the air temperature between the inlet and outlet of the ventilator after passing through the heat exchanger. The temperature, humidity, and daylight measurement data were carried out for 36 consecutive hours using a multichannel data logger at several locations; ventilator inlet, ventilator outlet, water in the tub, and outside air. The measurement results show that the designed water-to-air heat exchanger provides a significant passive cooling effect and can reduce air temperature to 6.88 °C. By utilizing the passive cooling effect, the cooling energy gain obtained during the measurement period in the ventilation system of this building is 8.3 kWh. The methodology and results of this research are expected to make a positive contribution to the development of the concept of energy-efficient buildings by using passive cooling techniques. [ABSTRACT FROM AUTHOR]

Representatives of Schizomida, known as short-tailed whip scorpions, are an understudied group within Megoperculata. They are found subterraneanly in tropical and sub-tropical regions. They lack eyes, have superior mobility, and possess a flagellum which is relevant to their mating, but in general little is known about their general biology. Fossil representatives of Schizomida from a variety of time periods are available for study. Using 23 fossil specimens (14 of which are described here for the first time) and 86 extant individuals from the literature, changes in both body size and flagella shape in Schizomida were compared over time. Measurements of prosoma length and leg length were used as a proxy for body size, and a comparative size analysis was carried out. Individuals from the Cretaceous period were found to be significantly smaller than extant individuals, contrary to our expectations. For flagellum shape, images were used to create reconstructions, which were then analysed using an elliptic Fourier analysis followed by a principal component analysis. The morphological diversity of the male flagellum shape was found to have decreased significantly between the Cretaceous and modern fauna. We discuss potential explanations for our findings, although a greater understanding of the general biology of Schizomida is required to properly interpret our results. [ABSTRACT FROM AUTHOR]

Background: Polyalthia sclerophylla (P. sclerophylla) is a member of the Annonaceae family, with a wide distribution in tropical and subtropical regions. In traditional Chinese medicine, various members of this genus have been employed as medicinal plants to address refractory ailments. The current study aims to extract the leaves of Polyalthia sclerophylla (TLPS) and determine their chemical contents using GSMass and standard phytochemical techniques. Methods: The antibacterial and cytotoxicity activities of TLPS were used to evaluate its bio-medical characteristics. In that sequence, three solvents were used to extract TLPS to produce three samples: MTLPS, DTLPS, and HTLPS. Results: Phytochemical analysis indicated terpenoids and glycosides in all prepared models, but no alkaloids were observed. The GC-Mass data showed twenty-one chemical compounds. Pyridine, 2-Undecanol, 2-methyl-2-oxiranyl- and cyclobutanone were observed with higher percentages, while the 2(5H)-Furanone, 5-methyl, 1,1,3-Trimethylcyclopentane and 1,6-Heptadiene were observed with lower rates. The cytotoxicity study of TLPS was performed using Alamar blue assay using MG-63 cells. However, results show no detrimental influence at any dosage as cell availability increased. MTLPS, DTLPS and HTLPS were treated with six bacteria pathogens, and all of them showed significant effects against these bacteria to inhibit the growth of the bacteria. The extract of methanol (MLPS) was more effective in inhibiting the development of the bacteria compared with the DTLPS and HTLPS. Conclusion: The current work has shown that the chemical composition of crude TPLS varies, leading to notable chemical, biological, and medicinal features, and their non-toxic impact. [ABSTRACT FROM AUTHOR]

The present study investigates the impact of northern mid-winter major stratospheric warming on tropical convection over the Indian region by examining the five Mid-winter Major Stratospheric Warming (MSW) events 2003/04, 2005/06, 2008/09, 2012/13, and 2018/19. The dynamical variables like temperature, wind components, and Outgoing Longwave Radiation are utilized from ECMWF ERA-Interim Reanalysis and NOAA site. Eliassen Palm (E-P) flux is used to visualize the upward and equator-ward propagation of extratropical Planetary Waves (PWs) from the lower atmosphere and their reach to the tropical region. The dominance of extratropical PW forcing from high to low latitudes is seen in all mid-winter cases. Further, the transfer of PW energy to low latitudes modifies the convection pattern over the Indian region. The author found depleted convection in the latitude band -15-20oN for the MSW 2003/04 and 2018/19, with frequent changes seen during MSW 2012/13 and 2005/06. On the other hand, the MSW 2008/09 show enhanced convection in the entire latitude band 20oS-20oN. This work suggests that the modification of OLR depends on the PW energy, onset time, peak temperature, and wind-reversed state during MSW. [ABSTRACT FROM AUTHOR]

Background: The spider family Ctenidae Keyserling, 1877 has a worldwide distribution with 584 species belonging to 49 genera. Amongst these, 141 species are from Asia, including 130 species assigned to Cteninae Keyserling, 1877. New information: Nine new species belonging to three genera of Cteninae are reported from Asia: Amauropelma krabi sp. n. (female; Krabi, Thailand), Am. phangnga sp. n. (male; Phang Nga, Thailand), Am. saraburi sp. n. (male and female; Saraburi, Thailand); Anahita medog sp. n. (male and female; Tibet, China); Bowie ninhbinh sp. n. (male; Ninh Binh, Vietnam) and B. vinhphuc sp. n. (male and female; Vinh Phuc, Vietnam) from the robustus-species group; B. borneo sp. n. (male; Sabah, Malaysia) from the chinagirl-species group; B. engkilili sp. n. (female; Engkilili, Malaysia); B. sabah sp. n. (male and female; Sabah, Malaysia) from the scarymonsters-species group. The male of An. popa Jäger & Minn, 2015 and the female of B. fascination Jäger, 2022 (robustus-species group) are described for the first time. B. fascination Jäger, 2022 is reported from China for the first time. In addition, the DNA barcodes of all the species in this study were obtained, except for B. vinhphuc sp. n. [ABSTRACT FROM AUTHOR]

In the tropics, outdoor areas are important arenas of social life and the scene of economic and daily activities. Yet, outdoor areas are not often detected due to destructive post-depositional processes and low archaeological visibility. Here, we use microarchaeology to establish the settlement history and outdoor use of space at Lo Gach in Long An Province, southern Vietnam. The radiocarbon chronology identifies two phases of occupation: an initial presence at 3300–3000 cal. BP and later activity at 2750–2400 cal. BP. Microarchaeological analysis of the stratigraphy reveals complex sequences of organic waste severely transformed by chemical diagenesis. The results indicate that the excavated area at Lo Gach was an outdoor 'backyard' containing external surfaces utilised for a range of activities including rice processing, disposal of combustion residues, in situ burning, and recurrent foot traffic. Intensified rice agriculture and the systematic management of organic waste were the main structuring rhythms of social life that were performed at the Lo Gach settlement. [ABSTRACT FROM AUTHOR]

We report on a set of laboratory experiments to investigate the effect of polar warming on the mid-latitude jet stream. Our results show that a progressive decrease in the meridional temperature difference slows down the eastward propagation of the jet stream and complexifies its structure. Temperature variability decreases in relation to the laboratory "Arctic warming" only at locations representing the Earth's polar and mid-latitudes, which are influenced by the jet stream, whilst such a trend is reversed in the subtropical region south of the simulated jet. The reduced variability results in narrower temperature distributions and hence milder extreme events. However, our experiments also show that the frequency of such events increases at polar and mid-latitudes with decreased meridional temperature difference, whilst it decreases towards the subtropics. Despite missing land–sea contrast in the laboratory model, we find qualitatively similar trends of temperature variability and extreme events in the experimental data and the National Centers for Environmental Prediction (NCEP) reanalysis data. [ABSTRACT FROM AUTHOR]

Atmospheric general circulation changes from March 1979 to February 2022 are examined using the ERA5 reanalysis. Maps of linear trends and time series for specific areas are presented. Attention is concentrated on monthly, seasonal and annual means, but shorter-timescale variability is also considered, including extremes. Changes in near-tropopause winds are the main focus, but related changes in temperature, wind and other variables throughout the troposphere are discussed. Middle- and upper-tropospheric warming is larger in the subtropics and outer tropics than in the deep tropics, except over the Pacific. This is linked with a strengthening and meridional expansion of the tropical easterlies that has received little previous attention. The change occurs predominantly over the first half of the period. Warming over several mid-latitude and subtropical land areas comes close to matching the large warming of the Arctic, in some seasons at least. Westerly upper-level winds in general weaken over the Arctic in winter but strengthen in northern middle latitudes, contrary to arguments based on circulation changes due solely to amplified Arctic warming. The jet-stream region over the eastern North Atlantic and western Europe shifts southward. Westerlies strengthen in a band stretching south-eastwards from the tropical western Pacific to southern Australia, as well as in the polar-jet-stream region that surrounds Antarctica. Extreme jet-stream winds increase over the North Atlantic. Net kinetic energy also increases, mostly associated with sub-monthly variability along the mid-latitude storm tracks and over the tropical Pacific. Available potential energy changes less. Geopotential height shows a distinct pattern of change in stationary long-wave structures. There are increases in surface pressure over the North Pacific and southern mid-latitudes and decreases over the Arctic Ocean and offshore of Antarctica. Several comparisons are made between ERA5 and the JRA-55 reanalysis and between ERA5 and the observations it assimilated. They show reassuring agreement, but some regional differences require further investigation. [ABSTRACT FROM AUTHOR]

Can geomagnetic storms during low solar activity trigger formation of extreme equatorial plasma bubbles (EPBs) that affect low and midlatitudes? We analyzed the ionospheric response to the 25–26 August 2018 geomagnetic storm and revealed formation of intense ionospheric plasma irregularities over broad latitudinal ranges from equatorial toward middle latitudes in the American and Pacific sectors. Storm‐induced penetration electric fields created favorable conditions for strong fountain effect uplifted the equatorial ionosphere, enhancement of the equatorial ionization anomaly (EIA), and postsunset EPBs generation. We found two patterns of equatorial ionospheric irregularities expansion toward low and middle latitudes: (a) storm‐induced EPBs developed over a large latitudinal extent between widely spread EIA crests, (b) narrow channel of the ionospheric irregularities stretched away from the EPB location toward the auroral zone in the northwestward direction. The EPBs latitudinal extent largely exceeded climatological‐based expectations for solar minimum conditions; EPBs reached atypically high latitudes (20°–25° magnetic latitude [MLAT]) in the Pacific Ocean sector. The poleward‐streaming plasma density depletions were registered along the western coast of North America. The ionospheric irregularities transported in the northwestward direction toward midlatitudes reaching as high as 40°–45° MLAT. The passage of these ionospheric irregularities coincided with the spread‐F conditions recorded at a midlatitude ionosonde (42° MLAT)—rather atypical phenomenon for midlatitudes. It is suggested that enhanced westward drifts associated with prompt penetration and Sub Auroral Polarization Stream electric fields can support the northwestward plasma transportation. Plain Language Summary: The 25–26 August 2018 geomagnetic storm occurred at the background of very low solar activity. For this storm, we registered occurrence of very intense ionospheric plasma irregularities developed in the equatorial region and expanded toward much higher latitudes. We revealed that the storm‐induced equatorial ionospheric irregularities expended toward middle latitudes in two ways: (a) storm‐induced plasma bubbles initially developed with a large latitudinal extent in the uplifted equatorial ionosphere, and (b) poleward part of the largely expanded can be involved into transportation in the northwestward across midlatitudes. The ionospheric irregularities were transported in the northwestward direction toward middle latitudes reaching as high as 40°–45° magnetic latitude (MLAT). The passage of these ionospheric irregularities coincided with the spread‐F conditions recorded at a midlatitude ionosonde (42° MLAT)—it is rather atypical phenomenon for midlatitudes, such scattered echoes are typically observed at nighttime at ionosondes located in the equatorial region. It is suggested that enhanced westward drifts associated with strong storm‐time electric fields can support the northwestward plasma transportation. Key Points: Geomagnetic storm in solar minimum initiated development of equatorial ionospheric irregularities of large latitudinal extent upto 25° magnetic latitude (MLAT)Plasma depletions of equatorial origin transported in northwestward direction across midlatitudes toward auroral zoneAtypical ionospheric irregularities moving toward higher latitudes cause rare spread‐F echoes at a midlatitude ionosonde (42° MLAT) [ABSTRACT FROM AUTHOR]

We present measurements of the equatorial topside ionosphere above Jicamarca made during extremely low solar flux conditions during the deep solar minimum of 2019–2020. Measurements were made in October, 2019, February, 2020, and September, 2020. The main features observed are a large and extended decrease in noontime temperatures unlike that seen in studies at moderate solar flux levels, predawn ionospheric heating as early as 0300 LT, large day‐to‐day variability in the O+/H+ transition height, and negligible helium ion concentration at all altitudes. Data from the Ion Velocity Meter (IVM) instrument onboard the Ionospheric Connection Explorer (ICON) and the Topside Ionospheric Plasma Monitor (SSIES) onboard the Defense Meteorological Satellite Program (DMSP) satellites are used to assess agreement with ISR data and assist with the analysis of the predawn heating phenomena. We also analyze the data in light of the SAMI2‐PE model which shows less agreement with the data than at higher solar flux. The main areas of discrepancy with the data are outlined, such as the absence of significant predawn heating, less pronounced decreases in noontime temperatures, and much higher O+ fractions at high altitudes, particularly in September. Finally, a sensitivity analysis of the model to various forcing agents such as neutral winds, plasma drifts, solar flux, and heat flow is performed. A discussion is presented on bridging the discrepancies in future model runs. Novel techniques of clutter removal and noise power bias correction are introduced and described in the appendices. Key Points: New Jicamarca ISR topside measurements of the 2019–2020 solar minimum are presentedISR comparison with DMSP and with ICON for first time at very low solar flux shows consistency and provides insight into predawn heatingComparisons between ISR and SAMI2‐PE model outputs reveals new insight into composition and energetics of topside [ABSTRACT FROM AUTHOR]

The summer monsoon anticyclones are the dominant climatological features of the Northern Hemispheric (NH) summertime circulation in the upper troposphere and lower stratosphere (UTLS). However, the response of these anticyclones to the increased levels of CO2 remains highly uncertain, as does the impact on the distribution of UTLS ozone and other tracers. This study examines the response of the NH summertime monsoon anticyclones and UTLS ozone to the abrupt increase in CO2 forcing using output from a suite of coupled ocean–atmosphere general circulation model simulations. These models show an equatorward shift of the Asian summer monsoon anticyclone, a weakening of the North American summer monsoon anticyclone, and a stronger westerly flow penetrating deep into the tropics above the Pacific Ocean and North America. We use additional idealized experiments from atmosphere‐only general circulation models with prescribed SSTs and sea ice concentration to isolate the direct atmospheric radiative effects from the indirect effect of SST warming on the UTLS monsoon anticyclones. Comparison between atmosphere‐only and coupled ocean–atmosphere experiments shows that SST warming is the principal mechanism producing UTLS monsoonal circulation changes. The 4×CO2 experiments result in a significant reduction up to 40%–50% of the UTLS ozone in the northern tropics, which could have an impact on radiative balance near the surface. Key Points: Models simulate an equatorward shift of the Asian and disappearance of the North American monsoon anticyclones in 4 × CO2 simulationsChanges in the upper troposphere and lower stratosphere anticyclones are dominated by the effect of indirect SST warming by CO2Circulation changes due to 4 × CO2 result in a significant reduction of ozone in the northern tropics at 100 hPa [ABSTRACT FROM AUTHOR]

Various studies have provided insights about how green roof rainfall retention capacity is affected by factors including typology, vegetation, growing media's physical-chemical-biological properties, drainage system, climate conditions, and roof age. Despite its importance, little has been studied about the effect of drainage area on green roof retention capacity. In this work, three experimental extensive green roof units with different drainage areas (1 m2 , 3 m2 , and 12 m2) were assessed to evaluate how the rainfall characteristics and the scale dynamics of the green roofs impact the retention during rainfall events. The findings showed that the drainage area had a significant impact on rainfall retention and outflow volumes. The average retention capacity increased, and the outflow generation capacity decreased with increasing drainage area. The largest green roof area (12 m2) presented better performance with respect to rainfall retention, being 36% higher than the 1 m2 area, and 13% higher than the 3 m2 green roof area. In turn, the performance of the 3 m2 green roof was 21% higher than the 1 m2 area. Factors such as rainfall depth and maximum 1-h rainfall intensity also affected the retention and outflow behavior. However, the antecedent dry weather period had little effect on retention and outflow, possibly due to frequent rainfall caused by subtropical climate. [ABSTRACT FROM AUTHOR]

We investigate the relationship between convective available potential energy (CAPE), precipitation, the number and size of storms and overshooting tops, and lightning stroke density (f) over the Central America region. While f increases almost linearly with CAPE1/2 over land, f is nearly muted over the ocean when CAPE is small. In the high‐CAPE regime, on the contrary, oceanic storms produce as many lightning flashes as land storms. We show that individual oceanic storms are smaller and contain fewer overshooting tops compared to land storms, although the difference exists across low‐ and high‐CAPE regimes. While f increases as individual storm size increases, the storm size required to produce lightning appears to be disproportionately high in the low‐CAPE regime, likely due to the stronger entrainment effect. The entrainment effect on f in the low‐CAPE regime appears to be much weaker over land. Applying the CAPE threshold for lightning over the ocean to the CAPE‐based lightning parameterization scheme of Romps et al. (2014), https://doi.org/10.1126/science.1259100 improves its performance, in particular, at representing the land‐sea contrast in f. Key Points: Over the tropical ocean, storms seldom produce lightning when convective available potential energy (CAPE) is smallThe inhibition of lightning in the low CAPE environment is likely due to the storm size being too small to produce a strong updraftImplementing a CAPE threshold for lightning over the ocean improves the performance of a CAPE‐based lightning parameterization scheme [ABSTRACT FROM AUTHOR]

The intertropical convergence zone (ITCZ) exports energy and imports moisture. This has been understood for decades. By analyzing a set of uniform, nonrotating aquaplanet simulations, we show that energy export and moisture convergence are general characteristics of warm humid regions, and not just of the ITCZ. Using an analysis method based on the column relative humidity, we find that the absorption of longwave radiation by clouds supplies the energy that is exported from humid regions. The longwave absorption also induces a thermally direct circulation that lifts water vapor and converges moisture into regions that are already quite humid. An additional set of simulations shows that strong atmospheric energy convergence is absent when radiation is homogenized across the domain. Key Points: Cloud‐longwave feedbacks discussed in previous studies may be examples of a general feedback driven by atmospheric cloud radiative effectsWarm, humid regions export energy and import moisture in a way similar to the intertropical convergence zoneThe atmospheric cloud radiative effect as a function of column relative humidity is nearly independent of the sea surface temperature [ABSTRACT FROM AUTHOR]

The SAMI3/equatorial spread F (Sami3 is also a model of the ionosphere/ESF) code is used to simulate the growth of equatorial plasma bubbles in the presence of a background wind field based on measured winds. The measured winds exhibit the well‐known "midnight temperature maximum" (MTM) pattern, in which an equatorward wind occurs simultaneously with a cessation in the zonal wind. The MTM is often preceded by strong equatorward winds (about 100 m/s). The circumstance where the MTM winds are symmetric across the equator is considered; here the meridional wind component in the southern hemisphere is the reverse of the northern meridional wind. The timing of the wind pattern relative to the imposition of a seed for the ESF instability is explored. We find that the simultaneous occurrence of a seed wave and a strong converging meridional wind pattern can produce post‐midnight ESF. We further find that the seed wave and the sudden cessation of the zonal winds can also produce post‐midnight ESF. The Magnetic mEridional NeuTrAl Thermospheric code verifies the occurrence of converging meridional wind patterns such as those simulated here, based on ionosonde data. Results suggest that regional‐scale wind measurements would aid in the prediction signal‐disrupting ionospheric bubbles. Plain Language Summary: The local ionosphere often becomes unstable after dusk, with low‐density "bubbles" rising from the bottom of the ionosphere F layer upwards to altitudes of 1,000 km or more. The jump in the local ionosphere density at the edges of these bubbles can disrupt signal transmission between Earth and space. The instability usually occurs after dusk but sometimes also occurs after midnight. We consider nighttime winds measured over an area covering most of the continental United States. The applicability of such measurements to prediction of bubbles is explored. The measured winds, which exhibit a phenomenon known as the midnight temperature maximum (MTM), are shown to enable post‐midnight bubbles. Two separate mechanisms are considered: (1) a north/south converging meridional wind of the sort that often precedes the MTM and (2) the sudden cessation of the zonal wind that often occurs during the MTM. In each case, post‐midnight equatorial spread F can occur if the timing between the winds and a "seed" wave is optimum. Key Points: The timing of midnight temperature maximum winds affects the growth of post‐midnight equatorial spread F (ESF)Regional area wind measurements can aid in the prediction of ionospheric bubbles associated with the ESF instabilityPrediction of ESF bubbles requires wind measurements or wind predictions in both hemispheres [ABSTRACT FROM AUTHOR]

This research aims to advance our understanding towards forest transition, which is about the shift from net deforestation to net reforestation over a given area during certain period, through a case study of a western city in China from 1990 to 2015. Three main contributions are made to the theory and practice of forest land management. First, this research enriches forest transition theory with a meso-level exploration on forest land change in subtropic Chongqing, which echoes the "U" shape transition rules widely observed in the Euro-American context but was found a time lag of the turning point until 2000s. Second, it intentionally identifies the subtype of forests--the artificial plantation, which is considered influential on performance of forest's carbon sequestration but not paid sufficient attention to. Third, it adds knowledge on forest transition pathway at an intraurban scale through the identified significance degree of forest transition dynamics, which implies that economic development matters but is less important than topography in a mountainous city like Chongqing, and different dimensions of economy impact differently on forest transition. [ABSTRACT FROM AUTHOR]

This study systematically evaluates the warm sea surface temperature (SST) bias in the Subtropical Eastern North Pacific, a problem plaguing most Coupled Model Intercomparison Project Phase 6 models, using the Energy Exascale Earth System Model version 1 (E3SM). In the model at its standard resolution (1° atmosphere, 30-60 km ocean), the SST bias, exceeding several degrees, is mainly concentrated along the coast between 25°N and 40°N. In the high-resolution (0.25° atmosphere, 18-6 km ocean) version of the model, the nearshore SST bias improves considerably with a better representation of coastal upwelling. However, the offshore SST bias, approximately centered at 125°W and 25°N, is relatively stronger in the high-resolution version. To better understand the offshore warm bias in the model, a mixed-layer heat budget analysis is performed. While errors in surface radiative fluxes occur at both resolutions, positive biases in horizontal heat advection also play a role in the SST bias at high-resolution. Analysis of HighResMIP models indicates that the shift in the location of the prominent SST bias from nearshore to offshore with an increase in model spatial resolution, is not native to E3SM alone. [ABSTRACT FROM AUTHOR]