Warm Climatic Conditions Research Articles

Effect of Accelerant Additives in Concrete with Limestone Aggregate in Warm Weather

Additives are chemical compounds that are added to concrete during its manufacture to modify one or more of its properties. The first additive used in modern concrete was the accelerator, intended to shorten the time during which the material is not capable of supporting stress. Traditionally, accelerators have been made from calcium chloride, but today the trend is to use chloride-free additives to prevent reinforcing steel from corroding and thereby make constructions durable. The objective of this study was to evaluate the effects on the concrete of two types of accelerating admixture, using limestone aggregates, under warm sub-humid climate conditions. The applied methodology consisted of the measurement in the laboratory of some of the main properties of concrete in fresh and hardened states, in samples manufactured both with and without accelerators. The results showed that the accelerator without chloride was less effective than the one based on calcium chloride and that without doses of the accelerator, the effectiveness documented by the manufacturers was achieved.

Deep-water paleoenvironmental changes based on early-middle Miocene benthic foraminifera from Malta Island (Central Mediterranean)

A detailed quantitative, statistical and isotopic study on benthic foraminiferal assemblages from the upper Burdigalian - lower Langhian of Malta Island (St. Peter's Pool section) was carried out in order to gain more insights on paleoenvironmental changes that affected the central part of the Mediterranean Basin during the early-middle Miocene. The most abundant and/or palaecologically significant taxa were grouped into Group A (oxic/oligotrophic and oxic/oligo-mesotrophic opportunistic behaving) and Group B (hypoxic/eutrophic) and, on the base of their microhabitat in superficial microhabitat taxa (epifaunal + epifaunal to shallow infaunal taxa), intermediate microhabitat taxa (shallow infaunal + shallow to intermediate infaunal taxa) and deep microhabitat taxa (deep infaunal species). The changes in the structure of the benthic foraminiferal assemblages, together with isotopic data and statistical analysis results, identify five main intervals SPP1-SPP5, testifying the evolution of bottom water conditions between 16.12 and 15.36 Ma, corresponding to warm climate conditions due to the onset of the Miocene Climatic Optimum (MCO). The main benthic foraminiferal turnover occurred between 16.01 and 15.91 Ma. It has been recorded in both the palaecological and geochemical data and can be related to the Miller's Mi2 cooling event. This turnover correlates to a sea level falling that we believe caused an increase of the primary productivity due to runoff intensification. We suggest that the fluctuations of superficial microhabitat oxic/oligo/oligo-mesotrophic Group A, opposite to those of intermediate and deep microhabitat hypoxic/eutrophic Group B, and the occurrence of the superficial microhabitat, oxic/oligo-mesothrophic opportunistic behaving species are indicative of increased seasonality, which in turn affect food flux and oxygenation at the sea-floor. Moreover, the calculation of %P and the well-defined depth distribution range of some significant species allowed us to estimate a middle bathyal paleodepth, ranging from 600 m to 1000 m for the entire composite section.

Paleoenvironmental Conditions during the Paleocene–Eocene Transition Imprinted within the Glauconitic Giral Member of the Barmer Basin, India

The roughly 6 m thick limestone–green shale alternation within the lignite-bearing Giral Member of the Barmer Basin corresponds to a marine flooding event immediately after the Paleocene–Eocene transition. A detailed characterization of the glauconite using Electron Probe Micro Analyzer (EPMA), X-Ray Diffraction (XRD), Mössbauer and Field Emission Gun-Scanning Electron Microscope (FEG-SEM) reveals its origin in the backdrop of prevailing warm climatic conditions. The glauconite pellets vary from fine silt-sized to coarse sand-sized pellets, often reaching ~60% of the rock by volume. Mineralogical investigation reveals a ‘nascent’ to ‘slightly evolved’ character of the marginal marine-originated glauconite showing considerable interstratification. The chemical composition of the glauconite is unusual with a high Al2O3 (>10 wt%) and moderately high Fe2O3(total) contents (>15 wt%). While the K2O content of these glauconites is low, the interlayer sites are atypically rich in Na2O, frequently occupying ~33% of the total interlayer sites. The Mössbauer spectrum indicates 10% of the total iron is in ferrous form. High tetrahedral Al3+ of these glauconites suggests a high-alumina substrate that transformed to glauconite by octahedral Al-for-Fe substitution followed by the addition of K into the interlayer structure. The unusually high Na2O suggests the possibility of a soda-rich pore water formed by the dissolution of alkaline volcanic minerals. The Giral glauconite formation could have been a part of the major contributors in the Fe-sequestration cycle in the Early Eocene shelves. Warm climate during the Early Eocene time favored the glauconitization because of the enhanced supply of Fe, Al, and Si and proliferation of an oxygen-depleted depositional environment.

Thermal model of a photovoltaic module with heat-protective film

Research on reducing the working temperature of PV modules is gaining attention to improve their electrical performance, efficiency, and life especially in warm climatic conditions. This study describes the use of novel heat-protective film based on holographic coating with a total internal reflection prism layer applied to maintain the operating temperature of the photovoltaic module. A mathematical model of thermal protection based on the holographic film is described. MATLAB/Simulink simulation was used to estimate the current-voltage and output power–solar irradiance characteristics of a photovoltaic module with and without holographic film. Regression models were developed based on field testing to determine a relationship between the temperature of heat-protected/unprotected PV panels and ambient temperature. The results showed that a temperature reduction of 3.54 °C is obtained for solar modules with thermal protection film compared to the one without holographic film. The modeling and field performance results confirm the effectiveness of the thermal protective film in reducing the temperature and improving the photovoltaic panel performance in hot climates.

The organic geochemical characteristics from the Palaeogene lacustrine source rock in the Nyima Basin, Central Tibet, and their geological significance

The Lunpola Basin is a fault‐depression type residual Palaeogene continental basin, and it is the only basin located in Tibet in which industrial oil has been discovered. In recent years, as research has progressed, quantities of oil shale and asphalt were discovered in the adjacent Nyima Basin, which shows a good prospect for exploration. In this study, the organic geochemistry, n‐alkanes, biomarkers, and maturity parameters of the samples were analysed using gas chromatography (GC) and mass spectrometry (MS). The organic geochemistry revealed that the Niubao Formation has a high organic matter abundance (total organic carbon content of 0.15–8.43 wt% and hydrogen index of 31.25–1721.15) and is dominated by type I–II2 kerogen. The GC and MS analyses indicate that the oil shales of the Nyima Basin have a high organic matter abundance and a good hydrocarbon production potential, and the main organic matter sources were aquatic algae and terrestrial plants, as evidenced from the unimodal/bimodal distributions of the n‐alkanes. Besides, the high phytoalkane, gammacerane, homohopane, and gypsiferous mudstone contents in the Nyima Basin indicate a deep, hypoxic, well‐stratified, saline lacustrine sedimentary environment. Under warm climatic conditions, accelerated continental weathering increased nutrient input, leading to water‐mass eutrophication and algal blooms in the water column, while arid conditions and intensified evaporation induced saline stratification, leading to enhanced preservation of organic matter and the formation of high‐quality source rock layers in this lake basin. Therefore, the Eocene global greenhouse effect may have been the main reason for the formation of the large sets of oil shales in the Nyima Basin.

Analysis of Compounds with Oenological Interest in Somatic Variants of Grapevines

Grapevine varieties can be identified genetically by microsatellite markers. However, these molecular markers are not available to discriminate between somatic mutations that give rise to clones. Therefore, the study of compounds with oenological interest could be used to identify variability in grapevine somatic variants. In this research, sugars (glucose, fructose), acids (tartaric and malic acid) and polyphenols (22 phenolic compounds, including 13 anthocyanins) were analyzed in grape berries of two somatic variants known with different names—‘Graciano’ and ‘Tintilla de Rota’—cultivated in the same vineyard under warm climate conditions. The organic acid results show significant differences between the performance of the two accessions. Regarding phenolic compound (excluding anthocyanins) content, significant differences were observed between the two accessions. Kaempferol, caftaric acid and epicatechin were the compounds responsible for the reported differences. Differences in anthocyanin content showed opposite behavior between ‘Tintilla de Rota’ and ‘Graciano’. In this sense, ‘Graciano’ accession showed an increase in all forms of anthocyanins, with a remarkable increment of peonidin 3-O-glucoside. Principal component analysis of polyphenolic compounds revealed clearly distinguished behaviors concerning these compounds, besides showing similar tendencies between the two accessions during the ripening stage. These results could allow for the discrimination of the two accessions into somatic variants highlighting their individual identity.

Genetic Drift Versus Climate Region Spreading Dynamics of COVID-19.

Background: The current propagation models of COVID-19 are poorly consistent with existing epidemiological data and with evidence that the SARS-CoV-2 genome is mutating, for potential aggressive evolution of the disease. Objectives: We looked for fundamental variables that were missing from current analyses. Among them were regional climate heterogeneity, viral evolution processes versus founder effects, and large-scale virus containment measures. Methods: We challenged regional versus genetic evolution models of COVID-19 at a whole-population level, over 168,089 laboratory-confirmed SARS-CoV-2 infection cases in Italy, Spain, and Scandinavia at early time-points of the pandemic. Diffusion data in Germany, France, and the United Kingdom provided a validation dataset of 210,239 additional cases. Results: Mean doubling time of COVID-19 cases was 6.63 days in Northern versus 5.38 days in Southern Italy. Spain extended this trend of faster diffusion in Southern Europe, with a doubling time of 4.2 days. Slower doubling times were observed in Sweden (9.4 days), Finland (10.8 days), and Norway (12.95 days). COVID-19 doubling time in Germany (7.0 days), France (7.5 days), and the United Kingdom (7.2 days) supported the North/South gradient model. Clusters of SARS-CoV-2 mutations upon sequential diffusion were not found to clearly correlate with regional distribution dynamics. Conclusion: Acquisition of mutations upon SARS-CoV-2 spreading failed to explain regional diffusion heterogeneity at early pandemic times. Our findings indicate that COVID-19 transmission rates are rather associated with a sharp North/South climate gradient, with faster spreading in Southern regions. Thus, warmer climate conditions may not limit SARS-CoV-2 infectivity. Very cold regions may be better spared by recurrent courses of SARS-CoV-2 infection.

Testing of a Radiant Wall Cooling System with Pipes Coupled to Aerated Blocks

Thermal output, surface temperatures, and supply and return water temperature were measured for a wall cooling system involving pipe attached to a wall section made of thermally insulating blocks. The experiment was performed for warm climatic conditions typical of, e.g., summer in Central and Northern Europe. The outdoor environment was simulated by a climatic chamber while the indoor climate was simulated by attaching a hotbox to the wall surface. The sensitivity of thermal output to several design parameters was investigated by 2D numerical simulations. The measurements showed a fast thermal response of the wall system. The cooling output was 38.3 W per m2 of the cooling area which equalled about 4.8 W/m2 per 1 K temperature difference between water and hotbox. The lowest surface temperature of 19.6 °C was measured at the pipe. Thus, the cooling output could be enhanced by reducing the surface temperature closer to the dew point temperature. The temperature of water in the pipe was very close to the surface temperature. It was illustrated how this characteristic of the wall cooling system tested positively affects the efficiency and cooling capacity of an air-to-water heat pump.

Calcareous nannofossil biostratigraphy of Nag El Quda, South of Dababiya, Eastern side of the Nile Valley, Egypt.

The biostratigraphy of calcareous nannofossils of the upper Paleocene-lower Eocene sequence in Nag El Quda area (South of Dababiya, Eastern Side of the Nile Valley, Egypt carried out in detail. This study of the P-E transition, allow us to recognize some of the prominent and abrupt events that characterize the P/E boundary, and to relocate this boundary with respect to the recent redefinition of the Paleocene/Eocene boundary. The present stratigraphic study of the P/E interval based on close sampling. This study has provided a high resolution litho- and biostratigraphic data based on calcareous nannofossils. The study interval includes from the base to top; El Hanadi, Dababiya, and El Mahmiya members. The P/E boundary is situated at the NP9a/NP9b boundary, which lies at El Hanadi/Dababiya contact. We identify the first occurrence (FO) of excursion taxa (Discoaster anartios, D. araneus, Rhomboaster spp.) at the base of the Eocene. These taxa are adapted to warm climatic conditions that prevailed at this boundary. An abrupt and sharp decrease in the diversity, abundance of the genus Fasciculithus occurs at the NP9a/NP9b (Paleocene/Eocene boundary), and disappeared completely shortly afterwards. The lowermost Eocene sediments studied here only yield F. tympaniformis and F. involutus.

Estimating Terrestrial Radiation for Human Thermal Comfort in Outdoor Urban Space

Cities inadvertently create warmer and drier urban climate conditions than their surrounding areas through urbanization that replaces natural surfaces with impervious materials. These changes cause heat-related health problems and many studies suggest microclimatic urban design (MUD) as an approach to address these problems. In MUD-related research, although terrestrial radiation plays an important role in human thermal comfort and previous studies use thermal comfort models to identify human heat stress, few studies have addressed the effect of terrestrial radiation. This study develops the ground ratio factor (GRF) model to estimate the different terrestrial radiation according to different ground conditions. Three types of ground materials (asphalt, concrete, and grass) were considered in the model, and field studies were conducted in humid subtropical climate (Cfa) zone during the hot season (13 July to 19 September 2020). The model was validated by comparing the predicated terrestrial radiation (PTR) from the model with the actual terrestrial radiation (ATR). The results showed that there is a statistically significant strong correlation between PTR and ATR. The model can contribute to MUD strategies by updating existing human energy budget models, which can lead to the measurement of more accurate human thermal comfort for mitigating thermal environments.

Hydrocarbon Potential of the Late Permian and the Late Triassic Source Rocks from the Qamdo (Changdu) Basin, Eastern Tibet and Its Linkage with the Sea Level Change

The Qamdo Basin in eastern Tibet has significant petroleum potential and previous studies indicate that the basin contains thick potential source rocks of the Late Permian and the Late Triassic ages. In this paper, the petroleum potential of samples from measured the Upper Permian and Upper Triassic outcrop sections were evaluated on the basis of sedimentological, organic petrographic and geochemical analyses. Initial evaluations of total organic carbon contents indicated that shale samples from the Upper Permian Tuoba Formation and the Upper Triassic Adula and Duogala Formations have major source rock potential, while carbonate rocks from the Upper Triassic Bolila Formation are comparatively lean in organic matter More detailed analyses of OM-rich shale samples from the Tuoba, Adula and Duogala Formations included Rock-eval, elemental analyses, gas chromatography and organic petrography. Maceral compositions and plots of atomic O/C versus H/C indicate that the organic matter present in the samples is primarily Type II with a mixed source. Analyses of acyclic isoprenoid biomarkers indicate the organic matter was deposited under reducing and sub-to anoxic conditions. Based on the high vitrinite reflectance (Ro>1.3%) and Rock-eval data, the samples are classified as highly to over-mature, suggesting that the Tuoba, Adula and Duogaila Formation shales may generate thermogenic gas. Source rock intervals in the three formations are interpreted to have been deposited in marginal-marine environment during transgressions and under a warm and moist climatic condition.

Molecular data attest to the occurrence of autochthonous Daphnia pulex (Crustacea, Branchiopoda) populations in Sicily, Italy

Biological invasions are known to be among the most important threats to the long-term conservation of native biota, and their effects might be even more difficult to contrast when they are cryptic, i.e., when the non-native invaders cannot be easily recognised based on morphology, and can thus be confused with native taxa. Such cryptic invasions are known to widely occur in the cladoceran genus Daphnia O.F. Müller, 1785, so that the actual distribution and status of most species and lineages need to be checked with a genetic approach. In the frame of this work, we investigated if the Sicilian populations of D. (Daphnia) pulex Leydig, 1860 belonged to the allochthonous North American lineage, which is known to occur in several regions of the Palearctic and Afrotropical biogeographical regions, or rather to the autochthonous European lineage of the species. The molecular results obtained, based on a fragment of the mitochondrial gene encoding for NADH subunit dehydrogenase 5 (ND5), allowed us to rule out the allochthonous status of the species, confirming the presence of autochthonous relictual lineages of D. pulex in Sicily. The native status of these populations is in agreement with their local distribution, limited to natural and poorly-impacted water bodies mostly located in wooded areas at medium and high altitudes. The current local distribution of D. pulex in Sicily is possibly linked to the end of the last glacial maximum and the onset of warmer climatic conditions in the early Holocene, which led the species to take refuge in colder microthermal refugia located at high altitudes, determining their current relictual distribution.

Climate and ecology in the Rocky Mountain interior after the early Eocene Climatic Optimum

Abstract. As atmospheric carbon dioxide (CO2) and temperatures increase with modern climate change, ancient hothouse periods become a focal point for understanding ecosystem function under similar conditions. The early Eocene exhibited high temperatures, high CO2 levels, and similar tectonic plate configuration as today, so it has been invoked as an analog to modern climate change. During the early Eocene, the greater Green River Basin (GGRB) of southwestern Wyoming was covered by an ancient hypersaline lake (Lake Gosiute; Green River Formation) and associated fluvial and floodplain systems (Wasatch and Bridger formations). The volcaniclastic Bridger Formation was deposited by an inland delta that drained from the northwest into freshwater Lake Gosiute and is known for its vast paleontological assemblages. Using this well-preserved basin deposited during a period of tectonic and paleoclimatic interest, we employ multiple proxies to study trends in provenance, parent material, weathering, and climate throughout 1 million years. The Blue Rim escarpment exposes approximately 100 m of the lower Bridger Formation, which includes plant and mammal fossils, solitary paleosol profiles, and organic remains suitable for geochemical analyses, as well as ash beds and volcaniclastic sandstone beds suitable for radioisotopic dating. New 40Ar / 39Ar ages from the middle and top of the Blue Rim escarpment constrain the age of its strata to ∼ 49.5–48.5 Myr ago during the “falling limb” of the early Eocene Climatic Optimum. We used several geochemical tools to study provenance and parent material in both the paleosols and the associated sediments and found no change in sediment input source despite significant variation in sedimentary facies and organic carbon burial. We also reconstructed environmental conditions, including temperature, precipitation (both from paleosols), and the isotopic composition of atmospheric CO2 from plants found in the floral assemblages. Results from paleosol-based reconstructions were compared to semi-co-temporal reconstructions made using leaf physiognomic techniques and marine proxies. The paleosol-based reconstructions (near the base of the section) of precipitation (608–1167 mm yr−1) and temperature (10.4 to 12.0 ∘C) were within error of, although lower than, those based on floral assemblages, which were stratigraphically higher in the section and represented a highly preserved event later in time. Geochemistry and detrital feldspar geochronology indicate a consistent provenance for Blue Rim sediments, sourcing predominantly from the Idaho paleoriver, which drained the active Challis volcanic field. Thus, because there was neither significant climatic change nor significant provenance change, variation in sedimentary facies and organic carbon burial likely reflected localized geomorphic controls and the relative height of the water table. The ecosystem can be characterized as a wet, subtropical-like forest (i.e., paratropical) throughout the interval based upon the floral humidity province and Holdridge life zone schemes. Given the mid-paleolatitude position of the Blue Rim escarpment, those results are consistent with marine proxies that indicate that globally warm climatic conditions continued beyond the peak warm conditions of the early Eocene Climatic Optimum. The reconstructed atmospheric δ13C value (−5.3 ‰ to −5.8 ‰) closely matches the independently reconstructed value from marine microfossils (−5.4 ‰), which provides confidence in this reconstruction. Likewise, the isotopic composition reconstructed matches the mantle most closely (−5.4 ‰), agreeing with other postulations that warming was maintained by volcanic outgassing rather than a much more isotopically depleted source, such as methane hydrates.

Emerging agricultural expansion in northern regions: Insights from land-use research

Emerging agricultural expansion in northern regions: Insights from land-use research

Palaeoclimate in the Low Tatras of the Western Carpathians during MIS 11–6: Insights from multiproxy speleothem records

Two speleothems from the Demänova Cave of Liberty, located in the Low Tatras in Slovakia, were studied in detail. Age-depth modelling based on U-series dating allowed us to constrain the growth period for both speleothems to between approximately 375 and 157 ka. Based on a multiproxy approach, it was possible to identify periods with dominant warm climatic conditions, which enabled long and continuous speleothem growth during most of the marine isotope stage (MIS) 9 and in MIS 7c. Unfavourable for speleothem growth climate included glacial conditions, such as in MIS 10 or MIS 8, and periods connected with diminished rainfall or lower temperature such as in MIS 9b, MIS 7e or MIS 7b. The growth interruptions of the speleothems are related to maximum glacial episodes like in MIS 10a and late MIS 6, or were connected with a decrease in rainfall in MIS 9a and cold, harsh climate conditions in MIS 7d. The obtained records suggest relatively mild glacial periods (MIS 8 and MIS 10) and warm interglacial periods (MIS 9 and MIS 7) enabling long periods of speleothem growth. Gathered results indicate a large diversity of climate conditions during MIS 7, with atypical MIS 7d major stadial occurring within the interglacial complex. Compared records also showed the important role of local factors and changes in the alimentation area, which affected the isotopic composition of speleothem and may cause significant differences in the isotope records from the same cave system, especially during intense climate changes.

Palaeoclimatic significance of non - striate disaccate pollen in Yellandu coalfield of Godavari graben, Telangana State

The present palaeopalynological study deals with the significance of non - striate disaccate pollen from bore hole Q - 563 of Yellandu coalfield (Jawahar Khani - 5 coal block), Kothagudem sub-basin and to determine the age and palaeoclimatic interpretations of the study area based on the pollen morphological characters. For the palynological investigation, sixty samples were thoroughly analyzed in which fairly diversified palynofloral assemblages of Gondwanic affinity were recorded. About 30 genera and 50 species of palynomorphs, belong to Glossopteridales, Coniferales, Cordaitales of gymnospermous pollen, pteridophytic spores. In the present communication, the palynoflora belongs to Glossopteridales viz. Scheuringipollentites barakarensis, S. maximus, S. tentulus, Ibisporites diplosaccus, Primuspollenites levis, P. densus and Sahnites thomasii etc. Frequency distribution pattern of the palynotaxa reveals that the assemblage is dominated by the non - striate disaccates followed by striate disaccates, monosaccates (gymnosperms) and pteridophytic spores. The diversified palynoassemblage of both non striate and striate disaccates pollen strongly signifies that the Yellandu coal belt of Godavari graben belongs to Barakar Formation of Early Permian age (Late Sakmarian – Early Artinskian). Predominance of non - striate disaccate pollen recorded from the Yellandu sediments indicates a warm and high humid climatic condition with fluvial environment of deposition.

Embryonic Development of Grasshopper Populations Along Latitudinal Gradients Reveal Differential Thermoaccumulation for Adaptation to Climate Warming

Climate warming has a remarkable effect on the distribution, phenology, and development of insects. Although the embryonic development and phenology of non-diapause grasshopper species are more susceptible to warming than those of diapause species, the responses of developmental traits in conspecifically different populations to climate warming remain unknown. Here, we compared the mtDNA sequences and embryonic development of eight populations of grasshopper species (Chorthippus dubius) in field-based manipulated warming and laboratory experiments. The mtDNA sequences showed a significant genetic differentiation of the southernmost population from the other seven populations on the Mongolian Plateau. The embryonic development of the southernmost population was significantly slower than those of the northern populations at the same incubation temperatures. Interestingly, laboratory experiments showed that a significant difference exists in the effective accumulated degree days (EADD) but not in the lower development threshold temperatures (LDTT) among the different populations. The high-latitude populations required less EADD than the low-latitude populations. The warming treatments significantly accelerated the embryonic development in the field and decreased duration from embryos to hatchlings of all eight populations in the incubation. In addition, warming treatments in field significantly increased EADD requirement per stage in the incubation. Linear regression model confirmed that the embryonic development characteristics of eight populations were correlated with the annual mean temperature and total precipitation of embryonic development duration. The results indicated that grasshopper species have evolved a strategy of adjusting their EADD but not their LDTT to adapt to temperature changes. The variations in the EADD among the different populations enabled the grasshopper eggs to buffer the influences of higher temperatures on development and preserve their univoltine nature in temperate regions while encountering warmer climatic conditions. Thus, the findings of this study is valuable for our understanding species variation and evolution, and as such has direct implication for modeling biological response to climate warming.

Increased tropical vegetation respiration is dually induced by El Niño and upper atmospheric warm anomalies

Tropical vegetation respiration (TVR) is affected by extreme climate change. As it is very difficult to directly observe TVR, our understanding of the land-ocean-atmosphere carbon cycle, and particularly the regulatory effect of El Niño-Southern Oscillation (ENSO) on TVR and the land-atmosphere carbon balance, is very limited. Therefore, usingModerate Resolution Imaging Spectroradiometer (MODIS) products and meteorological data, we investigated the response of TVR to changes in ENSO during 2000–2015. The influence of El Niño on TVR was approximately 10.8% higher than that of La Niña. During El Niño years, a significant and anomalous increase in thermal measures related to TVR and ENSO and a significant and anomalous decrease in related hydrological measures favor the formation of warmer and drier climate conditions. Furthermore, the zonal distributions of air temperature and vertical velocity at 200–1000 hPa during El Niño years show that a stronger atmospheric inversion over tropical regions causes an increase in the surface temperature. Moreover, anomalous atmospheric subsidence inhibits the upward transport of water vapor, leading to a decrease in the cloud formation probability and reduced precipitation. In summary, increased surface temperatures caused by increased solar radiation and enhanced atmospheric inversion and decreased precipitation cause warmer and drier climate conditions, which forces TVR to increase. As TVR constitutes the key node of the land-atmosphere‑carbon cycle process, we focus on TVR and its close linkage with ENSO events and further establish a knowledge framework for understanding the land-atmosphere-ocean carbon cycle. This study deepens our understanding of not only the mechanism of the land-atmosphere carbon balance but also the ocean-induced terrestrial ecosystem processes spurred by ENSO-involved climate change. Plain language summaryVegetation respiration regulates the carbon balance of the land and atmosphere. As it is very difficult to directly observe vegetation respiration, our understanding of the land-ocean-atmosphere carbon cycle involved and the roles of vegetation respiration and El Niño-Southern Oscillation (ENSO) in regulating the land-atmosphere carbon balance is very limited. Therefore, using MODIS products and meteorological data, we investigated the response of tropical vegetation respiration to changes in ENSO during 2000–2015. We found that during El Niño years, warmer and drier climate conditions over tropical regions increased vegetation respiration. Exacerbating the warmer and drier climate conditions, upper atmospheric warm anomalies further caused a remarkable increase in tropical vegetation respiration. Based on the land-atmosphere‑carbon cycle process, we establish a knowledge framework for understanding the land-atmosphere-ocean carbon cycle. This knowledge deepens our understanding of not only the mechanism of the land-atmosphere carbon balance but also the ocean-induced terrestrial ecosystem processes spurred by ENSO-involved climate change.

Geochemical Behavior of Different Chemical Elements during Weathering of the Basalts in Changbai Mountain, Northeast China

Rock weathering is the main source of element geochemical cycle, which has a very important impact on the environment. Three well-developed basalt weathering profiles in Changbai Mountain area are selected in this study, and the samples of parent rock, parent material layer, sedimentary layer, and leaching layer are systematically collected. The systematic study showed that the basalt in the study area experienced moderate chemical weathering under warm and humid climate conditions, with leaching of some major elements such as silicon and aluminum. The distribution of the rare earth elements (REE) in the weathering products recalls that of an alkali-basalt, with an evident fractionation between light- and heavy-REE. Such a feature is therefore referable to the parent volcanic rock, although with some degree of leaching.

Studies of ventilation and thermal comfort in different wind tower-room configurations considering humidification for a warm climate of Mexico

Air conditioning systems in buildings demand a high energy consumption and will only be exacerbated by the threat of climate change, as coping with the increased temperatures will require a higher consumption of electricity for ventilation and cooling. The use of passive techniques to save energy and provide thermal comfort inside the buildings should be a priority for research. This work investigates the effectiveness of the passive natural ventilation system called the wind tower (windcatcher) to provide thermal comfort in a room without and with air humidification, for warm climatic conditions. The study was carried out using CFD considering three-dimensional turbulent flow for the continuous phase and a Lagrangian approach for the discrete phase. In addition, the parameters and indices of natural ventilation and thermal comfort were calculated. 54 different configurations of the wind tower and the room outlet window were evaluated. The influence of a chamfer in the tower and the optimization of water consumption in the humidifier were also investigated. The results showed that the selection of a suitable configuration and the use of a chamfer, can substantially improve ventilation and thermal comfort. In addition, the optimal mass flow rate for humidification that provides a sensation of neutral thermal comfort and minimal water consumption was found. The use of a wind tower and the application of humidification at the critical hours of the day, will provide thermal comfort throughout the day with a predicted percentage of dissatisfied lower than 10%. These results show that low energy consuming systems utilizing natural ventilation and air humidification in a wind tower-room system can be sufficient for appropriate cooling and thermal comfort.