Equatorial Climate Research Articles

New terrestrial gastropods from mid-Cretaceous Burmese amber

Gastropod fossils are abundant, but they are rarely preserved in amber. Two new terrestrial gastropods, Euthema naggsi gen. et sp. nov. and Cretatortulosa multilinea gen. et sp. nov., are described from mid-Cretaceous amber of northern Myanmar. Euthema naggsi and Cretatortulosa multilinea are the earliest records of the Diplommatinidae and Pupinidae, respectively. The discovery is consistent with the evidence suggesting a tropical rainforest climate for the mid-Cretaceous Burmese amber forest.

Baltic amber impact on historical biogeography and palaeoclimate research: oriental rove beetle Dysanabatium found in the Eocene of Europe (Coleoptera, Staphylinidae, Paederinae)

AbstractBaltic amber is a rich source of fossilized organisms and a valuable tool for evolutionary, biogeographical and palaeoenvironmental research. Because it is found in several deposits around the Baltic Sea, the exact area of origin, age in the Eocene and palaeoenvironment of the amber forest form a subject for ongoing discussion. Furthermore, there is a puzzling connection between Eocene climate change and the co‐occurrence of thermophilic and temperate insect taxa in Baltic amber, sometimes even in the same inclusions. We revisit these issues through a new piece of evidence: the rare South‐East Asian rove beetle genus Dysanabatium (11 extant species) found to be abundant in Baltic amber. We describe four new extinct species of Dysanabatium based on 13 specimens from 8 amber pieces collected in Denmark, Poland, Ukraine and Russia. These species are Dysanabatium kechrimparense sp. nov., D. aenaum sp. nov., D. damgaardi sp. nov. and D. johannesi sp. nov. The occurrence of one species, D. kechrimparense sp. nov., in the amber from all countries, as well as its co‐occurrence with D. damgaardi sp. nov. in one amber piece from Russia, suggest a possible common origin of Baltic amber from all these deposits. Dysanabatium adds to a plethora of fossil species congeneric with extant species restricted to South‐East Asia, which points to the warm and equable climate of the north European Eocene amber forest.

Inverse correlation between daily outdoor temperature and blood pressure in six US cities.

This study aims to evaluate the relationship between mean outdoor temperature and mean daily blood pressure (BP) and heart rate (HR) among six, large, geographically and climatically diverse US cities. We collected BP and HR data from Higi stations, located in a wide range of neighborhood grocery stores and retail pharmacies, from six US cities (Houston, Los Angeles, Miami, Boise, Chicago, and New York City). Outdoor daily temperature data were collected from the National Centers for Environmental Information’s database. Pearson’s correlation was used to assess the linear relationship between mean daily outdoor temperature and mean daily BP and HR for each city from May 2016 through April 2017. A total of 2 140 626 BP and HR readings were recorded in the six study cities. Mean outdoor temperature was inversely correlated with both mean daily average systolic (r=−0.69, P<0.0001) and diastolic (r=−0.71; P<0.0001) BPs, but not HR (r<0.0001, P=0.48). We also found that temperature change had a larger impact on BP in equatorial climates such as Miami compared with colder and more temperature variable cities like Chicago and Boise. Previous studies have found that BP varies seasonally, but few have looked at the impact of daily temperature on both BP and HR changes. Our study is one of the largest and most climatically diverse populations ever looking at this relationship. Our results suggest that temperature, and perhaps geography, should play a role in tailoring individualized evaluation and treatment for hypertensive diseases.

Tropical cyclogenesis in warm climates simulated by a cloud-system resolving model

Here we investigate tropical cyclogenesis in warm climates, focusing on the effect of reduced equator-to-pole temperature gradient relevant to past equable climates and, potentially, to future climate change. Using a cloud-system resolving model that explicitly represents moist convection, we conduct idealized experiments on a zonally periodic equatorial β-plane stretching from nearly pole-to-pole and covering roughly one-fifth of Earth’s circumference. To improve the representation of tropical cyclogenesis and mean climate at a horizontal resolution that would otherwise be too coarse for a cloud-system resolving model (15 km), we use the hypohydrostatic rescaling of the equations of motion, also called reduced acceleration in the vertical. The simulations simultaneously represent the Hadley circulation and the intertropical convergence zone, baroclinic waves in mid-latitudes, and a realistic distribution of tropical cyclones (TCs), all without use of a convective parameterization. Using this model, we study the dependence of TCs on the meridional sea surface temperature gradient. When this gradient is significantly reduced, we find a substantial increase in the number of TCs, including a several-fold increase in the strongest storms of Saffir–Simpson categories 4 and 5. This increase occurs as the mid-latitudes become a new active region of TC formation and growth. When the climate warms we also see convergence between the physical properties and genesis locations of tropical and warm-core extra-tropical cyclones. While end-members of these types of storms remain very distinct, a large distribution of cyclones forming in the subtropics and mid-latitudes share properties of the two.

Epidemiology of traumatic myiasis due to Chrysomya bezziana in Indonesia

&lt;p&gt;Epidemiology of traumatic myiasis in Indonesia was studied by the widespread collection of fly larvae from infested livestock in passive case detection surveys involving veterinary clinics. In addition, monthly data from Kediri regency in Eastern Java were analysed from 2006-2009 to explore the seasonality of myiasis. Larvae from a total of 260 cases from the nationwide survey and 341 cases from Kediri were identified. Except for 5 cases of chicken infestation due to Musca species in the nationwide survey, all other cases were exclusively caused by the Old World screwworm (OWS) fly, Chrysomya bezziana (Diptera: Calliphoridae). The monthly numbers of cases at Kediri were very variable, with cases in all months, but there was statistical evidence for an increase in cases in January and December, during the rainy season. The greatest numbers of infestations recorded were from cattle and goats. The most frequently infested sites nationwide and in Kediri were the vulva and umbilicus, associated with calving, which is a major risk period for traumatic myiasis. Mitochondrial DNA typing of 176 specimens was useful for detecting multiple infestations, but no association was found between genetic lineage and host. The equatorial climate of Indonesia, combined with poor husbandry systems are factors that help to support OWS fly development year round. Even if not considered a disease of strategic importance, screwworm myiasis remains a threat to livestock production in Indonesia and a major welfare issue that requires constant interventions by farmers. The new and collated epidemiological data presented represent the most extensive survey of traumatic myiasis in Indonesia to date and provide a valuable baseline to support integrated pest management programs.&lt;/p&gt;

Evaluation of Rain Attenuation Models in Satellite Links under Tropical and Equatorial Climates

Attenuation induced by rain is the most relevant propagation effect in satellite communications at frequencies above 10 GHz. Recent research suggests that classical and widely accepted prediction models, such as ITU-R P.618-11 and Crane, do not perform well at intense rain regime found in tropical regions. Over the last decade, several models formulated specifically for equatorial and tropical climate were proposed. This paper summarizes some of the new rain attenuation models, describing its parameters and applications. The models were tested comparing predicted attenuation values to measurements available at the ITU propagation data bank (ITU DBSG3), taken from 10 locations over the Brazilian territory. The prediction error evaluation was carried out according to the ITU Recommendation P.311. The evaluation results show that some of those prediction methods can provide better accuracy than ITU-R P.618-11 for climates found in Brazil. The use of these models satellite link budget planning can lead to a target reliability while avoiding the over dimensioned systems.

Latitudinal Variation in Childhood Diarrhoea is associated with Local Rainfall and Population Density

Background/Aim: Scientists have long predicted the impacts of climate-related infectious disease emergence, and yet the extent to which local socioeconomic and demographic drivers can mask the influence of weather variation and environmental settings on child health is widely debated. Models that couple weather and environmental conditions with demographic factors offer a potentially improved approach for estimating shifts in disease distribution and risk under climate change. Methods: With a focus on childhood diarrhoea caused by the parasite Cryptosporidium spp., – an infection easily controlled by public health interventions but also strongly linked to environmental conditions through waterborne spread, we systematically review and empirically model the effects of local weather and flooding history on cryptosporidiosis, after controlling for seasonality, publication bias, access to improved sanitation, health resources and population density at a global scale. Results: We examined 1588 papers on childhood cryptosporidiosis and identified 36 studies representing a range of geographic locations and climatic, environmental and socio-economic conditions. Generalized linear mixed effects models for equatorial, sub-tropical and temperate climates found local rainfall and population density were the most important determinants of childhood cryptosporidiosis across all regions. In lower latitudes, local rainfall and population density were significant and positively associated with childhood cryptosporidiosis. In temperate latitudes there was a significant negative association of disease with rainfall and a positive association with population density. Conclusions: This global empirical analysis indicates that climate and demographic change can affect childhood cryptosporidiosis, with differential patterns between low and high latitude regions. These findings underscore the need to consider locality specific environmental and demographic factors when assessing disease distributional shifts and risks due to climate change. These results may have implications for developing environment-focused public health policies to manage health risks of climate change for future generations.

Process-level improvements in CMIP5 models and their impact on tropical variability, the Southern Ocean, and monsoons

Abstract. The performance of updated versions of the four earth system models (ESMs) CNRM, EC-Earth, HadGEM, and MPI-ESM is assessed in comparison to their predecessor versions used in Phase 5 of the Coupled Model Intercomparison Project. The Earth System Model Evaluation Tool (ESMValTool) is applied to evaluate selected climate phenomena in the models against observations. This is the first systematic application of the ESMValTool to assess and document the progress made during an extensive model development and improvement project. This study focuses on the South Asian monsoon (SAM) and the West African monsoon (WAM), the coupled equatorial climate, and Southern Ocean clouds and radiation, which are known to exhibit systematic biases in present-day ESMs. The analysis shows that the tropical precipitation in three out of four models is clearly improved. Two of three updated coupled models show an improved representation of tropical sea surface temperatures with one coupled model not exhibiting a double Intertropical Convergence Zone (ITCZ). Simulated cloud amounts and cloud–radiation interactions are improved over the Southern Ocean. Improvements are also seen in the simulation of the SAM and WAM, although systematic biases remain in regional details and the timing of monsoon rainfall. Analysis of simulations with EC-Earth at different horizontal resolutions from T159 up to T1279 shows that the synoptic-scale variability in precipitation over the SAM and WAM regions improves with higher model resolution. The results suggest that the reasonably good agreement of modeled and observed mean WAM and SAM rainfall in lower-resolution models may be a result of unrealistic intensity distributions.

Tetrapod distribution and temperature rise during the Permian-Triassic mass extinction.

The Permian–Triassic mass extinction (PTME) had an enormous impact on life in three ways: by substantially reducing diversity, by reshuffling the composition of ecosystems and by expelling life from the tropics following episodes of intense global warming. But was there really an ‘equatorial tetrapod gap', and how long did it last? Here, we consider both skeletal and footprint data, and find a more complex pattern: (i) tetrapods were distributed both at high and low latitudes during this time; (ii) there was a clear geographic disjunction through the PTME, with tetrapod distribution shifting 10–15° poleward; and (iii) there was a rapid expansion phase across the whole of Pangea following the PTME. These changes are consistent with a model of generalized migration of tetrapods to higher latitudinal, cooler regions, to escape from the superhot equatorial climate in the earliest Triassic, but the effect was shorter in time scale, and not as pronounced as had been proposed. In the recovery phase following the PTME, this episode of forced range expansion also appears to have promoted the emergence and radiation of entirely new groups, such as the archosaurs, including the dinosaurs.

Hyperosmotic versus Hypoosmotic Stress in Plants

The balance of water between the cell and its environment is crucial to all organisms, but especially for root plant cells that are exposed to extrinsic condition directly. High salt concentration in soil leads to loose of water from the plant cell (hyper-osmotic stress). Sufficient supply with water causes that the plant cell is turgid (i.e. increases its volume, the cell membrane experiences turgor pressure from the cell interior against the resistance of the cell wall), which is healthy state for most plants. However, upon repeated flooding (e.g. in a tropical rain-forest climate), the plants may experience a prolonged hypo-osmotic stress. Whereas the hyper-osmotic stress is one of the most studied abiotic stress factor, hypo-osmotic is at the edge of scientists´ interest, still considered as “physiological conditions”. However, both types of osmotic stress are characterized by involvement of stress sensing, oxidative burst, and signal transduction. In this study, sensors of osmotic stress (mechano-sensitive ion channels), osmolytes, and processes followed hypo- and hyper-osmotic stress are emphasized, although hypo-osmotic stress in comparison to hyper- have to be largely studied.

Effect of clay mineral types on the strength and microstructure properties of soft clay soils stabilized by epoxy resin

Soft clay soils due to their various geotechnical problems, stabilized with different additives. Traditional additives such as cement and lime will not able to increase the soil strength properties significantly. So, it seems necessary to use new additives for increasing strength parameters of soft clay soils significantly. Among the new additives, epoxy resins have excellent physical and mechanical properties, low shrinkage, excellent resistance to chemicals and corrosive materials, etc. So, in this research, epoxy resin used for stabilization of soft clay soils. For comprehensive study, three clay soil samples with different PI and various clay mineral types were studied. A series of uniaxial tests, SEM and XRD analysis conducted on the samples. The results show that using epoxy resin increases the strength parameters such as UCS, elastic modulus and material toughness about 100 to 500 times which the increase was dependent on the type of clay minerals type in the soil. Also, In addition to water conservation, the best efficiency in the weakest and most sensitive soils is the prominent results of stabilization by epoxy resin which can be used in different climatic zones, especially in hot and dry and equatorial climate which will be faced with water scarcity.

DISTRIBUTION OF THE GENUS CEDRELA IN ECUADOR

The genus Cedrela in Ecuador has four species: C. odorata, C. montana, C. fissilis and C. nebulosa. Cedrela was one of the economically most important timber in the past, due to its wood properties. The genus has a long history of overharvesting and selective logging; as a consequence a substantial genetic degradation have occurred in Ecuador. Currently, three species of Cedrela are included in the IUCN Red List. C. odorata and C. nebulosa are listed as vulnerable species and C. fissilis as endangered species. In spite of their conservation status and priority, few studies related to geographical distribution have been done. Then, the geographic distribution at local level had been carried out to provide a valuable tool to the conservation and management of these species. Field sampling and herbarium compilation showed C. montana is restricted to the Ecuadorian highlands in the western and eastern Andean montane region between 805 to 3200 masl (meters above sea level). Cedrela nebulosa is located in Andean region about 1400 to 2300 masl. C. odorata is the most widely distributed, occupying areas in the Amazon (200-1300 masl), Pacific (330-825 masl) and insular regions (350 masl). While, Cedrela fissilis is only found in the Amazon Region about 200 to 510 masl. This basic information about current distribution and abundance of cedar species is primordial to generate sufficient tools to formulate the strategies of management and conservation of these species in the country. The widespread distribution of C. odorata have been found in the Amazonian and Pacific regions, indicating that it is adapted to tropical rainforest and tropical monsoon climates. To prove if there are adaptations to both habitats morphological, ecological and phylogenetic studies must be carried out.

Satisfaction of Residents Towards Internal Courtyard Buildings

Residential buildings that were designed with internal courtyards offer a comfortable and pleasant indoor environment. Past research on the benefits of internal courtyards have been scientifically proven, however, the results seemed disreputable in terms of its satisfaction by occupants of a building. A survey using a set of questionnaire was conducted at two selected residential colleges in the University of Malaya to gauge the satisfaction level of residents towards an existing internal courtyard. It is evident that the majority of respondents at both colleges have given positive feedback on the satisfaction of the building layout quality, comfort level in terms of the natural daylighting, thermal comfort and indoor air quality as well as the degree of their work productivity. These findings indicate that the internal courtyard is relevant to be applied when designing a building, particularly low-rise residential buildings in the equatorial climate region.

The emergence of equatorial deep jets in an idealised primitive equation model: an interpretation in terms of basin modes

Ocean circulation models do not generally exhibit equatorial deep jets (EDJs), even though EDJs are a recognised feature of the observed ocean circulation along the equator and they are thought to be important for tracer transport along the equator and even equatorial climate. EDJs are nevertheless found in nonlinear primitive equation models with idealised box geometry. Here we analyse several such model runs. We note that the variability of the zonal velocity in the model is dominated by the gravest linear equatorial basin mode for a wide range of baroclinic vertical normal modes and that the EDJs in the model are dominated by energy contained in vertical modes between 10 and 20. The emergence of the EDJs is shown to involve the linear superposition of several such neighbouring basin modes. Furthermore, the phase of these basin modes is set at the start of the model run and, in the case of the reference experiment, the same basin modes can be found in a companion experiment in which the amplitude of the forcing has been reduced by a factor of 1000. We also argue that following the spin-up, energy must be transferred between different vertical modes. This is because the model simulations are dominated by downward phase propagation following the spin-up whereas our reconstructions imply episodes of upward and downward propagation. The transfer of energy between the vertical modes is associated with a decadal modulation of the EDJs.

Sympatric occurrence and population dynamics of Scylla spp. in equatorial climate: Effects of rainfall, temperature and lunar phase

Mud crabs (Scylla spp.) are known to exist sympatrically in the wild. However, information on their population dynamics and the influence of climate parameters and lunar phase, especially along the equatorial region, are limited. Four sampling stations representing three seas (the Strait of Malacca, South China Sea and Sulu Sea) along the equator were selected. Mud crabs were collected using baited traps during spring tides from April 2012 to July 2013. All three Scylla species, S. olivacea, S. tranquebarica and S. paramamosain live in sympatry in the three seas. Scylla olivacea is the most prevalent species in the Strait of Malacca and South China Sea, whereas S. paramamosain dominates the Sulu Sea. The total crab abundance was not affected by rainfall or temperature. The abundance of S. tranquebarica in Strait of Malacca was negatively correlated with temperature and positively correlated with rainfall whereas the abundance of S. paramamosain positively correlated with temperature only at South China Sea. Scylla tranquebarica was the largest in terms of body size and it showed interchanging abundance trends with S. paramamosain. The average body size of S. paramamosain did not differ significantly with that of S. tranquebarica and S. olivacea. This decrease is most likely attributed to overfishing. Significant seasonal fluctuations in mean carapace width were detected in S. tranquebarica and S. paramamosain, but not in S. olivacea. The monthly sex ratio of all three species occasionally fluctuates above the equal sex ratio value. Lunar phase did not affect species abundance, but males and females were significantly heavier during full moon. These findings serve as a baseline of seasonal variation in crab population dynamics that are useful in mud crab fisheries and resource management.

The Climate Range Expansion of Aedes albopictus (Diptera: Culicidae) in Asia Inferred From the Distribution of Albopictus Subgroup Species of Aedes (Stegomyia).

We compared climatic distribution ranges between Aedes albopictus (Skuse) (Diptera: Culicidae) and the five wild (nondomesticated) species of Albopictus Subgroup of Scutellaris Group of Aedes (Stegomyia) in southern Asia. Distribution sites of the wild species concentrate in seasonal forest and savannah climate zones in India, Indochina, and southern China. The distribution of Ae. albopictus is broader than the wild species under 1) tropical rain-forest climate, 2) steppe and temperate savannah climate, and 3) continental climate with large seasonal temperature variation (hot summer and cold winter) at temperate lowlands (northernmost sites 40°N in Ae. albopictus vs 32°N in the wild species). However, the distribution of Ae. albopictus is more limited at tropical and subtropical highlands where the climate is cool but less continental (small seasonal variation, mild summer, and winter). We discuss a possibility that the broader climate ranges of Ae. albopictus are ecological or eco-evolutionary consequences of adaptation to human habitats. We also propose a general scenario for the origin, dispersal, and adaptation of Ae. albopictus in Asia as a hypothesis for future research.

Thermal comfort improvement of naturally ventilated patient wards in Singapore

Located near the equator, Singapore has a tropical rainforest climate with high temperature and high humidity. In hospitals of Singapore, the subsidized patient wards are designed to be naturally ventilated, considering the affordability for patients. However, due to the high occupant density of the patient wards and the hot humid climate, occupants may feel discomfort, especially in the older hospital wards which were not well designed for natural ventilation. In this paper, the thermal comfort level of occupants at Singapore's Changi General Hospital (CGH) is evaluated based on both in-situ measurements and modeling analysis. Against this backdrop, several low energy solution concepts that potentially improve the thermal comfort level of occupants in patient wards are analyzed and simulated using detailed building thermodynamic and airflow simulation. We found that this approach of combining thermodynamics, computational fluid dynamics, and thermal comfort level models was effective for analyzing and comparing the thermal comfort impact of alternative, low-energy building retrofit concepts. We also found that passive solutions to ventilation could be used effectively for a patient hospital ward, even in the tropical warm climate of Singapore.

Techno-economic evaluation of roof thermal insulation for a hypermarket in equatorial climate: Malaysia

One of the effective measures to save cooling energy in countries with an equatorial climate like Malaysia is through the use of roof thermal insulation. This paper focuses on the economic evaluation of commonly used thermal insulation solutions for a typical hypermarket roof in Malaysia. Eight commonly used thermal insulation systems have been identified and evaluated. In order to find the most cost-effective thermal insulation measure, three types of economic evaluation methods i.e. life-cycle savings, discounted payback period and internal rate of return have been used. All the eight thermal insulation systems were ranked accordingly to these three methods It has been found that insulation system using small bubble aluminium foil ranked first with the highest life-cycle savings, internal rate of return and the shortest payback period. Sensitivity analyses have also been carried out to identify the effects of changes in the key parameters for example cost of capital and lifetime period have on the evaluation results. The analyses show that small bubble aluminium foil is least susceptible to fluctuation of these two parameters relative to other examined insulation materials.

Importance of lithology in defining natural background concentrations of Cr, Cu, Ni, Pb and Zn in sedimentary soils, northeastern Brazil

The sedimentary basins of Recôncavo and Tucano, Bahia, represent the most important Brazilian Phanerozoic continental basin system, formed during fracturing of Gondwana. The northern basin of Tucano has a semiarid climate (Bsh) while the southern basin of Recôncavo has a tropical rainforest climate (Af). The aim of this study was to determine the distribution of trace metals in soils derived from various sedimentary rocks and climates. Soils were collected at 30 sites in 5 geological units at 0–20 cm and 60–80 cm deep under native vegetation. Physical and chemical attributes (particle size distribution, pH, Al, exchangeable bases, organic matter) were determined, as well as the pseudo-total concentrations (EPA 3050 b) and the total concentrations (X-ray fluorescence) of Cr, Cu, Ni, Pb and Zn. The concentrations of metals were overall correlated to soil texture, according to lithologic origin. Shales resulted in Vertisols 30.4 (Zn), 27.2 (Ni), 16.9 (Cu), 7.5 (Cr) and 2.5 (Pb) times more concentrated than Arenosols derived from the sandstones. High Cr and Ni values in clay soils from shales were attributed to diffuse contamination by erosion of mafic rocks of the Greenstone Belt River Itapicuru (from 3 km northwest of the study area) during the late Jurassic. Tropical rainforest climate resulted in a slight enrichment of Pb and Cr, and Ni had the higher mobility during soil formation (enrichment factor up to 6.01). In conclusion, the geological environment is a much more controlling factor than pedogenesis in the concentration of metals in sedimentary soils.

Coleoptera from the middle-upper Eocene European ambers: generic composition, zoogeography and climatic implications

The paper contains a review of coleopteran genera known from Baltic, Bitterfeld and Rovno amber localities. Altogether 420 genera (191 extinct and 229 extant) from 78 families are listed from these three Lagerstätten (as of 7 March 2017). The listed beetles were analyzed zoogeographically and distributional maps for 72 genera were compiled. One-quarter (56) of the genera that have survived since the Eocene have cosmopolitan ranges at present; 35 extant genera have been extripated from the Palaearctic since the Eocene. Approximately 40% of beetle genera from the middle-upper Eocene European ambers can be encountered in the wild in present-day Europe, while 5 of these genera are supposed to be European relict endemics originating in Fennosarmatia. The general similarity of the Baltic amber (s.l.) beetle assemblage to modern south Palaearctic fauna is the strongest, the Nearctic elements are more numerous in the middle-upper Eocene European ambers than the Oriental taxa. The simplified Mutual Climatic Range (MCR) method was used for palaeoclimate reconstruction based on fossil beetles. The coleopteran assemblage of Baltic amber is interpreted as indicative of warm temperate, humid, equable climate with reduced thermal seasonality [annual average temperatures range from +10–20˚C; mean of the coldest month temperatures around +10˚C; mean of the hottest month temperature around +20–24˚C; annual precipitation around 750–1500 mm]. The primary importance of high humidity for existence of the Eocene biota is pointed out.