Sea Breeze Front and Outdoor Thermal Comfort during Summer in Northeastern Brazil

Characterizing the behaviour of the sea breeze phenomenon is the foremost factor in the reduction in the heat stress and the achievement of the pleasant environment in coastal cities globally. However, this seminal study shows that the Sea Breeze Front (SBF) development can be related to an increase in outdoor thermal discomfort in a northeastern Brazilian city during summer. We explored the relationship between SBF and thermal comfort conditions using in situ meteorological observations, the SBF identification method, local climate zones (LCZs) classification, and the Physiological Equivalent Temperature (PET) thermal comfort index. SBF days and Non-SBF days were characterized in terms of weather conditions, combining meteorological data and technical bulletins. SBF days included hot and sunny days associated with the centre of the Upper Tropospheric Cyclonic Vortices (UTCV). In contrast, Non-SBF days were observed in UTCV’s periphery because of cloudy sky and rainfall. The results showed that the mean temperature and PET in the SBF days were 2.0 C and 3.8 C higher, respectively, compared to Non-SBF days in all LCZ sites. The highest PET, of 40.0 C, was found on SBF days. Our findings suggest that SBF development could be an aggravating factor for increasing heat stress of the people living in the northeastern coast of the Brazilian city, after SBF passage.info:eu-repo/semantics/publishedVersio

Unsteady Land-Sea Breeze Circulations in the Presence of a Synoptic Pressure Forcing

Unsteady land-sea breezes (LSBs) resulting from time-varying surface thermal contrasts are explored in the presence of a constant synoptic pressure forcing, Mg, when the latter is oriented from sea to land versus land to sea. Large eddy simulations reveal the development of four distinctive regimes depending on the joint interaction between (Mg, orientation) and thermal contrasts in modulating the fine-scale dynamics. Time lags, computed as the shifts that maximize correlation coefficients of the dynamics between transient and the corresponding steady state scenarios at maximum thermal contrast, are found to be significant and to extend 2 hours longer for sea to land compared to land to sea. These diurnal dynamics result in non-equilibrium flows that behave differently over the two patches for both orientations. Turbulence is found to be out of equilibrium with the mean flow, and the mean itself is found to be out of equilibrium with the thermal forcing. The sea surface heat flux is consistently more sensitive than its land counterpart to the time-varying external forcing, and more so for synoptic forcing from land-to-sea. Hence, although the land reaches equilibrium faster, the sea patch is found to exert a stronger control on the final turbulence-mean flow equilibrium response. Finally, vertical velocity profile at the shore and shore-normal velocity transects at the first grid level are shown to encode the multiscale regimes of the LSBs evolution, and can thus be used to identify these regimes using k-means clustering.Comment: 41 pages, 10 figure

Computational modeling of land surface temperature using remote sensing data to investigate the spatial arrangement of buildings and energy consumption relationship

The effect of urban form on energy consumption has been the subject of various studies around the world. Having examined the effect of buildings on energy consumption, these studies indicate that the physical form of a city has a notable impact on the amount of energy consumed in its spaces. The present study identified the variables that affected energy consumption in residential buildings and analyzed their effects on energy consumption in four neighborhoods in Tehran: Apadana, Bimeh, Ekbatan-phase I, and Ekbatan-phase II. After extracting the variables, their effects are estimated with statistical methods, and the results are compared with the land surface temperature (LST) remote sensing data derived from Landsat 8 satellite images taken in the winter of 2019. The results showed that physical variables, such as the size of buildings, population density, vegetation cover, texture concentration, and surface color, have the greatest impacts on energy usage. For the Apadana neighborhood, the factors with the most potent effect on energy consumption were found to be the size of buildings and the population density. However, for other neighborhoods, in addition to these two factors, a third factor was also recognized to have a significant effect on energy consumption. This third factor for the Bimeh, Ekbatan-I, and Ekbatan-II neighborhoods was the type of buildings, texture concentration, and orientation of buildings, respectively

Making 'chemical cocktails' - evolution of urban geochemical processes across the periodic table of elements.

Urbanization contributes to the formation of novel elemental combinations and signatures in terrestrial and aquatic watersheds, also known as 'chemical cocktails.' The composition of chemical cocktails evolves across space and time due to: (1) elevated concentrations from anthropogenic sources, (2) accelerated weathering and corrosion of the built environment, (3) increased drainage density and intensification of urban water conveyance systems, and (4) enhanced rates of geochemical transformations due to changes in temperature, ionic strength, pH, and redox potentials. Characterizing chemical cocktails and underlying geochemical processes is necessary for: (1) tracking pollution sources using complex chemical mixtures instead of individual elements or compounds; (2) developing new strategies for co-managing groups of contaminants; (3) identifying proxies for predicting transport of chemical mixtures using continuous sensor data; and (4) determining whether interactive effects of chemical cocktails produce ecosystem-scale impacts greater than the sum of individual chemical stressors. First, we discuss some unique urban geochemical processes which form chemical cocktails, such as urban soil formation, human-accelerated weathering, urban acidification-alkalinization, and freshwater salinization syndrome. Second, we review and synthesize global patterns in concentrations of major ions, carbon and nutrients, and trace elements in urban streams across different world regions and make comparisons with reference conditions. In addition to our global analysis, we highlight examples from some watersheds in the Baltimore-Washington DC region, which show increased transport of major ions, trace metals, and nutrients across streams draining a well-defined land-use gradient. Urbanization increased the concentrations of multiple major and trace elements in streams draining human-dominated watersheds compared to reference conditions. Chemical cocktails of major and trace elements were formed over diurnal cycles coinciding with changes in streamflow, dissolved oxygen, pH, and other variables measured by high-frequency sensors. Some chemical cocktails of major and trace elements were also significantly related to specific conductance (p<0.05), which can be measured by sensors. Concentrations of major and trace elements increased, peaked, or decreased longitudinally along streams as watershed urbanization increased, which is consistent with distinct shifts in chemical mixtures upstream and downstream of other major cities in the world. Our global analysis of urban streams shows that concentrations of multiple elements along the Periodic Table significantly increase when compared with reference conditions. Furthermore, similar biogeochemical patterns and processes can be grouped among distinct mixtures of elements of major ions, dissolved organic matter, nutrients, and trace elements as chemical cocktails. Chemical cocktails form in urban waters over diurnal cycles, decades, and throughout drainage basins. We conclude our global review and synthesis by proposing strategies for monitoring and managing chemical cocktails using source control, ecosystem restoration, and green infrastructure. We discuss future research directions applying the watershed chemical cocktail approach to diagnose and manage environmental problems. Ultimately, a chemical cocktail approach targeting sources, transport, and transformations of different and distinct elemental combinations is necessary to more holistically monitor and manage the emerging impacts of chemical mixtures in the world's fresh waters

Identification of patterns in long-term observations of the cloudy boundary layer

Understanding atmospheric boundary layer (ABL) processes is a key aspect in improving parameterizations in weather forecast and climate prediction models, but also for renewable energy and air quality studies. The ABL, as the lowest part of the atmosphere, can be directly affected by heterogeneities in land surface properties like soil, vegetation and topography, creating patterns at different temporal and spatial scales. In this context, turbulent mixing plays an important role in connecting the atmosphere to the Earth's surface. The turbulent motions are responsible for the thermodynamic structure of the ABL by redistributing heat and moisture and the transport of constituents like aerosols and pollutants away from the surface. These processes are the main drivers for the development of ABL clouds, which in turn feed back to the ABL and surface through interaction with solar radiation, coupling to the large-scale circulation and precipitation formation. This links back to the aim of model improvement, since clouds are one of the largest source of uncertainty in global models. Therefore interdisciplinary research is required to capture the interplay between the different compartments of the Earth. The Transregional Collaborative Research Centre 32 (TR32) in its third phase is dedicated to find these patterns in the soil-vegetation-atmosphere system by a monitoring, modelling and data assimilation approach. Within the TR32 project D2 special emphasis is on measuring, modelling and understanding the spatio-temporal structures in land surface-atmosphere exchange at the Jülich ObservatorY for Cloud Evolution (JOYCE). For the typical ABL process scales of seconds to hours and meters to kilometers, ground-based remote sensing observations are well suited to continuously gather comprehensive information on the atmospheric state in a long-term perspective. With additional model simulations the conceptual process understanding can be improved. This study focuses on the long-term characterisation of the cloudy boundary layer to identify patterns that can be further linked to surface properties at JOYCE. For this purpose, a classification for characterizing ABL turbulence is developed (Publication I). The classification, based on Doppler wind lidar (DWL) data, identifies turbulence regions in the ABL and assigns a mixing source using multiple DWL quantities. In this way, convective, wind shear and cloud driven turbulence can be distinguished under most atmospheric conditions. The method is applied at two research sites, showing a distinct behavior for different climate regimes in terms of the diurnal and seasonal cycle of ABL development. In the analysis of the long-term data sets, nocturnal low-level jets (LLJ) are identified as an important source of shear generated mixing. Therefore, a long-term record of LLJ periods, compiled with DWL observations, is investigated in Publication II. The high frequency of occurrence and wind speeds, associated with significant turbulence close to the surface, reveal the relevance of LLJs for wind energy applications. In addition, a strong interaction of the wind field with the surrounding topography can be seen in the DWL measurements, as well as in the results of a high-resolution large-eddy simulation (LES). Also during the day, when the buoyancy production represents the main factor of convective ABL mixing, the interaction between the land surface and the atmosphere is strongly influenced by surface properties. In particular, the local transport of water vapor in moist thermals is a key mechanism for the coupling of clouds to the underlying land surface and a spatially heterogeneous distribution of land use types can lead to patterns in atmospheric water vapor fields (Publication III). Besides a scanning microwave radiometer (MWR), also satellite and LES data are taken into account, showing a good agreement in identifying the direction of water vapor sources. Convective clouds, that are frequently forming in the ABL due to this convective humidity transport, often contain small amounts of liquid water. These thin liquid water clouds, with a low liquid water path (LWP), are important in terms of their interaction with radiation. In the range of low LWP values, the radiative fluxes are very sensitive to small changes in the amount liquid water contained in the clouds. For a correct representation of the cloud microphysical and optical properties, statistical retrievals using a neural network approach are developed in Publication IV. The retrievals with low computational demand are derived from ground-based observations and make use of the distinct sensitivities in different spectral regimes. While the microwave regime suffers from high uncertainties in low LWP situations, the infrared regime reveals saturation effects for higher LWP. A combination of both spectral regimes yields the best results for the whole range of LWP values

Remote Sensing of the Urban Heat Island Effect Across Biomes in the Continental USA

Impervious surface area (ISA) from the Landsat TM-based NLCD 2001 dataset and land surface temperature (LST) from MODIS averaged over three annual cycles (2003-2005) are used in a spatial analysis to assess the urban heat island (UHI) skin temperature amplitude and its relationship to development intensity, size, and ecological setting for 38 of the most populous cities in the continental United States. Development intensity zones based on %ISA are defined for each urban area emanating outward from the urban core to the nonurban rural areas nearby and used to stratify sampling for land surface temperatures and NDVI. Sampling is further constrained by biome and elevation to insure objective intercomparisons between zones and between cities in different biomes permitting the definition of hierarchically ordered zones that are consistent across urban areas in different ecological setting and across scales. We find that ecological context significantly influences the amplitude of summer daytime UHI (urban-rural temperature difference) the largest (8 C average) observed for cities built in biomes dominated by temperate broadleaf and mixed forest. For all cities combined, ISA is the primary driver for increase in temperature explaining 70% of the total variance in LST. On a yearly average, urban areas are substantially warmer than the non-urban fringe by 2.9 C, except for urban areas in biomes with arid and semiarid climates. The average amplitude of the UHI is remarkably asymmetric with a 4.3 C temperature difference in summer and only 1.3 C in winter. In desert environments, the LST's response to ISA presents an uncharacteristic "U-shaped" horizontal gradient decreasing from the urban core to the outskirts of the city and then increasing again in the suburban to the rural zones. UHI's calculated for these cities point to a possible heat sink effect. These observational results show that the urban heat island amplitude both increases with city size and is seasonally asymmetric for a large number of cities across most biomes. The implications are that for urban areas developed within forested ecosystems the summertime UHI can be quite high relative to the wintertime UHI suggesting that the residential energy consumption required for summer cooling is likely to increase with urban growth within those biomes

The potential impact of climate change on the genetic diversity of the endangered western leopard toad, Sclerophrys pantherina

Climate change is now considered to be one of the greatest threats to the persistence of biodiversity. Much work has focused on the potential for climatic shifts to alter species' ranges, phenology, physiology, and behaviour, addressing higher level units of biodiversity from populations to biomes. However, the potential effects of climate change on the most fundamental unit of biodiversity, intraspecific genetic diversity, has only recently received research attention. Studies to date suggest that the accelerated climatic changes we currently face could cause a loss of intraspecific diversity, hampering the ability of populations to respond to further environmental change. Amphibians are considered to be one of the most vulnerable taxa to climate change. The amphibians of the Western Cape of South Africa provide a powerful opportunity to study the impact of climate change on genetic diversity, as many are endemic, threatened, and generally considered to be poor dispersers, limiting their ability to respond to climatic changes through range shifts. This project had two aims: first, to explore the potential impact of climatic shifts on the genetic landscape of the endemic and Endangered western leopard toad, Sclerophrys pantherina, a species with a disjunct distribution on either side of the Cape Flats. Second, I aimed to test the hypothesis that climatic fluctuations drive genetic divergence, a mechanism which may explain the potential overlap of high diversity areas with areas of high climatic instability. Population genetic analyses supported the findings of previous genetic work on S. pantherina, that populations in the Cape Metropole and the Overstrand Municipality (to the west and east of the Cape Flats, respectively) are genetically distinct, and thus should be treated as separate conservation units. Higher haplotype diversity was identified in the populations in the Cape Metropole when compared with the Overstrand, highlighting the importance of urban habitat patches in harbouring diversity in the species. Distinct pockets of low haplotype diversity were identified at Observatory and Hout Bay, suggesting a lack of connectivity between these and adjacent breeding sites, likely due to urban-associated habitat fragmentation. Species distribution modelling revealed that the species could lose a substantial amount of climatically suitable space in its current area of occurrence by 2070. Furthermore, the degree of loss was not uniform across the species' distribution. The populations of the Cape Metropole were predicted to experience greater losses in climatically suitable space than populations in the Overstrand. Additionally, the change in climatic suitability between the mid-Holocene (6,000 years ago) and present as well as the change in suitability between future (2050 and 2070) and present were significant predictors of genetic diversity, where areas of the greatest change in suitability between time periods were associated with the highest genetic diversity. Future efforts to conserve the species should focus on establishing connectivity between breeding sites to allow for the rescue of genetically depauperate sites. Efforts to mitigate the drastic negative effects of climate change predicted by the species distribution models should prioritise the breeding sites in the Cape Metropole, which are both higher in diversity and at greater risk from climate change. Mitigation efforts will likely require the application of engineered solutions to promote the maintenance of suitable wetland habitat for the species

The Impact of Mount Washington on the Height of the Boundary Layer and the Vertical Structure of Temperature and Moisture

Discrimination of the type of air mass along mountain slopes can be a challenge and is not commonly performed, but is critical for identifying factors responsible for influencing montane weather, climate, and air quality. A field campaign to measure air mass type and transitions on the summit of Mount Washington, New Hampshire, USA was performed on 19 August 2016. Meteorological observations were taken at the summit and at several sites along the east and west slopes. Ozone concentrations were measured at the summit and on the valley floor. Additionally, water vapor stable isotopes were measured from a truck that drove up and down the Mount Washington Auto Road concurrent with radiosonde launches that profiled the free atmosphere. This multivariate perspective revealed thermal, moisture, and air mass height differences among the free atmosphere, leeward, and windward mountain slopes. Both thermally and mechanically forced upslope flows helped shape these differences by altering the height of the boundary layer with respect to the mountain surface. Recommendations for measurement strategies hoping to develop accurate observational climatologies of air mass exposure in complex terrain are discussed and will be important for evaluating elevation-dependent warming and improving forecasting for weather and air quality

The use of satellite data, meteorology and land use data to define high resolution temperature exposure for the estimation of health effects in Italy

Introduction. Despite the mounting evidence on heat-related health risks, there is limited evidence in suburban and rural areas. The limited spatial resolution of temperature data also hinders the evidence of the differential heat effect within cities due to individual and area-based characteristics. Methods. Satellite land surface temperature (LST), observed meteorological and spatial and spatio-temporal land use data were combined in mixed-effects regression models to estimate daily mean air temperature with a 1x1km resolution for the period 2000-2010. For each day, random intercepts and slopes for LST were estimated to capture the day-to-day temporal variability of the Ta–LST relationship. The models were also nested by climate zones to better capture local climates and daily weather patterns across Italy. The daily exposure data was used to estimate the effects and impacts of heat on cause-specific mortality and hospital admissions in the Lazio region at municipal level in a time series framework. Furthermore, to address the differential effect of heat within an urban area and account for potential effect modifiers a case cross-over study was conducted in Rome. Mean temperature was attributed at the individual level to the Rome Population Cohort and the urban heat island (UHI) intensity using air temperature data was calculated for Rome. Results. Exposure model performance was very good: in the stage 1 model (only on grid cells with both LST and observed data) a mean R2 value of 0.96 and RMSPE of 1.1°C and R2 of 0.89 and 0.97 for the spatial and temporal domains respectively. The model was also validated with regional weather forecasting model data and gave excellent results (R2=0.95 RMSPE=1.8°C. The time series study showed significant effects and impacts on cause-specific mortality in suburban and rural areas of the Lazio region, with risk estimates comparable to those found in urban areas. High temperatures also had an effect on respiratory hospital admissions. Age, gender, pre-existing cardiovascular disease, marital status, education and occupation were found to be effect modifiers of the temperature-mortality association. No risk gradient was found by socio-economic position (SEP) in Rome. Considering the urban heat island (UHI) and SEP combined, differential effects of heat were observed by UHI among same SEP groupings. Impervious surfaces and high urban development were also effect modifiers of the heat-related mortality risk. Finally, the study found that high resolution gridded data provided more accurate effect estimates especially for extreme temperature intervals. Conclusions. Results will help improve heat adaptation and response measures and can be used predict the future heat-related burden under different climate change scenarios.Open Acces