Response of Near-Surface Meteorological Conditions to Advection under Impact of the Green Roof

Due to rapid urbanization, the near-surface meteorological conditions over urban areas are greatly modulated. To capture such modulations, sophisticated urban parameterizations with enhanced hydrological processes have been developed. In this study, we use the single-layer urban canopy model (SLUCM) available within the Weather Research and Forecasting (WRF) model to assess the response of near-surface temperature, wind, and moisture to advection under the impact of the green roof. An ensemble of simulations with different planetary boundary layer (PBL) schemes is conducted in the presence (green roof (GR)) and absence (control (CTL)) of green roof systems. Our results indicate that the near-surface temperature is found to be driven primarily by the surface heat flux with a minor influence from the zonal advection of temperature. The momentum budget analysis shows that both zonal and meridional momentum advection during the evening and early nighttime plays an important role in modulating winds over urban areas. The near-surface humidity remains nearly unchanged in GR compared to CTL, although the physical processes that determine the changes in humidity were different, in particular during the evening when the GR tends to have less moisture advection due to the reduced temperature gradient between the urban areas and the surroundings. Implications of our results are discussed.

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Role of Advection on the Evolution of Near-Surface Temperature and Wind in Urban-Aware Simulations

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-20-0068.1 ◽

2020 ◽

Author(s):

Pallav Ray ◽

Haochen Tan ◽

Mukul Tewari ◽

James Brownlee ◽

R. S. Ajayamohan ◽

...

Keyword(s):

Surface Temperature ◽

Urban Areas ◽

Single Layer ◽

Windward Side ◽

Leeward Side ◽

Land Use Patterns ◽

Near Surface ◽

Horizontal Advection ◽

The City

AbstractThe role of advection of heat and momentum on the evolution of near-surface temperature and wind is evaluated in urban-aware simulations over Houston under dry conditions on a light-wind day. Two sets of experiments, each consisting of four simulations using different planetary boundary layer (PBL) schemes, were conducted over 48 hours using the default urban scheme (BULK) and the single-layer urban canopy model (SLUCM) available within the Weather Research and Forecasting (WRF) model. We focus on understanding and quantifying the role played by temperature and momentum advection, particularly on the windward and leeward sides of the city. Previous studies have largely ignored any quantitative analysis of impacts from the advection of momentum over an urban area.The horizontal advection of temperature was found to be more important in the BULK because of the larger surface temperature gradient caused by warmer surface temperatures over urban areas than in the SLUCM. An analysis of the momentum budget shows that horizontal advection of zonal and meridional momentum plays a prominent role during the period of peak near-surface winds, and this effect is more pronounced in the windward side of the city. The local tendency in peak winds in the leeward side lags that in the windward side by about 1-2 hours, similar to the lag found in horizontal momentum advection. The sensitivity of the results to different urban and PBL schemes was explored. The results imply that representation and influence of land-use patterns via sophisticated urban parameterizations generates locally driven winds that best resemble observations.

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Evaluation of Urban Heat Island (UHI) Using Satellite Images in Densely Populated Cities of South Asia

Earth ◽

10.3390/earth2010006 ◽

2021 ◽

Vol 2 (1) ◽

pp. 86-110

Author(s):

Manisha Maharjan ◽

Anil Aryal ◽

Bijay Man Shakya ◽

Rocky Talchabhadel ◽

Bhesh Raj Thapa ◽

...

Keyword(s):

Surface Temperature ◽

Urban Heat Island ◽

South Asia ◽

Land Surface ◽

Urban Areas ◽

Well Being ◽

Heat Island ◽

Rapid Urbanization ◽

Urban Heat ◽

The Impact

Rapid Urbanization, and other anthropogenic activities, have amplified the change in land-use transition from green space to heat emission in built-up areas globally. As a result, there has been an increase in the land surface temperature (LST) causing the Urban Heat Island (UHI) effect, particularly in large cities. The UHI effect poses a serious risk to human health and well-being, magnified in large developing cities with limited resources to cope with such issues. This study focuses on understanding the UHI effect in Kathmandu Valley (KV), Delhi, and Dhaka, three growing cities in South Asia. The UHI effect was evaluated by analyzing the UHI intensity of the city with respect to the surroundings. We found that the central urban area, of all three cities, experienced more heat zones compared to the peri-urban areas. The estimated average surface temperature ranged from 21.1 ∘C in March 2014 to 32.0 ∘C in June 2015 in KV, while Delhi and Dhaka experienced surface temperature variation from 29.7 ∘C in June 2017 to 40.2 ∘C in June 2019 and 23.6 ∘C in March 2017 to 33.2 ∘C in March 2014, respectively. Based on magnitude and variation of LST, highly built-up central KV showed heat island characteristics. In both Delhi and Dhaka, the western regions showed the UHI effect. Overall, this study finds that the UHI zones are more concentrated near the urban business centers with high population density. The results suggest that most areas in these cities have a rising LST trend and are on the verge of being UHI regions. Therefore, it is essential that further detailed assessment is conducted to understand and abate the impact of the temperature variations.

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Remote Sensing-based Spatiotemporal Analysis of Near-Surface Temperatures for Cities Located in Different Climatic Zones

10.5194/egusphere-egu21-8788 ◽

2021 ◽

Author(s):

Sriram Jallu ◽

Poorna Chander Reddy Bommineni ◽

Roshan Srivastav

Keyword(s):

Surface Temperature ◽

Land Surface Temperature ◽

Rural Areas ◽

Land Surface ◽

Urban Areas ◽

Vegetation Index ◽

Quantitative Relation ◽

Rapid Urbanization ◽

Near Surface ◽

Spatio Temporal

Urbanization has a major impact on the spatio-temporal variation of near-surface temperature for world cities. Recent studies indicate that the understanding of changes in temperature with urbanization has provided greater insights into the effects of Urban Heat Islands (UHI) on various issues such as excessive energy consumption, health hazard and climate change. In this study, spatio-temporal variations of near-surface temperature for India&#8217;s three major cities with different climatic conditions are evaluated. In addition, an attempt is made to establish a quantitative relation between land surface temperature (LST) and various geographical indices indicating vegetation cover (NDVI, Normalized Difference Vegetation Index), water surfaces (NDWI, Normalized Difference Water Index), and impervious land (NDBI, Normalized Difference Built-up Index). The dataset is selected for years 2014 to 2020 for three major cities: (i) Chennai (coastal); (ii) Hyderabad (inland); and (ii) Mumbai (coastal). The study uses Landsat &#8211; 8 OLI / TIRS images to derive land use/cover types, land surface temperature datasets, NDVI, NDBI, and NDWI. The preliminary evaluations indicate that the maximum contribution towards the UHI is impervious land, and the effect is more prominent in the areas of rapid urbanization. Urban areas relatively have a high temperature compared to the surrounding rural areas, and the effect is more prominent during night times. The analysis derived from the study will be useful for decision-makers or stakeholders to take necessary actions for reducing the effects of UHI and planning for urban sprawl.

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Improving WRF-Hydro Runoff Predictions of Heavy Floods Through Higher Spatio-Temporal Sea Surface Temperature Products

10.22541/au.161278398.86885570/v1 ◽

2021 ◽

Author(s):

Berina Kilicarslan ◽

ismail yucel ◽

Heves Pilatin ◽

Eren Duzenli ◽

Mustafa Yılmaz

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Wrf Model ◽

Sea Surface ◽

Model Parameters ◽

Flood Events ◽

Near Surface ◽

Daily Streamflow ◽

Spatio Temporal ◽

The Impact

In this study, the impact of spatio-temporal accuracy of four different sea surface temperature (SST) datasets on the accuracy of the Weather Research and Forecasting (WRF)-Hydro system to simulate hydrological response during two catastrophic flood events over Eastern Black Sea (EBS) and Mediterranean (MED) regions of Turkey is investigated. Three time-varying and high spatial resolution external SST products (GHRSST, Medspiration, and NCEP-SST) and one coarse-resolution and invariable SST product (ERA5- and GFS-SST for EBS and MED regions, respectively) already embedded in the initial and boundary condition dataset of WRF model are used in deriving near-surface weather variables through WRF. After the proper event-based calibration performed to the WRF-Hydro using hourly and daily streamflow data of small catchments in both regions, uncoupled model simulations for independent SST events are conducted to assess the impact of SST-triggered precipitation on simulated extreme runoff. Some localized and temporal differences in the occurrence of the flood events with respect to observations depending on the SST representation are noticeable. SST products represented with higher temporal and spatial correlation revealed significant improvement in flood hydrographs for both regions. The higher spatial and temporal correlations of GHRSST dataset show RMSE reduction up to 20% and increase in correlation from 0.3 to 0.8 with respect to the invariable SST (ERA5) in simulated runoffs over the EBS region. The error reduction with GHRSST reached 35% after the calibration of hydrological model parameters compared to not calibrated model. The use of both GHRSST and Medspiration SST data characterized with high spatiotemporal correlation resulted in runoff simulations exactly matching the observed runoff peak of 300 m3/s by reducing the overestimation seen in not calibrated runs over the MED region.

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Seasonal Variations of Daytime Land Surface Temperature and Their Underlying Drivers over Wuhan, China

Remote Sensing ◽

10.3390/rs13020323 ◽

2021 ◽

Vol 13 (2) ◽

pp. 323

Author(s):

Liang Chen ◽

Xuelei Wang ◽

Xiaobin Cai ◽

Chao Yang ◽

Xiaorong Lu

Keyword(s):

Surface Temperature ◽

Land Surface Temperature ◽

Land Surface ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Maximum Temperature ◽

Maximum Temperature Difference ◽

Rapid Urbanization ◽

The Impact ◽

The City

Rapid urbanization greatly alters land surface vegetation cover and heat distribution, leading to the development of the urban heat island (UHI) effect and seriously affecting the healthy development of cities and the comfort of living. As an indicator of urban health and livability, monitoring the distribution of land surface temperature (LST) and discovering its main impacting factors are receiving increasing attention in the effort to develop cities more sustainably. In this study, we analyzed the spatial distribution patterns of LST of the city of Wuhan, China, from 2013 to 2019. We detected hot and cold poles in four seasons through clustering and outlier analysis (based on Anselin local Moran’s I) of LST. Furthermore, we introduced the geographical detector model to quantify the impact of six physical and socio-economic factors, including the digital elevation model (DEM), index-based built-up index (IBI), modified normalized difference water index (MNDWI), normalized difference vegetation index (NDVI), population, and Gross Domestic Product (GDP) on the LST distribution of Wuhan. Finally, to identify the influence of land cover on temperature, the LST of croplands, woodlands, grasslands, and built-up areas was analyzed. The results showed that low temperatures are mainly distributed over water and woodland areas, followed by grasslands; high temperatures are mainly concentrated over built-up areas. The maximum temperature difference between land covers occurs in spring and summer, while this difference can be ignored in winter. MNDWI, IBI, and NDVI are the key driving factors of the thermal values change in Wuhan, especially of their interaction. We found that the temperature of water area and urban green space (woodlands and grasslands) tends to be 5.4 °C and 2.6 °C lower than that of built-up areas. Our research results can contribute to the urban planning and urban greening of Wuhan and promote the healthy and sustainable development of the city.

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Relative Role of Turbulent and Radiative Flux on the Near-Surface Temperature in a Single-Layer Urban Canopy Model over Houston

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-17-0088.1 ◽

2017 ◽

Vol 56 (8) ◽

pp. 2173-2187 ◽

Cited By ~ 8

Author(s):

James Brownlee ◽

Pallav Ray ◽

Mukul Tewari ◽

Haochen Tan

Keyword(s):

Heat Flux ◽

Surface Temperature ◽

Single Layer ◽

Urban Canopy ◽

Heat Fluxes ◽

Radiative Flux ◽

Hydrological Processes ◽

Urban Canopy Model ◽

Near Surface ◽

Canopy Model

AbstractNumerical simulations without hydrological processes tend to overestimate the near-surface temperatures over urban areas. This is presumably due to underestimation of surface latent heat flux. To test this hypothesis, the existing single-layer urban canopy model (SLUCM) within the Weather Research and Forecasting Model is evaluated over Houston, Texas. Three simulations were conducted during 24–26 August 2000. The simulations include the use of the default “BULK” urban scheme, the SLUCM without hydrological processes, and the SLUCM with hydrological processes. The results show that the BULK scheme was least accurate, and it overestimated the near-surface temperatures and winds over the urban regions. In the presence of urban hydrological processes, the SLUCM underestimates these parameters. An analysis of the surface heat fluxes suggests that the error in the BULK scheme is due to a lack of moisture at the urban surface, whereas the error in the SLUCM with hydrological processes is due to increases in moisture at the urban surface. These results confirm earlier studies in which changes in near-surface temperature were primarily due to the changes in the turbulent (latent and sensible heat) fluxes in the presence of hydrological processes. The contribution from radiative flux was about one-third of that from turbulent flux. In the absence of hydrological processes, however, the results indicate that the changes in radiative flux contribute more to the near-surface temperature changes than the turbulent heat flux. The implications of these results are discussed.

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The impact of urbanization expansion on agricultural land in Ethiopia: A review

Environmental & Socio-economic Studies ◽

10.2478/environ-2020-0024 ◽

2020 ◽

Vol 8 (4) ◽

pp. 73-80

Author(s):

Assefa Ayele ◽

Kassa Tarekegn

Keyword(s):

Urban Areas ◽

Agricultural Land ◽

Urban Expansion ◽

Rural Livelihoods ◽

Vital Role ◽

Rapid Urbanization ◽

Economic Resource ◽

House Construction ◽

Impact Of Urbanization ◽

The Impact

AbstractIn a country like Ethiopia where the vast majority of the populations are employed in agriculture, land is an important economic resource for the development of rural livelihoods. Agricultural land in peri-urban areas is, however, transformed into built-up regions through horizontal urban expansion that has an effect on land use value. In recent years Ethiopia has been experiencing rapid urbanization, which has led to an ever-increasing demand for land in peri-urban areas for housing and other nonagricultural activities that pervades agricultural land. There is a high demand for informal and illegal peri-urban land which has been held by peri-urban farmers, and this plays a vital role in the unauthorized and sub-standard house construction on agricultural land. This urbanization has not been extensively reviewed and documented. In this review an attempt has been made to assess the impacts of rapid urbanization on agricultural activities. Urban expansion has reduced the areas available for agriculture, which has seriously impacted upon peri-urban farmers that are often left with little or no land to cultivate and which has increased their vulnerability. Housing encroachments have been observed to be uncontrolled due to a weak government response to the trend of unplanned city expansion. This has left peri-urban farmers exposed to the negative shocks of urbanization because significant urbanization-related agricultural land loss has a positive correlation with grain production decrease. Appropriate governing bodies should control urban development in order to control the illegal and informal spread of urbanization on agricultural land that threatens food production.

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Impact of Multitemporal Land Use and Land Cover Change on Land Surface Temperature Due to Urbanization in Hefei City, China

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi10120809 ◽

2021 ◽

Vol 10 (12) ◽

pp. 809

Author(s):

Jing Sun ◽

Suwit Ongsomwang

Keyword(s):

Land Use ◽

Land Cover ◽

Surface Temperature ◽

Land Surface Temperature ◽

Land Surface ◽

Urban Areas ◽

Decomposition Analysis ◽

Lulc Change ◽

Main Components ◽

The Impact

Land surface temperature (LST) is an essential parameter in the climate system whose dynamics indicate climate change. This study aimed to assess the impact of multitemporal land use and land cover (LULC) change on LST due to urbanization in Hefei City, Anhui Province, China. The research methodology consisted of four main components: Landsat data collection and preparation; multitemporal LULC classification; time-series LST dataset reconstruction; and impact of multitemporal LULC change on LST. The results revealed that urban and built-up land continuously increased from 2.05% in 2001 to 13.25% in 2020. Regarding the impact of LULC change on LST, the spatial analysis demonstrated that the LST difference between urban and non-urban areas had been 1.52 K, 3.38 K, 2.88 K and 3.57 K in 2001, 2006, 2014 and 2020, respectively. Meanwhile, according to decomposition analysis, regarding the influence of LULC change on LST, the urban and built-up land had an intra-annual amplitude of 20.42 K higher than other types. Thus, it can be reconfirmed that land use and land cover changes due to urbanization in Hefei City impact the land surface temperature.

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Effects of Dubai coastline extreme urbanization in land and sea on local near-surface climate variables patterns

10.5194/egusphere-egu21-6348 ◽

2021 ◽

Author(s):

Emily Elhacham ◽

Pinhas Alpert

Keyword(s):

Urban Heat Island ◽

Heat Island ◽

Rapid Urbanization ◽

Near Surface ◽

Modis Data ◽

The World ◽

Urban Heat ◽

Surface Urban Heat Island ◽

Coastal Urbanization ◽

The Impact

Over a billion people currently live in coastal areas, and coastal urbanization is rapidly growing worldwide. Here, we explore the impact of an extreme and rapid coastal urbanization on near-surface climatic variables, based on MODIS data, Landsat and some in-situ observations. We study Dubai, one of the fastest growing cities in the world over the last two decades. Dubai's urbanization centers along its coastline &#8211; in land, massive skyscrapers and infrastructure have been built, while in sea, just nearby, unique artificial islands have been constructed.Studying the coastline during the years of intense urbanization (2001-2014), we show that the coastline exhibits surface urban heat island characteristics, where the urban center experiences higher temperatures, by as much as 2.0&#176;C and more, compared to the adjacent less urbanized zones. During development, the coastal surface urban heat island has nearly doubled its size, expanding towards the newly developed areas. This newly developed zone also exhibited the largest temperature trend along the coast, exceeding 0.1&#176;C/year on average.Overall, we found that over land, temperature increases go along with albedo decreases, while in sea, surface temperature decreases and albedo increases were observed particularly over the artificial islands. These trends in land and sea temperatures affect the land-sea temperature gradient which influences the breeze intensity. The above findings, along with the increasing relative humidity shown, directly affect the local population and ecosystem and add additional burden to this area, which is already considered as one of the warmest in the world and a climate change 'hot spot'.&#160;References:E. Elhacham and P. Alpert, "Impact of coastline-intensive anthropogenic activities on the atmosphere from moderate resolution imaging spectroradiometer (MODIS) data in Dubai (2001&#8211;2014)", Earth&#8217;s Future, 4, 2016. https://doi.org/10.1002/2015EF000325E. Elhacham and P. Alpert, "Temperature patterns along an arid coastline experiencing extreme and rapid urbanization, case study: Dubai", submitted.

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Population-level effects of diet, lifestyle, and health environment on obesity and non-communicable diseases in India

10.21203/rs.2.16683/v1 ◽

2019 ◽

Author(s):

Kuhu Joshi ◽

Devesh Roy ◽

Lora Iannotti ◽

Aishwarya Nagar ◽

Avinash Kishore

Keyword(s):

Urban Areas ◽

Population Level ◽

Overweight And Obesity ◽

Lifestyle Changes ◽

Exact Matching ◽

Rapid Urbanization ◽

Rural And Urban Areas ◽

Rural And Urban ◽

Linear Probability ◽

The Impact

Abstract Background: Obesity is rising in developing countries like India and is associated with an increase in cardiometabolic problems. Rising incomes, rapid urbanization, and mechanization have induced lifestyle changes like consumption of more obesogenic foods and sedentary habits at work and leisure, contributing to a transition from under- to over-nutrition. This study maps the prevalence of adult (15-49 years) overweight and obesity across regions and socioeconomic groups in India, and estimates its association with lifestyle, health environment, dietary patterns, diabetes, and hypertension.Methods: We employ a combination of 3 latest nationally representative datasets with over 700,000 adults. We use a linear probability regression model to identify the correlates of overweight/obesity and their relative magnitudes. We use intra-household regression to identify differences between men and women and coarsened exact matching to causally estimate the impact of obesity on diabetes and hypertension.Results: Overweight/obesity rates have increased across all states, in rural and urban areas, and for all wealth levels. Women are more likely to be overweight/obese than men, even in the same household. Improved health environment (toilets, piped water, clean cooking fuel), urban jobs, television watching, and processed snacks increase the risk of overweight/obesity. Adults who are overweight/obese have a 5.6% higher risk of diabetes and a 9.7% higher risk of hypertension.Conclusions: Our results underscore the need for policy intervention to reduce the burden of obesity and NCD’s in India.

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