DOCSLIB.ORG

Impacts of Inhomogeneous Landscapes in Oasis Interior on the Oasis Self-Maintaining Mechanism by Integrating Numerical Model with Satellite Data X

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Impacts of Inhomogeneous Landscapes in Oasis Interior on the Oasis Self-Maintaining Mechanism by Integrating Numerical Model with Satellite Data X Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Hydrol. Earth Syst. Sci. Discuss., 9, 1979–2004, 2012 Hydrology and www.hydrol-earth-syst-sci-discuss.net/9/1979/2012/ Earth System doi:10.5194/hessd-9-1979-2012 Sciences © Author(s) 2012. CC Attribution 3.0 License. Discussions This discussion paper is/has been under review for the journal Hydrology and Earth System Sciences (HESS). Please refer to the corresponding final paper in HESS if available. Impacts of inhomogeneous landscapes in oasis interior on the oasis self-maintaining mechanism by integrating numerical model with satellite data X. Meng, S. Lu, T. Zhang, Y. Ao, S. Li, Y. Bao, L. Wen, and S. Luo Key laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Science, 320 Donggang West Road, 730000 Lanzhou, Gansu, China Received: 31 January 2012 – Accepted: 3 February 2012 – Published: 14 February 2012 Correspondence to: X. Meng ([email protected]) Published by Copernicus Publications on behalf of the European Geosciences Union. 1979 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract Mesoscale meteorological modeling is an important tool to help understand the energy budget of the oasis. While basic dynamic and thermodynamic processes for oasis self- maintaining in the desert environment is well investigated, influence of heterogeneous 5 landscapes of oasis interior on the processes are still important and remain to be in- vestigated. In this study, two simulations are designed for investigating the influence of inhomogeneity. In the first case, land surface parameters including land-use types, vegetation cover fraction, and surface layer soil moisture are derived by satellite remote sensing data from EOS/MODIS, and then be used specify the respective options in the 10 MM5 model, to describe a real inhomogeneity for the oasis interior. In the other run, land use types are set to MM5 default, in which landscapes in the oasis interior is rel- ative uniform, and then surface layer soil moisture and vegetation fraction is set to be averages of the first case for the respective oasis and desert surface lying, to represent a relative homogeneity. Results show that the inhomogeneity leads to a weaker oasis 15 “cold-wet island” effect and a stronger turbulence over the oasis interior, both of which will reduce the oasis-desert secondary circulation and increase the evaporation over the oasis, resulting in a negative impact on the oasis self-protecting mechanism. The simulation of homogeneity indicates that the oasis may be more stable even with rela- tive lower soil moisture if landscapes in the oasis interior are comparatively uniform. 20 1 Introduction The interaction between the atmosphere and the underlying surface, a phenomenon of great interest for climate theory and weather forecasting, is primarily manifested in the heat, moisture, and momentum exchanges between air masses and soil or water (Kukharets and Nalbandyan, 2006). Flying over a landscape in mid-latitudes 25 presents a fantastic view of patchy fields with various surface properties and different sizes (Friedrich and Molders,¨ 2000). Obviously, this surface heterogeneity can result 1980 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | in more complicated interactions between the atmosphere and the underlying surface, affecting moist convection, producing or impacting the atmospheric circulations locally and even globally (Friedrich and Molders,¨ 2000; Molders¨ and Raabe, 1996; Chen and Avissar, 1994; Chen et al., 2003; Courault et al., 2007; Lynn et al., 1995; Patton et al., 5 2005; Reen et al., 2006; Yates et al., 2003; Zhang et al., 2010). In many situations, these locally induced circulations are important in determining mesoscale weather conditions (Wu and Raman, 1997). Indeed, in the atmospheric boundary layer (ABL), surface heterogeneities affect the microscale to mesoscale cir- culations through non-linear processes (Patton et al., 2005; Mahrt et al., 1994; Baidya 10 Roy and Avissar, 2002). Turbulent surface fluxes are strongly affected by the ability of the surface to redistribute the radiative energy absorbed from the sun and the at- mosphere into sensible and latent heat fluxes (Mahrt et al., 1994; Chen et al., 2003). Surface heterogeneities thus induce spatial variability in surface heat fluxes that can create “inland breezes”, “oasis effect”, ““glacier wind” et al.” similar to sea-land breeze 15 systems (Mahfouf et al., 1987; Mahrt et al., 1994; Chu et al., 2005; Gao et al., 2004; Lu et al., 2004; Sun et al., 2007). Such phenomena are known to contribute significantly to energy, water and matter transport (Bastin and Drobinski, 2006; Meng et al., 2009; Chu et al., 2005). As unique intrazonal landscapes, oases surrounded by deserts and Gobi play im- 20 portant role in arid and semiarid regions of the world. In China, oases take up only 4–5 % of the total area of the region, but over 90 % of the population and over 95 % of the social wealth in northwest China is concentrated within the oases (Han, 2001; Gao et al., 2008). In the last half century, however, the rapid growth of population and the overexploitation of water, soil and biological resources have led to drought, 25 salinization, and desertification and consequently have hindered the development of sustainable agriculture, resulting in an urgency to understand the oasis-desert interac- tion and processes (Liu et al., 2006, 2007; Li et al., 2011). Studies have been done to investigate the land-atmosphere interaction over the oasis-desert system, indicating that the local circulations driven by the thermal 1981 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | heterogeneity between the oasis and desert is the key factor to maintain the oasis (Chu et al., 2005). Such thermally driven circulations similar as the sea breezes in the convective boundary layer are called as the non-classical mesoscale circulations (Segal and Arritt, 1992), and have been observed in the field experiment (Chen et al., 5 2005). In addition, the oasis is wetter and colder than the surrounded desert due to the evaporation and thermal processes in the afternoon on fair weather days, which will develop an inversion layer over the oasis. Both the mesoscale circulation and the inversion layer will help to prevent water vapor over the oasis flowing to the desert (Chu et al., 2005). These processes are totally called the oasis self-maintaining mech- 10 anism. However, the oasis interior are very inhomogeneous, constituting with water, cropland, urban, shelterbelt, natural vegetation, Gobi and desert, particularly when the cropland is irrigated during the growing season in Northwest of China (Fig. 1). While the basic dynamic and thermodynamic processes over the oasis-desert system is well investigated, the impacts of inhomogeneous oasis interior on oasis self-maintaining 15 mechanism are still very important and remain to be investigated. Numeric simulation is quite an efficient technique to study the mesoscale weather and boundary layer structure over the inhomogeneous landscape (Prabha et al., 2007; Kukharets and Nalbandyan, 2006; Ament and Simmer, 2006; Avissar and Liu, 1996; Chen and Avissar, 1994; Desai et al., 2006; Lynn et al., 1995; Molders¨ and Raabe, 20 1996). Ye and Jia (1995) investigated the impact of well watered mesoscale wheat over mid-latitude arid areas on mesoscale boundary layer structures and climate by modeling, indicating that a horizontal pressure gradient associated with mesoscale perturbations in temperature and humidity is created during the day, which results from more water transpired from the vegetation canopy and evaporated from underlying wet 25 soil. Zhang et al. (2010) design a number of experiments to examine the effects of changes in heterogeneity patterns on numerical simulations of surface flux exchanges, near-surface meteorological fields, atmospheric planetary boundary layer (PBL) pro- cesses, mesoscale circulations, and mesoscale fluxes, indicating that the increased heterogeneity losses in the model lead to substantial, nonlinear changes in temporal 1982 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | evaluations and spatial patterns of PBL dynamic and thermodynamic processes. Meng et al. (2009) improved meteorological simulations in the Jinta oasis in Northwest China, especially for description of the inhomogeneous characteristics over the oasis by in- volving satellite data. This paper is a continuity of the work in Meng et al. (2009), in 5 which they presented that the numerical simulation including satellite data can provide a better description for inhomogeneous underlying surface, while this work will make an attempt to understand the influence of heterogeneous oasis interior on the oasis self-maintaining mechanism. The paper is structured as follows. Section 2 briefly presents a description of the 10 study area and the datasets used in this work. Section 3 describes the MM5 model and the experimental design. Section 4 evaluates the simulation results and assesses the impact of the inhomogeneous landscape on the oasis self-maintaining mechanism. The final section summarizes the findings and identifies areas requiring future investi- gation. 15 2 Study area and datasets 2.1 Study area The study area is Jinta oasis, situated between 98◦390 E and 99◦080 E and 39◦560 N and 40◦170 N in the middle of the Heihe river
Load more

Recommended publications
  • An Alternative Explanation of the Semiarid Urban Area Oasis Effect
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, D24113, doi:10.1029/2011JD016720, 2011 An alternative explanation of the semiarid urban area “oasis effect” M. Georgescu,1 M. Moustaoui,1 A. Mahalov,1 and J. Dudhia2 Received 12 August 2011; revised 10 October 2011; accepted 12 October 2011; published 22 December 2011. [1] This research evaluates the climatic summertime representation of the diurnal cycle of near-surface temperature using the Weather Research and Forecasting System (WRF) over the rapidly urbanizing and water-vulnerable Phoenix metropolitan area. A suite of monthly, high-resolution (2 km grid spacing) simulations are conducted during the month of July with both a contemporary landscape and a hypothetical presettlement scenario. WRF demonstrates excellent agreement in the representation of the daily to monthly diurnal cycle of near-surface temperatures, including the accurate simulation of maximum daytime temperature timing. Thermal sensitivity to anthropogenic land use and land cover change (LULCC), assessed via replacement of the modern-day landscape with natural shrubland, is small on the regional scale. The WRF-simulated characterization of the diurnal cycle, supported by previous observational analyses, illustrates two distinct and opposing impacts on the urbanized diurnal cycle of the Phoenix metro area, with evening and nighttime warming partially offset by daytime cooling. The simulated nighttime urban heat island (UHI) over this semiarid urban complex is explained by well-known mechanisms (slow release of heat from within the urban fabric stored during daytime and increased emission of longwave radiation from the urban canopy toward the surface). During daylight hours, the limited vegetation and dry semidesert region surrounding metro Phoenix warms at greater rates than the urban complex.
    [Show full text]
  • The Oasis Effect and Summer Temperature Rise in Arid Regions
    www.nature.com/scientificreports OPEN The oasis effect and summer temperature rise in arid regions - case study in Tarim Basin Received: 30 June 2016 Xingming Hao, Weihong Li & Haijun Deng Accepted: 29 September 2016 This study revealed the influence of the oasis effect on summer temperatures based on MODIS Land Published: 14 October 2016 Surface Temperature (LST) and meteorological data. The results showed that the oasis effect occurs primarily in the summer. For a single oasis, the maximum oasis cold island intensity based on LST (OCILST) was 3.82 °C and the minimum value was 2.32 °C. In terms of the annual change in OCILST, the mean value of all oases ranged from 2.47 °C to 3.56 °C from 2001 to 2013. Net radiation (Rn) can be used as a key predictor of OCILST and OCItemperature (OCI based on air temperature). On this basis, we reconstructed a long time series (1961–2014) of OCItemperature and Tbase(air temperature without the disturbance of oasis effect). Our results indicated that the reason for the increase in the observed temperatures was the significant decrease in theOCI temperature over the past 50 years. In arid regions, the data recorded in weather stations not only underestimated the mean temperature of the entire study area but also overestimated the increasing trend of the temperature. These discrepancies are due to the limitations in the spatial distribution of weather stations and the disturbance caused by the oasis effect. An oasis is a type of medium-sized or small-sized non-zonal landscape that occurs in dry climates and is sup- ported by natural or artificial rivers in deserts1,2.
    [Show full text]
  • The Urban Heat Island Effect and Sustainability Science: Causes, Impacts, and Solutions 275
    Chapter 14 The Urban Heat Island Effect and Sustainability Science: Causes, Impacts, and Solutions Darren Ruddell, Anthony Brazel, Winston Chow, Ariane Middel Introduction As Chapter 3 described, urbanization began approximately 10,000 years ago Urbanization The process when people first started organizing into small permanent settlements. whereby native landscapes While people initially used local and organic materials to meet residential are converted to urban land and community needs, advances in science, technology, and transportation uses, such as commercial systems support urban centers that rely on distant resources to produce and residential development. engineered surfaces and synthetic materi- als. This process of urbanization, Urbanization is also defined which manifests in both population and spatial extent, has increased over as rural migration to urban the course of human history. For instance, according to the 2014 US Census, centers. the global population has rapidly increased from 1 billion people in 1804 to 7.1 billion in 2014. During the same period, the global population living in urban centers grew from 3% to over 52% (US Census, 2014). In 1950, there were 86 cities in the world with a population of more than 1 million. This number has grown to 512 cities in 2016 with a projected 662 cities by 2030 (UN, 2016). Megacities (urban agglomerations with populations greater than 10 million) have also become commonplace throughout the world. In Megacities Urban 2016, the UN determined that there are 31 megacities globally and agglomerations, including estimate that this number will increase to 41 by 2030. The highest rates of all of the contiguous urban urbanization and most megacities are in the developing world, area, or built-up area.
    [Show full text]
  • Understanding the Impact of Urbanization on Surface Urban Heat Islands—A Longitudinal Analysis of the Oasis Effect in Subtropical Desert Cities
    remote sensing Article Understanding the Impact of Urbanization on Surface Urban Heat Islands—A Longitudinal Analysis of the Oasis Effect in Subtropical Desert Cities Chao Fan 1,2,*, Soe W. Myint 1, Shai Kaplan 3, Ariane Middel 4, Baojuan Zheng 5, Atiqur Rahman 6, Huei-Ping Huang 7, Anthony Brazel 1 and Dan G. Blumberg 8 1 School of Geographical Sciences and Urban Planning, Arizona State University, Tempe, AZ 85287, USA; [email protected] (S.W.M.); [email protected] (A.B.) 2 Keller Science Action Center, The Field Museum, Chicago, IL 60605, USA 3 ASU-BGU Partnership Project, Ben-Gurion University of the Negev, Beer Sheva 8499000, Israel; [email protected] 4 Department of Geography and Urban Studies, Temple University, Philadelphia, PA 19122, USA; [email protected] 5 Geospatial Sciences Center of Excellence, South Dakota State University, Brookings, SD 57007, USA; [email protected] 6 Department of Geography, Jamia Millia Islamia, New Delhi 110025, India; [email protected] 7 School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ 85287, USA; [email protected] 8 Research and Development, Ben-Gurion University of the Negev, Beer Sheva 8499000, Israel; [email protected] * Correspondence: [email protected]; Tel.: +1-312-665-6013 Academic Editors: Janet Nichol and Prasad S. Thenkabail Received: 30 March 2017; Accepted: 25 June 2017; Published: 30 June 2017 Abstract: We quantified the spatio-temporal patterns of land cover/land use (LCLU) change to document and evaluate the daytime surface urban heat island (SUHI) for five hot subtropical desert cities (Beer Sheva, Israel; Hotan, China; Jodhpur, India; Kharga, Egypt; and Las Vegas, NV, USA).
    [Show full text]
  • Case Study: Middle Draa Valley
    echnology f T a o n l d a O n r p t u i m o Global Journal of J i z l a a t b i o o Karmaoui, et al., Global J Technol Optim 2015, 6:1 l n G DOI: 10.4172/2229-8711.1000170 ISSN: 2229-8711 Technology & Optimization Research Article Open Access Sustainability of the Moroccan Oasean System (Case study: Middle Draa Valley) Ahmed Karmaoui*, Issam Ifaadassan, Mohammed Messouli and Mohammed Yacoubi Khebiza Department of Environmental Sciences, Cadi Ayyad University, Marrakech, Morocco *Corresponding author: Karmaoui A, Department of Environmental Sciences, Cadi Ayyad University, Marrakech, Morocco, Tel: +212-524-43-46-49; Fax: +212-524-43-67-69; E-mail: [email protected] Received date: January 08, 2015; Accepted date: January 20, 2015; Published date: January 28, 2015 Copyright: © 2015 Karmaoui A. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract The oases of the Draa are part of the biosphere reserve recognized by UNESCO, 2000. These oases are agro systems located in the Saharan region of southern Morocco. They are the main sources of livelihood of the indigenous population. The sustainability of the oasean system for centuries has made him a rich and resilient ecosystem. Despite its aridity and isolation, the population had always been able to adapt and optimize natural resources, which are scarce. However, during the last 50 years extreme events (droughts, floods and locust attacks) have become increasingly frequent, and have a considerable threat.
    [Show full text]
  • Urban Heat Island Demonstration and Temperature Progression Using Oklahoma City, Oklahoma Elliot Quinn Peltier
    University of North Dakota UND Scholarly Commons Theses and Dissertations Theses, Dissertations, and Senior Projects January 2017 Urban Heat Island Demonstration And Temperature Progression Using Oklahoma City, Oklahoma Elliot Quinn Peltier Follow this and additional works at: https://commons.und.edu/theses Recommended Citation Peltier, Elliot Quinn, "Urban Heat Island Demonstration And Temperature Progression Using Oklahoma City, Oklahoma" (2017). Theses and Dissertations. 2308. https://commons.und.edu/theses/2308 This Thesis is brought to you for free and open access by the Theses, Dissertations, and Senior Projects at UND Scholarly Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UND Scholarly Commons. For more information, please contact [email protected]. URBAN HEAT ISLAND DEMONSTRATION AND TEMPERATURE PROGRESSION USING OKLAHOMA CITY, OKLAHOMA By Elliot Quinn Peltier Bachelor of Science – Secondary Science, Turtle Mountain Community College, 2014 A Thesis Submitted to the Graduate Faculty of the University of North Dakota in partial fulfillment of the requirements for the degree of Master of Science Grand Forks, North Dakota December 2017 Copyright 2017 Elliot Peltier ii This thesis, submitted by Elliot Peltier in partial fulfillment of the requirements for the Degree of Master of Science from the University of North Dakota, has been read by the Faculty Advisory Committee under whom the work has been done and is hereby approved. _______________________________________ Dr. Christopher Atkinson, Chair _______________________________________ Dr. Douglas Munski, Committee Member _______________________________________ Dr. Jeffrey VanLooy, Committee Member This thesis is being submitted by the appointed advisory committee as having met all of the requirements of the School of Graduate Studies at the University of North Dakota and is hereby approved.
    [Show full text]
  • Evapotranspiration and Simulation of Soil Water Movement in Small Area Vegetation
    INTERNATIONAL Agrophysics www.international-agrophysics.org Int. Agrophys., 2013, 27, 445-453 doi: 10.2478/intag-2013-0015 Evapotranspiration and simulation of soil water movement in small area vegetation C. Paraskevas1, P. Georgiou1*, A. Ilias2, A. Panoras2, and C. Babajimopoulos1 1Department of Hydraulics, Soil Science and Agricultural Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece 2Land Reclamation Institute, National Agricultural Research Foundation, 57400, Sindos, Greece Received May 14, 2012; accepted December 12, 2012 A b s t r a c t. In Greece, crops are frequently cultivated in Frequently, fields in Greece are very small (<1 000 m2) small isolated areas in close proximity to roads and bare soils and representing typical non-standard conditions. Under these therefore evapotranspiration is affected by local advection. Under circumstances, the crops are growing under conditions of these circumstances, oasis effect conditions are present and evapo- the oasis effect resulting in very high evapotranspiration transpiration is higher than what is expected. In this paper, the evapotranspiration and soil water dynamics of a cotton crop culti- values. Increased evapotranspiration is also observed at the vated in small areas under the oasis effect is studied. To this end, upwind series of crops resulting in lower yields since these two isolated free-drainage lysimeters cultivated with cotton in the series obtain the same amount of water as the interior series. year 2007 were used. Soil moisture of the soil profile of both the Therefore, the overall yield is reduced because of the lysimeters was monitored with two capacitance water content pro- non-satisfactory yield of the upwind series.
    [Show full text]
  • The Urban Heat Island Effect in Malta and the Adequacy of Green Roofs in Its Mitigation Jonathan Scicluna James Madison University
    James Madison University JMU Scholarly Commons Masters Theses The Graduate School Spring 2016 The urban heat island effect in Malta and the adequacy of green roofs in its mitigation Jonathan Scicluna James Madison University Follow this and additional works at: https://commons.lib.jmu.edu/master201019 Part of the Environmental Health and Protection Commons, Environmental Studies Commons, Other Earth Sciences Commons, and the Sustainability Commons Recommended Citation Scicluna, Jonathan, "The urban heat island effect in Malta and the adequacy of green roofs in its mitigation" (2016). Masters Theses. 467. https://commons.lib.jmu.edu/master201019/467 This Thesis is brought to you for free and open access by the The Graduate School at JMU Scholarly Commons. It has been accepted for inclusion in Masters Theses by an authorized administrator of JMU Scholarly Commons. For more information, please contact [email protected]. THE URBAN HEAT ISLAND EFFECT IN MALTA AND THE ADEQUACY OF GREEN ROOFS IN ITS MITIGATION Jonathan Scicluna A dissertation submitted to the UNIVERSITY OF MALTA and JAMES MADISON UNIVERSITY In Partial Fulfilment of the Requirements for the degree of Master of Science in Sustainable Environmental Resources Management/ Master of Science in Integrated Science and Technology 2016 To my Family ii Acknowledgements I would like to express my gratitude to my supervisors Mr Antoine Gatt and Dr Wayne S. Teel as well as to Prof Louis F. Cassar. I would also like to thank the course coordinators Dr Elisabeth Conrad and Dr Maria Papadakis as well as the administrative staff at the Valletta Campus especially Mr Mario Cassar and Ms Mersia Mackay Zammit.
    [Show full text]
  • Clothesline Effect (Tanner 19S7)
    Measuring Forest EVdrPOTRANSPlRAtlOW -Theory and Problems by C. Anthony Federer U.S.D.A. FOREST SERVICE RESEARCH PAPER NE-165 1970 NORTHEASTERN FOREST EXPERIMENT STATION, UPPER DARBY, PA. FOREST SERVICE, U.S. DEPARTMENT OF AGRICULTURE RICHARD D. LANE. DIRECTOR THE AUTHOR C. ANTHONY FEDERER, meteorologist, received a bach- elor of science degree in forestry from the University of Massachusetts in 1959. He joined the Forest Service in 1964 after receiving a Ph.D. degree in soil science from the University of Wisconsin. He is now on the staff of the water yield improvement project at the Northeastern For- est Experiment Station's research unit in Durham, N. H. SOME BASIC PROBLEMS A SATISFACTORY general method of measuring forest evapotranspiration has yet to be developed. Many pro- cedures have been tried, but only the soil-water budget method and the micrometeorological methods offer any degree of suc- cess. This paper is a discussion of these procedures and the prob- lems that arise in applying them. It is designed as a reference for scientists and management specialists working in forest hydrology and meteorology. In forest hydrology, problems that require knowledge of the amount of water being lost to the atmosphere by evaporation and transpiration can be divided into two major groups: (1) esti- mating evapotranspiration from an existing fully forested sur- face, and (2) predicting the changes in evapotranspiration that would follow any given treatment. These problems can generally be subdivided according to the time and area scales involved. Water-yield problems may be of concern on an annual, seasonal, monthly, or even weekly basis.
    [Show full text]
  • Urban Heat Islands: Global Variation and Determinants in Hot Desert and Hot Semi-Arid Desert Cities
    Urban heat islands: Global variation and determinants in hot desert and hot semi-arid desert cities Ronald R. Rindfuss Soe Myint Anthony Brazel Chao Fan Baojuan Zheng ABSTRACT The urban heat island (UHI) phenomenon affects local, as well as regional and global climates, yet most of what is known about UHI comes from local case studies using methodologies that vary considerably from case to case. We present the first global examination of UHI for hot desert and hot semi-arid desert cities using data and methodology consistent across 159 cities. By using a global approach it is apparent that desert cities cluster at the edges of climate zones. As suggested in the case-study literature, the majority, but not all, desert cities have negative UHI during the daytime, but positive at night. Vegetation in the cities, compared to bare ground in the rural buffer is an important contributor to the negative daytime UHI. But there are a variety of other biophysical factors including nearness to an ocean, the Humboldt current, elevation, and the Indian monsoon, that are important. Even after all the biophysical factors are controlled, development, whether measured by GDP, energy consumed or electricity consumed, reduces the size of the oasis UHI effect, confirming that anthropogenic effects go beyond planting and irrigating vegetation. INTRODUCTION The urban heat island phenomenon (UHI) is well-known, with urban areas warmer than their surrounding rural countryside. Cities produce their own microclimates, affecting local behavior, health, and economies as well as regional and global climates. The reasons for UHI include building and road materials absorbing radiant heat in the daytime, slowly releasing it at night; HVAC systems and motor vehicles generating heat; lower proportion of surface area covered in water; manufacturing activities releasing heat; and human metabolism itself.
    [Show full text]
  • The Benefits of Green Infrastructure for Heat Mitigation and Emissions
    CLIMATE-SMART CITIES™ The benefits of green infrastructure for heat mitigation and emissions reductions in cities Written by the Urban Climate Lab at the Georgia Institute of Technology For The Trust for Public Land’s Climate-Smart Cities™ program June 2016 The benefits of green infrastructure for heat mitigation and emissions reductions in cities: A review of the literature Executive Report Printed on 100% recycled paper. © 2016 The Trust for Public Land. The Trust for Public Land creates parks and protects land for people, ensuring healthy, livable communities for generations to come. tpl.org Table of contents List of figures ............................................................................................................................ 5 1 Introduction ........................................................................................................................... 6 2 Urban scale climate change ................................................................................................ 8 2.1 Drivers of climate change in cities .................................................................................. 8 2.2 Public health ................................................................................................................ 9 2.3 Green infrastructure ........................................................................................................ 10 3 Green infrastructure strategies ......................................................................................... 12 3.1 Urban trees
    [Show full text]
  • 1 Lecture 33, Canopy Evaporation
    Lecture 33, Canopy Evaporation and Transpiration, part 3, Theory November 19, 2014 Instructor: Dennis Baldocchi Professor of Biometeorology Ecosystem Science Division Department of Environmental Science, Policy and Management 345 Hilgard Hall University of California, Berkeley Berkeley, CA 94720 [email protected] Topics Concepts, 1 1. Evaporation 2. Potential Evaporation 3. Equilibrium Evaporation 4. Transpiration 5. Dew, Condensation, Distillation Modeling Approaches A. Bowen Ratio B. Thornthwaite Equation C. Penman’s Combination Equation D. Penman Monteith Equation E. Isothermal Energy Balance F. Equilibrium Evaporation G. Priestly-Taylor Equation Concepts, 2 1. Canopy conductance 2. Coupling Theory, Canopy Scale 3. Sensitivity and Feedbacks L33.1. Introduction Evaporation is the “physical process by which a liquid or solid is converted to a gaseous state” (Glossary of Meteorology). 1 Plant canopies introduce water vapor into the atmosphere via transpiration and the evaporation of water from the soil and free water on the leaves and stems. Some scientists call the summed rate evapotranspiration. This field has a long and rich history with over 7000 peer-reviewed articles identified on the web of science, circa 2008. Different and opposing views have been used historically to define evaporation (Jarvis and McNaughton, 1986). Meteorologists argue from the thermodynamic viewpoint that energy is required to drive the latent heat of vaporization. Evaporation also causes the surface and surrounding air to cool, which condensation releases heat. Physiologists counter that evaporation is driven by a potential difference between the humidity of the surface and the free atmosphere. The problem these opposing arguments is that they are valid for the scale at which they were defined and applied.
    [Show full text]