metr202- study urban climate system using satellite remote sensing and climate model
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METR202- Study Urban Climate System Using Satellite Remote Sensing and Climate Model. Professor Menglin Jin San Jose State University. Outline: Key Urban Features Satellite Approach Model Approach Future Directions. We studied: Urban Heat Island Effect - PowerPoint PPT PresentationTRANSCRIPT
METR202- Study Urban Climate System Using Satellite Remote Sensing and Climate Model
Professor Menglin JinSan Jose State University
Outline:Key Urban FeaturesSatellite ApproachModel ApproachFuture Directions
We studied:
Urban Heat Island EffectUrban aerosol effect on clouds and rainfall
•Urban is an extreme case of human-change natural land cover.
•Urban regions has strong pollution, greenhouse emission.
•60% people in USA live in cities
•Urban has unique water and heat cycles what directly affect human life
Why do we need to Study Urban regions?
Related PublicationsJin, M, 2012; Development of UHI index. J. of ClimateJin, M., J. M. Shepherd, M. D. King, 2005: Urban aerosols and their
interaction with clouds and rainfall: A case study for New York and Houston. J. Geophysical Research, 110, D10S20, doi:10.1029/2004JD005081.
Jin, M, R. E. Dickinson, and D-L. Zhang, 2005: The footprint of urban areas on global climate as characterized by
MODIS. Journal of Climate, vol. 18, No. 10, pages 1551-1565
Jin, M. and J. M. Shepherd, 2005: On including urban landscape in land surface model – How can satellite data help? Bull. AMS, vol 86, No. 5, 681-689.
Jin, M. J. M. Shepherd, and Christa Peters-Lidard, 2007: Development of A Parameterization For Simulating the Urban Temperature Hazard Using Satellite Observations In Climate Model in press by Natural Hazards.
Jin, M. and M. J. Shepherd, 2007: Aerosol effects on clouds and rainfall: urban vs. ocean. Revised for JGR
SF, 2008
Urban Heat Island Effect (UHI)
This phenomenon describes urban and suburban temperatures that are 2 to 10°F (1 to 6°C) hotter than nearby rural areas.
UHI impacts:
Elevated temperatures can impact communities by increasing peak energy demand, air conditioning costs, air pollution levels, and heat-related illness and mortality
High temperature also enhances surface convection, and causes more clouds and rainfall
Urban Heat Island Effect (UHI): Urban surface is hotter than that of surrounding non-urban regions
Surface temperature
We need to understand why and what are UHI effects
Traditional Way to Measure Urban Surface Temperature
UHI is function of city size, location, geographic conditions, population
Video: Urban Heat Island Effect (UHI)
http://www.met.sjsu.edu/metr112-videos/MET%20112%20Video%20Library-MP4/urban%20system/
Urban Heat Island.mp4
reasons for UHI
how to reduce UHI
Video: Urban Rainfall Effect
http://www.met.sjsu.edu/metr112-videos/MET%20112%20Video%20Library-MP4/urban%20system /
Urban Rainfall Effect.mp4
% of Land Area Built-up3 - 6%
43% of Land Area Dominated by Agriculture
Our Research Approach
• Using Satellite Remote Sensing to detect features of urban system
• Using Climate Model (land surface model) to simulate UHI and aerosol effects
Satellite observations retrieve urban system: Land surface properties: surface temperature, surface albedo, emissivity, soil moisture, vegetation cover
Atmosphere conditions: aerosol, clouds, and rainfall
urbanization significantly changes weather and climate
It shows that
1. Satellite remote sensing on urban regions
MODIS land coverRed color means urban built-up
Night Light of Tokyo
Night Light of Paris
pictures made by U.S. Defense Meteorological Satellites Program (DMSP)
Dr. Menglin Jin San Jose State University
(1-α)Sd +LWd-εσTskin4 +SH+LE + G= 0
Urbanization Effects
Land Surface Energy Budget:
Dr. Menglin Jin San Jose State University
(1-α)Sd +LWd-εσTskin4 +SH+LE + G= 0
Urbanization Effects
Land Surface Energy Budget:
Urbanization changes:Albedo (black surface)Vegetation ocverage (EP, roughness length)Sd, LWd (by aerosols, clouds)Tskin, SH/LE/G
EOS MODIS observed monthly mean daytime shows evident urban heat island effect (Copied from Jin et al, 2005a). The red areas show the dense building regions of Beijing.
Urbanization impacts on skin temperature
10°C !!!
Urbanization changes surface albedo (MODIS)
Urban surface albedo has a 4-6% decrease -> more solar radiation will be absorbed at surface\increase surface temperature
Urbanization reduces surface emissivity (MODIS)
(Jin et al. 2005, J. of Climate)
Urban reduces surface emissivity ->Less longwave radiation emitted from surface More heat is kept at surfaceSurface temperature increases
3. Urban Aerosols and Their Direct Effects on Clouds, Surface Insolation, and Surface Temperature
Urban Pollution Sources
Traffic
Industry
Indoor warming
Aerosols are solid/liquid particles pending in atmosphere
Size -0.01-100μm
Residence time – hours-days
Video
• Urban aerosol effect on rainfall
http://www.met.sjsu.edu/metr112-videos/MET%20112%20Video%20Library-MP4/urban%20system/
Summer Precip w-Pollution.mp4
Winter Precip w-Pollution.mp4
July 2005
NASA MODIS observed Aerosol Distribution
Indirect Effect: serve as CCN
Cloud dropRain dropIce crystalIce precipitation
Aerosol Direct Effect: Scattering Absorb
0oC
surface
Black carbon heats atmosphere and surfaceMost aerosols cool surface
More aerosol ->small cloud effective radius->high cloud albedo->cooling (Kaufmann and Koren 2006)
More aerosol->reduce rainfall (Rosenfeld 2000)
Total solar radiation decreased by aerosol= 20Wm-2
(Jin, Shepherd, and King, 2005, JGR)
Aerosol decreases surface insolation
Based on NASA GMAO radiative transfer model
par AOT
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New York
6-year averaged AERONET measurements
6-year daily averaged aerosol optical thickness (AOT) show •significant differences between Beijing and New York City•seasonal variation of urban aerosol
Beijing
New York City
Beijing Ftotal
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Reduction of surface insolation, Beijing
Urban Effects on Climate: An Analogue
Urban Effects on Radiative Forcing Known, but Effects on Water Cycle Processes (e.g. Precipitation Variability) Less Understood (IPCC, 2007)
Urban Heat Island Effect (UHI)
Is it a
• day time phenomenon only
• night time phenomenon only
• both day+night phenomenon
How to deal with UHI?
http://www.youtube.com/watch?feature=endscreen&NR=1&v=t-sXHl3l-rMWatch video:
A case for San Jose-SF Bay Area, China
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