1. METR112- Global Climate Change: Urban Climate System Professor Menglin Jin San Jose State University Outline: Urban observations Urban heat island effect Urban aerosol Urban rainfall

3. SF, 2008

4. 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

5. 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

6. Video: Urban Rainfall Effect http://www.met.sjsu.edu/metr112- videos/MET%20112%20Video%20Library- MP4/urban%20system/ Urban Rainfall Effect.mp4

7. Video Observe urban system effect http://www.met.sjsu.edu/metr112- videos/MET%20112%20Video%20Library- MP4/urban%20system/ Animation of Atlanta Tornado

8. 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?

9. Related Publications Jin, 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

10. % of Land Area Built-up 3 - 6% 43% of Land Area Dominated by Agriculture

11. % of Land Area Built-up 3 - 6% 43% of Land Area Dominated by Agriculture

12. 1. Satellite remote sensing on urban regions MODIS land cover Red color means urban built-up

13. Night Light of Tokyo

14. Night Light of Paris

15. pictures made by U.S. Defense Meteorological Satellites Program (DMSP)

17. The Afternoon Satellites “A-Train” of Earth Observing System (EOS)  The Afternoon constellation consists of 7 U.S. and international Earth Science satellites that fly within approximately 30 minutes of each other to enable coordinated science  The joint measurements provide an unprecedented sensor system for Earth observations Courtesy of M. King

18. Aura Launched July 15, 2004  Is the stratospheric ozone layer recovering?  What are the processes controlling air quality?  How is the Earth’s climate changing? HIRDLS TES MLS OMI

19. Satellite measurements show unique features of Land cover – urbanization coverage Surface Temperature – Urban Heat Island Effect Vegetation coverage Emissivity Albedo Clouds Rainfall Aerosol Urban Surface Atmosphere

20. 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

21. 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

22. 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

23. Dr. Menglin Jin San Jose State University (1-α)S d +LW d -εσT skin 4 +SH+LE + G= 0 Urbanization Effects Land Surface Energy Budget:

24. Dr. Menglin Jin San Jose State University (1-α)S d +LW d -εσT skin 4 +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

25. 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 !!!

26. 50km Local Urbanization changes surface temperature Urban heat island effect Daytime Nighttime 50km MODIS

27. Jin et al. 2005 J. of Climate MODIS Observed Global urban heat island effect

28. Urbanization changes surface albedo (MODIS) Urban surface albedo has a 4-6% decrease -> more solar radiation will be absorbed at surface  \ increase surface temperature

29. 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 surface  Surface temperature increases

30. Existing Coupled Land-Atmosphere Models: Coarse Resolution, Biogeophysics Focus e.g., CLM: (NCAR, DAO) NOAH: (NCEP) Turbulence production Urban thermal properties Radiation trapping Radiation attenuation Canopy heating & cooling

31. What Can be Done ? to reduce negative Urban heat island effects? Education : a key component of many heat island reduction effort Cool Roofs: Over 90% of the roofs in the United States are dark-colored. These low-reflectance surfaces reach temperatures of 150 to 190°F (66 to 88°C) Trees and Vegetation Cool Pavements

32. Cool Roofs Cool roof systems with high reflectance and emittance stay up to 70°F (39°C) cooler than traditional materials during peak summer weather. The Utah Olympic Oval uses cool roof technology.

33. What Is a "Cool Roof"? Cool roof materials have two important surface properties: a high solar reflectance – or albedo a high thermal emittance Solar reflectance is the percentage of solar energy that is reflected by a surface. Thermal emittance is defined as the percentage of energy a material can radiate away after it is absorbed.

34. 3. Urban Aerosols and Their Direct Effects on Clouds, Surface Insolation, and Surface Temperature

35. Video Urban aerosol effect on rainfall http://www.met.sjsu.edu/metr112- videos/MET%20112%20Video%20Library- MP4/urban%20system/http://www.met.sjsu.edu/metr112- videos/MET%20112%20Video%20Library- MP4/urban%20system/ Summer Precip w-Pollution.mp4 Winter Precip w-Pollution.mp4

36. July 2005 NASA MODIS observed Aerosol Distribution

37. Urban Pollution Sources Traffic Industry Indoor warming Aerosols are solid/liquid particles pending in atmosphere Size -0.01-100μm Residence time – hours-days

38. Indirect Effect: serve as CCN Cloud drop Rain drop Ice crystal Ice precipitation Aerosol Direct Effect: Scattering Absorb surface Black carbon heats atmosphere and surface Most aerosols cool surface More aerosol ->small cloud effective radius-> high cloud albedo->cooling (Kaufmann and Koren 2006) More aerosol->reduce rainfall (Rosenfeld 2000)

39. 3.2. Remote Sensing of Aerosol Properties International satellite sensors enabling remote sensing of tropospheric aerosols –AVHRR, TOMS, ATSR-2, OCTS, POLDER, SeaWiFS, MISR, MODIS, AATSR, MERIS, GLI, and OMI Michael King, NASA GSFC

40. 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

41. 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

42. Reduction of surface insolation, Beijing

43. 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)

44. Human Activities In Arid Urban Environments Can Affect Rainfall And Water Cycle http://www.sciencedaily.com/releases/2006/06/060619222554.htm Professor Marshall Shepherd of The University of Georgia found: a 12-14 percent increase (which scientists call an anomaly) in rainfall in the northeast suburbs of Phoenix from the pre-urban (1895-1949) to post-urban (1950-2003) periods.

45. A case for Shang Hai, China

46. UHI Is observed for nighttime for all months in year Menglin Jin, San Jose State University

49. Class participation: Climate Game!

50. City A

51. City B

52. City C

53. City D

54. City E

55. City F

56. City G

57. Climate Game Names Match the city with the corresponding climatology by indicating the appropriate letter ° Sacramento, California (38°N) _____________ Phoenix, Arizona (33°N)_____________ Denver, Colorado (40°N)_____________ Iquitos, Peru (4°S)_____________ ° Mobile, Alabama (30°N)_____________ ° Winnipeg, Canada (50°N)_____________ ° Fairbanks, Alaska (65°N)_____________