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

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

6. 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?

7. 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

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

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

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

11. Night Light of Tokyo

12. Night Light of Paris

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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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:

22. 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 !!!

23. 50km Local Urbanization changes surface temperature Urban heat island effect Daytime Nighttime 50km MODIS

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

25. Comparison of skin temperature for urban and nearby forests MODIS Cities have higher T skin than forests

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

27. 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

28. MODIS15_A2 Leaf Area Index (LAI) over Houston regions Often times, urban regions reduce surface vegetation cover

29. 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

30. (1-α)S d +LW d -εσT skin 4 +SH+LE + G= 0 Simulate Urbanization to Examine Its Effects Land Surface Energy Budget:

31. (1-α)S d +LW d -εσT skin 4 +SH+LE + G= 0 2. How to Simulate Urban? Urbanization Modifies Surface Energy Budget: Urban add new physical processes

32. 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

33. 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.

34. 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.

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

36. 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

37. July 2005 NASA MODIS observed Aerosol Distribution

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

39. 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)

40. Aerosol Dynamic Effect: Reduce Wind and Precipitation surface “aerosolized particles created from vehicle exhaust and other contaminants can accumulate in the atmosphere and reduce the speed of winds closer to the Earth's surface, which results in less wind power available for wind-turbine electricity and also in reduced precipitation…” (Jacobson and Kaufmann 2006) wind

41. 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

42. Aerosol-Cloud Relation AOD vs. water cloud effective radius More aerosols lead to smaller cloud droplets!

43. 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

44. 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

45. Reduction on surface insolation, New York City

46. Reduction of surface insolation, Beijing

47. MM5-Urban Model Study: Extreme case (Solar radiation reduced by -100wm -2 ) How cold can the surface become due to the surface insolation decrease, in an urban environment? For Beijing, aerosols cold the surface by more than 5°C in daytime. Beijing

48. Urban model simulation over New York City For June 15-16, 2006 For NYC, aerosol colds the surface by 1°C in daytime.

49. 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)

50. 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.

51. A case for Shang Hai, China

52. ShangHai city Rural regions

53. Daytime, monthly skin temperature of Shanghai is higher than surrounding cropland ShangHai cropland Menglin Jin, San Jose State University UHI

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

61. Class participation: Climate Game!

62. City A

63. City B

64. City C

65. City D

66. City E

67. City F

68. City G

69. 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)_____________