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Urban Aerosol Impacts on Downwind Convective Storms

Urban Aerosol Impacts on Downwind Convective Storms. VAN DEN HEEVER,S. AND WILLIAM R. COTTON J. Appl. Meteor. Climate.,46,828-850. Speaker: 陳文彬. St .Louis 8 June 1999. 雷達回波： contour:10dBZ. Grid1 ： 37.5km Grid2 ： 7.5km Grid3 ： 1.5km. Aerosol initialization concentrations.

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Urban Aerosol Impacts on Downwind Convective Storms

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  1. Urban Aerosol Impacts on Downwind Convective Storms VAN DEN HEEVER,S. AND WILLIAM R. COTTON J. Appl. Meteor. Climate.,46,828-850 Speaker:陳文彬

  2. St .Louis8 June 1999 雷達回波：contour:10dBZ

  3. Grid1：37.5kmGrid2：7.5kmGrid3：1.5km

  4. Aerosol initialization concentrations

  5. 方形矩陣：downwindcalculation

  6. Time evolution of the RURAL-H - NOCITY-H temperature and water vapor mixing ratio fields Shaded : T Contours: water vapor mixing ratio

  7. Higher background aerosol concentrationresults

  8. RURAL-H test Contoured at 750m: Updraft velocity Shaded:CCN個數at500m

  9. NOCITY-H test

  10. URBAN-H test.

  11. Time series of the total hydrometeor mass

  12. Time series of the accumulated volumetric precipitation

  13. Lower background aerosol concentration results

  14. RURAL-L simulation

  15. URBAN-L simulation

  16. Time series of (a) the maximum updraft within the downwind region and (b) the average of the maximum updraft Maximum downdraft within the downwind region

  17. Time series of the (left) cloud and (right) rain mixing ratios

  18. RURAL-L URBAN-L accumulated surface precipitation

  19. Conclusions • When GCCN or both CCN and GCCN concentrations were enhanced, cloud water and rain formed more rapidly. The updrafts were also stronger initially, and the downdrafts developed more quickly. • Greater amounts of surface precipitation were also produced in these cases during the first 1.25–1.5 h. When CCN alone were enhanced, the formation of cloud water, rain, and all of the ice species was delayed, as was the development of both the updrafts and downdrafts. • The surface precipitation was suppressed in the presence of urban-enhanced CCN concentrations.

  20. Conclusions • GCCN and both GCCN and CCN are enhanced leads to earlier in the storm life cycle than in the control simulation. • Urban aerosol effects on downwind convection and precipitation could be expected to be greater in less industrialized regions of the United States, as well as in countries such as Canada and Australia, where the background aerosol concentrations are generally lower. • The extremely complex, nonlinear relationships between the microphysics and dynamics therefore make it difficult to make absolute statements regarding the impacts of urban-enhanced CCN and GCCN on downwind convection and precipitation.

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