耶鲁大学 - 南京信息工程大学大气环境中心 土地利用变化对能量通量和地表气候的影响 LAND USE CHANGES, ENERGY FLUXES AND THE SURFACE CLIMATE 李旭辉 XUHUI LEE

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1 耶鲁大学 - 南京信息工程大学大气环境中心 土地利用变化对能量通量和地表气候的影响 LAND USE CHANGES, ENERGY FLUXES AND THE SURFACE CLIMATE 李旭辉 XUHUI LEE

2 Bulletin o the American Meteorological Society

3 Urban airshed GHG luxes Box model 3 C tracer technique Nanjing NOAA lask data Fossil inventory Urban lux partitioning

4 Drivers and pathways o atmospheric change Atmospheric state Physical state Climate-active agents Chemical state Climate-inactive agents Biophysical -Evaporation -Sunlight relection -Surace roughness Biogeochemical -GHGs -VOC -NOx and SOx -Aerosols -Mercury Land use change (deorestation, urbanization) Fossil combustion Intensive agriculture

5 Eects o deorestation on the climate system Biogeochemical eect arising rom increases in atmospheric CO 2 concentration causing changes in radiative orcing o the atmosphere consequences at global scale; no direct local impact Biophysical eect associated with changes in albedo, surace roughness and evaporation causing changes in energy balance and redistribution impact at both global and local scale Questions: Does small-scale deorestation increase or decrease the surace temperature? Which o these biophysical actors has the largest eect?

6 Source: alaska-in-pictures.com Blame the trees or global warming?

7 Albedo comparison, Saskatchewan, Canada Source: Betts and Ball (997) J Geophys Res 2:

8 Yatir Forest, Israel

9 Radiation balance, Yatir Forest TOA 7 33 Solar 238 W m Solar Forest Shrub land Data source: Rotenberg and Yakir (2) Science, 327:

10 Radiative orcing, longwave radiation eedback, and energy redistributions TOA Atmospheric boundary layer Solar Longwave Evaporation Convection

11 Response o surace temperature to local deorestation T a K L T a Blending height Forest T s Open land Deorestation signal DT s

12 2 2 2 ) ( ) ( R R S T n n s D D D D Response o surace temperature to local deorestation a a s p r T T C H H LE a a a s p r r r T C D D ) ( 4 3 Energy redistribution /roughness K a S ) ( ) ( 4 3 s a p T r C = /(4T a3 ) Albedo change ) ( D D a s p r T C Energy redistribution /Bowen ratio

13 Climate sensitivity Intrinsic sensitivity and.3 K per W m -2 at the global scale.2 K per W m -2 at the local scale Apparent sensitivity At the global scale ~.8 K per W m -2 At the local scale DT s DS ( ) 2 R n D ( ) 2 R n D 2

14 NCAR s Community Land Model Source: Oleson et al (23) NCAR s Technical Note

15 Urban heat island intensity or cities in North America AH s AH s n AH s n n Q Q Q Q R Q Q R R T D D D D D ) ( ) ( ) ( ) ( 2 * 2 * 2 * Daytime Nighttime

16 Urban heat island intensity or cities in North America Sum o components another ormulation

17 Attribution o deorestation eect 2 a 2 b a: Boreal / harvested b: Boreal / burnt - - c: temperate humid d: temperate semi-arid e: tropical DT s or DT (K) 2-2 e c 2-2 d : tropical - Observed DT - Radiative orcing Observed DTs Energy distr/roughness Source: Lee, Goulden, Hollinger et al. (2) Nature 497: Calculated DTs Energy distr/bowen ratio

18 FluxNet: A global network o CO 2 lux measurements Source:

19 Weather stations Poznan, Poland Dongshan ( 东山 ), Jiangsu, China Great Mountain Forest, Connecticut Braunschweig, Germany

20 Annual mean dierence in surace air temperature (open land minus orest) Annual mean dierence DT (K) y = -.7(?.2) x + 2.6(?.9) n = 37, R 2 =.3, p <.5 a Latitude ( o N) Source: Lee, Goulden, Hollinger et al. (2) Nature 497:

21 Annual mean dierence in surace air temperature (open land minus orest) N/S America Asia Source: Zhang, Lee, Yu, et al. (24) Environ Res Letters 9: 342

22 Annual mean dierence in surace air temperature (open land minus orest) FLUXNET Data Climate model Source: Zhang, Lee, Yu, et al. (24) Environ Res Letters 9: 342

23 Source: Zhang, Lee, Yu, et al. (24) Environ Res Letters 9: 342 Diurnal temperature range

24 Dependence o daytime urban heat island on precipitation Model calculation MODIS observation Source: Zhao, Lee, Smith, Oleson (24) Nature 5: 26-29

25 Attribution o urban heat island daytime: b, e, d nighttime: c, g, Source: Zhao, Lee, Smith, Oleson (24) Nature 5: 26-29

26 Eicient convectors Image source: Farlow Image source: Margolis

27 Smooth suraces help make cities into sizzling urban heat islands

28 Summary Sub-grid scale microclimate variables produced by climate models can be used or attribution o the biophysical eect. Small-scale deorestation cools the surace at high latitudes and warms the surace at low latitudes. The high-latitude deorestation cooling is greater than the low-latitude warming. Changes in convection eiciency are the main driver o UHI variations across climate gradients

29 Chicago Source: Mackay et al. (22) Building & Environ 49:

30 Albedo along a jack pine chronosequence Saskatchewan, Canada.35 Annual Albedo Data source: Alan Barr Age (year)