Changes of anthropogenic contributions of mineral dust from the 1880s to 2000s

Transcription

1 Changes of anthropogenic contributions of mineral dust from the 1880s to 2000s Tanja Stanelle, Isabelle Bey, Christian Reick, Thomas Raddatz, Ina Tegen Image: NASA

2 Introduction Objectives: To quantify the impacts of Climate Change (CC) and Anthropogenic Land Cover Changes (ALCC) on changes of mineral dust emission and burden between the 1880s and today To estimate how these changes influence the radiative forcing of aerosols

3 Modeling system

4 Atmospheric component ECHAM6 GHG & aerosol concentrations, Aerosol effect on clouds Temperature, Humidity, etc. Winds, Temperature, Radiation, etc. Aerosol component HAM2.1 Emission fluxes Natural Emission Module e.g., Biogenic organic compounds, Mineral dust Albedo, Roughness length, LAI, etc. Land Surface Component (JSBACH)

5 New: Determination of potential dust source areas The grid cell fraction covered with bare soil is a potential source area. Bare soil Bare soil = 1 veg_ratio_max Forest Shrubs Pasture /grass Crop Area covered with vegetation (veg_ratio_max) Tiles

6 New: Trees: no dust emissions Determination of potential dust source areas Grass, shrubs, pasture: lai max (i,itile) f A(i,itile) = fr(i,itile) e clump (PFT(i,itile)) Shrubs Crops: During growing season treated like grass After harvest: A(i,itile) = fr(i,itile)*1 LAI Potential dust source area in grid cell i: A tot (i) = ntile itile=1 +1 (1 veg ratio _ max (i)) A(i,itile) veg ratio _ max (i) e.g. grass crop harvest seeding time

7 Evaluation of the modified system

8 - MODIS March 2007 AOD@550nm - MODIS Deep Blue AOD@550nm - MISR AOD@550nm - CALIOP AOD@550nm - ECHAM6-HAM2.1 std AOD@550nm - ECHAM6-HAM2.1 new

9 Evaluation of modified scheme Comparison with satellite measurements: North Africa AOD CALIOP MISR MODIS E6H2 std E6H2 new J F M A M J J A S O N D month

10 Summary Evaluation: The new method does not degrade the dust simulations Land cover change can be accounted for interactively

11 Impact of Anthropogenic Land Cover Changes (ALCC) on Dust Particle Emissions and Associated Impact on Radiation Performed Simulations: Free, T63L31, AMIP SST and SIC, ACCMIP emissions Name Climate Land use PD HT PCHL HCPL

12 Present day Dust emissions Present day - HT 60 o N Gg/a o N Gg/a o N o N o o 0 30 o S o S o S o S o 150 o W120 o W90 o W60 o W30 o W 0 o 30 o E 60 o E 90 o E120 o E150 o E 180 o 180 o 150 o W120 o W90 o W60 o W30 o W 0 o 30 o E 60 o E 90 o E120 o E150 o E 180 o Present day - PCHL emission present - alcc Present day - HCPL emission present - cc 60 o N Gg/a o N o N o N o 0 0 o 0 30 o S o S o S o S o 150 o W120 o W90 o W60 o W30 o W 0 o 30 o E 60 o E 90 o E120 o E150 o E 180 o 180 o 150 o W120 o W90 o W60 o W30 o W 0 o 30 o E 60 o E 90 o E120 o E150 o E 180 o

13 Dust emissions Name Climate Land use PD HT PCHL HCPL Tg/a North Africa Tg/a North America Tg/a PD HT PCHL HCPL Australia PD HT PCHL HCPL PD HT PCHL HCPL

14 Name Climate Land use PD HT PCHL HCPL Dust burden Tg 6" 4" 2" 0" North Africa Present" PD HT Past" PCHL ALCC" HCPL CC" Tg 0.4" North America Tg 1.5" Australia 0.3" 0.2" 0.1" 1" 0.5" 0" Present" PD HT Past" PCHL ALCC" CC" HCPL 0" Present" PD HT Past" PCHL ALCC" HCPL CC"

15 Net forcing clear TOA sky TOP (clear present sky) PD Net forcing TOA PD - HT forcing clear sky TOP present-past W/m 2 2 W/m W/m W/m W/m W/m W/m W/m Net forcing forcing clear sky TOA TOP PD present-alcc - PCHL Net forcing forcing clear sky TOA TOP PD present-cc - HCPL W/m W/m W/m W/m W/m W/m W/m W/m

16 Summary ² Approach to interactively account for land cover changes. ² Evaluation indicates satisfying model performance -> we are able to calculate changes in dust emissions due to ALCC ² Changes in dust emissions and burden are caused by CC in North Africa; whereas both CC and ALCC influence dust in North America and Australia. ² Locally, there are changes in radiative forcing of more than 2 W/m 2 between HT and PD due to changes in dust emissions. The global change in net-forcing at TOA is W/m 2 between HT and PD (IPCC estimates of the direct forcing of anthropogenic aerosols are ±0.5 W/m 2 ). ² Both, CC and ALCC should be considered for estimating changes in radiative forcing due to dust.

17 Thank you!!! Frankfurter Allgemeine, , Staubsturm in Deutschland