Observation study of dust aerosolcloudprecipitation interactions over East Asia Jianping Huang, Wencai Wang, Bin Chen, Jing Su, Hongru Yan and Jianron Bi College of Atmospheric Sciences Lanzhou University http://climate.lzu.edu.cn/~jhuang Aug. 1819, 29, YinChun, China
outline The actuality of Northwest China The direct, indirect and semidirect effect of aerosols Results Conclusion
Northwest China is arid/semiarid area
Weather/Climate disasters frequently happen Debris flow, drought
This area is the a major source region of dust storm Distribution of Dust Storm over China
Many kinds of other aerosols in this area
Sensitive to global warming 5 3.9.8.7.6.5.4.3.2.1.1.2.3.4 Loess Plateau Humidity Region 2 8 9 1 11 12 13 1 Longterm trend of temperature in China Variation of annual mean temperature anomalies for Loess Plateau (red solid lines) and Humidity Region (black dashed lines) 5 3 11 1 9 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 Loess Plateau Humidity Region 2 8 9 1 11 12 13 1 Longterm trend of precipitation in China Variation of annual mean precipitation anomalies for Loess Plateau (red solid lines) and Humidity Region (black dashed lines)
Lan Zhou ( Fu et al. 26, Science ) Why the warming rate of the arid / semiarid area obviously higher than the humid area? The adjustment of circulation was caused by global warming Local aerosol effect on regional climate
Aerosols Direct Effect SemiDirect Effect Indirect Effect Diffusion Absorption & Scattering Cloud Formation Plant Production & Carbon Sink Atmospheric Radiation Budget Precipitation & Land Process Carbon Cycle Energy Cycle Water Cycle Aerosols Effect on Climate
The direct dust aerosol effect Absorb solar radiation! Heating Atmosphere!
Indirect aerosol effect Higher droplet Concentration (CCN) Smaller droplets Lower Precipitation rate Clouds longer lived More reflective cloud (Cooler climate)
Indirect Effect of Dust Aerosol Reduce the ice diameter and increase high cloud cover Huang et al., GRL, 26a Comparison of ice cloud diameter over the dustfree cloud (CLD) and clouds over the dust (COD) region. Correlation between Taklamagan dust storm index and ISCCP high cloud amount.
The semidirect aerosol effect Absorb solar radiation Evaporation of the cloud! Reduce low cloud cover Evaporation Warm the climate as low clouds scatter solar radiation back to space. Huang et al., GRL, 26b
SemiDirect Effect of Dust Aerosol Reduce low cloud water Path Huang et al., GRL, 26b Comparison of low cloud water path over the dustfree cloud (CLD) and clouds over the dust (COD) region.
SemiDirect Effect of Dust Aerosol Reduce low cloud water Path Huang et al., GRL, 26b Comparison of the cloud water path for dustfree with cloud over dust region as a function of effective cloud top temperature Te for (a) IWP, (b) LWP.
Dusty cloud reduced net TOA cloud cooling effect by % and may lead to warm atmosphere. 3 25 NET RF (COD) NET RF (CLD) CRF 2 15 1 5 Su et al, ACP 28 23 24 25 26 Year Comparison of the annual mean net radiative forcing at the TOA.
Su et al, ACP 28
81% dusty cloud warming effect is contributed by indirect/semidirect effect, 19% from direct effect. Su et al, ACP, 28
Ice cloud Dust transport Dust transport water cloud Dust transport Dust transport Dust aerosols longdistance transport
CALIPSO measurements can help to find dust transport paths 532nm total attenuated backscatter Back trajectories Huang et al., JGR, 28
35 N 45 N 7 E 11 E 35 N 45 N 12 E 16 E Two regions we choose
Data observe aerosols and clouds at the same altitude calculate the properties and radiative forcing of cloud
Definition of the dusty cloud
Dusty cloud can be identified by CALIPSO and CloudSat
Case in Source Region (a) (b) (c) (d) Vertical profiles of dusty cloud parameters in the source region, March 5, 27. CloudSat cloud mask image, CALIPSO 532nm total backscatter, volume depolarization ratio, 164nm/532nm backscatter color ratio.
Case in Remote Region (a) (b) (c) (d) Vertical profiles of dusty cloud parameters in the remote region, April 18, 27. CloudSat cloud mask image, CALIPSO 532nm total backscatter, volume depolarization ratio, 164nm/532nm backscatter color ratio.
Water cloud Results ice cloud Frequency(%) 1 8 6 2 Pure Cloud(11.65) Dusty Cloud(9.3) Frequency(%) 1 8 6 2 Pure Cloud(43.99) Dusty Cloud(35.69) 2 6 1 14 18 22 26 3 34 38 1 3 5 7 9 11 13 Re of Water Cloud in Source Region(um) De of Ice Cloud in Source Region(um) Frequency(%) 1 8 6 2 Pure Cloud(11.88) Dusty Cloud(11.68) Frequency(%) 1 8 6 2 Pure Cloud(55.28) Dusty Cloud(51.65) 2 6 1 14 18 22 26 3 34 38 Re of Water Cloud in Remote Region(um) 1 3 5 7 9 11 13 De of Ice Cloud in Remote Region(um) Comparison of water (Re) and ice (De) cloud particle size between the source and remote regions.
Water cloud ice cloud Frequency(%) 1 8 6 2 Pure Cloud(48.33) Dusty Cloud(33.26) Frequency(%) 1 8 6 2 Pure Cloud(139.13) Dusty Cloud(18.62) 5 15 25 35 45 55 65 75 85 95 15 45 75 15 135 165 195 225 255 285 LWP of Water Cloud in Source Region(g/m*2) IWP of Ice Cloud in Source Region(g/m*2) Frequency(%) 1 8 6 2 Pure Cloud(11.7) Dusty Cloud(74.13) Frequency(%) 1 8 6 2 Pure Cloud(273.24) Dusty Cloud(185.3) 5 15 25 35 45 55 65 75 85 95 LWP of Water Cloud in Remote Region(g/m*2) 15 45 75 15 135 165 195 225 255 285 IWP of Ice Cloud in Remote Region(g/m*2) Comparison of liquid water path (LWP) and ice water path (IWP) between the source and remote regions.
Water cloud ice cloud Frequency(%) 1 8 6 2 Pure Cloud(273.19) Dusty Cloud(274.45) Frequency(%) 1 8 6 2 Pure Cloud(242.45) Dusty Cloud(246.9) 21 22 23 2 25 26 27 28 29 3 31 32 Temperature of Water Cloud in Source Region(K) 21 22 23 2 25 26 27 28 29 3 31 32 Temperature of Ice Cloud in Source Region(K) Frequency(%) 1 8 6 2 Pure Cloud(27.) Dusty Cloud(274.16) Frequency(%) 1 8 6 2 Pure Cloud(246.21) Dusty Cloud(254.77) 21 22 23 2 25 26 27 28 29 3 31 32 Temperature of Water Cloud in Remote Region(K) 21 22 23 2 25 26 27 28 29 3 31 32 Temperature of Ice Cloud in Remote Region(K) Comparison of water and ice cloud temperature between the source and remote regions.
Water cloud ice cloud Re(um) 3 25 2 15 1 Dusty Cloud(9.3) Pure Cloud(11.65) De(um) 12 1 8 6 Dusty Cloud(35.63) Pure Cloud(43.99) 5 2 5 15 25 35 45 55 65 75 85 15 45 75 15 135 165 195 225 255 285 LWP in Source Region(g/m*2) IWP in Source Region(g/m*2) Re(um) 3 25 2 15 1 Dusty Cloud(11.68) Pure Cloud(11.88) De(um) 12 1 8 6 Dusty Cloud(51.65) Pure Cloud(55.28) 5 2 5 15 25 35 45 55 65 75 85 95 15 LWP in Remote Region(g/m*2) 15 45 75 15 135 165 195 225 255 285 IWP in Remote Region(g/m*2) Comparison of Re (De) as a function of LWP (IWP) between dusty and pure cloud over the source and remote regions.
Water cloud ice cloud Re(um) 3 25 2 15 1 5 Dusty Cloud(9.3) Pure Cloud(11.65) De(um) 1 8 6 2 Dusty Cloud(35.63) Pure Cloud(43.99) 1 3 5 7 9 11 13 1 3 5 7 9 11 OPD in Source Region OPD in Source Region Re(um) 3 25 2 15 1 Dusty Cloud(11.68) Pure Cloud(11.88) De(um) 1 8 6 Dusty Cloud(51.65) Pure Cloud(55.28) 5 2 1 3 5 7 9 11 13 OPD in Remote Region 1 3 5 7 9 11 OPD in Remote Region Comparison of Re (De) as a function of OPD between dusty and pure cloud over the source and remote regions.
The effective number concentration The perpendicular attenuated backscatter The effective radius 1um The parallel attenuated backscatter The layerintegrated depolarization ratio The equation for calculate the effective number concentration [Hu, et al., 27].
The effective number concentration Source Region Remote Region Frequency(%) 1 8 6 2 Dusty Cloud(131.52) Pure Cloud(8.11) Frequency(%) 1 8 6 2 Dusty Cloud(56.15) Pure Cloud(49.51) 2 6 1 1 18 22 26 3 3 38 2 6 1 1 18 22 26 3 3 38 The effective number concentration in source region(cm3) The effective number concentration in remote region(cm3) Comparison of the effective number concentration for dusty and pure cloud over the source and remote regions.
Radiative Forcing of Dusty and Pure Cloud C sw = F sw clr F sw C lw = F lw clr F lw C net = C sw The cloud radiative forcing is defined as the difference between the clearsky and the totalscene radiation results [Ramanathan et al., sw lw 1989], where F clr and F clr are the CERES clear sky broadband SW and LW radiative fluxes at the top of atmosphere (TOA), Fsw and Flw are SW and LW RF at the TOA for clouds (including dusty clouds) and for no cloud observation. + C lw
D Dusty P Pure W Water I Ice TOA NET radiative forcing of dusty and pure clouds in the source and remote regions.
SW RF of Water Cloud 6 5 3 2 1 Pure Cloud(154.13) Dusty Cloud(94.15) 25 26 27 28 29 3 SW RF of Water Cloud 6 5 3 2 1 Pure Cloud(248.9) Dusty Cloud(29.1) 25 26 27 28 29 Source Region LW RF of Water Cloud 2 15 1 5 Pure Cloud(76.8) Dusty Cloud(5.9) LW RF of Water Cloud 2 15 1 5 Pure Cloud(41.66) Dusty Cloud(28.34) Remote Region NET RF of Water Cloud 25 26 27 28 29 3 6 5 3 2 1 Pure Cloud(77.33) Dusty Cloud(44.6) 25 26 27 28 29 3 Temperature NET RF of Water Cloud 6 5 3 2 1 25 26 27 28 29 Pure Cloud(27.23) Dusty Cloud(18.75) 25 26 27 28 29 Temperature
SW RF of Ice Cloud 6 5 3 2 1 Pure Cloud(27.82) Dusty Cloud(139.67) 22 23 2 25 26 27 28 SW RF of Ice Cloud 6 5 3 2 1 Pure Cloud(342.86) Dusty Cloud(229.) 22 23 2 25 26 27 Source Region LW RF of Ice Cloud 2 15 1 5 Pure Cloud(98.5) Dusty Cloud(65.65) LW RF of Ice Cloud 2 15 1 5 Pure Cloud(69.56) Dusty Cloud(52.74) Remote Region NET RF of Ice Cloud 6 5 3 2 1 22 23 2 25 26 27 28 Pure Cloud(19.32) Dusty Cloud(74.2) 22 23 2 25 26 27 28 NET RF of Ice Cloud 6 5 3 2 1 22 23 2 25 26 27 Pure Cloud(273.29) Dusty Cloud(176.27) 22 23 2 25 26 27 Temperature Temperature
Summery and Conclusion Those studies shows some evidence of the direct, indirect and semidirect effect of Asian dust aerosol. The absorption of Asian dust aerosol can cause: heating atmosphere evaporate cloud droplets reduce cloud water path and optical depth reduce cloudcooling effect lead to warm local climate lower precipitation rate The dust aerosol warming effect may be dominated by semidirect effect.