Vertical Distribution Of Aerosols And Effects On Cloud Phase

The vertical distribution of aerosols can regulate the Earth's radiation budget and global water cycle system by affecting the cloud phases at different temperature levels.The active satellite observations can provide unique advantages in studying the effects of aerosols on the cloud phase and evaluating the accuracy of the vertical distribution characteristics of aerosols in reanalysis data.And it has important scientific significance in educing the uncertainty of cloud-aerosol interactions in climate models.Based on the above considerations,the horizontal distribution,vertical distribution and long-term change characteristics of dust on different temperature layers were first studied based on the CALIPSO aerosol layer products and VFM products.And the regional applicability of the vertical distribution of the dust mixing ratio in the MERRA-2 aerosol reanalysis data during the same period were evaluated.Then,we studied the influence of different aerosol types and atmospheric dynamic parameters on the supercooled liquid cloud fraction(SCF)at global scale base on the CALIPSO-GOCCP vertical cloud phase distribution dataset,CALIPSO aerosol layer products,and meteorological parameters from ERA-Interim reanalysis data.The statistical results are shown as following:(1)In terms of the vertical distribution of aerosols occurrence frequency and AOD,our statistical results show that the occurrence frequency and AOD of aerosols decrease as the the temperature layers decrease.The aerosol in equatorial high latitudes is gradually divided into two zonal and moves toward the poles.At 0°C ~ 10°C temperature layer,there are dust and smoke latitudinal transmission belts.As the temperature decreases,the dust belts gradually increases and reaches the maximum at-20°C ~-10°C temperature layer.(2)Based on the CALIPSO spaceborne lidar evaluating MERRA-2 reanalysis data,we find that there are inconsistencies in different regions and seasons.The vertical distribution of dust can be described well by occrurrence frequency,DCB and MC in the ocean,especially for the Atlantic.,but it isn't applicable in other regions.In the spring,CALIPSO layer product data can detect dust at the-60°C temperature layer in the Pacific,while the MERRA-2 reanalysis data detect dust aerosols at the-30°C temperature layer.(3)Among five areas that we selected,the occurrence frequency of dust in northwest of China had a significant drop in 2013,while other four areas did not have a particularly noticeable changes.In the Sahara Desert,there has been a steady supply of dust in all seasons,and its occurrence frequency has been rich for many years.In the Atlantic,the seasonal variations of the occurrence frequency,DCB and MC of dust over all temperature layers are relatively consistent.(4)The regional and long-term changes of the SCF at different temperature levels not only depend on the aerosol frequency and types,but also are closely related to meteorological parameters.The results indicate that the statistical relationship between the meteorological parameters and SCF is not stable and varies with different regions.The apparent negative correlation between the SCF and vertical velocity/relative humidity indicates that SCF in the condition of the higher vertical velocity and relative humidity is smaller.(5)The effects of atmospheric stability(LTSS),skin temperature,and horizontal wind speed on the SCF are more complex than those of vertical velocity and relative humidity.Their temporal correlation with SCF depends on latitude or surface type.By analyzing their spatial correlation under different aerosol types,we found that there is also a negative correlation between the SCF and the vertical velocity(or skin temperature),however,there is a positive correlation between the SCF and the U wind.