HR: 1340h
AN: A23D-1567    [Abstracts]
TI: Deep Convective Cloud Properties and Aerosol Influences as Observed from A-Train Satellites
AU: * Yuan, T
EM: yuan@atmos.umd.edu
AF: AOSC, Dept. Atmospheric and Oceanic Sciences, University of MD, College Park, MD 20742,
AU: * Yuan, T
EM: yuan@atmos.umd.edu
AF: ESSIC, Earth System Science Interdisciplinary Center, Univ. Of MD, College Park, MD 20742,
AU: Li, Z
EM: zli@atmos.umd.edu
AF: AOSC, Dept. Atmospheric and Oceanic Sciences, University of MD, College Park, MD 20742,
AU: Li, Z
EM: zli@atmos.umd.edu
AF: ESSIC, Earth System Science Interdisciplinary Center, Univ. Of MD, College Park, MD 20742,
AB: Deep convective clouds (DCC) are studied with the Aqua and Terra MODIS cloud products of cloud optical depth (COD), ice particle effective radius (IER), frequency of occurrence, etc. The DCC cloud properties are analyzed together with aerosol retrievals. IER is shown to be affected by cloud top brightness temperature, surface elevation, aerosol concentration and availability of giant cloud condensation nuclei (GCCN). DCCs developed over elevated areas tend to have smaller IER at the cloud top. We attribute this to colder cloud base and thinner cloud depth for mountainous region. Simultaneous observations of aerosols and clouds made by NASA's A-Train provide direct evidence of aerosol-cloud interaction for DCC. Increased level of aerosols reduces IER because of more activated droplets, delayed coalescence processes and possibly homogeneous freezing of numerous small droplets. On the other hand, larger IER is observed for clouds developed near the source of dust. We argue that activation of large dust particles as GCCN and/or as heterogeneous freezing ice nuclei may lead to early glaciation and thus larger IER. We studied the latitudinal variations of IER's dependence on temperature for DCCs and explain it through a simple thermodynamic model. We found a strong connection between DCC frequency pattern and precipitation pattern for several parts of the world. The diurnal variation of DCC top microphysical properties is linked to diurnal precipitation. General properties of DCCs presented in this study and their variations are useful for cloud parameterization in GCM models and our findings of aerosol influence on cloud top properties provides new insight to the aerosol-cloud-precipitation interaction.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0321 Cloud/radiation interaction
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting