Observations of Mid-level Convective Clouds During Nauru99
Jensen, M.P.(a) and Del Genio, A.D.(b), Department of Applied Physics and Applied Mathematics, Columbia University/ NASA GISS (a), NASA Goddard Institute for Space Studies
Twelfth Atmospheric Radiation Measurement (ARM) Science Team Meeting
It has long been recognized that there is an abundance of different convective cloud types in the tropics. Tropical convective cloud populations have often been considered to be dominated by shallow trade-wind cumulus and deep cumulonimbus. However, radar and satellite studies have shown the presence of a relative peak in cloud occurence in the mid-troposphere that may be attributed to cumulus congestus clouds. These clouds are characterized by cloud-base heights near the lifting condensation level, cloud-top heights near the freezing level, a general lack of ice-phase hydrometeors and often precipitation reaching the surface. They are thought to play a role in the pre-conditioning of the mid-tropspheric humidty profile for the onset of deep convection. These clouds are especially well-suited for study by the ARM suite of instruments becasue they occur frequently over the TWP ARM sites and the full depth of the clouds can be observed by the MMCR. We present some initial observations of several mid-level convective cloud cases with an emphasis on characterizing the position of cloud-top, the modulation of the atmospheric thermodynamic profile, estimating entrainment and their radiative impacts.
Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).
