The time-space exchangeability of satellite retrieved relations between cloud top temperature and particle effective radius I. M. Lensky1 and D. Rosenfeld2 1Department of Geography and Environmental Studies, Bar-Ilan University, Ramat-Gan, Israel 2Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
Abstract. A 3-minute 3-km rapid scan of the METEOSAT Second Generation geostationary
satellite over southern Africa was applied to tracking the evolution of
cloud top temperature (T) and particle effective radius (re) of
convective elements. The evolution of T-re relations showed little
dependence on time, leaving re to depend almost exclusively on T.
Furthermore, cloud elements that fully grew to large cumulonimbus stature
had the same T-re relations as other clouds in the same area with
limited development that decayed without ever becoming a cumulonimbus.
Therefore, a snap shot of T-re relations over a cloud field provides
the same relations as composed from tracking the time evolution of T and
re of individual clouds, and then compositing them. This is the essence
of exchangeability of time and space scales, i.e., ergodicity, of the
T-re relations for convective clouds. This property has allowed
inference of the microphysical evolution of convective clouds with a snap
shot from a polar orbiter. The fundamental causes for the ergodicity are
suggested to be the observed stability of re for a given height above
cloud base in a convective cloud, and the constant renewal of growing cloud
tops with cloud bubbles that replace the cloud tops with fresh cloud matter
Citation: Lensky, I. M. and Rosenfeld, D.: The time-space exchangeability of satellite retrieved relations between cloud top temperature and particle effective radius, Atmos. Chem. Phys., 6, 2887-2894, doi:10.5194/acp-6-2887-2006, 2006.