Abstract
The anvil productivities of tropical deep convection are investigated and compared among eight climatological regions using 4 yr of collocated and combined CloudSat and CALIPSO data. For all regions, the convective clusters become deeper while they become wider and tend to be composed of multiple rainy cores. Two strong detrainment layers from deep convection are observed at 6–8 km and above 10 km, which is consistent with the trimodal characteristics of tropical convection that are associated with different divergence, cloud detrainment, and fractional cloudiness. The anvil productivity of tropical deep convection depends on the convection scale, convective life stage or intensity, and large-scale environment. Anvil ice mass ratio related to the whole cluster starts to level off or decrease when the cluster effective scales Weff (the dimension of an equivalent rectangular with the same volume and height as the original cluster) increase to about 200 km wide, while the ratios of anvil scale and volume keep increasing from 0.4 to 0.6 and 0.15 to 0.4, respectively. The anvil clouds above 12 km can count for more than 20% of cluster volume, or more than 50% of total anvil volume, but they only count less than about 2% of total ice mass in the cluster. Anvil production of younger convection of the same Weff is higher than that of the decaying convection. The regional difference in the composite anvil productivities of tropical convective clusters sorted by Weff is subtle, while the occurrence frequencies of different scales of convection vary substantially.
Highlights
The tri-modal characteristics of tropical convection (Johnson et al 1999) indicates prominent stable layers that exist over the Pacific warm pool and the tropical eastern Atlantic, which are associated with tri-modal distributions of divergence, cloud detrainment, and fractional cloudiness
Ice cloud microphysical properties are from CloudSat 2C-ICE product, which is a synergetic ice cloud retrieval from combining the Cloud Profiling Radar (CPR) and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements using a variational method to provide the profiles of extinction coefficient, ice water content (IWC) and effective radius for ice particles (Deng et al, 2010, 2013)
Without counting the stratiform rain, the anvil clouds detrained from convection count for 0.4 to 0.8 of the cluster horizontal fraction, 0.2 to 0.6 of the cluster cross section volume, and 0.05 to 0.20 of the cluster ice mass, depending on the cluster scales
Summary
The tri-modal characteristics of tropical convection (Johnson et al 1999) indicates prominent stable layers that exist over the Pacific warm pool and the tropical eastern Atlantic, which are associated with tri-modal distributions of divergence, cloud detrainment, and fractional cloudiness. From ISCCP C2 climatology, Chou et al (1999), Houze (1989), and Machado and Rossow (1993) showed that high cirrus fraction tends to increase strongly as deep cloud top temperature drops, which is referred as the cirrus-detrainment-temperature (CDT) relation Such a finding stimulated further investigations about climate feedbacks associated with cirrus clouds (Ramanathan et al 1989, 1991; Chou et al 1999; Lindsen et al 2002; Hartmann et al 2002; Stephens 2005). Cirrus clouds at 1416 km tend to be too tenuous to be detected by CloudSat, whose occurrence can be as high as ~60% (Sassen and Wang 2008) The combination of these two active sensors provides the full cross section of deep convection system, which has been used to study the tropical convection evolution during the MJO cycle (Del Genio et al 2012).
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