Radar and satellite determined cloud top heights in Darwin as a function for wet season regime
Poster PDF
Authors
Robert Jackson — Argonne National Laboratory
Scott Matthew Collis — Argonne National Laboratory
Alain Protat — Australian Bureau of Meterology
Valentin Henri Louf — Bureau of Meteorology Australia
Wuyin Lin — Brookhaven National Laboratory
Andrew M. Vogelmann — Brookhaven National Laboratory
Satoshi Endo — Brookhaven National Laboratory
Category
Convective clouds, including aerosol interactions
Description
A known deficiency of general circulation models (GCMs) is that convection is typically parameterized using given assumptions such as on entrainment rate and mass flux. Furthermore, mechanisms coupling large scale forcing and convective organization are not well represented, leading to a poor representation of the macrophysical properties of convection. The U.S. Department of Energy (DOE) Energy Exascale Earth System Model (E3SM) aims to run at a 12 km resolution. At this scale mesoscale motions are partially resolved but how they interact with the convective parameterization is unknown. This prompts the need for observational datasets to validate the macrophysical characteristics, including cloud top heights, of convection in simulations and guide model development in E3SM in several regions of the globe.
This presentation will highlight a study of convective systems observed at the Tropical Western Pacific (TWP) ARM site in Darwin, Australia and the surrounding maritime continent. In Darwin clear forcing regimes occur during the wet season from November to April with the onset and break of the Northern Australian Monsoon and the phase of the Madden-Julian Oscillation (MJO) which can alter the characteristics of convection over the region. The echo top heights (ETHs) are derived using a novel technique based on reflectivity and velocity texture from fifteen years of continuous plan position indicator scans from the C-band POLarimetric (CPOL) radar. ETHs in convective regions are 2 to 3 km lower than those retrieved by the Multifunctional Transport Satellites over Darwin, suggesting that the radar underestimates the vertical extent of convection. Bimodal distributions of convective echo top heights have been observed, with increased unimodality when the convective phase of the MJO is over Australia. When the MJO is inactive over Australia, the distributions of ETHs show a greater occurrence of deep convection over the Tiwi Islands, suggesting that Hector and seabreeze convection play a greater role in the formation of deep convection over Darwin when the MJO is inactive over Australia.
