Characteristics of Latent Heating Rate From GPM and Convective Gravity Wave Momentum Flux Calculated Using the GPM Data

Abstract

Parameterizations of convective gravity-wave (CGW) drag (CGWD) require cloud information as input parameters. As cloud information provided from reanalyses includes some uncertainties, observed cloud information is required for better representation of CGWs. For this, characteristics of the latent heating rate (LHR) based on the Global Precipitation Measurement (GPM) satellite over 6 yr (June 2014 to May 2020) are investigated, and the CGW momentum flux and CGWD based on an offline CGWD parameterization are calculated using the GPM-LHR and the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) background variables. Additionally, they are compared with those using LHR afforded by MERRA-2. The averaged cloud-bottom height is lower than that from MERRA but the cloud top height is similar for the both data, yielding deeper clouds from GPM that can generate more high phase-speed components of CGWs. The column-maximum heating rate, which is an input of the CGW momentum flux, of GPM-LHR is maximal near the equator and the secondary maximum locates in the winter hemisphere storm tracks. The maximum of the cloud top momentum flux (CTMF) of CGWs locates in the winter hemisphere storm tracks, with the GPM-CTMF being much larger than MERRA-CTMF, as extreme convective events occur more frequently in GPM. In the equatorial region above z = 40 km, the GPM-CGWD is significantly larger because high phase-speed components of CGWs that survive up to the upper stratosphere are abundant for GPM-CTMF, and this will contribute to drive more realistic semi-annual oscillation.