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.
Latent heating (LH) profiles from the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement mission (GPM) were employed to examine the LH distribution during the quasi‐biennial oscillation (QBO) disruption in the 2015/2016 Northern Hemispheric (NH) winter. We used the LH anomalies from the observation era climatology to compensate for the discontinuity between the TRMM and GPM LH. The difference in the LH anomalies (LHd) between the 2015/2016 winter and the typical winter coinciding with the westerly QBO phase revealed that deeper convective systems in the 2015/2016 winter shifted to the equator, releasing more latent heat relative to the convective systems in the winters coinciding with the westerly QBO phase. Comparison of the LHds calculated for each winter of 1998–2019 shows that the changes in the convective systems in the 2015/2016 winter were statistically exceptional among the changes in other winters. Inside the convective systems, stronger latent heat release and more frequent occurrences of deep convective and deep‐stratiform rain cells made up the total LHd during the 2015/2016 winter. Specifically, convective rain cells mainly derived the LHd of the convective systems in the 2015/2016 winter, except in February 2016. The results suggest that the LH increase from the typical winter with the westerly QBO phase may be considered an unusual equatorial wave source during the 2015/2016 QBO disruption. The signatures of the LHd profiles in the 10°S–10°N zonal band are sourced from the abnormal convective systems that were shifted from the western Pacific to the central‐to‐eastern Pacific.
Passive microwave radiative transfer models are strongly influenced by the cloud and precipitation hydrometeor properties. Particularly, they can sensitively interact with frozen hydrometeors through multiple high-frequency channels. However, frozen hydrometeors are one of the most difficult parameters to comprehend due to the lack of insitu data. Until recently, studies have attempted to describe more reasonable hydrometeor distributions using various microphysics parameterizations coupled with the weather research and forecasting (WRF) models. Herein, we aim to apply the proposed methods to passive microwave radiative transfer simulations. We implemented a passive microwave radiative transfer simulation that considers various microphysical assumptions by creating a new Mie scattering look-up table. Furthermore, we evaluated the bulk microphysics parameterizations (WDM6, Morrison, Thompson, and P3 schemes) for the tropical cyclone Krosa (2019) that were observed by the global precipitation measurement microwave imager instrument, specifically concentrating on the rimed and aggregated ice categories (snow, graupel, and P3 ice). Based on the evaluation results, we concluded the following: WDM6 graupel and Morrison snow afford excessive scattering signals at 37 GHz. However, at 166 GHz, none of the parameterizations produce sufficient scattering signals for comparison with the observations. The P3 ice affords significantly underestimated scattering signals at 89 GHz and above despite its sophisticated assumptions. In contrast, Thompson snow affords scattering signals similar to the observations, despite a shape-related error. In summary, this study introduced a method for implementing a microphysical-consistent radiative transfer computation and successfully showed how various microphysical assumptions of clouds can change the passive microwave radiative signatures.
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