Spatiotemporal Characteristics of Momentum Flux of Convective Gravity Waves Calculated Using the Latent Heating Rate from Satellite Observed Data

다국어 초록 (Multilingual Abstract)

In this study, we calculate the convective gravity wave (CGW) momentum flux of the off-line CGW parameterization utilizing the latent heating rate obtained from satellite measurements data of Global Precipitation Measurement (GPM) for 6 years (June 2014 to May 2020), and the results are compared with those using the latent heating rate provided from MERRA-2. The first peak of the zonally averaged column maximum latent heating rate (CMHR) from GPM is 7.3 K day^-1 in the equatorial region, with the secondary peak of 3.2 K day^-1 in the storm track regions. Semiannual and annual cycles are statistically significant in the equatorial regions, while the annual cycle is dominant in other regions. The zonally averaged cloud-top momentum flux (CTMF) of CGWs is maximum in the storm track regions of the winter hemisphere of both hemispheres where the secondary peak of CHMR exists, as CTMF is determined not only by CHMR but other factors such as large-scale wind, stability, and cloud top and bottom heights. In the storm track regions, strong westward momentum flux is dissipated in the lower mesosphere without filtering under westerly background wind below, resulting in the deceleration of the polar jet above 3 hPa, while the eastward momentum flux is mostly filtered out in the stratosphere. In the equatorial region, vertical wind shear associated with the quasi-biennial oscillation (QBO) determines the sign of CGW drag; positive drag during the westerly QBO and opposite during the easterly QBO. There exist several differences in the CTMF and drag calculated using the latent hearing rate from GPM compared with that from MERRA-2: (i) CTMF magnitude is generally larger, in particular in the southern hemispheric storm tracks, and (ii) CGW drag is larger in the equatorial lower mesosphere, compared with those calculated using the MERRA-2 latent heating rate.