Tropical Cyclone-Radiation Interaction in NASA Reanalysis and Model Products as Compared to CloudSat Observations

Tropical cyclone (TC)-radiation interaction has been regarded as a relevant process for TC development. Suppressing TC-radiation interaction generally leads to delayed tropical cyclogenesis, slower TC intensification rate and weaker TC intensity in numerical simulations. However, deeper understanding of the TC-radiation interaction based on observational measurements are needed to validate its representation in reanalysis and climate model simulations, which depict substantial variability in their estimation of TC-radiative interaction. In our study, CloudSat satellite retrievals of moisture and cloud properties, radiative heating, and TC radiative feedbacks are used to construct a long-term composite over 2006—2019 with respect to TC intensity. We find that inner-core averages of column-integrated water vapor path, liquid water path and ice water path from CloudSat increase substantially with TC intensity. However, when considering the average within a 1000-km radius of the TC center, only the column-integrated water vapor path experiences a significant dependence on TC intensity (in which it decreases with intensity). The dependence of inner-core moisture and cloud properties on TC intensity leads to greater tropospheric greenhouse trapping of longwave (LW) radiation and larger blocking of incoming shortwave (SW) radiation in the inner core as TC intensity increases. Therefore, the positive LW feedback further increases, and the negative SW feedback further decreases with TC intensity, augmenting the moist static energy (MSE) variance in TCs, especially for weak TCs and over the inner core. However, normalizing the radiative feedbacks by the radial-mean MSE variance substantially reduces their dependence on TC intensity. Decomposing the radiative feedbacks into contributions from moisture and cloud properties and both LW and SW reveals that the presence of ice clouds dominates the total-sky effect on both the LW and SW feedbacks for the feedback magnitude, sign of feedback value, and dependence on TC intensity. The liquid-cloud and clear-sky effects generally provide feedbacks of the opposite sign, an order of magnitude smaller feedback, and reversed dependence on TC intensity for both LW and SW radiation compared to the ice-cloud effect. In ongoing work, the above-mentioned analyses are extended to the MERRA-2 reanalysis and free-running MERRA-2 AMIP (M2AMIP) simulations. We aim to validate the representation of TC-radiative interactions in MERRA-2 and M2AMIP against that derived from the CloudSat measurements.