Work

VARiational Analysis of Nonhydrostatic Dynamics Using Short‐Time Delayed Microwave Measurements, VARAND 2

Year: 2026

Type: article

Abstract: ABSTRACT Deep convective clouds play a central role in the Earth water and energy cycles, yet their rapid vertical development remains difficult to characterize. The COMODO mission relies on a tandem of two passive microwave radiometers flying sequentially with a time separation ranging from 45 to 135 s. This configuration enables the estimation of short‐time brightness temperature differences that informs on convective dynamics. In this study, we introduce VARAND, a one‐dimensional variational method that exploits multi‐temporal passive microwave observations like those provided by COMODO to retrieve key dynamical properties of deep convection. VARAND retrieves the vertical profile and short‐time evolution of the Ice Water Content (IWC), as well as a parametrized vertical profile of air vertical velocity (), characterized by its maximum amplitude () and the corresponding altitude (). These quantities are estimated through a dynamic observation operator that links short‐time variations of IWC and brightness temperature via an embedded vertical advection scheme. Applied to simulated COMODO observations for a tropical convective case, VARAND provides consistent reconstructions of , with coefficients of determination () of 0.71 and 0.72 for the retrieval of and , respectively. These results highlight the potential of multi‐temporal passive microwave observations to improve the characterization of deep convective updrafts and their representation in weather and climate models.

Source: Atmospheric Science Letters

DOI: 10.1002/asl2.70063

Authors: Thomas Lefebvre, Hélène Brogniez, Laura Hermozo, Frédéric Chevallier