Assimilation of DAWN Doppler wind lidar data during the 2017 Convective Processes Experiment (CPEX): impact on precipitation and flow structure

Abstract

Abstract. An improved representation of 3-D air motion and precipitation structure through forecast models and assimilation of observations is vital for improvements in weather forecasting capabilities. However, there are few independent data to properly validate a model forecast of precipitation structure when the underlying dynamics are evolving on short convective timescales. Using data from the JPL Ku/Ka-band Airborne Precipitation Radar (APR-2) and the 2 µm Doppler Aerosol Wind (DAWN) lidar collected during the 2017 Convective Processes Experiment (CPEX), the NASA Unified Weather Research and Forecasting (WRF) Ensemble Data Assimilation System (EDAS) modeling system was used to quantify the impact of high-resolution sparsely sampled DAWN measurements on the analyzed variables and on the forecast when the DAWN winds were assimilated. Overall, the assimilation of the DAWN wind profiles had a discernible impact on the wind field as well as the evolution and timing of the 3-D precipitation structure. Analysis of individual variables revealed that the assimilation of the DAWN winds resulted in important and coherent modifications of the environment. It led to an increase in the near-surface convergence, temperature, and water vapor, creating more favorable conditions for the development of convection exactly where it was observed (but not present in the control run). Comparison to APR-2 and observations by the Global Precipitation Measurement (GPM) satellite shows a much-improved forecast after the assimilation of the DAWN winds – development of precipitation where there was none, more organized precipitation where there was some, and a much more intense and organized cold pool, similar to the analysis of the dropsonde data. The onset of the vertical evolution of the precipitation showed similar radar-derived cloud-top heights, but delayed in time. While this investigation was limited to a single CPEX flight date, the investigation design is appropriate for further investigation of the impact of airborne Doppler wind lidar observations upon short-term convective precipitation forecasts.

Impact of Lidar Data Assimilation on Simulating Afternoon Thunderstorms near Pingtung Airport, Taiwan: A Case Study

“…As in the study of Ref. [56], our findings suggest that assimilation of Doppler lidar wind profiles into a WRF-3DVAR system creates conditions that favor the development of ATs and upscale growth. Although the results of this study are only supported by a single case, they provide valuable clues to improve the prediction of ATs by using the assimilation of lidar wind profiler data at Pingtung Airport.…”

Global Three‐Dimensional Water Vapor Feature‐Tracking for Horizontal Winds Using Hyperspectral Infrared Sounder Data From Overlapped Tracks of Two Satellites

“…In contrast, GEO AMVs have a higher horizontal resolution of a few kilometers and resolve the diurnal cycle (but with the disadvantage of being available at only one pressure level for a given location and time). The temporal and spatial restrictions of our 3D AMVs limit their usability for mesoscale events (Hristova‐Veleva et al., 2021). Furthermore, as argued in Section 3.1, this low horizontal resolution leads to considerably low speed bias.…”

Near‐Storm Environmental Relationships With Tropical Oceanic Convective Structure Observed During NASA CPEX and CPEX‐AW

“…Nevertheless, the unique capabilities of the CPEX(‐AW) remote sensing instrumentation in their ability to capture essential small‐scale (both spatially and temporally) near‐storm environmental features and variability are highlighted in this study, and they serve as an important benchmark for future TOC studies. The CPEX(‐AW) instrumentation, particularly DAWN, offer a glimpse into the potential of future spaceborne remote sensing, with higher resolution measurements capable of improving modeling efforts through improved process‐level knowledge of tropical convection (e.g., Mazza & Chen, 2021; Turk et al., 2020), data assimilation (e.g., Cui et al., 2020; Hristova‐Veleva et al., 2021; Minamide & Posselt, 2022), and model evaluation (e.g., Cui et al., 2020; Minamide & Posselt, 2022).…”

“…The DC‐8 aircraft was equipped with, amongst other instrumentation, a multi‐wavelength airborne precipitation radar, a Doppler wind lidar, and dropsondes. Together, these instruments provided rare, coincident, high‐resolution profiling of spatial three‐dimensional (3‐D) convective structure and near‐storm winds and moisture for convective systems of different spatial scales and intensities (Hristova‐Veleva et al., 2021; Turk et al., 2020). Given the uniqueness of this suite of observations, the CPEX and CPEX‐AW field campaigns present an exceptional opportunity to analyze their region's near‐storm environmental relationships with tropical oceanic 3‐D convective structure, which will be the focus of this study.…”