Simultaneous assimilation of radar and satellite observations to improve ensemble forecasts of convection initiation
Open Access
Author:
Eure, Keenan
Graduate Program:
Meteorology and Atmospheric Science
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 12, 2021
Committee Members:
David Jonathan Stensrud, Thesis Advisor/Co-Advisor Yunji Zhang, Committee Member Steven J Greybush, Committee Member David Jonathan Stensrud, Program Head/Chair Paul Markowski, Committee Member Matthew R. Kumjian, Committee Member
Keywords:
convection data assimilation satellite radar ensemble
Abstract:
Accurate predictions of the location and timing of convection initiation (CI) remains a challenge, even in high-resolution convection allowing models (CAMs). Many of the processes necessary for daytime CI occur in the planetary boundary layer (PBL), the evolution and properties of which numerical models struggle to accurately predict. In order to better observe the processes that influence CI and improve their representation in CAM analyses, we use novel data from both the national network of WSR-88D radars as well as the GOES-16 satellite. The WSR-88D radars provides PBL height and clear-air radial wind velocities within the PBL while the GOES-16 satellite provides observations of brightness temperature (BT). For the CAM ensemble forecasts, we employ the Advanced Research Weather Research and Forecasting (WRF-ARW) High Resolution Rapid Refresh (HRRR) configuration. The novel WSR-88D and GOES-16 observations from a CI event on 18 May 2018 are assimilated over a 4-h period into a 40-member ensemble using the Gridpoint Statistical Interpolation (GSI) Ensemble Kalman filter (EnKF) system of the National Centers for Environmental Prediction (NCEP). Results show that the addition of the WSR-88D and GOES-16 observations improves the CI forecasts out to 5 h in terms of timing and location.
