Start
November 16, 2018 - 2:00 pm
End
November 16, 2018 - 3:00 pm
Address
120 David L. Boren Blvd, Room 5600, Norman, OK 73072 View mapAssimilation of Boundary Layer Profilers: Implications for the Prediction of Nocturnal Convection Initiation and Atmospheric Bores
Recent upgrades to observational networks such as Doppler radars and satellites have greatly enhanced the warning and forecasting capabilities of national weather services across the world. Although the addition of such datasets has also considerably increased the forecast skill of numerical weather prediction models, the meteorological community continues to insist on the need for more adequate observations in and above the boundary layer (BL). The impact of insufficient observations in the lower troposphere is magnified at night, as many convective processes occur above the surface inversion. Technological advances in remote sensing have given rise to novel BL profilers that could potentially close the existing observation gap. The Plains Elevated Convection at Night (PECAN) project provides a novel observation set that includes, among others, high-frequency thermodynamic and kinematic profilers. This study outlines the main lessons learnt in the process of assimilating various PECAN BL instruments in a high-resolution GSI-based ensemble data assimilation and forecasting system.
Results are discussed separately in the context of a 26 June 2015 case study, which features a large nocturnal CI event initiated along the terminus of a nocturnal low-level jet, and a 6 July 2015 case study, which features a large nocturnal MCS maintained by a convectively-generated bore. Firstly, the experimental design and data availability for the presented case studies are described, with a special emphasis on how the location of the assimilated profilers is relevant for improving the respective events. In addition, we outline key aspects of the observation pre-processing and error treatment in the context of the GSI system. The second part of the talk makes use of ensemble forecast results to highlight the relative merits of assimilating each novel instrument type. We particularly focus on how the BL profilers modify the thermodynamic and kinematic environment in the model. In view of the topics discussed throughout the talk, key recommendations for the operational incorporation of BL profilers in future observation networks are provided.