In 3DVAR analysis, the background error covariance (BE) is mainly setup to distribute the analysis increemant homogenously and isotropically, which can be problem for the analysis in the inhomogeneous and anisoptric environments, such as observations in a front zone or surface observations in complex terrain or near the coastal line area. The hybrid EnVar analysis introduces the follow-dependence features through ensemble perturbations and greatly improved GSI analysis for large scale system. But GSI hybrid analysis with GFS EnKF ensemble forecast was found to have minor benefits to PBL and surface analysis and forecast from the test and evaluation in RAP/HRRR applications. The possible reasons can be the coarse resolution of the GFS EnKF ensemble and rank deficince of the limited ensemble members.
GSD RAP/HRRR group is running real-time test of HRRR ensemble system to provide GSI analysis with high resolution ensemble forecast. But the number of ensemble still very limited because of the limitation of the computer resources. To overcome the rank deficince of HRRRE ensemble, we start to collect one month of the HRRRE ensemble to acccumlate enough enemble perturbations to generate a climate high resolution ensemble perturbations, with the idea that those climate pertrubations will be able to represent to local features that do not change with time, such as terrain or land surface types.
In this studay, we will apply those clamite perturbations from HRRRE through the GSI hybrid to see if we can effective surface analysis surface observations in complex terrain area. Retrospective cases for the forecast and pure analysis will be conducted to test and verify the impact of those climate high resolution perturbations. Results from those tests will be discussed during the conference.
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