Background

In the current operational system, snow analysis is based on 2D-OI separated from the SEKF (for soil moisture analysis) and the 1D-OI (for soil temperature and snow temperature). As a first step towards a unified land data assimilation system, snow analysis has been implemented in the SEKF. This page shows details of the changes and the first result.

Branches

dako_CY48R1.1_SEKF_snow

• ifs-scripts: https://git.ecmwf.int/users/dako/repos/ifs-scripts/browse?at=refs%2Fheads%2Fdako_CY48R1.1_SEKF_snow
• ifs-source: https://git.ecmwf.int/users/dako/repos/ifs-source/browse?at=refs%2Fheads%2Fdako_CY48R1.1_SEKF_snow
• ifs-suites: https://git.ecmwf.int/users/dako/repos/ifs-suites/browse?at=refs%2Fheads%2Fdako_CY48R1.1_SEKF_snow

Configurations to analyse snow water equivalent in the SEKF

• Input increments from the 2D-OI for snow depth (arpifs/obs_preproc/obsgen.F90)
• Input additional EDA Jacobians related to snow (arpifs/sekf/sekf_geteda_jacobians.F90)
  • Covariances between soil moisture and snow depth are set to 0
  • Covariances between snow water equivalent and 2m temperature, relative humidity and soil moisture are also set to 0
  • Jacobians between snow water equivalent and snow depth are based on the relationship in the model (set to 1/rsn)
• Analyse snow water equivalent using the increments and Jacobians (arpifs/sekf/sm_ekf_main.F90)

Result