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- Input analysed snow depth by the 2D-OI (arpifs/obs_preproc/obsgen.F90)
- Calculate and input additional EDA Jacobians related to snow (gen/fetchmars, 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, soil moisture are also set to 0
- These 2 settings mean that observations to analyse each control variable are similar to the current system
- Jacobians between snow water equivalent and snow depth are set to 1/rsn (based on the relationship in the model)
- Analyse snow water equivalent using the analysed snow depth and Jacobians (arpifs/sekf/sm_ekf_main.F90)
- σo=0.01 [m]
- σb=2.0 [kg/m2] (=0.01 [m] if ρ=200 [kg/m3])
- So far, increments for snow water equivalent are not reflected to the analysis field (offline calculation only)
Result (01/12/2021 00UTC)
1.Analysis increments in the 2D-OI | 2.Analysis increments in the SEKF (observation: SD from the 2D-OI) | 3.Analysis increments in the SEKF (observation: SWE from the 2D-OI) |
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- Similar pattern is seen for analysis increments in (1) the 2D-OI and (2) the SEKF.
- Note that large differences are seen in some regions due to inconsistency of snow density between the 2D-OI analysis and trajectory (lower limit of 100kg/m3 for snow depnsity in the 2D-OI). When SWE is assimilated in the SEKF (3), such differences are not seen.
| sekf_inc_l1.grib(SM1) | sekf_inc_l2.grib(SM2) | sekf_inc_l3.grib(SM3) | |
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| Cntl |
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| Test |
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- Analysis increments for soil moisture are similar between before and after the changes.
Future work
- Input snow observations directly in the SEKF (the same task as soil moisture analysis using analysed 2m temperature and relative humidity)
- Need to implement a localization in observation space
- Each QC also should be implemented in the SEKF
- Consider flow-dependent background errors
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