Skip to content

Latest commit

 

History

History
54 lines (37 loc) · 1.99 KB

CLWRetSymmetricMW.rst

File metadata and controls

54 lines (37 loc) · 1.99 KB
Raw

CLWRetSymmetricMW

This function estimates the Cloud Liquid Water (CLW) content at the observation location from both the model background CLWm and the observation derived CLWo. CLW is used in radiance assimilation as an indication of the presence of cloud.

The estimate is the mean of the model and observed content: CLWsym = 0.5 * (CLWm + CLWo).

The mean is used so that the CLW is a symmetric function of CLWo and CLWm. Since the observation error for radiances is inflated in presence of cloud, as indicated by CLW, the symmetrical dependence on the model and observations better deals with situations when CLWm and CLWo are very different.

References

Geer A. J. and P Bauer, 2010: Enhanced use of all-sky microwave observations sensitive to water vapour, cloud and precipitation. ECMWF Technical Memoranda 620. http://dx.doi.org/10.21957/mi79jebka

Geer A. J. and P Bauer, 2011: Observation errors in all-sky data assimilation. https://doi.org/10.1002/qj.830

Required yaml parameters

Requires CLWRetMW inputs, and clwret_types of ObsValue (observations) TBs, and simulated bias-corrected TBs GsiHofXBc.

Returns clw_symmetric_amount.

Example configuration

AMSU-A Example (function_clwretmean.yaml), see "obs function" section below:

observations:
- obs space:
    name: amsua_n19
    obsdatain:
      obsfile: Data/ufo/testinput_tier_1/amsua_n19_obs_2018041500_m_qc.nc4
    simulated variables: [brightness_temperature]
    channels: 1, 2
  geovals:
    filename: Data/ufo/testinput_tier_1/amsua_n19_geoval_2018041500_m_qc.nc4
  obs function:
    name: CLWRetSymmetricMW@ObsFunction
    options:
      clwret_ch238: 1
      clwret_ch314: 2
      clwret_types: [ObsValue, GsiHofXBc]
    variables: [clw_symmetric_amount]
    tolerance: 1.0e-8