NearSSTRetCheckIR

This obsFunction is designed to perform QC using retrieved near-sea-surface temperature (NSST) from Infrared radiances. This QC includes two steps: (1) Perform NSST retrieval from radiances at obs location following NCEP GDAS scheme, and obtained increment of NSST from its first guess value; (2) For surface sensitive channels, remove them from assimilation if the retrieved NSST increment from step (1) is larger than a pre-defined threshold. The output of this obsFunction is the default JEDI QC flags: 0 = channel is retained for assimilation; 1 = channel is not retained for assimilation.

Required input parameters:

channels

List of channel to which the QC is performed

use_flag

Use flag (-1: not used; 0: monitoring; 1: used) for each channel in channel list

Optional input parameters:

test_obserr

Name of the data group to which the observation error is applied (default is ObsErrorData)

test_hofx

Name of the HofX group used to replace the default group (default is HofX)

test_qcflag

Name of the data group to which the QC flag is applied (default is QCflagsData)

Required fields from obs/geoval

geovals

GeoVaLs/water_area_fraction , GeoVaLs/surface_temperature_where_sea

obsDiag

ObsDiag/brightness_temperature_jacobian_surface_temperature , ObsDiag/brightness_temperature_jacobian_air_temperature, ObsDiag/brightness_temperature_jacobian_humidity_mixing_ratio

from observation space:

ObsValue/brightnessTemperature, ObsError/brightnessTemperature, MetaData/sensorCentralFrequency. In addition, brightness_temperature observation error, QC flags, and simulated values at the observatioin locations will come from JEDI default values or or from the input defined by test_obserr, test_qcflag and test_hofx

Example configurations:

Here is an example to use this obsFunction inside the Bounds Check filter. The brightness_temperature is rejected if the QC flags from this ObsFunction output value is bigger than maxvalue=1.0e-12.

- filter: Bounds Check
  filter variables:
  - name: brightnessTemperature
    channels: *all_channels
  test variables:
  - name: ObsFunction/NearSSTRetCheckIR
    channels: *all_channels
    options:
      channels: *all_channels
      test_bias: GsiObsBias
      use_flag: [ -1,  1,  1, -1,  1, -1,  1, -1,  1,  1,
                   1,  1,  1,  1, -1,  1, -1,  1, -1,  1,
                  -1,  1, -1,  1, -1,  1, -1,  1, -1,  1,
                  -1,  1, -1,  1, -1,  1, -1,  1, -1,  1 ]
  maxvalue: 1.0e-12
  action:
    name: reject