CloudDetectMinResidualIR¶

This obsFunction is designed to perform cloud detection using the Minimum Residual Method for Infrared sensors using selected channels from 15 microns CO2 absorption band.

The output of this function is:

0 = channel is not affected by clouds (clear channel)

1 = channel is affected by clouds (cloudy channel)

2 = channel is not affected by clouds but too sensitive to surface condition

Required input parameters:¶

channels: List of channel to which the cloud detection is performed
use_flag: Use flag (-1: not used; 0: monitoring; 1: used) for each channel in channel list
use_flag_clddet: Useflag (-1: not used; 1: used) indicating if the channel is used for cloud detection
obserr_dtempf: Observation error scale factors applied to surface temperature jacobians over 5 surface types: [sea, land, ice, snow and mixed]

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: water_area_fraction@GeoVaLs , ice_area_fraction@GeoVaLs, land_area_fraction@GeoVaLs , surface_snow_area_fraction@GeoVaLs average_surface_temperature_within_field_of_view@GeoVaLs , air_pressure@GeoVaLs air_temperature@GeoVaLs , tropopause_pressure@GeoVaLs
obsDiag: brightness_temperature_jacobian_surface_temperature@ObsDiag , brightness_temperature_jacobian_air_temperature@ObsDiag, transmittances_of_atmosphere_layer@ObsDiag, pressure_level_at_peak_of_weightingfunction@ObsDiag
from observation space:: brightness_temperature@ObsValue, brightness_temperature@ObsError. 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: brightness_temperature
    channels: *all_channels
  test variables:
  - name: CloudDetectMinResidualIR@ObsFunction
    channels: *all_channels
    options:
      channels: *all_channels
      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 ]
      use_flag_clddet: [ -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 ]
      obserr_dtempf: [0.50, 2.00, 4.00, 2.00, 4.00]
  maxvalue: 1.0e-12
  action:
    name: reject