CloudDetectMinResidualAVHRR¶

Cloud Detection Algorithm (Minimum Residual Method) for Infrared sensors (specifically AVHRR in this case) using selected channels from 15 microns CO2 absorption band.

Output of this function:

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 YAML Parameters¶

channels: List of channels available for assimilation.
use_flag: Useflag (-1: not used; 0: monitoring; 1: used) for each channel in channels.
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 YAML Parameters¶

test_obserr: Name of the data group to which the observation error is applied (default: ObsErrorData).
test_hofx: Name of the HofX group used to replace the default group (default is HofX).
test_bias: Name of the bias correction group used to replace the default group (default is ObsBias).
test_qcflag: Name of the data group to which the QC flag is applied (default is QCflagsData).

Example configuration¶

AVHRR3 Metop-A Example (from avhrr3_metop-a.yaml)

- filter: Bounds Check
  filter variables:
  - name: brightness_temperature
    channels: *avhrr3_metop-a_channels
  test variables:
  - name: CloudDetectMinResidualAVHRR@ObsFunction
    channels: *avhrr3_metop-a_channels
    options:
      channels: *avhrr3_metop-a_channels
      use_flag: [ 1,  1,  1 ]
      use_flag_clddet: [ 1,  1,  1 ]
      obserr_dtempf: [0.50,2.00,4.00,2.00,4.00]
  maxvalue: 1.0e-12
  action:
    name: reject