Geostationary IR Channel Brightness Temperature - GridSat B1

Dataset Description

The following is a summary of the dataset variables and attributes. It should be considered as an overview of the dataset variables and is supplemented by the dataset attributes available in the file, which can be viewed using various tools (like ncdump). A sample ncdump of the file headers is available for Nov. 13, 1999 here. Information not provided below can be ascertained from the netCDF attributes (e.g., units of the varibles).

Spatial variables

The following table provides a summary of the variables having spatial dimensions.

Name Dimensions Purpose
irwin_cdr lat-lon Primary CDR Variable.
The nadir-most infrared window observation.
irwin_2 lat-lon or sparse When two satellites overlap, this layer provides the second-best observation (based on view zenith angle
irwin_3 lat-lon or sparse When three satellites overlap, this layer provides the third-best observation (based on view zenith angle. This is useful for reconstructing the entire view for a particular satellite
irwin_vza_adj lat-lon Provided to allow users to reverse the view zenith correction for the irwin_cdr variable.
irwvp lat-lon The nadir-most infrared water vapor observation.
irwvp_2 lat-lon or sparse When two satellites overlap, this layer provides the second-best observation (based on view zenith angle
vschn lat-lon The nadir-most visible channel observation.
vcshn_2 lat-lon or sparse When two satellites overlap, this layer provides the second-best observation (based on view zenith angle
satid_ir lat-lon The packed satellite index value (provides information for both the irwin_cdr and irwin_2 variables).
satid_ir3 lat-lon or sparse The satellite index for the irwin_3 variable.
satid_wv lat-lon The packed satellite index value (provides information for both the irwvp and irwvp_2 variables).
satid_vs lat-lon The packed satellite index value (provides information for both the vschn and vschn_2 variables).

Satellite-specific variables

The following table provides a summary of the variables that describe the satellites used to make the observations.

Name Description
satlat Latitude of the sub-satellite point at the time of observation.
satlon Longitude of the sub-satellite point
satrad Distance from the center of the Earth to the satellite (e.g., radius)
satname Satellite name
b1ufile Filename of the ISCCP B1U file corresponding to this satellite image.
b1file Filename of the ISCCP B1 file corresponding to this satellite image. This is very similar to the B1U filename and is provided for completeness.
calslp_irwin
caloff_irwin
calslp_irwvp
caloff_irwvp
vis_rad_slope
vis_dc_slope
vis_dc_offset

Other variables

Name Purpose
sparse2ir Values of the sparse irwin_2 array. Data are sparsely packed only when this variable has more than 2 values.
sparse3ir Values of the sparse irwin_3 array. Data are sparsely packed only when this variable has more than 2 values.
sparse2wv Values of the sparse irwvp_2 array. Data are sparsely packed only when this variable has more than 2 values.
sparse2vs Values of the sparse vschn_2 array. Data are sparsely packed only when this variable has more than 2 values.

Helpful global attributes

Name Description
references Digital Object Identifiers (DOIs) of the peer-reviewed references describing this dataset and how it was calibrated.

Helpful variable attributes

Name Description
intergeo_cal_flag When intergeo_cal_flag=1, it means that a geostationary satellite images was deemed to have been in error based on comparisons with neighboring geostationary satellites and a correction was applied to reduce the inter-satellite brightness difference. When set to 1, the following attributes are also present: intergeo_cal_satid, intergeocal_slp, intergeo_cal_off
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