Standard Names For Satellite Observations

Global Space-based Inter-Calibration System (GSICS)

The GSICS netCDF format convention requires that each variable has a standard_name attribute. This attribute is adopted from the Climate and Forecast (CF) metadata convention which maintains a list of official shared variable names. Not many standard names in that list are relevant to GSICS data so additional names are proposed here. The new names and accompanying information will follow the CF guidelines.

Proposed Names

Proposed Standard Name	Canonical units	Definition	Comments/Questions
instrument_channel_identifier	Not Applicable	Alphanumeric identifier of instrument's channel.
datetime_iso8601	Not Applicable	String containing date-time information in one of the ISO 8601 formats. Variables with this standard name cannot serve as coordinate variables.
instrument_zenith_angle	degree	The angle between the line of sight to the instrument and the local vertical.
satellite_scan_angle	degree	The angle between the line of sight from the satellite and the nadir line. Nadir is the direction given by the vertical from the satellite looking towards the center of the Earth.
instrument_azimuth_angle	degree	The horizontal angle between the line of sight to the instrument and a reference direction which is often due north. The angle is measured clockwise.
relative_instrument_azimuth_angle	degree	Difference between two instrument_azimuth_angle values.
time_interval	s	An interval of time.
toa_outgoing_spectral_radiance	mW m-2 sr-1 (cm-1)-1	"toa" means top of atmosphere; "outgoing" means emitted toward outer space; "spectral" means per unit wavenumber or as a function of wavenumber. Radiance is the radiative flux in a particular direction, per unit of solid angle.
toa_outgoing_spectral_radiance_mean_within_collocation_scene	mW m-2 sr-1 (cm-1)-1	An average of toa_outgoing_spectral_radiance observations within a collocation scene. Collocation scene is a grouping of instrument's adjacent field of views (FOVs) centered on a collocation target. Collocation target is an area on the Earth's surface at which observations from at least two instruments are collected. Its size is defined by the instrument with the largest FOV footprint. Collocation scene's size is typically about an order of magnitude larger than its collocation target.
toa_outgoing_spectral_radiance_stdev_within_collocation_scene	mW m-2 sr-1 (cm-1)-1	Standard deviation of toa_outgoing_spectral_radiance observations within a collocation scene. Collocation scene is a grouping of instrument's adjacent field of views (FOVs) centered on a collocation target. Collocation target is an area on the Earth's surface at which observations from at least two instruments are collected. Its size is defined by the instrument with the largest FOV footprint. Collocation scene's size is typically about an order of magnitude larger than its collocation target.
toa_outgoing_spectral_radiance_mean_within_collocation_target	mW m-2 sr-1 (cm-1)-1	An average of toa_outgoing_spectral_radiance observations from instrument's adjacent field of views within a collocation target. Collocation target is an area on the Earth's surface at which observations from at least two instruments are collected. Its size is defined by the instrument with the largest field of view footprint.
toa_outgoing_spectral_radiance_stdev_within_collocation_target	mW m-2 sr-1 (cm-1)-1	Standard deviation of toa_outgoing_spectral_radiance observations from instrument's adjacent field of views within a collocation target. Collocation target is an area on the Earth's surface at which observations from at least two instruments are collected. Its size is defined by the instrument with the largest field of view footprint.
linear_term_of_spectral_radiance_correction_due_to_intercalibration	1	Linear term (slope) of the formula for correcting measured spectral radiance. The correction is derived from intercalibration between the monitored and the reference instrument. The resulting corrected spectral radiance of the monitored instrument becomes comparable with measured spectral radiance of the reference instrument. "Spectral" means per unit wavenumber or as a function of wavenumber. Radiance is the radiative flux in a particular direction, per unit of solid angle.
constant_term_of_spectral_radiance_correction_due_to_intercalibration	mW m-2 sr-1 (cm-1)-1	Constant term (offset) of the formula for correcting measured spectral radiance. The correction is derived from intercalibration between the monitored and the reference instrument. The resulting corrected spectral radiance of the monitored instrument becomes comparable with measured spectral radiance of the reference instrument. "Spectral" means per unit wavenumber or as a function of wavenumber. Radiance is the radiative flux in a particular direction, per unit of solid angle.
covariance_between_constant_and_linear_terms_of_spectral_radiance_correction	mW m-2 sr-1 (cm-1)-1	Covariance between constant_term_of_spectral_radiance_correction_due_to_intercalibration and linear_term_of_spectral_radiance_correction_due_to_intercalibration values.
toa_brightness_temperature_of_standard_scene	K	"toa" means top of atmosphere. Brightness temperature of a body is the temperature of a black body which radiates the same power per unit solid angle per unit area. Standard scene is a physical model of the Earth surface and atmosphere that is accepted as a reference. This model is used in a radiative transfer simulation to calculate top-of-atmosphere radiance for a given viewing geometry. The resultant top-of-atmosphere radiance is then integrated with an instrument's spectral response function and converted to equivalent brightness temperature.
toa_brightness_temperature_bias_at_standard_scene_wrt_intercalibration	K	The difference between intercalibrated simulated top-of-atmosphere (TOA) brightness temperature of the reference instrument and simulated TOA brightness temperature of the monitored instrument. Intercalibration is a process of deriving an equation by which observations from the monitored instrument become comparable to observations from the reference instrument. This difference is a measure of the quality of intercalibration. Standard scene is a physical model of the Earth surface and atmosphere that is accepted as a reference. Brightness temperature of a body is the temperature of a black body which radiates the same power per unit solid angle per unit area. TOA brightness temperatures for both the monitored and referenced instruments are calculated using the standard scene model and a radiative transfer simulation. The resultant top-of-atmosphere radiance is then integrated with each instrument's spectral response functions and converted to equivalent brightness temperature.
number_of_days_in_smoothing_period	1	Number of calendar days forming a smoothing period. Smoothing is a mathematical technique that removes excess data variability while maintaining a correct underlying trend. Smoothing period is a time interval used to select data to which a smoothing operation is applied.
percentage_of_missing_days_in_smoothing_period	%	Percentage of calendar days without data within one smoothing period. Smoothing is a mathematical technique that removes excess data variability while maintaining a correct underlying trend. Smoothing period is a time interval used to select data to which a smoothing operation is applied.
toa_brightness_temperature_bias_at_homogeneous_scene_wrt_intercalibration	K	TBD
toa_brightness_temperature_calibration_lookup_table	K	TBD