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Description

This level 2 support product is generated by the SiFSAP (Single Field-of-View Sounder Atmospheric Products) algorithm. The SIFSAP algorithm provides retrieval for each sounder Field of View (FOV), therefore, it has 3-times higher horizontal spatial resolution and 9-time denser products compared to other current IR sounder products. Since SiFSAP is an FOV-based algorithm, its product variables have an additional dimension which represents the number of FOVs. For CrIS instrument, there are 9 FOVs for each Field of Regard (FOR). The SiFSAP Level-2 retrieval products contain a variety of geophysical parameters retrieved from IR/MW sounder suites measurements, including profiles of temperature, water vapor and trace gas species as well as clouds and surface properties. This support product provides height vertical sampling (up to 98 levels) and also includes more detailed Empirical Orthogonal Function (EOF) information like averaging kernels. A level 2 granule has been set as 6 minutes of data. There are 240 granules per day, with an orbit repeat cycle of approximately 16 day.

Product Summary

Platforms
Suomi-NPP
Instruments
ATMS ,
CrIS
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Location
GLOBAL
Coordinate System
GEODETIC
Granule Spatial Representation
GEODETIC
Temporal Extent
2015-11-02
Data Partner
Goddard Earth Sciences Data and Information Services Center (formerly Goddard DAAC), Terrestrial Information Systems Laboratory, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/GESDI
Concept ID
C2782339991-GES_DISC
Data State
ACTIVE
Number of Files/Granules
460114
Processing Level
2
Published
Updated
Science Keywords
Surface Pressure ,
Surface Temperature ,
Air Temperature ,
Upper Air Temperature ,
Layered Precipitable Water ,
Total Precipitable Water ,
Water Vapor Profiles ,
Skin Temperature ,
Sea Surface Temperature ,
Liquid Water Equivalent ,
Relative Humidity ,
Specific Humidity ,
Atmospheric Ozone ,
Total Ozone ,
Atmospheric Carbon Monoxide ,
Methane ,
Cloud Optical Depth/Thickness ,
Temperature Gradient Rate

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Liu, X. (2022). Sounder SIPS: Suomi NPP CrIMSS Level 2 SiFSAP Support: Atmosphere cloud and surface geophysical state per footprint V2 [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/XQMJMVTQSGIS Date Accessed: 2026-02-17

Documents

READ-ME

ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD)

SCIENCE DATA PRODUCT VALIDATION

Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
air_pres pressure levels Pa float32 9.9692099683869E+36 N/A N/A
air_pres_h2o H2O vapor pressure levels Pa float32 9.9692099683869E+36 N/A N/A
air_pres_h2o_nsurf One-based index in air_pres_h2o of the level at the surface. Values at indices greater than this are invalid, representing data below the Earth's surface. 1 int16 -32767 N/A N/A
air_pres_nsurf One-based index in air_pres of the level at the surface. Values at indices greater than this are invalid, representing data below the Earth's surface. 1 int16 -32767 N/A N/A
air_temp air temperature profile kelvin float32 9.9692099683869E+36 N/A N/A
air_temp_dof The trace of the averaging kernel matrix as a measure of the amount of information about the air temperature profile extracted from the measured radiation. 1 float32 9.9692099683869E+36 N/A N/A
air_temp_err air_temp error estimate kelvin float32 9.9692099683869E+36 N/A N/A
air_temp_qc air_temp QC flag N/A int8 -127 N/A N/A
asc_flag ascending orbit flag: 1 if ascending, 0 descending N/A uint8 255 N/A N/A
asc_node_local_solar_time local apparent solar time at the last ascending node before time_coverage_end in hours from midnight hours float32 9.9692099683869E+36 N/A N/A
asc_node_lon Longitude of the last ascending node of spacecraft orbit before time_coverage_end. degrees_east float32 9.9692099683869E+36 N/A N/A
asc_node_tai93 TAI93 time of the last ascending node of spacecraft orbit before time_coverage_end. seconds since 1993-01-01 00:00 float64 9.9692099683869E+36 N/A N/A
atms_bandwidth ATMS bandwidth of sum of 1, 2, or 4 channels MHz float32 9.9692099683869E+36 N/A N/A
atms_beam_width ATMS Nominal beam width degree float32 9.9692099683869E+36 N/A N/A
atms_center_freq ATMS Channel center frequency MHz float32 9.9692099683869E+36 N/A N/A
atms_chan_band Name of band for each ATMS channel N/A OTHER N/A N/A N/A
atms_if_offset_1 ATMS Offset of first intermediate frequency stage (zero for no mixing) MHz float32 9.9692099683869E+36 N/A N/A
atms_if_offset_2 ATMS Offset of second intermediate frequency stage (zero for no mixing) MHz float32 9.9692099683869E+36 N/A N/A
attitude_lbl list of rotational directions (roll, pitch, yaw) N/A OTHER N/A N/A N/A
aux/adj_fcast_surf_pres Surface pressure from the forecast, adjusted for the difference between surf_alt and fcast_surf_alt. Pa float32 9.9692099683869E+36 N/A N/A
aux/air_pres_gas Constituent pressure levels Pa float32 9.9692099683869E+36 N/A N/A
aux/air_pres_gas_nsurf One-based index in air_pres_gas of the level at the surface. Values at indices greater than this are invalid, representing data below the Earth's surface. 1 int16 -32767 N/A N/A
aux/ch4_mmr Methane mass mixing ratio to dry air kg / kg float32 9.9692099683869E+36 N/A N/A
aux/ch4_mmr_err ch4_mmr error estimate kg / kg float32 9.9692099683869E+36 N/A N/A
aux/ch4_mmr_qc ch4_mmr QC flag N/A int8 -127 N/A N/A
aux/chi2_ch4 Methane chi^2 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_co Carbon Monoxide chi^2 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_co2 Carbon Dioxide chi^2 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_mw MW chi^2 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_n2o Nitrous Oxide chi^2 1 float32 9.9692099683869E+36 N/A N/A
aux/chi2_o3 Ozone chi^2 1 float32 9.9692099683869E+36 N/A N/A
aux/cost_func Total cost function (IR + MW) (Jo) 1 float32 9.9692099683869E+36 N/A N/A
aux/cost_func_ir IR cost function 1 float32 9.9692099683869E+36 N/A N/A
aux/cost_func_mw MW cost function 1 float32 9.9692099683869E+36 N/A N/A
aux/co_mmr Carbon monoxide mass mixing ratio to dry air kg / kg float32 9.9692099683869E+36 N/A N/A
aux/co_mmr_err co_mmr error estimate kg / kg float32 9.9692099683869E+36 N/A N/A
aux/co_mmr_qc co_mmr QC flag N/A int8 -127 N/A N/A
aux/fcast_surf_alt surface altitude interpolated from the forecast surface at the center of the FOV. m float32 9.9692099683869E+36 N/A N/A
aux/fcast_surf_pres Surface pressure from the forecast, assuming fcast_surf_alt is the correct altitude. Pa float32 9.9692099683869E+36 N/A N/A
aux/max_rel_hum_unclipped Largest relative humidity before clipping. Set to fill if no clipping is needed. 1 float32 9.9692099683869E+36 N/A N/A
aux/min_pres_clipped_rel_hum Lowest pressure where relative humidity has been clipped. Set to fill if profile is not clipped. Pa float32 9.9692099683869E+36 N/A N/A
aux/mw_max_rel_hum_unclipped Largest MW-Only relative humidity before clipping. Set to fill if no clipping is needed. 1 float32 9.9692099683869E+36 N/A N/A
aux/mw_min_pres_clipped_rel_hum Lowest pressure where MW-Only relative humidity has been clipped. Set to fill if profile is not clipped. Pa float32 9.9692099683869E+36 N/A N/A
aux/n2o_mmr Nitrous Oxide mass mixing ratio to dry air kg / kg float32 9.9692099683869E+36 N/A N/A
aux/n2o_mmr_err n2o_mmr error estimate kg / kg float32 9.9692099683869E+36 N/A N/A
aux/n2o_mmr_qc n2o_mmr QC flag N/A int8 -127 N/A N/A
aux/prior_surf_pres Surface pressure used in the retrieval. Currently equivalent to fcast_surf_pres. Pa float32 9.9692099683869E+36 N/A N/A
aux/qc_ch4_flag Quality control flag for methane. 0: best; 1: good; 2: lower quality; 3: bad retrieval; 4: bad input data, no retrieval attempted. N/A int16 -32767 N/A N/A
aux/qc_co2_flag Quality control flag for carbon dioxide. 0: best; 1: good; 2: lower quality; 3: bad retrieval; 4: bad input data, no retrieval attempted. N/A int16 -32767 N/A N/A
aux/qc_co_flag Quality control flag for carbon monoxide. 0: best; 1: good; 2: lower quality; 3: bad retrieval; 4: bad input data, no retrieval attempted. N/A int16 -32767 N/A N/A
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