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Description

This level 2 standard 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 standard product provides retrievals on a reduced vertical profile (11 levels for water profiles and up to 27 for other profile variables). 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

Geographic Region
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
C2782356281-GES_DISC
Data State
ACTIVE
Number of Files/Granules
460006
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 Standard: 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/CTFP72D3K806 Date Accessed: 2025-12-14

Documents

READ-ME

ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD)

SCIENCE DATA PRODUCT VALIDATION

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
air_pres_h2o_stand Standard H2O vapor pressure levels Pa float32 9.9692099683869E+36 N/A N/A
air_pres_h2o_stand_nsurf One-based index in air_pres_h2o_stand of the level at the surface. Values at indices less than this are invalid, representing data below the Earth's surface. 1 int16 -32767 N/A N/A
air_pres_stand Standard pressure levels Pa float32 9.9692099683869E+36 N/A N/A
air_pres_stand_nsurf One-based index in air_pres_stand of the level at the surface. Values at indices less 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/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/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/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
aux/qc_flag Quality Control Flag. Overall quality for the retrieval. 0: chi2_mw, cost_func_ir, and cost_func_mw are all smaller than corresponding threshold values; 1: chi2_mw and cost_func_ir meet the criteria, but cost_func_mw is larger than the desired threshold value but still smaller than a relaxed threshold value; 2: chi2_mw meets the criteria, cost_func_ir does not meet the desired criterion, but meets the criterion defined by a relaxed threshold; 3: cost_func_ir is even larger than the relaxed threshold value; 4: No retrieval was attempted because of bad or missing input data. N/A int16 -32767 N/A N/A
aux/qc_mw_flag Quality control flag for MW-Only retrieval. 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_n2o_flag Quality control flag for nitrous oxide. 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_o3_flag Quality control flag for ozone. 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/surf_ir_emis_num_bad Number of Infrared Surface Emissivity hinge points at which limits were enforced. Zero indicates best quality. 1 int16 -32767 N/A N/A
bndry_lay_status bndry_lay calculation status flag: 0: sea success; 1: sea with pressure grid selected at the end of the allowed values (4000 m or next to bad input data); 4: sea with lowest allowed altitude, 250 m above the surface ; 8: sea with not enough good data; 16: land success; 17: land with pressure grid selected at the end of the allowed values (6000 m or next to bad input data); 20: land with lowest allowed altitude: 250 m above the surface; 24 land with not enough good data. N/A int8 -127 N/A N/A
bndry_lay_thick Geodetic thickness of the planetary boundary layer. This is determined from the maximum smoothed lapse rate of relative humidity over the range of 250-4000 meters over ocean, 250-6000 meters over land. The value is less reliable over land surfaces than ocean. m float32 9.9692099683869E+36 N/A N/A
bndry_lay_thick_qc bndry_lay_thick QC flag N/A int8 -127 N/A N/A
bndry_lay_top Pressure corresponding to bndr_lay_thick Pa float32 9.9692099683869E+36 N/A N/A
bndry_lay_top_qc bndry_lay_top QC flag N/A int8 -127 N/A N/A
bndry_lay_top_rel_hum_lapse_rate The slope of the smoothed relative humidity with respect to altitude at the top of the planetary boundary layer. 1/m float32 9.9692099683869E+36 N/A N/A
bndry_lay_top_rel_hum_lapse_rate_qc bndry_lay_top_rel_hum_lapse_rate QC flag N/A int8 -127 N/A N/A
ch4_dof The trace of the averaging kernel matrix as a measure of the amount of information about the methane profile extracted from the measured radiation. 1 float32 9.9692099683869E+36 N/A N/A
ch4_mmr_midtrop Methane mass mixing ratio to dry air at 40000 Pa, near the peak of sensitivity kg / kg float32 9.9692099683869E+36 N/A N/A
ch4_mmr_midtrop_err ch4_mmr_midtrop error estimate kg / kg float32 9.9692099683869E+36 N/A N/A
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