Data Fields - SMAP/Sentinel-1 L2 Radiometer/Radar 3 km EASE-Grid Soil Moisture, Version 1

This page provides a description of all data fields within the SMAP/Sentinel-1 L2 Radiometer/Radar 3 km EASE-Grid Soil Moisture (SPL2SMAP_S) product. The data are grouped into three main HDF5 groups:

For a description of metadata fields for this product, refer to the Metadata Fields document.

Soil_Moisture_Retrieval_Data_1km

Table 1 describes the data fields of a typical SPL2SMAP_S 1 km granule. Data in the 1 km group are research quality, meaning they have not undergone validation.

Note: Data fields containing SMAP a.m.-or-p.m. data are named with apm, such as disaggregated_tb_v_qual_flag_apm_3km. Note that if the SMAP a.m. pass is the closest, the two arrays will have the same values.

Table 1. Data Fields for Soil_Moisture_Retrieval_Data_1km
Data Field Name Concept Byte Unit Min Max Fill/Gap Value
EASE_column_index_1km integer 2 count 0 65535 66534
EASE_column_index_apm_1km integer 2 count 0 65535 66534
EASE_row_index_1km integer 2 count 0 65535 66534
EASE_row_index_apm_1km integer 2 count 0 65535 66534
SMAP_Sentinel-1_overpass_timediff_hr_1km integer 2 count -999999.9 999999.9 -9999.0
SMAP_Sentinel-1_overpass_timediff_hr_apm_1km integer 2 count -999999.9 999999.9 -9999.0
albedo_1km real 4 normalized 0.0 1.0 -9999.0
albedo_apm_1km real 4 normalized 0.0 1.0 -9999.0
bare_soil_roughness_retrieved_1km real 4 meters 0.0 2.0 -9999.0
bare_soil_roughness_retrieved_apm_1km real 4 meters 0.0 2.0 -9999.0
beta_tbv_vv_1km real 4 kelvin -35.0 0.0 -9999.0
beta_tbv_vv_apm_1km real 4 kelvin -35.0 0.0 -9999.0
disagg_soil_moisture_1km real 4 cm3/cm3 0.0 0.75 -9999.0
disagg_soil_moisture_apm_1km real 4 cm3/cm3 0.0 0.75 -9999.0
disaggregated_tb_v_qual_flag_1km bit flag 2 NA NA NA 66534
disaggregated_tb_v_qual_flag_apm_1km bit flag 2 NA NA NA 66534
gamma_vv_xpol_1km bit flag 2 NA 0.0 10.0 -9999.0
gamma_vv_xpol_apm_1km bit flag 2 NA 0.0 10.0 -9999.0
landcover_class_1km enum 1 NA NA NA 254
landcover_class_apm_1km enum 1 NA NA NA 254
latitude_1km real 4 degrees_north -90.0 90.0 -9999.0
latitude_apm_1km real 4 degrees_north -90.0 90.0 -9999.0
longitude_1km real 4 degrees_east -180.0 180.0 -9999.0
longitude_apm_1km real 4 degrees_east -180.0 180.0 -9999.0
retrieval_qual_flag_1km bit flag 2 NA NA NA 66534
retrieval_qual_flag_apm_1km bit flag 2 NA NA NA 66534
sigma0_incidence_angle_1km bit flag 2 NA 0.0 90.0 -9999.0
sigma0_incidence_angle_apm_1km bit flag 2 NA 0.0 90.0 -9999.0
sigma0_vh_aggregated_1km real 4 normalized 1.0 10.0 -9999.0
sigma0_vh_aggregated_apm_1km real 4 normalized 1.0 10.0 -9999.0
sigma0_vv_aggregated_1km real 4 normalized 1.0 10.0 -9999.0
sigma0_vv_aggregated_apm_1km real 4 normalized 1.0 10.0 -9999.0
soil_moisture_1km real 4 cm3/cm3 0.0 0.75 -9999.0
soil_moisture_apm_1km real 4 cm3/cm3 0.0 0.75 -9999.0
soil_moisture_std_dev_1km real 4 cm3/cm3 0.0 0.5 -9999.0
soil_moisture_std_dev_apm_1km real 4 cm3/cm3 0.0 0.5 -9999.0
spacecraft_overpass_time_seconds_1km real 8 seconds -99999999.9 99999999.9 -9999.0
spacecraft_overpass_time_seconds_apm_1km real 8 seconds -99999999.9 99999999.9 -9999.0
surface_flag_1km bit flag 2 NA NA NA 66534
surface_flag_apm_1km bit flag 2 NA NA NA 66534
surface_temperature_1km real 4 kelvin 200.0 350.0 -9999.0
surface_temperature_apm_1km real 4 kelvin 200.0 350.0 -9999.0
tb_v_disaggregated_1km real 4 kelvin 0.0 330.0 -9999.0
tb_v_disaggregated_apm_1km real 4 kelvin 0.0 330.0 -9999.0
tb_v_disaggregated_std_1km real 4 kelvin 0.0 100.0 -9999.0
tb_v_disaggregated_std_apm_1km real 4 kelvin 0.0 100.0 -9999.0
vegetation_opacity_1km real 4 normalized 0.0 1.0 -9999.0
vegetation_opacity_apm_1km real 4 normalized 0.0 1.0 -9999.0
vegetation_water_content_1km real 4 kg/m3 0.0 30.0 -9999.0
vegetation_water_content_apm_1km real 4 kg/m3 0.0 30.0 -9999.0
water_body_fraction_1km real 4 normalized 0.0 1.0 -9999.0
water_body_fraction_apm_1km real 4 normalized 0.0 1.0 -9999.0

Soil_Moisture_Retrieval_Data_3km [top]

Table 2 describes the data fields of a typical SPL2SMAP_S 3 km granule.

Table 2. Data Fields for Soil_Moisture_Retrieval_Data_3km
Data Field Name Concept Byte Unit Min Max Fill/Gap Value
EASE_column_index_3km integer 2 count 0 65535 66534
EASE_column_index_apm_3km integer 2 count 0 65535 66534
EASE_row_index_3km integer 2 count 0 65535 66534
EASE_row_index_apm_3km integer 2 count 0 65535 66534
SMAP_Sentinel-1_overpass_timediff_hr_3km integer 2 count -999999.9 999999.9 -9999.0
SMAP_Sentinel-1_overpass_timediff_hr_apm_3km integer 2 count -999999.9 999999.9 -9999.0
albedo_3km real 4 normalized 0.0 1.0 -9999.0
albedo_apm_3km real 4 normalized 0.0 1.0 -9999.0
bare_soil_roughness_retrieved_3km real 4 meters 0.0 2.0 -9999.0
bare_soil_roughness_retrieved_apm_3km real 4 meters 0.0 2.0 -9999.0
beta_tbv_vv_3km real 4 kelvin -35.0 0.0 -9999.0
beta_tbv_vv_apm_3km real 4 kelvin -35.0 0.0 -9999.0
disagg_soil_moisture_3km real 4 cm3/cm3 0.0 0.75 -9999.0
disagg_soil_moisture_apm_3km real 4 cm3/cm3 0.0 0.75 -9999.0
disaggregated_tb_v_qual_flag_3km bit flag 2 NA NA NA 66534
disaggregated_tb_v_qual_flag_apm_3km bit flag 2 NA NA NA 66534
gamma_vv_xpol_3km bit flag 2 NA 0.0 10.0 -9999.0
gamma_vv_xpol_apm_3km bit flag 2 NA 0.0 10.0 -9999.0
landcover_class_3km enum 1 NA NA NA 254
landcover_class_apm_3km enum 1 NA NA NA 254
latitude_3km real 4 degrees_north -90.0 90.0 -9999.0
latitude_apm_3km real 4 degrees_north -90.0 90.0 -9999.0
longitude_3km real 4 degrees_east -180.0 180.0 -9999.0
longitude_apm_3km real 4 degrees_east -180.0 180.0 -9999.0
retrieval_qual_flag_3km bit flag 2 NA NA NA 66534
retrieval_qual_flag_apm_3km bit flag 2 NA NA NA 66534
sigma0_incidence_angle_3km bit flag 2 NA 0.0 90.0 -9999.0
sigma0_incidence_angle_apm_3km bit flag 2 NA 0.0 90.0 -9999.0
sigma0_vh_aggregated_3km real 4 normalized 0.0 1.0 -9999.0
sigma0_vh_aggregated_apm_3km real 4 normalized 0.0 1.0 -9999.0
sigma0_vv_aggregated_3km real 4 normalized 0.0 1.0 -9999.0
sigma0_vv_aggregated_apm_3km real 4 normalized 0.0 1.0 -9999.0
soil_moisture_3km real 4 cm3/cm3 0.0 0.75 -9999.0
soil_moisture_apm_3km real 4 cm3/cm3 0.0 0.75 -9999.0
soil_moisture_std_dev_3km real 4 cm3/cm3 0.0 0.5 -9999.0
soil_moisture_std_dev_apm_3km real 4 cm3/cm3 0.0 0.5 -9999.0
spacecraft_overpass_time_seconds_3km real 8 seconds -99999999.9 99999999.9 -9999.0
spacecraft_overpass_time_seconds_apm_3km real 8 seconds -99999999.9 99999999.9 -9999.0
surface_flag_3km bit flag 2 NA NA NA 66534
surface_flag_apm_3km bit flag 2 NA NA NA 66534
surface_temperature_3km real 4 kelvin 200.0 350.0 -9999.0
surface_temperature_apm_3km real 4 kelvin 200.0 350.0 -9999.0
tb_v_disaggregated_3km real 4 kelvin 0.0 330.0 -9999.0
tb_v_disaggregated_apm_3km real 4 kelvin 0.0 330.0 -9999.0
tb_v_disaggregated_std_3km real 4 kelvin 0.0 100.0 -9999.0
tb_v_disaggregated_std_apm_3km real 4 kelvin 0.0 100.0 -9999.0
vegetation_opacity_3km real 4 normalized 0.0 1.0 -9999.0
vegetation_opacity_apm_3km real 4 normalized 0.0 1.0 -9999.0
vegetation_water_content_3km real 4 kg/m3 0.0 30.0 -9999.0
vegetation_water_content_apm_3km real 4 kg/m3 0.0 30.0 -9999.0
water_body_fraction_3km real 4 normalized 0.0 1.0 -9999.0
water_body_fraction_apm_3km real 4 normalized 0.0 1.0 -9999.0

Data Field Definitions [top]

EASE_column_index_[1km/3km]

The column index of the 1 km (or 3 km) EASE-Grid 2.0 cell that contains the associated data. This field contains SMAP a.m.-only data.

EASE_column_index_apm_[1km/3km]

The column index of the 1 km (or 3 km) EASE-Grid 2.0 cell that contains the associated data. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

EASE_row_index_[1km/3km]

The row index of the 1 km (or 3 km) EASE-Grid 2.0 cell that contains the associated data. This field contains SMAP a.m.-only data.

EASE_row_index_apm_[1km/3km]

The row index of the 1 km (or 3 km) EASE-Grid 2.0 cell that contains the associated data. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

SMAP_Sentinel-1_overpass_timediff_hr_[1km/3km]

 Number of hours difference between the SMAP overpass and the Sentinel-1 overpass. This field contains SMAP a.m.-only data.

SMAP_Sentinel-1_overpass_timediff_hr_apm_[1km/3km]

Number of hours difference between the SMAP overpass and the Sentinel-1 overpass. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

albedo_[1km/3km]

Diffuse reflecting power of the Earth's surface within the EASE-Grid 2.0 cell. This field contains SMAP a.m.-only data.

albedo_apm_[1km/3km]

Diffuse reflecting power of the Earth's surface within the EASE-Grid 2.0 cell. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

bare_soil_roughness_retrieved_[1km/3km]

Soil roughness provided by the MODIS International Geosphere-Biosphere Programme (IGBP) land cover map at 1 km (or 3 km) EASE-Grid 2.0 cell. The relative dominance of each land cover type is determined based on ranking among land cover classes using statistical mode. Table 4 provides a description of MODIS IGBP classes and the precentage of each land type. This field contains SMAP a.m.-only data.

bare_soil_roughness_retrieved_apm_[1km/3km]

Soil roughness provided by the MODIS International Geosphere-Biosphere Programme (IGBP) land cover map at 1 km (or 3 km) EASE-Grid 2.0 cell. The relative dominance of each land cover type is determined based on ranking among land cover classes using statistical mode. Table 4 provides a description of MODIS IGBP classes and the precentage of each land type. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

beta_tbv_vv_[1km/3km]

Beta parameter used in the Active/Passive retrieval algorithm for the corresponding EASE-Grid 2.0 cell, derived using time series Tbv and sigma0_vv. This field contains SMAP a.m.-only data.

beta_tbv_vv_apm_[1km/3km]

Beta parameter used in the Active/Passive retrieval algorithm for the corresponding EASE-Grid 2.0 cell, derived using time series Tbv and sigma0_vv. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

disagg_soil_moisture_[1km/3km]

Representative soil moisture measurement for the 1 km EASE-Grid 2.0 cell obtained from disaggregating the coarse resolution soil moisture. This field contains SMAP a.m.-only data.

disagg_soil_moisture_apm_[1km/3km]

Representative soil moisture measurement for the 1 km EASE-Grid 2.0 cell obtained from disaggregating the coarse resolution soil moisture. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

disaggregated_tb_v_qual_flag_[1km/3km]

Bit flags that record the conditions and the quality of the disaggregated vertical polarization brightness temperature for the option 1 soil moisture algorithm generated for the EASE-Grid 2.0 cell. Refer to Table 3 for bit flag definitions. This field contains SMAP a.m.-only data.

Table 3. Quality Bit Flag Definitions
Name Bit Position Description of Values (0:off, 1:on)
Disaggregated brightness temperature v-pol quality 0 0: Disaggregated vertical polarization brightness temperature has acceptable quality
1: Unable to disaggregate vertical polarization brightness temperatures into cells
Retrieval quality flag 1 0: Soil moisture retrieval has recommended quality
1: Soil moisture retrieval has uncertain quality

disaggregated_tb_v_qual_flag_apm_[1km/3km]

Bit flags that record the conditions and the quality of the disaggregated vertical polarization brightness temperature for for the option 1 soil moisture algorithm generated for the EASE-Grid 2.0 cell. Refer to Table 3 for bit flag definitions. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

gamma_vv_xpol_[1km/3km]

Gamma parameter used in the Active/Passive retrieval algorithm for the corresponding EASE-Grid 2.0 cell, derived using high resolution sigma0_vv and sigma0_xpol. This field contains SMAP a.m.-only data.

gamma_vv_xpol_apm_[1km/3km]

Gamma parameter used in the Active/Passive retrieval algorithm for the corresponding EASE-Grid 2.0 cell, derived using high resolution sigma0_vv and sigma0_xpol. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

landcover_class_[1km/3km]

An enumerated type that specifies the predominant surface vegetation found in the EASE-Grid 2.0 cell at 1 km or 3 km. Refer to Table 4 for classification values. This field contains SMAP a.m.-only data.

Class Description Percentage
Table 4. MODIS IGBP Land Classification and Percentage
0 Water -
1 Evergreen Needleleaf Forest 3.96
2 Evergreen Broadleaf Forest 10.04
3 Deciduous Needleleaf Forest 0.63
4 Deciduous Broadleaf Forest 1.59
5 Mixed Forests 4.69
6 Closed Shrublands 0.55
7 Open Shrublands 18.26
8 Woody Savannas 7.52
9 Savannas 6.97
10 Grasslands 9.27
11 Permanent Wetlands 0.22
12 Croplands 8.95
13 Urban and Built-Up 0.50
14 Cropland/Natural Vegetation Mosaic 2.10
15 Snow and Ice 11.04
16 Barren or Sparsely Vegetated

13.70

landcover_class_apm_[1km/3km]

An enumerated type that specifies the predominant surface vegetation found in the EASE-Grid 2.0 cell. Refer to Table 4 for classification values. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

latitude_[1km/3km]

Latitude of the center of the EASE-Grid 2.0 cell. This field contains SMAP a.m.-only data.

latitude_apm_[1km/3km]

Latitude of the center of the EASE-Grid 2.0 cell. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

longitude_[1km/3km]

Longitude of the center of the EASE-Grid 2.0 cell. This field contains SMAP a.m.-only data.

longitude_apm_[1km/3km]

Longitude of the center of the EASE-Grid 2.0 cell. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

retrieval_qual_flag_[1km/3km]

Bit flags that record the conditions and the quality of the retrieval algorithms that generate soil moisture for for the option 1 soil moisture algorithm generated for the EASE-Grid 2.0 cell. Refer to Table 3 for bit flag definitions. This field contains SMAP a.m.-only data.

retrieval_qual_flag_apm_[1km/3km]

Bit flags that record the conditions and the quality of the retrieval algorithms that generate soil moisture for for the option 1 soil moisture algorithm generated for the EASE-Grid 2.0 cell. Refer to Table 3 for bit flag definitions. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

sigma0_incidence_angle_[1km/3km]

The outcome of aggregating a set of 1 km (or 3 km) incidence angle of radar backscatter measurements into a 1 km (or 3 km) EASE-Grid 2.0 cell. This field contains SMAP a.m.-only data.

sigma0_incidence_angle_apm_[1km/3km]

The outcome of aggregating a set of 1 km (or 3 km) incidence angle of radar backscatter measurements into a 1 km (or 3 km) EASE-Grid 2.0 cell. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

sigma0_vh_aggregated_[1km/3km]

The outcome of aggregating a set of 1 km (or 3 km) cross-polarized radar backscatter measurements into a 1 km (or 3 km) EASE-Grid 2.0 cell. This field contains SMAP a.m.-only data.

sigma0_vh_aggregated_apm_[1km/3km]

The outcome of aggregating a set of 1 km (or 3 km) cross-polarized radar backscatter measurements into a 1 km (or 3 km) EASE-Grid 2.0 cell. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

sigma0_vv_aggregated_[1km/3km]

The outcome of aggregating a set of 1 km (or 3 km) vertical polarization radar backscatter measurements into a 1 km (or 3 km) EASE-Grid 2.0 cell. This field contains SMAP a.m.-only data.

sigma0_vv_aggregated_apm_[1km/3km]

The outcome of aggregating a set of 1 km (or 3 km) vertical polarization radar backscatter measurements into a 1 km (or 3 km) EASE-Grid 2.0 cell. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

soil_moisture_[1km/3km]

Representative soil moisture measurement for the 1 km (or 3 km) EASE-Grid 2.0 cell for option 1. This field contains SMAP a.m.-only data.

Note: The soil_moisture_3km field contains data for the baseline algorithm.

soil_moisture_apm_[1km/3km]

Representative soil moisture measurement for the 1 km (or 3 km) EASE-Grid 2.0 cell for option 1. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

soil_moisture_std_dev_[1km/3km]

Standard deviation of soil moisture measure for the 1km EASE-Grid 2.0 cell. This field contains SMAP a.m.-only data.

soil_moisture_std_dev_apm_[1km/3km]

Standard deviation of soil moisture measure for the 1km EASE-Grid 2.0 cell. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

spacecraft_overpass_time_seconds_[1km/3km]

Number of seconds since a specified epoch that represents the spacecraft overpass relative to the 9 km EASE-Grid 2.0 cell that contains each 1 km (or 3 km) EASE-Grid 2.0 cell represented in this data product. This field contains SMAP a.m.-only data.

spacecraft_overpass_time_seconds_apm_[1km/3km]

Number of seconds since a specified epoch that represents the spacecraft overpass relative to the 9 km EASE-Grid 2.0 cell that contains each 1 km (or 3 km) EASE-Grid 2.0 cell represented in this data product. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

surface_flag_[1km/3km]

Bit flags that record ambient surface conditions for the EASE-Grid 2.0 cell. Refer to the surface_flag_apm_[1km/3km] description below for a detailed description of the surface_flag fields and bit flag definitions. This field contains SMAP a.m.-only data.

surface_flag_apm_[1km/3km]

A 16-bit integer field whose binary representation consists of bits that indicate the presence or absence of certain surface conditions at a grid cell. In Table 5, a '0' indicates the presence of a surface condition favorable to soil moisture retrieval. Each surface condition is numerically compared against two non-negative thresholds: T1 and T2, where T1 < T2. In most cases, when a surface condition is found to be below T1, retrieval is attempted and flagged for recommended quality. Between T1 and T2, retrieval is still attempted but flagged for uncertain quality. Above T2, retrieval is skipped. A summary of surface conditions and their thresholds are listed below. The surface_flag field is internally linked to the surface_flag_option1 field produced by the baseline algorithm. Table 5 lists surface condition bit flag definitions.

As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

Note: Bit position '0' refers to the least-significant bit. Final bit positions and definitions are subject to future revision and expansion as needed.

Table 5. Surface Condition Bit Flag Definitions
Bit Surface Condition T1 T2 Bit Value and Interpretation
0 Static water 0.05 0.10 0: Water fraction less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
1 Radar-derived water body detection 0.05 0.10 0: Water fraction less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
2 Coastal proximity N/A 1.0 0: Distance to nearby significant water bodies greater than T2 (number of 36-km grid cells):
  • Greater than T2: Retrieval attempted and flagged for recommended quality
  • Less than T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
3 Urban area 0.50 1.00 0: Urban fraction less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
4 Precipitation 0.05 0.10 0: Precipitation fraction less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
5 Snow or ice 0.05 0.10 0: Snow fraction less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
6 Permanent snow or ice 0.05 0.10 0: Ice fraction less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
7

Radar frozen ground*
(from Sentinel-1 radar-derived F/T state)

0.00 0.90 0: Freeze/thaw fraction less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
8

Model frozen ground
(from GMAO TSURF)

 

0.00 0.90 0: Freeze/thaw fraction less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
9 Mountainous terrain 0: Slope standard deviation less than T2:
  • Less than T1: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
10 Dense vegetation 5.0 30.0 0: Vegetation Water Content (VWC) less than T2:
  • Less than T1 kg/m2: Retrieval attempted and flagged for recommended quality
  • Between T1 and T2: Retrieval attempted and flagged for uncertain quality
1: Otherwise:
  • Above T2: Retrieval skipped
11 Scene edge TBD TBD TBD
12 Anomalous sigma0 TBD TBD TBD
13-15 Undefined N/A N/A 0 (not used in SPL2SMP_E)

surface_temperature_[1km/3km]

 Temperature at land surface based on GEOS5 GMAO. This field contains SMAP a.m.-only data.

surface_temperature_apm_[1km/3km]

 Temperature at land surface based on GEOS5 GMAO. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

tb_v_disaggregated_[1km/3km]

Vertical polarization brightness temperature adjusted for the presence of water bodies and disaggregated from the 9 km EASE-Grid 2.0 cells into 1 km (or 3 km) EASE-Grid 2.0 cells. This field contains SMAP a.m.-only data.

tb_v_disaggregated_apm_[1km/3km]

Vertical polarization brightness temperature adjusted for the presence of water bodies and disaggregated from the 9 km EASE-Grid 2.0 cells into 1 km (or 3 km) EASE-Grid 2.0 cells. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

tb_v_disaggregated_std_[1km/3km]

Standard deviation of the vertical polarization brightness temperature adjusted for the presence of water bodies and disaggregated from the 9 km EASE-Grid 2.0 cells into 1 km (or 3 km) EASE-Grid 2.0 cells. This field contains SMAP a.m.-only data.

tb_v_disaggregated_std_apm_[1km/3km]

Standard deviation of the vertical polarization brightness temperature adjusted for the presence of water bodies and disaggregated from the 9 km EASE-Grid 2.0 cells into 1 km (or 3 km) EASE-Grid 2.0 cells. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

vegetation_opacity_[1km/3km]

The measured opacity of the vegetation in the EASE-Grid 2.0 cell. Estimated vegetation opacity at 1 km 3 km spatial scale. Note that this parameter is the same ‘tau’ parameter normalized by the cosine of the incidence angle in the ‘tau-omega’ model, where:

tau-omega equation

The valid minimum and maximum below are subject to further analysis. This field contains SMAP a.m.-only data.

vegetation_opacity_apm_[1km/3km]

The measured opacity of the vegetation in the EASE-Grid 2.0 cell. The measured opacity of the vegetation in the EASE-Grid 2.0 cell. Estimated vegetation opacity at 1 km 3 km spatial scale. Note that this parameter is the same ‘tau’ parameter normalized by the cosine of the incidence angle in the ‘tau-omega’ model, where:

tau-omega equation

The valid minimum and maximum below are subject to further analysis. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

vegetation_water_content_[1km/3km]

Representative measure of water in the vegetation within the 1 km (or 3 km) EASE-Grid 2.0 cell. This field contains SMAP a.m.-only data.

vegetation_water_content_apm_[1km/3km]

Representative measure of water in the vegetation within the 1 km (or 3 km) EASE-Grid 2.0 cell. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

water_body_fraction_[1km/3km]

Fraction of the area of 1 km (or 3 km) EASE-Grid 2.0 cell that is a permanent or transient water body. Derived from the Digital Elevation Model (DEM) and radar processing. This field contains SMAP a.m.-only data.

water_body_fraction_apm_[1km/3km]

Fraction of the area of 1 km (or 3 km) EASE-Grid 2.0 cell that is a permanent or transient water body. Derived from the DEM and radar processing. As noted by apm in the data field name, this field contains SMAP a.m.-or-p.m. data.

Metadata [top]

For a description of metadata fields for this product, refer to the Metadata Fields document.

Fill/Gap Values [top]

SMAP data products employ fill and gap values to indicate when no valid data appear in a particular data element. Fill values ensure that data elements retain the correct shape. Gap values locate portions of a data stream that do not appear in the output data file.

Fill values appear in the SPL2SMAP_S product when the SPL2SMAP_S SPS can process some, but not all, of the input data for a particular swath EASE-Grid 2.0 cell. Fill data may appear in the product in any of the following circumstances:

  • One of Science Production Software (SPS) executables that generate the SPL2SMAP_S product is unable to calculate a particular science or engineering data value. The algorithm encounters an error. The error disables generation of valid output. The SPS reports a fill value instead.
  • Some of the required science or engineering algorithmic input are missing. Data over the region that contributes to particular EASE-Grid 2.0 cell may appear in only some of the input data streams. Since data are valuable, the SPL2SMAP_S product records any outcome that can be calculated with the available input. Missing data appear as fill values.
  • Non-essential information is missing from the input data stream. The lack of non-essential information does not impair the algorithm from generating needed output. The missing data appear as fill values.
  • Fill values appear in the input SPL3SMP_E product. If only some of the input that contributes to a particular EASE-Grid 2.0 cell is fill data, the Level SPL2SMAP_S SPS will most likely be able to generate some output. However, some portion of the SPL2SMAP_S output for that EASE-Grid 2.0 cell may appear as fill values.

SMAP data products employ a specific set of data values to connote that an element is fill. The selected values that represent fill are dependent on the data type. No valid value in the SPL2SMAP_S product is equal to the values that represent fill. If any exceptions should exist in the future, the SPL2SMAP_S content will provide a means for users to discern between elements that contain fill and elements that contain genuine data values. This document will also contain a description of the method used to ascertain which elements are fill and which elements are genuine.

The SPL2SMAP_S product records gaps when entire frames within the time span of a particular data granule do not appear. Gaps can occur under one of two conditions:

  • One or more complete frames of data are missing from all data streams.
  • The subset of input data that is available for a particular frame is not sufficient to process any frame output.

The Level SPL2SMAP_S product records gaps in the product level metadata. The following conditions will indicate that no gaps appear in the data product:

  • Only one instance of the attributes Extent/rangeBeginningDateTime and Extent/rangeEndingDateTime will appear in the product metadata.
  • The character string stored in metadata element Extent/rangeBeginningDateTime will match the character string stored in metadata element OrbitMeasuredLocation/halfOrbitStartDateTime.
  • The character string stored in metadata element Extent/rangeEndingDateTime will match the character string stored in metadata element OrbitMeasuredLocation/halfOrbitStopDateTime.

One of two conditions will indicate that gaps appear in the data product:

  • The time period covered between Extent/rangeBeginningDateTime and Extent/RangeEndingDateTime does not cover the entire half orbit as specified in OrbitMeasuredLocation/halfOrbitStartDateTime and OrbitMeasuredLocation/halfOrbitStartDateTime.
  • More than one pair of Extent/rangeBeginningDateTime and Extent/rangeEndingDateTime appears in the data product. Time periods within the time span of the half orbit that do not fall within the sets of Extent/rangeBeginningDateTime and Extent/rangeEndingDateTime constitute data gaps.

Notations [top]

Table 6 lists the notations used in this document.

Table 6. Notation Definitions
Notation Definition
Int8 8-bit (1-byte) signed integer
Int16 16-bit (2-byte) signed integer
Int32 32-bit (4-byte) signed integer
Uint8 8-bit (1-byte) unsigned integer
Uint16 16-bit (2-byte) unsigned integer
Float32 32-bit (4-byte) floating-point integer
Float64 64-bit (8-byte) floating-point integer
Char 8-bit character
H-pol Horizontally polarized
V-pol Vertically polarized