Parameters for this data set are surface soil moisture (0-5 cm) in m3/m3 and surface soil temperature (0-50) in °C.
Sample Data Record

SMAP radiometer and radar soil moisture data products are matched with in situ-based soil moisture estimates from core validation sites to produce this data set. These data provide performance assessments of various SMAP soil moisture products.
First release of data set
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STANDARD Level of Service
Data: Data integrity and usability verified
Documentation: Key metadata and user guide available
User Support: Assistance with data access and usage; guidance on use of data in tools
Parameter(s): |
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Spatial Coverage: |
N: 85.044, S: -85.044, E: 180, W: -180 |
Spatial Resolution: |
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Temporal Coverage: |
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Temporal Resolution: | Varies |
Data Format(s): |
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Platform(s) | GROUND STATIONS, SMAP Observatory |
Sensor(s): | SMAP L-BAND RADIOMETER, SMAP L-Band Radar, SOIL MOISTURE PROBE, SOIL TEMPERATURE PROBE |
Version: | V1 |
Data Contributor(s): | Andreas Colliander, Aaron Berg, Carsten Montzka, Jose Martinez-Fernandez, Mark Seyfried, Hala Al Jassar, Wouter Dorigo, Jeffrey Walker, Mehrez Zribi |
Metadata XML: | View Metadata Record |
As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.
Colliander, A., H. Al Jassar, W. Dorigo, J. Martinez-Fernandez, C. Montzka, M. Seyfried, et al. 2017. SMAP/In Situ Core Validation Site Land Surface Parameters Match-Up Data, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/DXAVIXLY18KM. [Date Accessed].SMAP radiometer and radar soil moisture data products are matched with in situ-based soil moisture estimates from core validation sites to produce this data set. These data provide performance assessments of various SMAP soil moisture products. The SMAP radiometer and radar soil moisture retrieval algorithms are described in corresponding Algorithm Theoretical Basis Documents (ATBD).
The SMAP products matched with in situ data are:
Parameters for this data set are surface soil moisture (0-5 cm) in m3/m3 and surface soil temperature (0-50) in °C.
Data are provided in ASCII files (.txt
). An associated Extensible Markup Language (.MET.xml
) metadata file is also provided for each data file.
Data are available on the HTTPS site at: https://n5eil01u.ecs.nsidc.org/SMAP_VAL/NSIDC-0712.001
Within this directory, files are organized in subdirectories by date such as 2015.04.01
. Dates are given in four-digit year, two-digit month, and two-digit day format.
Table 1 lists the information necessary to identify the contents of the data files, such as SMAP product IDs, versions, and Composite Release (CRIDs).
CRIDs indicate processing changes (such as algorithm and software) shared by a particular version. Note that major versions (Version 3, for example) can have multiple CRIDs. Refer to the SMAP Data Versions page for more information on versions and CRIDs.
Subdirectory | SMAP Product ID | SMAP ID in File Names for this Product | Version | CRID in this Match-Up Product1 | CRID(s) in Operational SMAP Products2 | Assessment Reports3 |
---|---|---|---|---|---|---|
2015.04.01 |
SPL2SMP | SMAPL2SMP | Version 3 | T12323 | R13080 | Report![]() |
2015.04.01 |
SPL2SMP | SMAPL2SMP | Version 4 | R13080 | R14010, R15060, R15152, R15180, R15181, R15182 | Report![]() |
2015.04.01 |
SPL2SMP | SMAPL2SMP | Version 5 | T15600 | R16000, R16010 | Report![]() |
2015.04.01 |
SPL2SMP_E | SMAPL2SMPE | Version 1 | D14000 | R14010, R15060, R15152, R15180, R15181, R15182 | Report![]() |
2015.04.01 |
SPL2SMP_E | SMAPL2SMPE | Version 2 | R16010 | R16000, R16010 | Report![]() |
2015.04.13 |
SPL2SMA | SMAPL2SMA | Version 3 | T12400 | R13080 | Report![]() |
2015.04.13 |
SPL2SMAP | SMAPL2SMAP | Version 3 | D12000 | R13080 | Report![]() |
1 CRIDs in this product are different than those in SMAP operational products (e.g. SPL2MP). To generate this match-up product, a separate offline (non-operational) processor is used for validation grid processing; this results in separate, corresponding CRIDs. 3 Match-up files correspond to the data used in the assessment reports. |
Table 2 describes the fields contained in the data files.
Data Field | Unit | Valid Range | Definition | Description | Source |
---|---|---|---|---|---|
ID | N/A | N/A | Reference pixel ID | Unique ID of the reference pixel | N/A |
Yr | N/A | N/A | Year | N/A | N/A |
Mo | N/A | N/A | Month | N/A | N/A |
Day | N/A | N/A | Day | N/A | N/A |
Hr | N/A | N/A | Hour | N/A | N/A |
Min | N/A | N/A | Minute | N/A | N/A |
TOY | N/A | N/A | Time of Year | Fractional day of year, where 01 January is 1 and 31 December is 365 (non leap year) | N/A |
WASM | m3/m3 | 0-0.6 | Weighted Average Soil Moisture of reference pixel | Obtained from the sensors deployed within the SMAP reference pixel area; includes arithmetic average and weighted average; weighting scheme independently decided for each pixel (default approach is Voronoi diagrams); soil moisture measurements are taken at a depth of 0-5 cm | in situ |
ASM | m3/m3 | 0-0.6 | Average Soil Moisture of reference pixel | Obtained from the sensors deployed within the SMAP reference pixel area | in situ |
WAST | °C | 0-50 | Weighted Average Soil Temperature of reference pixel | Obtained from the sensors deployed within the SMAP reference pixel area; includes arithmetic average and weighted average; weighting scheme independently decided for each pixel (default approach is Voronoi diagrams) | in situ |
AST | °C | 0-50 | Average Soil Temperature of reference pixel | Obtained from the sensors deployed within the SMAP reference pixel area | in situ |
sWASM | m3/m3 | 0-0.2 | Standard deviation of Weighted Average Soil Moisture of reference pixel | Used in computing the averages WASM and ASM. For weighted average, the weights are accounted for in the computation of the standard deviation | N/A |
sASM | m3/m3 | 0-0.2 | Standard deviation of Average Soil Moisture of reference pixel | Non-weighted standard deviation | N/A |
NUM | N/A | N/A | Number of sensors used to compute average | N/A | N/A |
Q-RP | N/A | 0=valid; 1=invalid | Reference pixel quality flag | Each in situ sensor is quality controlled. During the averaging process, these quality flags are aggregated to determine whether the averaged value is ok. If less than 10% of the contributing stations (after weighting) are compromised, the value is deemed valid (0) otherwise invalid (1). | N/A |
SM-1 | m3/m3 | 0-0.6 | SMAP soil moisture | Refer to Table 3 | SMAP |
Q-FLG-1 | N/A | N/A | SMAP retrieval quality flag | Can convert to a 16-bit binary to retrieve the individual flag values1. Refer to Table 3 | SMAP |
Tsurf (°C) | N/A | 0-50 | Surface Temperature from SMAP product | Model-based soil temperature from the Global Modeling and Assimilation Office (GMAO) for estimating effective surface temperature and computing emissivity | SMAP |
S-FLG | N/A | N/A | SMAP surface flag | Can convert to a 16-bit binary to retrieve the individual flag values1. Refer to the SPL2SMP Data Fields for more information. | SMAP |
SM-2 | m3/m3 | 0-0.6 | SMAP soil moisture | Refer to Table 3 | SMAP |
Q-FLG-2 | N/A | N/A | SMAP retrieval quality flag | Can convert to a 16-bit binary to retrieve the individual flag values1. Refer to Table 3 | SMAP |
SM-3 | m3/m3 | 0-0.6 | SMAP soil moisture | Refer to Table 3 | SMAP |
Q-FLG-3 | N/A | N/A | SMAP retrieval quality flag | Can convert to a 16-bit binary to retrieve the individual flag values1. Refer to Table 3 | SMAP |
SM-4 | m3/m3 | 0-0.6 | SMAP soil moisture | Refer to Table 3 | SMAP |
Q-FLG-4 | N/A | N/A | SMAP retrieval quality flag | Can convert to a 16-bit binary to retrieve the individual flag values1. Refer to Table 3 | SMAP |
SM-5 | m3/m3 | 0-0.6 | SMAP soil moisture | Refer to Table 3 | SMAP |
Q-FLG-5 | N/A | N/A | SMAP retrieval quality flag | Can convert to a 16-bit binary to retrieve the individual flag values1. Refer to Table 3 | SMAP |
SM-6 | m3/m3 | 0-0.6 | SMAP soil moisture | Refer to Table 3 | SMAP |
Q-FLG-6 | N/A | N/A | SMAP retrieval quality flag | Can convert to a 16-bit binary to retrieve the individual flag values1. Refer to Table 3 | SMAP |
SM-7 | m3/m3 | 0-0.6 | SMAP soil moisture | N/A | SMAP |
Q-FLG-7 | N/A | N/A | SMAP retrieval quality flag | Can convert to a 16-bit binary to retrieve the individual flag values1. Refer to Table 3 | SMAP |
ORB | N/A | N/A | Orbit number | Values are either ascending (positive) or descending (negative) orbits | N/A |
1Users should only consider the defined bits when interpretting data flags, not the entire 16 bit integer |
Table 3 provides descriptions of the SMAP soil moisture and quality data fields for each of the SMAP match-up products.
Data Fields | SPL2SMP/SPL2SMP_E | SPL2SMA | SPL2SMAP |
---|---|---|---|
SM-1 | Soil moisture retrieval from optional algorithm 1 - SCA-H. Corresponds to soil_moisture_option1 data field; refer to the SPL2SMP Data Fields page for more information. | Soil moisture retrieval from the time series algorithm. Corresponds to soil_moisture data field; refer to the SPL2SMA Data Fields page for more information. | Soil moisture retrieval from v-pol option1 algorithm – disaggregated/downscaled vertical polarization brightness temperature. Corresponds to soil_moisture_v_option1 data field; refer to the SPL2SMAP Data Fields page for more information. |
Q-FLG-1 | Quality flag for optional algorithm 1, SCA-H.* Corresponds to retrieval_qual_flag_option1 data field (refer to SPL2SMP Data Fields). | Quality flag for the soil moisture and freeze-thaw retrieval. Corresponds to retrieval_qual_flag data field (refer to SPL2SMA Data Fields). | Quality flag for the baseline soil moisture retrieval. Corresponds to retrieval_qual_flag data field (refer to SPL2SMAP Data Fields). |
SM-2 | Soil moisture retrieval from optional algorithm 2 - SCA-V. Corresponds to soil_moisture_option2 data field (refer to SPL2SMP Data Fields). | Soil moisture retrieval from normalized change. Corresponds to soil_moisture_change_index data field (refer to SPL2SMA Data Fields). | Soil moisture retrieval from v-pol option2 algorithm – disaggregated/ downscaled vertical polarization brightness temperature. Corresponds to soil_moisture_v_option2 data field (refer to SPL2SMAP Data Fields). |
Q-FLG-2 | Quality flag for baseline algorithm 2, SCA-V.* Corresponds to retrieval_qual_flag_option2 data field (refer to SPL2SMP Data Fields). | Quality flag for the soil moisture and freeze-thaw retrieval. Corresponds to retrieval_qual_flag_change_index data field (refer to SPL2SMA Data Fields). | Quality flag for the soil moisture retrieval. Corresponds to retrieval_qual_flag_option2 data field (refer to SPL2SMAP Data Fields). |
SM-3 | Soil moisture retrieval from optional algorithm 3 - DCA. Corresponds to soil_moisture_option3 data field (refer to SPL2SMP Data Fields). | Soil moisture retrieval from the Kim/van Zyl time series algorithm. Corresponds to soil_moisture_kvz data field (refer to SPL2SMA Data Fields). | Soil moisture retrieval from v-pol option 3 algorithm – disaggregated/downscaled vertical polarization brightness temperature. Corresponds to soil_moisture_v_option3 data field (refer to SPL2SMAP Data Fields). |
Q-FLG-3 | Quality flag for optional algorithm 3, DCA.* Corresponds to retrieval_qual_flag_option3 data field (refer to SPL2SMP Data Fields). | Quality flag for the soil moisture and freeze-thaw retrieval. Corresponds to the retrieval_qual_flag_kvz data field (refer to SPL2SMA Data Fields). | Quality flag for the baseline soil moisture retrieval. Corresponds to retrieval_qual_flag data field (refer to SPL2SMAP Data Fields). |
SM-4 | Soil moisture retrieval from optional algorithm 4 - MPRA. Corresponds to soil_moisture_option4 data field (refer to SPL2SMP Data Fields). | Soil moisture retrieval from the Shi snapshot algorithm. Corresponds to soil_moisture_snapshot_shi data field (refer to SPL2SMA Data Fields). | Soil moisture retrieval from h-pol option1 – disaggregated/downscaled horizontal polarization brightness temperature. Corresponds to soil_moisture_h_option1 data field (refer to SPL2SMAP Data Fields). |
Q-FLG-4 | Quality flag for optional algorithm 4, MPRA.* Corresponds to retrieval_qual_flag_option4 data field (refer to SPL2SMP Data Fields). | Quality flag for soil moisture and freeze-thaw retrieval. Corresponds to retrieval_qual_flag data value (refer to SPL2SMA Data Fields). | Quality flag for the baseline soil moisture retrieval. Corresponds to retrieval_qual_flag data field (refer to SPL2SMAP Data Fields). |
SM-5 | Soil moisture retrieval from optional algorithm 5 - E-DCA. Corresponds to soil_moisture_option5 data field (refer to SPL2SMP Data Fields). | Soil moisture retrieval from the snapshot algorithm. Corresponds to soil_moisture_snapshot data field (refer to SPL2SMA Data Fields). | Soil moisture retrieval from h-pol option2 – disaggregated/downscaled horizontal polarization brightness temperature. Corresponds to soil_moisture_h_option2 data field (refer to SPL2SMAP Data Fields). |
Q-FLG-5 | Quality flag for optional algorithm 5, E-DCA.* Corresponds to retrieval_qual_flag_option5 data field (refer to SPL2SMP Data Fields). | Quality flag for soil moisture and freeze-thaw retrieval. Corresponds to retrieval_qual_flag data field (refer to SPL2SMA Data Fields). | Quality flag for soil moisture retrieval. Corresponds to retrieval_qual_flag_option2 data field (refer to SPL2SMAP Data Fields). |
SM-6 | N/A | Soil moisture retrieval from the Dubois/van Zyl snapshot algorithm. Corresponds to soil_moisture_snapshot_DVZ data field (refer to SPL2SMA Data Fields). | Soil moisture retrieval from h-pol option3 soil moisture – disaggregated/downscaled horizontal polarization brightness temperature. Corresponds to soil_moisture_h_option3 data field (refer to SPL2SMAP Data Fields). |
Q-FLG-6 | N/A | Quality flag for soil moisture and freeze-thaw retrieval. Corresponds to retrieval_qual_flag data field (refer to SPL2SMA Data Fields). | Quality flag for the baseline soil moisture retrieval. Corresponds to retrieval_qual_flag data field (refer to SPL2SMAP Data Fields). |
SM-7 | N/A | Soil moisture retrieval from the time series algorithm. Corresponds to soil_moisture_time_series data field (refer to SPL2SMA Data Fields). | N/A |
Q-FLG-7 | N/A | Quality flag for soil moisture and freeze-thaw retrieval. Corresponds to retrieval_qual_flag data field (refer to SPL2SMA Data Fields). | N/A |
* Provided as a numerical value; can convert to a 16-bit binary to retrieve the individual flag values |
Files are named according to the following convention, which is described in Table 4:
NSIDC-0712_[Pixel ID]_SMAPL2SM[XXX]_[X]LVvvv_YYYYMMDD_yyyymmdd.txt
Where:
Variable | Description | ||||||||
---|---|---|---|---|---|---|---|---|---|
NSIDC-0712 |
Data Set ID | ||||||||
[Pixel ID] |
Pixel ID with four 2-digit variables [ID/SN/GS/PN ], where:ID: Site Principal Investigator IDSN: Site NumberGS: Grid ScalePN: Pixel number |
||||||||
SMAPL2SM[XXX] |
Associated SMAP product, where: |
||||||||
[X]LVvvv |
CRID [a 5-digit ID usually preceded by an R (for Release), which indicates processing changes (i.e. algorithm and software) shared by a particular version)] of SMAP product, where:
|
||||||||
YYYYMMDD |
Start date (4-digit year, 2-digit month, 2-digit day) | ||||||||
YYYYMMDD |
End date (4-digit year, 2-digit month, 2-digit day) | ||||||||
.txt |
ASCII text file extension | ||||||||
.MET.xml |
Metadata XML file extension |
Example: NSIDC-0712_03013602_SMAPL2SMP_T12323_20150401_20160229.txt
File sizes vary:
Metadata files are 2.2 KB each.
The data set volume is approximately 7 MB.
Spatial coverage for the SMAP data is global (N: 85.044, S: -85.044, E: 180, W: -180). Coverage for the in situ data varies based on the location of core sites, which are dispersed globally.
Refer to Table 5 for a list of the various core sites and their latitude and longitude.
In an effort to ensure the geographic distribution and diversity of conditions of the core validation sites (CVS), SMAP partnered with investigators around the globe. These Calibration/Validation (Cal/Val) partners play a crucial role in the execution of the SMAP Cal/Val Plan (Jackson et al., 2013). CVS candidates were selected based on a minimum requirement of continuous soil moisture measurements at 5 cm depth; the measurements also needed to be replicated within a grid cell of at least one of the SMAP spatial scales (although some sites have multiple pixels at 9 km and 3 km scale). Table 5 lists the site candidates. The sites are divided into two categories: (a) those where confidence that they are representative of a site at a certain spatial scale is high enough for using the site as a basis of computing the performance metrics (CVS), and (b) sites that can be utilized for algorithm testing but the confidence that they are representative is not high enough for using the site in the metrics computations (candidate sites).
Criteria for determining whether a site is a CVS include:
Sites that initially did not meet these requirements have the option of performing supplemental investigations such as additional field sampling and modeling studies to eventually reach CVS status. Because different SMAP surface soil moisture products have different spatial scales, the suitability of the various sites for validation of the different products must be evaluated separately. Currently qualified core validation sites represent land cover types that together extend over about 70% of the retrieval domain defined for the products. Upgrading some of the current candidate sites to CVS status would raise this figure close to 100% (Colliander et al., 2017).
Site Name | Site ID | Site PI | Location |
Latitude, Longitude |
Core Site Scales [km]I | Climate RegimeII | IGBPIII Land Cover | References | |
---|---|---|---|---|---|---|---|---|---|
1 | Tonzi Ranch | 2501 | M. Moghaddam | USA (California) | 38.43° N, 120.97° W | (Not a core site) | Temperate | Savannas woody | Clewley et al., 2017 |
2 | Walnut Gulch* | 1601 | D. C. Goodrich | USA (Arizona) | 31.72° N, 110.68° W | 3, 9, 36 | Arid | Shrub open | Keefer et al., 2008 |
3 | Reynolds Creek* | 0401 | M. Seyfried | USA (Idaho) | 31.72° N, 110.68° W | 9, 36 | Arid | Grasslands | Seyfried et al., 2001 |
4 | TxSON** | 4801 | T. Caldwell | USA (Texas) | 30.5° N, 98.5° W | 3, 9, 36 | Temperate | Grasslands | (Not available) |
5 | Fort Cobb* | 1603 | P. J. Starks | USA (Oklahoma) | 35.36° N, 98.55° W | 36 | Temperate | Grasslands | (Not available) |
6 | Little Washita* | 1602 | P. J. Starks | USA (Oklahoma) | 34.97° N, 97.97° W | 9, 36 | Temperate | Grasslands | Cosh et al., 2006 |
7 | South Fork* | 1607 | M. H. Cosh/J. Prueger | USA (Iowa) | 42.44° N, 93.44° | 3, 9, 36 | Cold | Croplands | Coopersmith et al., 2015 |
8 | St. Josephs* | 1606 | S. Livingston | USA (Indiana) | 41.449° N, 85.011° W | 9 | Cold | Croplands | (Not available) |
9 | Little River* | 1604 | D. Bosch | USA (Georgia) | 31.64° N, 83.65° W | 3, 9, 36 | Temperate | Cropland/natural mosaic | Bosch et al., 2007 |
10 | Millbrook | 2601 | M. Temimi | USA (New York) | 41.78° N, 73.73° W | (Not a core site) | Cold | Forest deciduous broadleaf | (Not available) |
11 | Kenaston* | 2701 | A. Berg | Canada | 50.45° N, 106.38° W | 3, 9, 36 | Cold | Croplands | Rowlandson et al,. 2015 |
12 | Carman* | 0901 | H. McNairn | Canada | 49.62° N, 97.98° W | 9, 36 | Cold | Croplands | McNairn et al., 2015 |
13 | Casselman* | 0902 | H. McNairn | Canada | 45.47° N, 74.73° W | 9 | Cold | Croplands | (Not available) |
14 | Tabasco | 3201 | J. Ramos | Mexico | 17.93° N, 92.84° W | (Not a core site) | Tropical | Croplands | (Not available) |
15 | Monte Buey* | 1902 | M. Thibeault | Argentina | 32.96° S, 62.52° W | 3, 9, 36 | Arid | Croplands | (Not available) |
16 | Bell Ville | 1901 | M. Thibeault | Argentina | 32.54° S, 62.61° W | 36 | Arid | Croplands | (Not available) |
17 | REMEDHUS* | 0301 | J. Martínez-Fernández | Spain | 41.3° N, 5.4° W | 9, 36 | Temperate | Croplands | Martinez-Fernandez and Ceballos, 2005 |
18 | Valencia* | 4101 | E. Lopez-Baeza | Spain | 39.57° N, 1.29° W | 3, 9 | Arid | Savannas woody | (Not available) |
19 | EURAC | 4401 | C. Notarnicola | Italy | 46.68° N, 10.59° E | (Not a core site) | Polar | Shrub open | Pasolli et al., 2015 |
20 | Twente* | 1204 | Z. Su | The Netherlands | 52.27° N, 6.67° E | 36 | Temperate | Cropland/natural mosaic | Dente et al., 2012 |
21 | TERENO | 0201 | C. Montzka | Germany | 50.5° N, 6.33° E | (Not a core site) | Temperate | Forest mixed | Zacharias et al., 2011 |
22 | HOAL | 0601 | M. Vreugdenhil/W. Dorigo | Austria | 48.2° N, 15.07° E | (Not a core site) | Temperate | Mixed forest | Blöschl et al., 2016 |
23 | Sodankyla | 1701 | J. Pulliainen | Finland | 67.37° N, 26.65° E | (Not a core site) | Cold | Savannas woody | Rautiainen et al., 2012; Ikonen et al,. 2016 |
24 | Saariselka | 1702 | J. Pulliainen | Finland | 67.97° N, 24.12° E | (Not a core site) | Cold | Savannas woody | (Not available) |
25 | Kuwait | 0501 | H. Jassar | Kuwait | 29.3° N, 47.33° E | (Not a core site) | Temperate | Barren/sparse | (Not available) |
26 | Mpala | 2401 | K. Caylor | Kenya | 0.49° N, 36.87° E | (Not a core site) | Temperate | Grasslands | (Not available) |
27 | Niger | 4501 |
B. Cappelaere/T. Pellarin |
Niger | 13.575° N, 2.663° E | (Not a core site) | Arid | Grasslands | Louvet et al., 2015 |
28 | Benin | 4502 |
S. Galle/ T. Pellarin |
Benin | 9.789° N, 1.679° E | (Not a core site) | Arid | Savannas | Louvet et al., 2015 |
29 | Ngari | 1203 | Z. Su | Tibet | 32.5° N, 79.97° E | (Not a core site) | Arid | Barren/sparse | Su et al., 2011; Su et al. 2013 |
30 | Naqu | 1201 | Z. Su | Tibet | 31.37° N, 91.88° E | (Not a core site) | Polar | Grasslands | Su et al., 2011; Su et al. 2013 |
31 | Maqu | 1202 | Z. Su | Tibet | 33.88° N,102.13° E | (Not a core site) | Cold | Grasslands | Su et al., 2011; Su et al. 2013 |
32 | Mongolian grasslands** | 5301 | J. Asanuma | Mongolia | n/a | 36 | Cold | Grasslands | Wen et al., 2014 |
33 | Yanco* | 0701 | J. Walker | Australia | 34.8° S, 146.11° E | 3, 9, 36 | Semi-Arid | Croplands/Grasslands | Panciera et al., 2014 |
34 | Kyeamba* | 0702 | J. Walker | Australia | 35.35° S, 147.52° E | 3, 9, 36 | Temperate | Grasslands | Smith et al., 2012 |
* Core site status at launch
** Core site status acquired after launch
I (Not a core site) = currently (Not a core site) at any scale (3, 9, or 36 km), but this may change in the future
II Koeppen-Geiger climate classification (Peel, et al., 2007)
II International Geosphere-Biosphere Programme (IGBP)
Spatial resolution for the in situ data is the same as the match-up SMAP data: 3, 9, and 36 km.
Approximate start and end dates are listed below. Note that not all files start or end on those exact dates, however.
Temporal resolution varies due to the coincidence of the in situ and SMAP data.
No special tools are required to view these data. Any word-processing program or Web browser will display the data.
For a detailed description of the SMAP instrument, visit the SMAP Instrument page at the JPL SMAP Web site. For the in situ data, investigators used various soil moisture and soil temperature probes.
The SMAP soil moisture data products in this data set are:
Information regarding SMAP data versions and CRIDs are provided in Table 1.
For information regarding algorithms and product specifications, refer to the Assessment Reports provided in Table 1.
As shown in Figure 2, in situ data provided by the Cal/Val partners goes through several processing steps before being matched with corresponding SMAP products.
The high level of automation in this process allows tracking the performance of the soil moisture products periodically and with low latency because repetitive, manual involvement is minimized. Match-up products are then used for validation and further development of SMAP algorithms. Refer to the Data Sources section above to access the SMAP ATBDs and other technical documentation.
Error sources are discussed in Jackson et al., 2016, Chan et al., 2016, and Colliander et al., 2017. SMAP retrieval algorithm uncertainties are discussed in the corresponding ATBD (O’Neill et al., 2015).
Information on quality assessment is provided in Jackson et al., 2016, Chan et al., 2016, and Colliander et al., 2017.
Andreas Colliander
Jet Propulsion Laboratory, California Institute of Technology
4800 Oak Grove Dr.
Pasadena, CA 91109
Carsten Montzka, Research Center Julich
Jose Martinez-Fernandez, University of Salamanca
Mark Seyfried, USDA Agriculture Research Service
Hala Al Jassar, Kuwait University
Wouter Dorigo, Technical University of Wien
Jeffrey Walker, Monash University
Mehrez Zribi, CNES
Heather McNairn, Agriculture and Agri-food Canada
Zhongbo Su, University of Twente
Michael Cosh, USDA Agriculture Research Service
Jouni Pulliainen, Finnish Meteorological Institute
Marc Thibeault, CONAE
Kelly Caylor, Princeton University
Mahta Moghaddam, University of Southern California
Marouane Temimi, City College of New York
Aaron Berg, University of Guelph
Judith Ramos Hernandez, National Autonomous University of Mexico
Ernesto Lopez-Baeza, University of Valencia
Claudia Notarnicola, European Academy of Bozen
Thierry Pellarin, University Joseph Fourier
Todd Caldwell, University of Texas Austin
February 2017
November 2018