SMAP L3 Radiometer Global and Northern Hemisphere Daily 36 km EASE-Grid Freeze/Thaw State, Version 2
Data set id:
SPL3FTP
DOI: 10.5067/YN94K53QM061
There is a more recent version of these data.
Version Summary
For the full major and minor version history, go to https://nsidc.org/data/smap/version-history
Version Summary
Changes to this version include:
- Implementation of a supplementary single-channel V-pol (SCV) algorithm
for areas of lower latitudes where the seasonal difference of the NPR algorithm is
too small to be effectively used to discriminate freeze/thaw state. This change
provides stronger flag agreement between Tair and Tsoil, and for ascending/p.m.
versus descending/a.m. overpasses due to physics (e.g. the NPR algorithm response to wet snow over frozen soil in spring). It also addresses an artifact of the validation approach (e.g. soils remain thawed for weeks after freeze onset in fall
due to insulation from snow). - With the addition of the new SCV algorithm to augment the NPR baseline
algorithm, spatial coverage of freeze/thaw data was extended to global. Data are
output on a fixed global 36 km EASE-Grid 2.0 and are provided in the Freeze_Thaw_Retrieval_Data_Global group. - Updated retrieval_quality_flag for water contamination/permanent
ice. - Implementation of false flag mitigation using TB screening and AMSR-E
weekly climatology maps, resulting in significantly fewer false flags.
For the full major and minor version history, go to https://nsidc.org/data/smap/version-history
Overview
This Level-3 (L3) product provides a daily composite of landscape freeze/thaw conditions retrieved by the Soil Moisture Active Passive (SMAP) radiometer from 6:00 a.m. descending and 6:00 p.m. ascending half-orbit passes. SMAP L-band brightness temperatures are used to derive freeze/thaw state and transition data, which are then resampled to both an Earth-fixed, Northern Hemisphere azimuthal 36 km Equal-Area Scalable Earth Grid (EASE-Grid 2.0), and to an Earth-fixed global 36 km EASE-Grid 2.0.
Parameter(s):
BRIGHTNESS TEMPERATUREFREEZE/THAWTRANSITION DIRECTION
Platform(s):
SMAP
Sensor(s):
SMAP L-BAND RADIOMETER
Data Format(s):
HDF5
Temporal Coverage:
31 March 2015 to 27 August 2020
Temporal Resolution:
- 1 day
Spatial Resolution:
- 36 km
- 36 km
Spatial Reference System(s):
WGS 84 / NSIDC EASE-Grid 2.0 North
EPSG:6931
WGS 84 / NSIDC EASE-Grid 2.0 Global
EPSG:6933
Spatial Coverage:
N:
85.044
S:
45
E:
180
W:
-180
N:
85.044
S:
-85.044
E:
180
W:
-180
Blue outlined yellow areas on the map below indicate the spatial coverage for this data set.
Data Access & Tools
This data set has been retired. There is a more recent version of these data.
Documentation
User Guide
ATBDs
General Resources
Quality Assessment Reports
Product Specification Documents
Help Articles
General Questions & FAQs
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How to Articles
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NASA's Global Imagery Browse Services (GIBS) provides up to date, full resolution imagery for selected NSIDC DAAC data sets.