JPL SMAP Level 2B CAP V5.0 provides validated sea surface salinity and extreme wind data from NASA's Soil Moisture Active Passive observatory. Data is available globally with a 6-hour latency, covering one 98-minute orbit per file starting from April 1, 2015. The dataset is produced by NASA's Jet Propulsion Laboratory using the Combined Active-Passive retrieval algorithm applied to SMAP's L-band radiometer measurements.
Use Cases
- Model global ocean salinity patterns using derived sea surface salinity (SSS) and ancillary reference surface salinity fields.
- Analyze correlations between extreme wind events and salinity by joining SSS data with wind speed/direction parameters.
- Validate satellite retrieval algorithms by comparing brightness temperatures for each radiometer polarization against in-situ measurements.
- Assess data quality and filter observations using provided quality flags and uncertainty metrics for sea surface salinity.
- Study surface roughness effects on salinity retrieval by incorporating collocated wind speed data for surface roughness correction.
Strengths
- Global observational coverage achieved approximately every 3 days due to a 1000km swath.
- Data has a near real-time latency of about 6 hours from observation to availability.
- Uses an enhanced calibration methodology for brightness temperatures, improving radiometric calibration and reducing biases between orbital passes.
- Provides data at a 25km swath grid with an approximate spatial resolution of 60 km.
Limitations
- Spatial resolution of approximately 60 km may be too coarse for studying small-scale oceanographic features.
- Relies on collocated wind speed data for surface roughness correction due to the malfunction of the SMAP scatterometer on July 7, 2015.
- The exact orbit repeat cycle is 8 days, which may limit temporal resolution for some high-frequency processes.
Provenance
- Source
- NASA Jet Propulsion Laboratory (JPL) / Soil Moisture Active Passive (SMAP) observatory.
- Collection Method
- Satellite remote sensing via SMAP's L-band radiometer (1.41GHz), processed with the JPL Combined Active-Passive (CAP) retrieval algorithm.
- Time Range
- April 1, 2015 to present (ongoing).
- Freshness
- Ongoing data stream with 6-hour latency.
- Geography
- Global.