Which Salinity Data are Best for You?
SMAP SSS Products Overview
| SMAP | ||
|---|---|---|
| RSS (V4) | JPL* (4.3) | |
| Antenna type | Spinning; 99% reflective (1% emissive) | |
| Global coverage / Repeat orbit | 3 days / 8 days (exact) | |
Data products available:
|
L2C: Standard L3: 8-day Running Mean; Monthly |
L2B: Standard; Near-real-time (6 hours) L3: 8-day Running Mean, Monthly |
| Gridding | 0.25° x 0.25° | 0.25° x 0.25° |
| Feature resolution | 70 km** | ~60 km** |
- * JPL's SMAP SSS data set is also referred to as the "Combined Active Passive (CAP)" product.
- ** SMAP's native 40-km variable is relatively noisy. As a result, SMAP products are spatially averaged to larger footprints (i.e., 70 km, 60 km) to reduce data noise, especially for open ocean applications.
SMAP Ancillary Data Sources
| RSS (V4) | JPL (4.3) | |
|---|---|---|
| SST | GHRSST Level 4 from Canadian Meteorological Center [CMC] | NOAA Optimum Interpolation [OI] |
| Atmospheric profile fields | NCEP GDAS 1-deg, 6-hour fields [GDAS] | N/A |
| Solar flux | Ancillary mean solar flux from NOAA Space Weather Prediction Center [SWPC] | N/A |
| Wind speed & direction | CCMP V2 [CCMP] | National Centers for Environmental Prediction Global Forecast System [GFS] |
| Land mask | ODPS static 1-km land/water mask from GSFC [ODPS] | US Geological Survey 30-second Land Use Data [USGS] integrated using SMAP antenna patterns |
| Rain | IMERG | Rain effect and rain roughness corrections are in development |
| Dielectric constant | Meissner and Wentz 2004, 2012 | Meissner and Wentz 2004, 2012 |
| Galactic map | Dinnat, E.; Le Vine, D.; Abraham, S.; Floury, N. Map of Sky Background Brightness Temperature at L-Band (2018) | Own derived galaxy correction (3.2.2 of User Guide) |
| Total electron content (TEC) | IGS IONEX TEC files [TEC] | N/A |
| Sea ice fraction | RSS Version 8 AMSR-2 ocean suite (Wentz et al., 2014) [RSS] | National Centers for Environmental Prediction [NCEP] |
| Argo salinity from Scripps Institution of Oceanography (SIO) | Included to facilitate comparison of rain-filtered SMAP SSS; not used in the actual salinity algorithm [SIO] | Used for comparison but not included in data files. |
| Reference salinity field | Hybrid Coordinate Ocean Model [HYCOM] | Hybrid Coordinate Ocean Model [HYCOM] |
| Significant wave height | N/A | NOAA WaveWatch III [WaveWatch III] |
Level-3 Gridded Products
An interactive, web-based tool to generate informative maps, animations, and plots that communicate and promote the discovery and analysis of the State Of The Oceans (SOTO). SOTO is a suite of tools presented through an interactive, web-based visualization front end. It provides access to a broad range of satellite-derived products and key parameters of interest to the oceanographic community. SOTO facilitates visual exploration and comparative analysis of physical oceanographic data, enabling your research.
The "+ ADD MORE" button can be used to activate sea surface salinity (SSS) data layers:
- SAC-D/Aquarius
- SMAP JPL
- SMAP JPL
Characteristics of layers can be updated:
- Repositioned (e.g., 1 is at top, 2 is just below, etc.)
- Toggled On/Off
- Changed in terms of opacity (i.e., to see multiple layers simultaneously)
Live Access Server (LAS) is a web-based Level-3 (L3) data visualization and subsetting tool, designed to provide flexible access to geo-referenced scientific data. It enables users to: visualize data with on-the-fly graphics; request custom subsets of variables in a choice of file formats; access background reference material about the data (metadata); compare (difference) variables from distributed locations.
The "Data Set" button can be used to access the following datasets (SSS data are marked by asterisks, *):
- SAC-D/Aquarius (16 data products)
- SMAP RSS (2 data products) with the following options
- Ancillary sea surface temperature
- Average land fraction (weighted by antenna gain)
- Average land fraction within 3dB contour
- Average sea ice fraction (weighted by antenna gain)
- Number of observations for L3 average of SSS at 40km resolution
- Number of observations for L3 average of SSS smoothed to approx. 70km resolution
- Reference sea surface salinity from HYCOM
- *SMAP sea surface salinity at original 40km resolution
- *SMAP sea surface salinity smoothed to approx. 70km resolution
- Characteristics of layers can be updated:
- Repositioned (e.g., 1 is at top, 2 is just below, etc.)
- Toggled On/Off
- Changed in terms of opacity (i.e., to see multiple layers simultaneously)
NOTE: To see changes to updates to data sets, map type, date, etc., click the "Update Plot" button at upper left.
A tutorial for using LAS with Aquarius salinity datasets is provided on YouTube.
Level-2 Swath Products
- SAC-D/Aquarius
- SMAP RSS