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SMOS Level 1 data products are designed for scientific and operational users who need to work with calibrated MIRAS instrument measurements, while SMOS Level 2 data products are designed for scientific and operational users who need to work with geo-located soil moisture and sea surface salinity estimation as retrieved from the L1 dataset.

Products from the SMOS Data Processing Ground Segment (DPGS) located at the European Space Astronomy Centre (ESAC), belonging to the latest processing baseline, have File Class OPER. Reprocessed SMOS data is tagged as REPR.

The Level 1A product comprises all calibrated visibilities between receivers (i.e. the interferometric measurements from the sensor including the redundant visibilities), combined per integration time of 1.2s (snapshot). The snapshots are consolidated in a pole-to-pole product file (50 minutes of sensing time) with a maximum size of about 215MB per half orbit (29 half orbits per day). Access to this products is restricted to SMOS Cal/Val users.

The Level 1B product comprises the result of the image reconstruction algorithm applied to the L1A data. As a result, the reconstructed image at L1B is simply the difference between the sensed scene by the sensor and the artificial scene. The brightness temperature image is available in its Fourier component in the antenna polarisation reference frame top of the atmosphere. Images are combined per integration time of 1.2 seconds (snapshot). The removal of foreign sources (Galactic, Direct Sun, Moon) is also included in the reconstruction. Snapshot consolidation is as per L1A, with a maximum product size of about 115MB per half orbit.

ESA provides the Artificial Scene Library (ASL) to add the artificial scene in L1B for any user that wants to start from L1B products and derive the sensed scene.

The Level 1C product contains multi-angular brightness temperatures in antenna frame (X-pol, Y-pol, T3 and T4) at the top of the atmosphere, geo-located in an equal-area grid system (ISEA 4H9 - Icosahedral Snyder Equal Area projection). The pixels are consolidated in a pole-to-pole product file (50 minutes of sensing time), with a maximum size of about 350MB per half orbit (29 half orbits per day). Spatial resolution is in the range of 30-50 km. For each L1C product there is also a corresponding Browse product containing brightness temperatures interpolated for an incidence angle of 42.5°. Two L1C products are available: Land for soil moisture retrieval and Sea for sea surface salinity retrieval.

The Level 2 Soil Moisture (SM) product comprises soil moisture measurements geo-located in an equal-area grid system ISEA 4H9. The product contains not only the retrieved soil moisture, but also a series of ancillary data derived from the processing (nadir optical thickness, surface temperature, roughness parameter, dielectric constant and brightness temperature retrieved at top of atmosphere and on the surface) with the corresponding uncertainties. The pixels are consolidated in a pole-to-pole product file (50 minutes of sensing time), with a maximum size of about 7MB (25MB uncompressed data) per half orbit (29 half orbits per day). This product is available in both Earth Explorer and NetCDF formats.

The Level 2 Ocean Salinity (OS) product comprises sea surface salinity measurements geo-located in an equal-area grid system ISEA 4H9. The product contains one single swath-based sea surface salinity retrieved with and without Land-Sea contamination correction, SSS anomaly based on WOA-2009 referred to Land-Sea corrected sea surface salinity, brightness temperature at the top of the atmosphere and at the sea surface with their corresponding uncertainties. The pixels are consolidated in a pole-to-pole product file (50 minutes of sensing time), with a maximum size of about 10MB (25MB uncompressed data) per half orbit (29 half orbits per day). This product is available in both Earth Explorer and NetCDF formats.

For an optimal exploitation of the SMOS L1 and L2 datasets, please refer to the Resources section below in order to access Product Specifications, read-me-first notes, etc.