October 6, 2014


Data Processing Flow

The SMOS data processing flow is illustrated and explained in the diagram below.

data processing

Raw Data

These are SMOS Payload data in their original format (CCSDS packets) comprised of instrument observation data and housekeeping telemetry, as received from the satellite.

Level 0 Data Products

These are SMOS Payload data in so-called Source Packets with added Earth Explorer product headers. They are chronologically sorted by Source Packet type : Observation Data and Housekeeping Telemetry.

Level 1A Data Products

These are the SMOS reformatted and calibrated Observation and Housekeeping data in engineering units. Level 1A products are physically consolidated in pole-to-pole time-based segments. Scientific SMOS Level 1A products are the so-called "Calibrated Visibilities".

Level 1B Data Products

The SMOS Level 1B products are the output of the image reconstruction of the SMOS observation measurements and consist of [no-lexicon]geo[/no-lexicon]-located vectors of Brightness Temperatures in the antenna polarisation reference frame.

Level 1C Data Products

Since Level 1B products are arranged as snapshots and not geographically sorted, SMOS Level 1C products constitute reprocessed Level 1B, which are geographically sorted, that is swath-based maps of Brightness Temperature.

Level 2 Data Products

Level 2 OS and SM products are geo-located geophysical products with all the calibration applied and with neither spatial nor temporal averaging. An inversion algorithm is applied to the set of the brightness temperatures from L1C. L2 OS and SM products keep the resolution of L1C. Level 2 products are of two separate types:

  • Soil Moisture swath-based maps
  • Ocean Salinity swath-based maps

Level 3 Data Products

L3 corresponds to re-sampled and temporally accumulated data. L3 is computed from L1B data via spatial and temporal aggregation and improvement for taking into account the instrument errors (calibration). L3 is based on more auxiliary data (and more consolidated auxiliary data) than L2 data as it has less operational constraints. There are at the present two basic products identified. It is quite sure that the level 3 will comprise other outputs such as daily temporal evolution over an area (land), or different spatio-temporal averaging over oceans etc...

  • Soil Moisture swath-based maps
  • Ocean Salinity swath-based maps

Level 4 Data Products

The list of potential L4 products is still open. Here after is a list of possible products:

  • Assimilation of SM fields to estimate root zone soil moisture for applications in meteorology and water resources management
  • Merge with optical data to use in SVATS for carbon cycle studies and flux assessment (latent and sensible), use in vegetation growth models etc...
  • Statistical analysis of SM temporal evolution for climate studies, for assessing precipitations, detecting anomalies (floods, droughts, freeze, snow?)
  • Produce regional maps and dis-aggregate over basins
  • Maps of rainfall affected areas (semi arid environment)?
  • Merge of AQUARIUS (HYDROS) and SMOS data and produce finer products if possible
  • Assimilate SSS in Ocean Circulation Models (Mercator like)
  • Use SSS for monitoring ENSO and NAO
  • Fire risks
  • ...