There are different data products associated with the levels of altimeter data processing:
Level-1A products contain geo-located bursts of Ku echoes (at ~9 kHz) with all calibrations
applied: these are the full rate complex waveforms, which are the starting point
for the (SAR) high resolution processing.
Poseidon-4 L1a, L1b and L2 products will be available to the general public. AMR-C products will be made available by NASA-JPL.
The P-4/MWR files are collected into a SAFE container. Level-1 and 2 products will be encapsulated in free-standing netCDF 4 product files.
Based on the synthesis of the operational applications, the following product services are identified. These services will be accompanied by a user support service to allow user registration, provision of mission information and support to data product access.
ALT-NRT Altimetry Near Real-Time
The Near Real-Time altimetry (ALT-NRT) product service delivers Level-2 products within 3 hours of sensing. This service requires dissemination to NWP centres and is mainly used for marine meteorology, air-sea interaction studies and real time operational oceanography. The main objective of the ALT-NRT product service is to provide information on the sea state, e.g. significant wave height and wind speed but also on sea surface height.
ALT-STC Altimetry Short Time-Critical
The Short Time-Critical altimetry (ALT-STC) product service delivers Level-2 products within 36 hours of sensing, which enables consolidation of some auxiliary data (e.g. preliminary restituted orbit data). Products are mainly used for operational oceanography and geophysical studies. The main objective of the ALT-STC product service is to support operational oceanography i.e. improved ocean state analysis, forecasts and hindcasts produced by Numerical Ocean Prediction (NOP) systems assimilating Sea Surface Height (SSH) measurements derived from a multi-mission constellation of spaceborne altimeters. This objective is further supported by the delivery of Level 3 products.
ALT-NTC Altimetry Non-Time-Critical
The Non-Time-Critical altimetry (ALT-NTC) product service delivers Level-2 products within 60 days of sensing, this additional delay allowing the further consolidation of some auxiliary data (e.g. precise orbit data, radiometer calibration) leading to higher accuracy of SSH products. The main objective of the ALT-NTC product service is to provide information on ocean topography and mean sea level in support of ocean and climate monitoring services.
RO-NRT Radio Occultation
The Near-Real-Time Radio Occultation (RO-NRT) product service delivers Level-1b and Level-2 products less than 3 hours after sensing, for direct assimilation into NWP models. The main objective of the RO-NRT product service is to provide bending angles or refractivity profiles, which contain information on atmospheric temperature, pressure, and humidity, for assimilation by NWP models. Further examples of RO-NRT Level-2 products are tropopause height, planetary boundary layer height and ionospheric information (gravity wave information is also being discussed).
RO-NTC The Non-Time-Critical Radio Occultation (RO-NTC) product service delivers Level-1b and Level 2 products within 60 days of sensing. This additional delay allows using longer time series of the instrument to obtain improved precise orbit/clock data, as well as to use updated auxiliary data (e.g. precise orbit/clock data of GNSS satellites). The main objective of the RO-NTC is to deliver the same products as the RO-NRT service but with higher precision, making this service particularly valuable for climate studies, including assimilation in re-analysis models.