Direct Dissemination is the delivery of data, products and services to a user reception station, transmitted directly from the Metop satellites.
Metop Direct READOUT
The Metop Direct Readout Service provides local user stations with real-time transmission of data, limited to the instantaneous sub-satellite observation.
The data source is the satellite as it passes over the user's field of view. Readout of all instrument data can be achieved via Advanced High Resolution Picture Transmission (AHRPT).
The NOAA direct readout HRPT system provides data from all NOAA-K,L,M,N spacecraft instruments. For further information on this service contact NOAA.
Metop-B provides a full, global Direct Readout Service. Due to an earlier failure of the Metop-A AHRPT side A, the Metop Direct Readout Service no longer supports full global coverage.
In the case of Metop-A, to minimise the risk of failure to the AHRPT-B unit, while still offering the user community a service, EUMETSAT implemented a 'partial' AHRPT service in those areas where the risk of damage from heavy ion radiation is reduced. For southbound passes, AHRPT side B is activated for all orbits over the North Atlantic and European area, starting at around 60°N. The AHRPT is then switched off before the spacecraft reaches the Southern Atlantic Anomaly region at around 10°N.
AHRPT operations are made in ascending orbits, but with more stringent risk reduction measures than applied for the descending passes given the availability of data via the Fast Dump Extract System (FDES) to cover the North Hemisphere. The same operational restrictions still apply over the polar caps and South Atlantic Anomaly.
TD 18 — Metop Direct Readout AHRPT Technical Description (PDF, 777 KB)
Multi-Mission Administrative Message (MMAM)
Users wishing to know the daily switch-on and off times of AHRPT and other spacecraft status information should consult the Metop Multi-MIssion Administrative Message. For help read the Multi-Mission Administrative Message User Guide (PDF, 714 KB)
AHRPT data is disseminated in L-Band, with a data rate of 3.5 Mbps. Local data coverage is of a radius of up to 1500 km.
Users operating existing HRPT stations will have to modify their stations in order to receive the 'Advanced' Metop data. The adaptations, whose feasibility and scope depend upon the design of the existing station, will mainly require a modification of the receiver and the processing software. For further information on station equipment consult a manufacturer.
Under nominal operations the Metop Direct Readout data are openly available to all users within the service footprint. For information on access during periods of Data Denial users should consult the Data Denial User Guide (PDF, 110 KB).
Key Dissemination System
The Metop Direct Readout Key Dissemination System (KDS) is designed to provide registered users in possession of Metop Station Key Units (SKU) with access to their Public Keys. Valid Public Keys are necessary for the operation of the SKU during periods of Metop data encryption. Access the Key Dissemination System.
For help with using the KDS, please see the User Guide for the EPS EEIS Key Dissemination System (PDF, 60 KB).
Local Processing Software and Tools
Data received by the Direct Readout station can be processed further. The following local processing software is available under licence from the NWP-SAF:
|Software name||Description||Software Supplier/More information|
|AAPP||ATOVS and AVHRR Pre-processing Package (AAPP) performs the end-to-end processing of Sounding and Imager data from the AHRPT/HRPT direct readout data stream.||SAF on Numerical Weather Prediction|
|RTTOVS||Radiative Transfer for TOVS (RTTOVS) is a very fast radiative transfer model for nadir viewing passive infrared and microwave satellite radiometers, spectrometers and interferometers.||SAF on Numerical Weather Prediction|