The 'Long Term Stability of the ATSR Instrument Series: SWIR Calibration, Cloud Masking and SAA' project, commonly known as the ATSR Long Term Stability (or ALTS) project is designed to explore new and innovative ways of enhancing the (A)ATSR data set, making use of the complete time-series from ATSR-1, ATSR-2 and AATSR and contributing to the preservation and improved understanding of this valuable data set within the frame of the Long Term Data Preservation (LTDP) programme.
The main areas of investigation in Phase 1 (July 2013 to June 2015) have been:
This work is being undertaken under ESA Contract No. 4000108531/13/I-NB
ATSR Document Retrieval
The curation of mission documentation has gained significant interest from numerous user communities and space agencies in recent years. This interest follows growing concerns that historic missions are now threatened by the permanent loss of invaluable information/knowledge that once proved fundamental to a missions' success and evolution (e.g. ATSR-1, ATSR-2 and AATSR).
The ATSR Quality Working Group (QWG) has expressed their concerns for the early ATSR missions as they begin to face a number of obstacles (e.g. the retirement of key personnel, the scatter of documentation across numerous locations/sites, the physical decay of documentation and the reading of old digital formats) that could threaten future ATSR curation and exploitation activities. As a result, ESA are supporting this new work package within the ALTS project that will investigate appropriate ATSR documentation retrieval and archiving strategies.
It is hoped that the successful implementation of these strategies will not only allow for the effective curation of ATSR documentation as well as the enhancement of the existing (A)ATSR data set (even though two decades has passed since the ending of ATSR-1 operations) but also, pave the way for similar curation activities for other ESA missions in the future.
Please do not hesitate to get in touch should you have any queries or questions regarding this particular work package, or if you have any information that you believe would be of value to the project. The ALTS team can be contacted at the following: firstname.lastname@example.org or Hannah.email@example.com.
AIRWAVE is based on the accurate knowledge of the instrument's physical characteristics, such as the spectral filter functions, in combination with advanced radiative transfer models and the sea surface spectral emissivity database produced by the University of Edinburgh. The retrievals, therefore, do not require algorithm tuning or adjustments to independent water vapour data sets. Additionally, AIRWAVE can be readily extended to the upcoming SLSTR instrument on the Sentinel-3 satellite series.
The atmospheric TCWV is retrieved at the spatial resolution of the ATSR Level 1 products, i.e. around 1 km2 for specific studies on restricted areas, and at a coarser resolution (0.25°x0.25°) for long term data analysis on global scale.
One of the main features of AIRWAVE is the enhanced sensitivity to ATSR radiometric calibration. This implies that any possible drift affecting the ATSR instruments will be significantly affecting the retrieved TCWV too. Far from being a drawback, this extreme sensitivity will be extremely useful for the assessment of the calibration of the ATSRs for the current and future calibration correction schemes.
Preliminary inter-comparisons with the SSM/I and ERA-Interim TCWV products have been carried out for a set of test cases. The initial results show that the AIRWAVE data at coarse resolutions have no bias and a precision of 4% for the ATSR-2 and AATSR instruments and 15% for the ATSR-1 instrument.
The next phase of the ALTS project will include:
Some examples of AIRWAVE products are shown in this section.