Working with CM SAF Data

CDRs provided by CM SAF
The CM SAF provides satellite-derived climate data records (CDRs), which fulfil stringent requirements concerning quality, length, consistency, and continuity. This makes the CDRs highly suitable for various climate applications. CDRs are used to support observations of the Earth system, such as studies of climate trends and variability and model verification to help improve climate models.

The CM SAF generates the following types of CDRs:

• Fundamental Climate Data Records (FCDR) are long-term satellite data records that involve a series of instruments, with potentially changing measurement approaches, but with overlaps and sufficient calibration to allow the generation of homogeneous products providing a measure of the independent variable that is accurate and stable enough for climate monitoring. FCDRs include the ancillary data used to calibrate them.
• Thematic Climate Data Records (TCDR) are geophysical variables derived from the FCDRs, specific to various disciplines, and often generated by blending satellite observations, in situ data, and model output.
• Interim Climate Data Records (ICDR) denote regular extensions of TCDRs with shorter time latency, and with algorithms and processing systems as consistent as possible to the generation of the reference TCDRs. An ICDR is usually based on the latest available inter-calibration and requires a different validation approach.
• Environmental Data Records (EDR) are time-tagged geo-located geophysical parameters produced from the sensor data. EDRs are derived in low to medium latency, not fulfilling strictest climate application requirements.

Satellite-based Climate Data Records produced by CM SAF Source: CM SAF

Working with CM SAF Climate Data
Depending on its characteristics, each kind of CDR has its own fields of application. A TCDR is the basis for all climate analysis and monitoring applications. As the TCDR holds the geophysical variables derived from a calibrated and homogenous FCDR, it can be used to study climate trends and variability. An ICDR is excellently suited to analyse the state of a parameter for instance for the last year, months or days. In addition, ICDR and TCDR data can be used together for climate analysis. For example, users can create an anomaly by subtracting the long-term mean of a specific month (based on TCDR) from the recent data of that month (based on ICDR), such as August 2020 minus mean (August 1983 to 2017). Since the ICDR is using the same retrieval algorithm as the corresponding TCDR the combination of both is suited for climate monitoring.

To work with the data, CM SAF provides the CM SAF R Toolbox, which is an easy-to-use tool to prepare, analyse and visualise CM SAF data. The Toolbox comes as part of the cmsaf R-package and offers a collection of more than 60 functions for analysis and manipulation of CM SAF NetCDF formatted data. The CM SAF R Toolbox is using a graphical user interface, which guides through all options. Thus, it requires no R or scripting experience. For further details, see the CM SAF R Tools website.

Overview of the functionality of the CM SAF R Toolbox Source: CM SAF

An example workflow would be to retrieve the latest CM SAF ICDR data via the CM SAF Web User Interface (a standing order set up is possible) or via EUMETCast, download the corresponding TCDR data once via the CM SAF Web User Interface, and analyse the data using the CM SAF R Toolbox. The TCDR data serve as reference to analyse the deviation from the climatological mean. This allows an easy creation of anomaly maps.

The combination of TCDR and ICDR data offers many possibilities for climate monitoring. Source: CM SAF

SK / July2021