Metrological support for climatic time series of satellite radiometric data

Abstract

A necessary condition for accumulating fundamental climate data records is the use of observation instruments whose stability and accuracy are sufficiently high for climate monitoring purposes; the number of instruments and their distribution in space should be sufficient for measurements with no spatial or temporal gaps. The continuous acquirement of data over time intervals of several decades can only be possible under the condition of simultaneous application of instruments produced by different manufacturers and installed on different platforms belonging to one or several countries.The design of standard sources for pre-flight calibrations and in-flight monitoring of instruments has to meet the most stringent requirements for the accuracy of absolute radiometric measurements and stability of all instruments. This means that the radiometric scales should be stable, accurate, and uniform.Current technologies cannot ensure the high requirements for stability and compatibility of radiometric scales: 0.1% per decade within the 0.3 -3 µm band and 0.01 K per decade within the 3 -25 µm band.It is suggested that this task can be aided through the use of the pure metals or eutectic alloy phase transition phenomenon that always occur at the same temperature. Such devices can be used for pre-flight calibrations and for on-board monitoring of the stability of radiometric instruments. Results of previous studies of blackbody models that incorporate phase transition phenomenon are quite promising. A study of the phase transition of some materials in small cells was conducted for future application in onboard monitoring devices and its results are positive and allow us to begin preparations for similar experiments in space.

Observational study: microgravity testing of a phase-change reference on the International Space Station

“…4,5 The purpose of these studies was to significantly reduce the size and volume of qualified containers and identify PCMs within the range of 273-303 K that could be used as calibration standards aboard Earth-observing satellites. This study was successful in identifying and characterizing several suitable eutectics to fill the gap in the ITS-90 temperature scale between the triple point of water and the melting point of Ga. SDL has continued research to further reduce the size and minimize volume of PCMs for an orbital thermal reference cell.…”

Framework for preparing and performing absolute radiometric measurements using electrooptical instruments for the earth observations

“…The stability of the EOI radiometric characteristics should be periodically controlled and the uncertainty of the achieved results should be presented (Sapritsky et al, 2009;Panfilov et al, 2010) as standard proce dures when EOIs are exploited. If the primary stan dard is traced in this case, this procedure can be inter preted as EOI verification (calibration), which should be reflected in the EOI standard documentation.…”

Spaceborne radiance temperature standard blackbody for Chinese high-precision infrared spectrometer

“…Long-term drift error severely affects the observation accuracy and effective observation lifetime of satellites. Therefore, establishing an accurate long-term climate record for trend monitoring and prediction is difficult [19,20]. To meet the urgent requirement of remote sensing quantitative application and climate change research, the infrared payload detection quantification and radiation measurement stability need improvement.…”