The Global Earth Observation System of Systems (GEOSS) and metrological support for measuring radiometric properties of objects of observations

Abstract

The international Global Earth Observation System of Systems is at its initial stage. We present some general information about the program and formulate the task of ensuring the uniformity of radiometric measurements to be conducted by all the participating national systems. Methods of solving the task are suggested on the basis of the wide application of standard sources that use phase transition of eutectic alloys and pure metals as well as with the help of improved ground calibration facilities.

Low-Temperature Blackbodies for IR Calibrations in a Medium-Background Environment

“…To meet the requirements for reproducibility and admissible uncertainty of measurements for the reference radiometric equipment used for the calibration of space-born radiometric instruments, it became necessary to develop low-temperature fixed points in the temperature range from 10.5 • C to 30 • C based on the phase transition of single-component substances, e.g., Ga, and inter-metallic eutectic alloys such as GaInSn, GaIn, GaSn, GaZn, and GaAl [1,2]. Fixed points are widely studied and used for ground-based thermometry and radiometry, and they possess potentially unique reproducibility of radiometric characteristics ensuing from the repeatability of the phasetransition temperature in itself.…”

“…The influence of external forces from bringing the spaceship onto orbit as well as from the factors of space flight make it necessary to ensure the constancy of the characteristics of the equipment; the use of phase transitions of single-component substances and eutectic alloys has been investigated for this purpose. Within the temperature range from 300 K to 450 K, reference temperatures can be provided by the single-component metals Ga and In and various eutectic alloys based on these metals [1,2], e.g., GaInSn (melting temperature about 10. The widening of the temperature interval between fixed points increases the accuracy of calibrations.…”

“…VNIIOFI has gained experience in prelaunch testing of the metrological characteristics of low-temperature fixed-point alloys based on Ga [1,2]. Five promising lowtemperature fixed points for application in IR preflight calibrations -Ga (302.9146 K), and the eutectics GaIn (288.806 K), GaSn (293.662 K), GaZn (298.42 K), and GaAl (300.08 K) have been investigated.…”

“…The solution of many important problems of space technology, space and astrophysical research, ecology, reliable weather prediction, and the monitoring of climatic changes on the Earth are directly connected with ensuring the uniformity of measurements in the framework of the Global Earth Observation System (GEOSS) by means of a unified radiometric scale [1]. The accuracy of measurements (e.g., the temperature of the ocean surface) required for monitoring and predicting climatic changes is 0.1 K. Hence, there are high demands on the accuracy of the preflight and in-flight radiometric calibration of the space-borne instruments, particularly within the IR range of wavelengths [2].…”

Predicting Air Quality: Current Status and Future Directions

“…These aspects are being explored in projects such as the European Union Global and regional Earth-system (Atmosphere) Monitoring using Satellite and in-situ data (GEMS) project. The integration of enhanced observing systems with modeling tools for use in air quality and climate change is a priority area within the Global Earth Observing System of Systems (GEOSS) [64] and the Integrated Global Atmospheric Chemistry Observations (IGACO) frameworks. IGACO is a highly focused strategy for bringing together ground-based, aircraft and satellite observations using atmospheric forecast models that assimilate not only meteorological observations but also chemical constituents.…”