DIFFERENCE OF ATMOSPHERIC XCO2 CONCENTRATION SENSITIVITY OBSERVED BY SCIAMACHY,GOSAT AND OCO-2

Hits: 71
Research areas:
Year:
2017
Type of Publication:
Article
Keywords:
SCIAMACHY,GOSAT, OCO-2, XCO2, sensitivity
Authors:
Changjiang Wu, Zhonghua He Nian Bie
Abstract:
Currently satellite instruments including the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), the Greenhouse gases Observing Satellite (GOSAT) and Orbiting Carbon Observatory-2(OCO-2) have been sent into space to measure CO2 column-averaged dry air mole fractions (XCO2). Temporal and spatial differences exists among retrieved XCO2 products derived from these instruments for many reasons including different averaging kernels, which indicates the altitude sensitivity of satellites in retrieving XCO2. This paper converts the level 2(L2)XCO2 observations of the SCIAMACHY Bremen optimal estimation (BESD), the GOSAT Atmospheric CO2 Observations from Space (ACOS) and the OCO-2 to a common prior CO2 profile (25 levels) by using the a prior CO2 profile of Carbon Tracker, which can correct the difference between these XCO2 observations caused by different response characteristics of sensors. By analyzing theses difference between the adjusted and original XCO2 data, we find that, data from SCIAMACHY presents a significant seasonal cycle with apeak-to-peak amplitude of approximately 0.8 ppm ranging from -0.6 to 0.2 ppm. The differences derived from SCIAMACHY XCO2 data are typically larger than those from other two satellite data sets, with the maximum and minimumoccurring in June and December,respectively, which corresponds well to the seasonal variation of CO2 absorption caused by vegetation activity in terrestrial ecosystems; the difference for GOSATalso shows seasonal variation with its amplitude(0.2 ppm)much lower than that of differencesfor SCIAMACHY; the differences for OCO-2 are always less than 0.05 ppm and presents little temporal variation. Therefore, the OCO-2 data performs better than the other two satellite product in sensitivity to the a priori CO2 profiles. This corrected method proposed in this paper can eliminate up to 1 ppm difference between SCIAMACHY-BESD-XCO2 and GOSAT-ACOS-XCO2.
Full text: 173.pdf [Bibtex]
You are here: Home ACRS ACRS Overview Proceedings difference-of-atmospheric-xco2-concentration-sensitivity-observed-by-sciamachy-gosat-and-oco-2