Optimization of the OCO-2 Cloud Screening Algorithm and Evaluation against MODIS and TCCON Measurements over Land Surfaces in Europe and Japan

Retrieved XCO2 Accuracy Improvement by Reducing Aerosol-Induced Bias for China’s Future High-Precision Greenhouse Gases Monitoring Satellite Mission

“…As for the cloud fraction over land surface in Europe in 2016, Chen et al found that the highest clear-sky fraction occurs in summer (55.1%), while the lowest occurs in winter (29.5%). The spring and fall have close values, which are 39.3% and 40.0%, respectively [6]. In winter, the Bialystok site has the lowest N DA because of its lower solar radiance located at high latitude.…”

“…∆rm = median|(rband,755 − rband,532)/rband,532 × 100%|. (6) rband means the radiance spectrum distributed from 6300 to 6400 cm −1 . The symbol of median || means calculating the median of radiance changes.…”

“…For example, it is easy to misestimate the influence on the upper atmospheric structure due to the lack of the ability to distinguish the upper layer (stratospheric) thin clouds and aerosols essentially. The data shows about a 20% deviation between cloud screen products from OCO-2 and cloud mask products from the Moderate Resolution Imaging Spectrometer (MODIS) [6]. The clouds and aerosols located at higher altitudes, such as stratospheric sulfate from volcanic eruptions, could cause larger XCO 2 bias (100 ppm) even with a small optical depth (such as AOD < 0.3) [7,18].…”

“…These two payloads make HGMS capable of simultaneous observation for CO 2 and aerosol information [5]. Since the influence of aerosols on XCO 2 retrieval is a recognized major issue [6][7][8][9][10], the simultaneous observation of XCO 2 and aerosols of HGMS will help estimate and correct the aerosol scattering effect on XCO 2 retrievals, which will significantly improve the accuracy of global XCO 2 measurements.…”