The spectra of O_2 A-band(0.76 μm) and CO_2 near-infrared emissions(1.6 μm) are simulated by the SCIATRAN radiative transfer model(V3.1.23), and compared with those observed by GOSAT-FTS(Greenhouse gases Observing S...The spectra of O_2 A-band(0.76 μm) and CO_2 near-infrared emissions(1.6 μm) are simulated by the SCIATRAN radiative transfer model(V3.1.23), and compared with those observed by GOSAT-FTS(Greenhouse gases Observing SATellite-Fourier Transform Spectrometer). Systematic deviations between the observed and simulated spectra are found to exist,especially for the O_2 A-band. The discrepancies are characterized by their mean differences averaged over the observed spectral ranges. A correction is applied to the observed GOSAT-FTS L1B(V141.141) spectra by scaling the spectral intensity measured by TANSO-FTS(Thermal and Near infrared Sensor for carbon Observation Fourier Transform Spectrometer) onboard GOSAT.The average columnar CO_2 concentrations(XCO_2) are retrieved from the observed and the corrected GOSAT-FTS spectra by using the SCIATRAN inversion algorithm. Compared with the GOSAT-FTS L2 XCO_2 data products retrieved from the observed spectra of GOSAT-FTS, the SCIATRAN retrievals from the corrected spectra show a much better agreement, with the relative error less than 1%. But the results of GOSAT TANSO-FTS(V161.160) show smaller residuals than GOSAT TANSO-FTS(V141.141) without mean residual correction. The results indicate that the mean residual correction would increase the precision of XCO_2 retrieval for spectra with systematic deviations.展开更多
文摘云顶压强可用于估计云高,对气象观测和云特性研究等具有重要的作用。基于高分五号卫星搭载的多角度偏振探测仪(DPC)在氧气A吸收带设置的763 nm和765 nm两个波段进行了云顶压强反演方法的研究。首先,通过辐射传输模拟和多项式拟合得到了大气压强的计算公式,并对拟合公式进行了误差分析和校正。然后,分析了气溶胶、大气廓线等因素对云顶压强反演结果的影响,并进一步利用晴空地表对反演方法进行了稳定性测试和原理性验证。测试结果表明氧气A带方法稳定性较好,可以适用于不同天气状况和观测角度;验证结果表明DPC反演压强与DEM估算压强有很好的一致性,地表压强的平均偏差约为47.6 h Pa。最后,将DPC反演的云顶压强与MODIS云顶压强产品(MYD06)进行了对比,结果表明两颗卫星的云顶压强观测结果具有较好的空间一致性。
基金supported by the National Major Project (Grant No. 32-Y30B089001-13/15)the State Key Program of National Natural Science Foundation of China (Grant No. 41530422)+2 种基金the National Natural Science Foundation of China (Grant Nos. 61540018, 61275184, 61405153)the National High Technology Research and Development Program of China (Grant No. 2012AA121101)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20130201120047)
文摘The spectra of O_2 A-band(0.76 μm) and CO_2 near-infrared emissions(1.6 μm) are simulated by the SCIATRAN radiative transfer model(V3.1.23), and compared with those observed by GOSAT-FTS(Greenhouse gases Observing SATellite-Fourier Transform Spectrometer). Systematic deviations between the observed and simulated spectra are found to exist,especially for the O_2 A-band. The discrepancies are characterized by their mean differences averaged over the observed spectral ranges. A correction is applied to the observed GOSAT-FTS L1B(V141.141) spectra by scaling the spectral intensity measured by TANSO-FTS(Thermal and Near infrared Sensor for carbon Observation Fourier Transform Spectrometer) onboard GOSAT.The average columnar CO_2 concentrations(XCO_2) are retrieved from the observed and the corrected GOSAT-FTS spectra by using the SCIATRAN inversion algorithm. Compared with the GOSAT-FTS L2 XCO_2 data products retrieved from the observed spectra of GOSAT-FTS, the SCIATRAN retrievals from the corrected spectra show a much better agreement, with the relative error less than 1%. But the results of GOSAT TANSO-FTS(V161.160) show smaller residuals than GOSAT TANSO-FTS(V141.141) without mean residual correction. The results indicate that the mean residual correction would increase the precision of XCO_2 retrieval for spectra with systematic deviations.
