High performance liquid chromatography(HPLC) is one of the analytical techniques used most frequently. Its chief limitation lies in the need to avoid the overlap of chromatographic peaks as much as possible. In this p...High performance liquid chromatography(HPLC) is one of the analytical techniques used most frequently. Its chief limitation lies in the need to avoid the overlap of chromatographic peaks as much as possible. In this paper, the overlapped chromatograms and spectra system of 1-chloro-2,4-dinitrobenzene and 3,5-dinitrobenzoic acid in the presence of 2,4-dinitrobenzoic acid were resolved by using the alternating trilinear decomposition(ATLD) combined with HPLC-DAD. Moreover, both were determined simultaneously, whose recoveries were(102.1±2.2)% and(97.6±3.6)%, respectively. The satisfactory results show that this experiment can be easily performed without paying out time-consuming and complicated procedures and quantifying accurately. It revealed the ATLD algorithm was one of the approaches to solve second-order calibration problem in HPLC-DAD.展开更多
Three types of landscape boundary (forest/pepper field, forest/cabbage field,and forest/grassland) were selected in the arid valley of upper reaches of Minjiang River,southwestern China. On the basis of vegetation div...Three types of landscape boundary (forest/pepper field, forest/cabbage field,and forest/grassland) were selected in the arid valley of upper reaches of Minjiang River,southwestern China. On the basis of vegetation diversity, the depth of edge influence (DEI) ondifferent types of landscape boundaries was estimated using principal components analysis (PCA)method and moving split-window techniques (MSWT). The results showed that in the 5 transects, PCAmethod was able to detect the edge influence depth with 3 transects, while MSWT could explain 4transects. It is concluded that PCA and MSWT both can be used to detect the depth of edge influencewithin 50 m from the edge to the interior. Similar conclusions were drawn in the forest of eachtransect with the two methods, but no similar conclusions were drawn in the pepper field of eachtransect. Although the two methods have advantages and disadvantages respectively, they are usefultools for characterizing edge dynamics. Comparing the two methods, MSWT is more successful.展开更多
The Visible and Infrared Spin-Scan Radiometer(VISSR) onboard the Fengyun-2(FY-2) satellite can provide valuable thermal infrared observations to help create a precipitable water vapor(PWV) product with high spatial an...The Visible and Infrared Spin-Scan Radiometer(VISSR) onboard the Fengyun-2(FY-2) satellite can provide valuable thermal infrared observations to help create a precipitable water vapor(PWV) product with high spatial and temporal resolutions. The current FY-2/VISSR PWV product in operation is produced by using a traditional two-band physical split-window(PSW) method, which produces low quality results under dry atmospheric conditions. Based on the sensitivity characteristics of FY-2 F/VISSR water vapor channel and two split-window channels to atmospheric water vapor, this study developed a new, robust operational PWV retrieval algorithm for FY-2 F to improve the operational precision of the current PWV product. The algorithm uses a modified three-band PSW method, which adds a scale for the water vapor channel in the improved three-band PSW method. Integrated PWV products from the radiosonde data in 2016 are used here to validate the precision of the PWV retrieved by the modified three-band and traditional two-band PSW methods. The mean bias, root mean square error(RMSE), and correlation coefficient of the PWV retrieved by the modified three-band PSW method are 0.28 mm, 4.53 mm, and 0.969, respectively. The accuracy is much better than the PWV retrieved by the two-band method, whose mean bias, RMSE, and correlation coefficient are 12.67 mm, 29.35 mm, and 0.23. Especially, in mid-or high-latitude regions, the RMSE of the PWV is improved from 10 to 2 mm by changing the inversion in the two-band method to the modified three-band PSW method. Furthermore, the modified three-band PSW results show a better consistency with the radiosonde PWV at any zonal belt and season than the two-band PSW results. This new algorithm could significantly improve the quality of the current FY-2 F/VISSR PWV product, especially at sites where the actual PWV are lower than 15 mm.展开更多
To further verify the modified Becker＇s split-window approach for retrieving land surface temperature （LST） from long-term Advanced Very High Resolution Radiometer （AVHRR） data, a cross-validation and a radiance-...To further verify the modified Becker＇s split-window approach for retrieving land surface temperature （LST） from long-term Advanced Very High Resolution Radiometer （AVHRR） data, a cross-validation and a radiance-based （R-based） validation are performed and examined in this paper. In the cross-validation, 3481 LST data pairs are extracted from the AVttRR LST product retrieved with the modified Becker＇s approach and compared with the Moderate Resolution Imaging Spectroradiometer （MODIS） LST product （MYDllA1） for the period 2002-2008, relative to the positions of 548 weather stations in China. The results show that in most cases, the AVHRR LST values are higher than the MYDllA1. When the AVHRR LSTs are adjusted with a linear regression, the values are close to the MYDllA1, showing a good linear relationship between the two datasets （R2 = 0.91）. In the R-based validation, comparison is made between AVHRR LST retrieved from the modified Becker＇s approach and the inversed LST from the Moderate Resolution Transmittance Model （MODTRAN） consolidated with observed temperature and humidity profiles at four radiosonde stations. The results show that the retrieved AVHRR LST deviates from the MODTRAN inversed LST by -1.3 （-2.5） K when the total water vapor amount is less （larger） than 20 mm. This provides useful hints for further improvement of the LST retrieval algorithms＇ accuracy and consistency.展开更多
文摘High performance liquid chromatography(HPLC) is one of the analytical techniques used most frequently. Its chief limitation lies in the need to avoid the overlap of chromatographic peaks as much as possible. In this paper, the overlapped chromatograms and spectra system of 1-chloro-2,4-dinitrobenzene and 3,5-dinitrobenzoic acid in the presence of 2,4-dinitrobenzoic acid were resolved by using the alternating trilinear decomposition(ATLD) combined with HPLC-DAD. Moreover, both were determined simultaneously, whose recoveries were(102.1±2.2)% and(97.6±3.6)%, respectively. The satisfactory results show that this experiment can be easily performed without paying out time-consuming and complicated procedures and quantifying accurately. It revealed the ATLD algorithm was one of the approaches to solve second-order calibration problem in HPLC-DAD.
基金This work was financially supported by the Major State Basic Research Program of China (973 Program: 2002CB111506).
文摘Three types of landscape boundary (forest/pepper field, forest/cabbage field,and forest/grassland) were selected in the arid valley of upper reaches of Minjiang River,southwestern China. On the basis of vegetation diversity, the depth of edge influence (DEI) ondifferent types of landscape boundaries was estimated using principal components analysis (PCA)method and moving split-window techniques (MSWT). The results showed that in the 5 transects, PCAmethod was able to detect the edge influence depth with 3 transects, while MSWT could explain 4transects. It is concluded that PCA and MSWT both can be used to detect the depth of edge influencewithin 50 m from the edge to the interior. Similar conclusions were drawn in the forest of eachtransect with the two methods, but no similar conclusions were drawn in the pepper field of eachtransect. Although the two methods have advantages and disadvantages respectively, they are usefultools for characterizing edge dynamics. Comparing the two methods, MSWT is more successful.
基金Supported by the National Key Research and Development Program of China(2016YFA0600101 and 2018YFA0605502)China Meteorological Administration Special Public Welfare Research Fund(GYHY201406001)National Natural Science Foundation of China(41571348)
文摘The Visible and Infrared Spin-Scan Radiometer(VISSR) onboard the Fengyun-2(FY-2) satellite can provide valuable thermal infrared observations to help create a precipitable water vapor(PWV) product with high spatial and temporal resolutions. The current FY-2/VISSR PWV product in operation is produced by using a traditional two-band physical split-window(PSW) method, which produces low quality results under dry atmospheric conditions. Based on the sensitivity characteristics of FY-2 F/VISSR water vapor channel and two split-window channels to atmospheric water vapor, this study developed a new, robust operational PWV retrieval algorithm for FY-2 F to improve the operational precision of the current PWV product. The algorithm uses a modified three-band PSW method, which adds a scale for the water vapor channel in the improved three-band PSW method. Integrated PWV products from the radiosonde data in 2016 are used here to validate the precision of the PWV retrieved by the modified three-band and traditional two-band PSW methods. The mean bias, root mean square error(RMSE), and correlation coefficient of the PWV retrieved by the modified three-band PSW method are 0.28 mm, 4.53 mm, and 0.969, respectively. The accuracy is much better than the PWV retrieved by the two-band method, whose mean bias, RMSE, and correlation coefficient are 12.67 mm, 29.35 mm, and 0.23. Especially, in mid-or high-latitude regions, the RMSE of the PWV is improved from 10 to 2 mm by changing the inversion in the two-band method to the modified three-band PSW method. Furthermore, the modified three-band PSW results show a better consistency with the radiosonde PWV at any zonal belt and season than the two-band PSW results. This new algorithm could significantly improve the quality of the current FY-2 F/VISSR PWV product, especially at sites where the actual PWV are lower than 15 mm.
基金Supported by the Meteorological Key Technology Integration and Application Program of the China Meteorological Administration(CMAGJ2013Z20 and CMAGJ2015Z19)
文摘To further verify the modified Becker＇s split-window approach for retrieving land surface temperature （LST） from long-term Advanced Very High Resolution Radiometer （AVHRR） data, a cross-validation and a radiance-based （R-based） validation are performed and examined in this paper. In the cross-validation, 3481 LST data pairs are extracted from the AVttRR LST product retrieved with the modified Becker＇s approach and compared with the Moderate Resolution Imaging Spectroradiometer （MODIS） LST product （MYDllA1） for the period 2002-2008, relative to the positions of 548 weather stations in China. The results show that in most cases, the AVHRR LST values are higher than the MYDllA1. When the AVHRR LSTs are adjusted with a linear regression, the values are close to the MYDllA1, showing a good linear relationship between the two datasets （R2 = 0.91）. In the R-based validation, comparison is made between AVHRR LST retrieved from the modified Becker＇s approach and the inversed LST from the Moderate Resolution Transmittance Model （MODTRAN） consolidated with observed temperature and humidity profiles at four radiosonde stations. The results show that the retrieved AVHRR LST deviates from the MODTRAN inversed LST by -1.3 （-2.5） K when the total water vapor amount is less （larger） than 20 mm. This provides useful hints for further improvement of the LST retrieval algorithms＇ accuracy and consistency.
