By using the eight-times-daily sampling data from an intensive radiosonde observation campaign at Yichang(111°18′E,30°42′N),China in August 2006 and January 2007,the diurnal variation of the planetary boun...By using the eight-times-daily sampling data from an intensive radiosonde observation campaign at Yichang(111°18′E,30°42′N),China in August 2006 and January 2007,the diurnal variation of the planetary boundary layer height determined by using a bulk Richardson(Ri)number approach,was studied in this paper.It was found that the boundary layer heights in both summer and winter months showed diurnal changes and the daily cycle was deeper in summer,which agreed well with the previous studies;the monthly averaged height was 103–1112 m and 89–450 m in summer and winter,respectively;the morning rise began at 0700 LT/1000 LT in summer/winter and the evening transition occurred at 1900 LT in both seasons;the maximum height occurred in the afternoon for most cases,except some peaks found in the winter night;the surface temperature and relative humidity dominated the variations of summer height,while the diurnal variation shown in January 2007 might have some connections with the dynamical processes in the lower troposphere,besides the surface effects.展开更多
The atmospheric reanalysis datasets have been widely used to understand the variability of atmospheric water va- por on various temporal and spatial scales for climate change research. The difference among a variety o...The atmospheric reanalysis datasets have been widely used to understand the variability of atmospheric water va- por on various temporal and spatial scales for climate change research. The difference among a variety of reanalysis datasets, however, causes the uncertainty of corresponding results. In this study, the climatology of atmospheric column-integrated wa- ter vapor for the period from 2000 to 2012 was compared among three latest third-generation atmospheric reanalyses including European Centre for Medium-range Weather Forecasts Interim Re-Analysis （ERA-Interim）, Modem-Era Retrospective Analy- sis for Research and Applications （MERRA）, and Climate Forecast System Reanalysis （CFSR）, while possible explanation on the difference between them was given. The results show that there are significant differences among three datasets in the mul- ti-year global distribution, variation of interannual cycle, long-term trend and so on, though high similarity for principal mode describing the variability of water vapor. Over oceans, the characteristics of long-term CWV variability are similar, whereas the main discrepancy among three datasets is located around the equatorial regions of the Intertropical Convergence Zone, the South Pacific Convergence Zone and warm cloud area, which is related with the difference between reanalysis models for the scheme of convective parameterization, the treatment of warm clouds, and the assimilation of satellite-based observations. Moreover, these CWV products are fairly consistent with observations （satellite-based retrievals） for oceans. On the other hand there are systematic underestimations about 2.5 kg/m2 over lands for all three CWV datasets, compared with radiosonde ob- servations. The difference between models to solve land-atmosphere interaction in complex environment, as well as the pauci- ty in radiosonde observations, leads to significant water vapor gaps in the Amazon Basin of South America, central parts of Africa and some mountainous regions. These results would help better understand the climatology difference among various reanalysis datasets better, and more properly choose water vapor datasets for different research requirements.展开更多
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2012CB825605)the National Natural Science Foundation of China(Grant No.41304125)ZHANG YeHui acknowledges support from the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘By using the eight-times-daily sampling data from an intensive radiosonde observation campaign at Yichang(111°18′E,30°42′N),China in August 2006 and January 2007,the diurnal variation of the planetary boundary layer height determined by using a bulk Richardson(Ri)number approach,was studied in this paper.It was found that the boundary layer heights in both summer and winter months showed diurnal changes and the daily cycle was deeper in summer,which agreed well with the previous studies;the monthly averaged height was 103–1112 m and 89–450 m in summer and winter,respectively;the morning rise began at 0700 LT/1000 LT in summer/winter and the evening transition occurred at 1900 LT in both seasons;the maximum height occurred in the afternoon for most cases,except some peaks found in the winter night;the surface temperature and relative humidity dominated the variations of summer height,while the diurnal variation shown in January 2007 might have some connections with the dynamical processes in the lower troposphere,besides the surface effects.
基金supported by the National Natural Science Foundation of China(Grant Nos.9133721341230419+5 种基金4137503041375148 and 41205126)the Special Funds for Public Welfare of China(Grant No.GYHY201306077)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05100303)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX2-EW-QN507)sponsored by the Jiangsu Provincial 2011 Program(Collaborative Innovation Center of Climate Change)
文摘The atmospheric reanalysis datasets have been widely used to understand the variability of atmospheric water va- por on various temporal and spatial scales for climate change research. The difference among a variety of reanalysis datasets, however, causes the uncertainty of corresponding results. In this study, the climatology of atmospheric column-integrated wa- ter vapor for the period from 2000 to 2012 was compared among three latest third-generation atmospheric reanalyses including European Centre for Medium-range Weather Forecasts Interim Re-Analysis （ERA-Interim）, Modem-Era Retrospective Analy- sis for Research and Applications （MERRA）, and Climate Forecast System Reanalysis （CFSR）, while possible explanation on the difference between them was given. The results show that there are significant differences among three datasets in the mul- ti-year global distribution, variation of interannual cycle, long-term trend and so on, though high similarity for principal mode describing the variability of water vapor. Over oceans, the characteristics of long-term CWV variability are similar, whereas the main discrepancy among three datasets is located around the equatorial regions of the Intertropical Convergence Zone, the South Pacific Convergence Zone and warm cloud area, which is related with the difference between reanalysis models for the scheme of convective parameterization, the treatment of warm clouds, and the assimilation of satellite-based observations. Moreover, these CWV products are fairly consistent with observations （satellite-based retrievals） for oceans. On the other hand there are systematic underestimations about 2.5 kg/m2 over lands for all three CWV datasets, compared with radiosonde ob- servations. The difference between models to solve land-atmosphere interaction in complex environment, as well as the pauci- ty in radiosonde observations, leads to significant water vapor gaps in the Amazon Basin of South America, central parts of Africa and some mountainous regions. These results would help better understand the climatology difference among various reanalysis datasets better, and more properly choose water vapor datasets for different research requirements.
