Recent studies have revealed that two boreal spring sea surface temperature （SST） indices have potential to predict the number of western North Pacific （WNP） tropical cyclones （TCs） in the following peak typhoon...Recent studies have revealed that two boreal spring sea surface temperature （SST） indices have potential to predict the number of western North Pacific （WNP） tropical cyclones （TCs） in the following peak typhoon season （June-October）： the northern tropical Atlantic （NTA） SST, and the SST gradient （SSTG） between the southwestern Pacific and western Pacic warm pool. The interannua[ and interdecadal variations of NTA SST and SSTG and their relationships to the number ofWNP TCs during 1950-2013 were compared. On the interdecadal timescale, SSTG showed better correlation with the number of WNP TCs than NTA SST. The interdecadal variation of NTA SST was closely associated with the Atlantic Multidecadal Oscillation, while that of SSTG was anti-correlated with the Central Pacific （CP） El Nino index at the interdecadal timescale. On the interannual timescale, both NTA SST and SSTG were modulated by two types of El Nino. The NTA SST revealed significant correlations with the number of WNPTCs beginning from the early 1960s; by contrast, SSTG showed significant correlations after the mid-1970s. Co-variability of NTA SST and SSTG existed after the late 1980s, induced by modulation from CP El Nino.The co-variability of these two spring SST predictors increased their prediction skill after the late 1980s, with enhanced correlation between the number of WNPTCs and the two predictors.展开更多
On the basis of information from the project ＂Land-surface Processes and their Experimental Study on the Chinese Loess Plateau＂, we analyzed differences in land-surface water and heat processes during the main dry a...On the basis of information from the project ＂Land-surface Processes and their Experimental Study on the Chinese Loess Plateau＂, we analyzed differences in land-surface water and heat processes during the main dry and wet periods of the semiarid grassland growing season in Yuzhong County, as well as the influences of these environmental factors. Studies have shown that there are significant differences in changes of land-surface temperature and humidity during dry and wet periods. Daily average normalized temperature has an overall vertical distribution of ＂forward tilting＂ and ＂backward tilting＂ during dry and wet periods, respectively. During the dry period, shallow soil above 20-cm depth is the active temperature layer. The heat transfer rate in soil is obviously different during dry and wet periods. During the dry period, the ratio of sensible heat flux to net radiation （H/Rn） and the value of latent heat flux to net radiation （LE/Rn） have a linear relationship with 5-cm soil temperature; during the wet period, these have a nonlinear relationship with 5-cm soil temperature, and soil temperature of 16℃ is the critical temperature for changes in the land-surface water and heat exchange trend on a daily scale. During the dry period, H/Rn and LE/Rn have a linear relationship with soil water content. During the wet period, these have a nonlinear relationship with 5-cm soil water content, and 0.21 m^3 m^-3 is the critical point for changes in the land-surface water and heat exchange trend at daily scale. During the dry period, for vapor pressure deficit less than 0.7 kPa, H/Rn rises with increased vapor pressure deficit, whereas LEIRn decreases with that increase. When that deficit is greater than 0.7 kPa, both H/Rn and LE/Rn tend to be constant. During the wet period, H/Rn increases with the vapor pressure deficit, whereas LE/Rn decreases. The above characteristics directly reflect the effect of differences in land-surface environmental factors during land-surface water and heat exchange processes, and indirectly reflect the influences of cloud precipitation processes on those processes.展开更多
基金funded by the Guangdong Natural Science Foundation[grant number 2015A030313796]the National Natural Science Foundation of China[grant numbers 41205026,41476009,41476010]+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number Xd A11010104]the National Program on Global Change and Air-Sea interaction[grant number GASi-i POVAi-04]the Knowledge innovation Program of the Chinese Academy of Sciences[grant number SQ201208]
文摘Recent studies have revealed that two boreal spring sea surface temperature （SST） indices have potential to predict the number of western North Pacific （WNP） tropical cyclones （TCs） in the following peak typhoon season （June-October）： the northern tropical Atlantic （NTA） SST, and the SST gradient （SSTG） between the southwestern Pacific and western Pacic warm pool. The interannua[ and interdecadal variations of NTA SST and SSTG and their relationships to the number ofWNP TCs during 1950-2013 were compared. On the interdecadal timescale, SSTG showed better correlation with the number of WNP TCs than NTA SST. The interdecadal variation of NTA SST was closely associated with the Atlantic Multidecadal Oscillation, while that of SSTG was anti-correlated with the Central Pacific （CP） El Nino index at the interdecadal timescale. On the interannual timescale, both NTA SST and SSTG were modulated by two types of El Nino. The NTA SST revealed significant correlations with the number of WNPTCs beginning from the early 1960s; by contrast, SSTG showed significant correlations after the mid-1970s. Co-variability of NTA SST and SSTG existed after the late 1980s, induced by modulation from CP El Nino.The co-variability of these two spring SST predictors increased their prediction skill after the late 1980s, with enhanced correlation between the number of WNPTCs and the two predictors.
基金supported by the National Basic Research Program of China(Grant No.2013CB430206,2012CB955304)National Natural Science Foundation of China(Grant Nos.41075008,40830957,41275118)+2 种基金China Postdoctoral Science Special Foundation(Grant No.2013T60901)China Postdoctoral Science Foundation(Grant No.20110490854)the Ten Talents Program of Gansu Meteorology Bureau
文摘On the basis of information from the project ＂Land-surface Processes and their Experimental Study on the Chinese Loess Plateau＂, we analyzed differences in land-surface water and heat processes during the main dry and wet periods of the semiarid grassland growing season in Yuzhong County, as well as the influences of these environmental factors. Studies have shown that there are significant differences in changes of land-surface temperature and humidity during dry and wet periods. Daily average normalized temperature has an overall vertical distribution of ＂forward tilting＂ and ＂backward tilting＂ during dry and wet periods, respectively. During the dry period, shallow soil above 20-cm depth is the active temperature layer. The heat transfer rate in soil is obviously different during dry and wet periods. During the dry period, the ratio of sensible heat flux to net radiation （H/Rn） and the value of latent heat flux to net radiation （LE/Rn） have a linear relationship with 5-cm soil temperature; during the wet period, these have a nonlinear relationship with 5-cm soil temperature, and soil temperature of 16℃ is the critical temperature for changes in the land-surface water and heat exchange trend on a daily scale. During the dry period, H/Rn and LE/Rn have a linear relationship with soil water content. During the wet period, these have a nonlinear relationship with 5-cm soil water content, and 0.21 m^3 m^-3 is the critical point for changes in the land-surface water and heat exchange trend at daily scale. During the dry period, for vapor pressure deficit less than 0.7 kPa, H/Rn rises with increased vapor pressure deficit, whereas LEIRn decreases with that increase. When that deficit is greater than 0.7 kPa, both H/Rn and LE/Rn tend to be constant. During the wet period, H/Rn increases with the vapor pressure deficit, whereas LE/Rn decreases. The above characteristics directly reflect the effect of differences in land-surface environmental factors during land-surface water and heat exchange processes, and indirectly reflect the influences of cloud precipitation processes on those processes.
