摘要
利用河西走廊东部1971—2010年4个气象站大风(≥6级,即10min平均风速≥10.8～13.8m/s)资料,系统分析了该区大风的时空分布、强度和持续性等气候特征。结果表明,河西走廊东部大风天气主要发生在山区和沙漠边缘;年、年代际大风日数总体呈减少趋势,3—5月是大风的高发期,占全年大风日数的34.8%～56.8%,其次是2月、6月和11月;各强度大风日数的变率较大,随着大风强度的增强,大风日数迅速减少;大风天气具有持续性特征,最大风速大多出现在持续大风时段内。采用2003—2007年逐日20时ECMWF数值预报格点场资料,按照Press准则进行预报因子初选,运用逐步回归预报方法进行预报因子精选,使用最优子集回归建立大风预报方程,并用双评分准则(CSC,couple score criterion)确定各季节各地大风预报全局最优的显著性方程,预报方程通过了α=0.01的显著性检验。预报方程回代拟合率为66.7%～73.4%,预报准确率为58.8%～67.5%,达到了一定的预报水平,可为大风的业务预报提供客观有效的指导产品。采用最大靠近原则确定了大风预报临界值和预报、预警的级别。
Using gale data （≥level 6 with ten minute average wind velocity≥10.8—13.8 m/s） of four meteorological stations in east Hexi corridor from 1971 to 2010,such climate characteristics as space and time distribution,intensity and endurance of the gales were analyzed systematically.The results show that gales mainly occur in the mountainous area and the edge of desert.Annual gale days and interdecadal gale days presents a reducing tendency.March to May is gale frequent period,which occupies 34.8%—56.8% of annual gale days.Then it is February,June and November.Gale days of different intensities vary a lot.The number of gale days reduces rapidly along with the elevation of gale intensity.Gale weather presents long-enduring characteristic and strong gale usually occur in sustained period of gale.Based on the daily data of ECMWF numerical forecast grid field at 20：00 BST from 2003 to 2007,forecast factor was initially elected by Press criterion and was further selected by stepwise regression forecast method.The gale forecast equations were built with optimal subset regression.The overall situation and the most superior significance forecast equations of the gale in every season in different areas were determined finally by the CSC double grading criterion.The forecast equations passed significance examination of α=0.01.Back substitution fitting rates of the prognostic equations were 66.7%—73.4% and forecast accuracy rates were 58.8%—67.5%,which achieved the forecast level to provide objective and effective instruction for gale forecast.The closest approaching principle was used to set forecast marginal value,ranks of gale forecast and early warning.
出处
《大气科学学报》
CSCD
北大核心
2012年第1期121-127,共7页
Transactions of Atmospheric Sciences
基金
公益性行业(气象)科研专项(GYHY(QX)201106029)
