摘要
利用1951 2011年NCEP/NCAR再分析资料和1960 2010年西南地区77站月平均气温数据,定义了冬季代表月(1月)青藏高原(下称高原)季风强度和位置的新指数,并分析了该指数与中国西南地区地面气温的关系,结果表明:(1)代表高原冬季风的冷高压强度和位置具有明显的年际、年代际变化,20世纪70年代末发生了由弱到强的突变,80年代中期则是由偏北到偏南的突变。在全球变暖的大背景下,高原冬季风强度的振荡频率加快,由较长的7年周期向4年周期转化;位置指数的4年与10年周期存在明显的反相变化,自2005年以来位置振荡周期由10年向4年转化,南北摆动更为频繁。(2)当高原冬季风偏强时,北方冷空气与西南暖湿空气在西南地区交汇减弱,云量减少,辐射增温作用使西南地区温度一致偏高,西南地区东部低层出现异常下沉运动中心,下沉增温作用使该地区温度偏高更明显;当偏弱时,则相反。(3)当高原冬季风偏北时,北方较强冷空气南下,南支槽加深,西南暖湿空气与北方冷空气交汇于川滇地区,产生异常上升运动,云量增多,接收的太阳辐射减少,且冷空气活动频繁,西南地区温度一致偏低,上升冷却作用使西部气温偏低更明显;当偏南时,则相反。
Based on the NCEP / NCAR reanalysis monthly data from 1951 to 2011 and monthly temperature data at 77 stations in southw est China from 1960 to 2011,the spacial-temporal variability of w inter monsoon over Qinghai-Xizang Plateau( WM QXP) and southw estern temperature in January has been analyzed by EOF method.M eanw hile,intensity and location indices of WM QXP are defined. For recent 60 years,WM QXP has significant annual and inter-annual variability. There is an abrupt change of WM QXP in late 1970 s from w eek to strong and mid 1980 s from north to south. Under the global w arming,the oscillation frequency of the intensity and location both accelerates that the period varies from 7 a to 4 a and from 10 a to 4 a,respectively. According to correlation and synthesis analysis,there exists a close contact betw een WM QXP and southw estern temperature. When the plateau high strengthens,the intersection betw een the northern cold air and southw est w arm air becomes less than normal,w hich causes less cloud. Otherw ise,abnormal dow ndraft center appears in the east of southw est China.The w hole southw estern region is consistent with higher temperature and eastern part is more obvious. Vice versa. When plateau high is located north,more w arm-w et air from the south and cold-dry air from the north join together at the eastern Qinghai-Xizang Plateau. Simultaneously,abnormal northeasterly w inds dominate the eastern part of southw est China,and the w estern part exist abnormal updraft and increases cloud cover. The w hole southw estern region is consistent with low er temperature and w estern part is more obvious. Vice versa. The relationship betw een the intensity and location of WM QXP and southw estern temperature has great significance to analyze the climate change of the latter.
出处
《高原气象》
CSCD
北大核心
2015年第1期11-20,共10页
Plateau Meteorology
基金
国家重点基础研究发展计划(973)项目(2013CB430202)
中国气象局成都高原气象研究所高原气象开放基金课题(LPM2013003)
国家自然科学基金项目(41305080)
高等学校博士学科点专项科研基金资助课题(博导类)(20113228110003)
江苏高校优势学科建设工程资助项目(PAPD)
关键词
高原冬季风
强度指数
位置指数
西南气温
Winter monsoon over Qinghai-Xizang Plateau
Intense index
Location index
Temperature over southw est China
