青藏高原东北缘地处现代亚洲季风影响的北界和中国干旱与半干旱气候的过渡地带,沉积物对气候变化敏感,是研究全新世高原冬夏季风系统对全球变化响应的理想地点。笔者根据粉尘搬运的动力学原理,利用温湿度组合、风力强度变化和粉尘源区收扩演变特点,分析了共和-贵德盆地全新世气候波动、区域环境变化以及冬夏季风关系等,主要取得了以下认识:(1)建立了大气粉尘的风力强度指数、粉尘搬运距离指数、大气湍流强度指数、春季近地面气温指数和有效湿度指数等估算方法。(2)全新世时期西南季风是影响共和-贵德盆地的主要夏季风系统,高原冬季风则是影响这个地区的主要冬季风,共和-贵德盆地近地面具有不同的风场演化模式。(3)共和-贵德盆地的全新世气候变化可划分为4个阶段:1大约6.5-4.2kaBP的全新世适宜期以湿度大幅增加、温度小幅升高的暖湿为特点。2在2.6-4.2kaBP期间出现了一次以冷干为特点、粉尘源区扩张、冬夏季风均减弱的环境恶化事件,这次恶化事件在高原季风系统的西北粉尘源区和亚洲季风系统的北方粉尘源区都同样存在。3大约1.2-2.6kaBP时期,粉尘源区收缩、环境好转,推测是夏季风小幅加强的时期。41.2kaBP以后,湿度增加、成壤强度先强后弱,总体环境趋于冷湿。
The northeastern margin of the Tibetan Plateau located at the northern boundary of modern Asian monsoon transition and transition zone of arid and semi-arid area in China, due to sediment sensitive to climate change, is an ideal place to study the plateau Holocene winter monsoon system response to global change. According to the dynamic principle of dusttransportation, by using characteristics of the combination of temperature and humidity, wind strength and dust source distance, the Holocene climatic fluctuations, regional environmental change and the relationship between winter and summer monsoons are analyzed in the study. The following conclusions are obtained:(1)The estimation methods of proxy indices of wind strength of atmospheric dust, dust transport distance, air-turbulence intensity, spring near-surface air temperature and humidity are established. (2)Southwest monsoon dominated Gonghe and Guide Basins during the Holocene period. Plateau winter monsoon is a key winter monsoon in the region and there has a different evolutionary pattern of near-surface wind field in the above region due to the effect of mountains. (3)Climatic change of the Holocene can be divided into four stages in Gonghe and Guide Basins, the first stage is about 6. 5 - 4. 2kaBP that is the Holocene Optimum, characterized by significantly increased humidity and slightly elevated temperature. The second stage is about 2.6-4.2kaBP and characterized by cold and dry climate, dust source expansion. Both winter and summer monsoon weakened in the stage. This cold and dry event was also appeared in the northwest dust source area of plateau monsoon system and dust source areas of Asian monsoon system. The third stage is about 1.2-2.6kaBP. In the period, dust source shrinked, eco-environment was improved and summer monsoon slightly enhanced. The fourth stage is after 1.2kaBP when humidity increased and climate tended to be cold and wet.