积雪变化导致格陵兰冰盖高度变化

地面冰盖对气候变化的反应可能会对未 来的海平面变化产生重大的影响.近年来格 陵兰南部的卫星调查显示,较大高度的冰盖 总体高度变化甚小,但空间变化很大.当然 仅仅依靠卫星数据难以测定是什么地球物理 过程引起了这种高度变化以及近年的变化速 率是否超过了正常变化速率.我们利用雪粒 密度增大的物理模型和根据高海拔12个冰 心再造的年雪堆积记录,获取了1978～1988 年格陵兰南部冰盖高度的变化. 地中海的干涸及其产生的后果 К.Н. Несис 很久以来就知道,地史最后阶段最具戏 剧性的事件之一就是大约在6Ma前的中新 世末期地中海的被隔离和完全干涸.据西西 里岛墨西拿城附近该时期著名的沉积剖面, 这个事件被称之为墨西拿盐量转变. 马建华摘译自 , 2000, Vol.406,No.24 周立君校     

Short period internal waves over the Huanghe (Yellow River) delta front

Internal waves with periods of about 5 minutes and trough to crest heights of up to 6.2 m were observed acoustically over the actively accreting delta front of the Huanghe (Yellow River) in the western portion of the Gulf of Bohai, Peoples Republic of China. The radian frequency of the internal waves was close to the locally-observed Brunt-Vaisala frequency. Through the relatively short (one hour) duration of an internal wave train, the amplitude was observed to decrease progressively with time. These internal waves may cause resuspension of delta-front sediments.