| 1. | The strongly negative correlation between winter sea - ice extent of davis strait and july rainfall of north china turns into weaker correlation
冬季戴维斯海峡海冰是影响华北7月降水的“强信号” 。 |
| 2. | The change range of sea - ice extent during the periods of february - april and august - october is small , while that during the periods of april - july and october - january is large
其中2 - 4月以及8 - 10月海冰面积变化幅度不大，而4 - 8月和10月-次年1月海冰面积变化幅度则相当大。 |
| 3. | The sea - ice extent of north arctic undergoes an evident decrease during the last 42 years ( from 1953 to 1994 ) , for which the unusual changes of the spring ( may - july ) north arctic sea - ice extent make the main contribution
北极海冰面积过去42年( 1953 - 1994年)来经历了一种趋势性的减少，春季( 5 - 7月)北极海冰异常变化对此做出了主要贡献。 |
| 4. | There is an evident decrease of the spring greenland sea - ice extent since the 1970s , especially from the 1980s to the 1990s . with the method of mann - kendall , we find that the spring greenland sea - ice extent clearly takes place a catastrophe around 1972
自二十世纪70年代以来，春季格陵兰海海冰面积有一明显的减少趋势，其中80年代至90年代这种减少趋势是十分显著的，由mann - kendall方法确定出春季格陵兰海冰面积在1972年发生突变。 |
| 5. | The interdecadal characteristics of correlation pattern of interannual relationship between winter sea - ice extent of davis strait and august 500hpa height of northern hemisphere is " + - + " pattern from ural mountains to north of sea of okhotsk which is strongly negatively correlated with the august rainfall of north china before 1974 , and it has not apparent correlation pattern in europe - asia continent after 1974
1974年前，冬季戴维斯海峡海冰面积和北半球8月500hpa位势高度场的相关系数呈一个自乌拉尔山开始到鄂霍次克海以北分布的“ + - + ”型，该型和8月华北降水的反相关较好； 1974年后，相关在欧亚大陆地区变差，没有明显的相关型，冬季戴维斯海峡海冰面积和8月华北降水关系变差。 |
| 6. | The apparent characteristics of interdecadal variability of interannual relationship between winter sea - ice extent of davis strait and summer , july and august rainfall of north china are : the strongly negative correlation between winter sea - ice extent of davis strait and summer rainfall of north china turns into bad correlation
冬季戴维斯海峡海冰面积与华北7月降水在年际变化尺度上有明显的反相关关系。冬季戴维斯海峡的海冰面积增多(少) ，同年华北7月降水偏少(多) 。 |
| 7. | All the turn - point year is around 1974 . another feature of interdecadal variability of interannual relationship between winter sea - ice extent of davis strait and summer , july and august rainfall of 160 stations is that the interannual correlation pattern have changed from east - west pattern to " + - + " north - south pattern around 1974 . the interdecadal characteristics of correlation distribution pattern of interannual relationship between winter sea - ice extent of davis strait and summer , july 500hpa height of northern hemisphere are : " - + - " pattern from the beginning of novoya zemlya island , by way of balkhash lake to japan sea which is strongly negatively correlated with the rainfall of north china at the same period before 1974 and " + - " pattern from the beginning of ural mountains , by way of bujr lake to hetao basin which is badly correlated with the rainfall of north china at the same period after 1974
冬季戴维斯海峡海冰面积与华北夏季及7 、 8月降水年际关系有明显的年代际变化特征：其与夏季总降水的年际关系由1974年前较好的负相关在1974年后变差，与7月降水的年际关系由1974年前较好的负相关在1974年后变弱，与8月降水的年际关系由1974年前较好的负相关在1974年后变差；另一方面，其与中国160站夏季及7 、 8月降水的年际关系在1974年前后发生变化的主要特征是：与夏季总降水、 7月、 8月降水的年际关系由1974年前的相关系数分布呈“东西型”变为1974年后相关系数分布呈“ - + - ”的“南北型” 。 |
| 8. | ( 3 ) by using the method of svd and its second spatial distribution pattern , we can find that there is an evident positive relationship between the spring greenland sea - ice extent and summer rainfall of north china , that is to say , if the spring sea - ice extent of greenland is larger ( smaller ) , then there is much more ( less ) summer rainfall in north china
( 3 )采用奇异值分解方法，由第二对空间分布型可以看出，春季格陵兰海冰与华北夏季降水存在明显的正相关关系，即春季格陵兰海冰面积偏大(小) ，则后期华北夏季降水偏多(少) 。 |
| 9. | ( 5 ) the spring greenland sea - ice extent is larger ( smaller ) : then during the following summer the high of the japanese sea is stronger ( weaker ) , and the low of the asian land is stronger ( weaker ) , which make the pattern of low west and high east easily ( uneasily ) form ; the ascending movement over north china is strengthened ( weakened ) ; the summer monsoon of east asia is stronger ( weaker ) , then the southeastern , warm and damp airflow towards the north china is stronger ( weaker ) , and the cold airflow of the high level over the north china is also stronger ( weaker ) , which make the convergence of the cold and warm air over north china easily ( uneasily ) form ; the sst of the east pacific ocean is lower ( higher ) , while the sst of west wind drift is higher ( lower )
( 5 )春季格陵兰海冰面积偏大(小) ：后期夏季日本海高压偏强(弱) ，而大陆上低压也偏强(弱) ，易(不易)形成西低东阻的形势；华北地区的上升运动增强(减弱) ；东亚夏季风偏强(弱) ，向华北地区输送的西南暖湿气流偏强(弱) ，而对应高空华北地区上空冷空气活动偏强(弱) ，利于(不利于)华北上空冷暖空气的交汇；夏季赤道东太平洋海温偏低(高) ，西风漂流区海温偏高(低) 。在以上的环流背景下，华北夏季降水偏多(少) ，易涝(旱) 。 |
| 10. | The different distributions of surface level pressure , wind ( 10 meter ) and surface air temperature before and after the regime shift indicate that the increase of aleutian low , position change of its core , and the change of wind field in accordance , especially during the winter months , are the major dynamic reasons for the significant reduction of ice extent in bering sea
结果表明： 20世纪70年代后期，海冰范围在白令海存在显著的均值突变现象，而楚科奇海在对应阶段则表现为更明显的变频现象；在突变点前后两个时段里，阿留申低压中心低压加强、核心位置偏移以及对应风场分布的变化是导致白令海海冰范围明显缩小的主要动力原因。 |
