Climate Characteristics,Effects And Its Influencing Factors Of Cold Vortex Over Northeast China

Northeastern cold vortex, the significant weather system over mid and high latitudes of East Asia, is playing an important role in the climate of Northeast China. Based on daily temperature and precipitation data, northeastern cold vortex calendar and NCEP/NCAR reanalysis data from1961to2010, the climatological characteristics and effects of northeast cold vortex, the source and sink structure of water vapor during the northeast cold vortex rainstorm, the atmospheric circulation anomalies and the correlation with atmospheric circulations, sea surface temperatures and sea ice were investigated in order to provide a scientific basis for establishing the monitoring index, finding the predicting signal, improving the monitoring level and prediction skill of northeast cold vortex. The results showed that:1. The climatological characteristics of the northeast cold vortex were studied in terms of cold vortex days, frequency, intensity, spatial scale, geographic distribution, cold vortex track.31.5percent of the weather situations in northeast China were accompanying with the cold vortex that mostly occurred in late spring and early summer with life of about4.85days.The day number and times of northeastern cold vortex were no significant trend, but were obviously interannual variability and large annual-scale periodic inter-annual scale periodic signal. The strength of cold vortex was strong in winter and weak in summer but overall displaying a weak decreasing trend. Furthermore, the average of closed contours was about2.63, the average outer diameter of those contours was of19.5longitudes more or less, and the spatial scale variances of these cold vortexes were not significant but small in summer while large in winter. As to the difference of northeastern cold vortex days, the North-South one was more significant than that of West-East.When the consideration was focused on the moving paths of northeastern cold vortex, three types of traces were founded covering Northwestern trace in winter, Southwestern and Western traces in summer.2. Frequent activities of northeastern cold vortex could induce temperature anomalies, thus the climatology effects of these situations were remarkable. One of them was the obvious cooling effects with a drop in average temperatures of0.8degrees Celsius but more significant drop during winter and this cooling effect on daily maximum temperature was much greater than that on the minimum temperature. In addition, when the activities of northeastern cold vortex became more frequent, the cold events were more than the normal and in the meantime the warm events as well as the monthly temperature extremes were less or lower than the normal. Therefore, the correlation between northeastern cold vortex days and the index of temperature extremes on the basis of daily maximum temperature was more significant than that of cold vortex days compared with the index formulated via daily minimum temperature.In fact,53.7percent of the extreme minimum temperature events were induced by the system of northeastern cold vortex in Northeastern sites. Northeast and the northern part of North China the highest temperature minimum and extreme minimum temperature in cold eddy days, the probability of significantly greater than the corresponding northeast extreme maximum temperature, maximum and minimum temperatures in the probability of the cold eddy south on the contrary.And the effect of northeastern cold vortex on the occurrence of cold or warm day determined by daily maximum temperature was greater than those of cold or warm night determined by daily minimum temperature.3. Frequent activities of northeastern cold vortex could also induce precipitation anomalies. The rainfall over Northeastern as well as Southern China would be greater than normal when northeastern cold vortex activities were frequent and while less than normal occurred along Northern China. Spring and winter, the northeast cold vortex number and Northeast regions of precipitation were greater than in summer. Northeast cold vortex precipitation has a close relationship with the summer monsoon,4-August the number of days with precipitation in Northeast Cold Vortex is significantly related to regional mobility characteristics exists from south to north, and the spatial and temporal characteristics coincide with the summer rain belt north. Northeast Cold Vortex number of days with moderate rain days of a significant positive correlation area moved northwards significantly with the seasons. Multi-eddy and less eddy-year precipitation differences are largest area in April-August summer rain belt north into the northward, over time, before the flood season in southern China in the Huaihe River basin in South China, Meiyu period in the southern North China in August, while in Northeast precipitation was a significant positive difference in District moved to Jilin, Liaoning, northern North to Heilongjiang north-central.Northeast cold vortex increased precipitation probability over Northeast China, while reduced the chance of rain of the western and southern parts of North China.36%of annual precipitations were related to the northeast cold vortex, the northeast cold vortex precipitation percentage of the spring maximum, winter minimum. Northeast Northeast Cold Vortex precipitation probability is32percent, the highest in summer and winter minimum. Northeast Cold Vortex frequent summer, extreme absolute precipitation events of the Huaihe River basin and the relative precipitation events may obviously more on the strong side, extreme precipitation is too large. Summer rainstorm of the Northeast30percent of the northeast cold vortex, northern and central cold eddy rainstorm percentage was higher than the southern. Northeast Cold Vortex rainstorm probability was0.25%, summer, spring minimum. Northeast Cold Vortex reduce the cold eddy in summer rainstorm probability, and increase the cold vortex in the spring and autumn rainstorm probability The days of the cold eddy the northeast region of the probability of extreme precipitation, while reducing the probability of the North China precipitation extremes. Northeast Cold Vortex days of the occurrence probability of extreme precipitation in the35-45%, the North is greater than the southern spring maximum and summer minimum.4. Frequent activities of northeastern cold vortex also strengthened the water vapor transports from mid and high latitudes to the low ones and meanwhile weakened the water vapor transports from monsoon regions to Northeastern China, thus reduced water vapor flux over Northeastern China and changed the circulation situation. Northeast Cold Vortex rainstorm, subject to the influence of the vortex structure of the cold eddy water vapor flux of the Northeast was the cyclonic distribution, water vapor is continued in the Northeast activities, if sufficient water vapor conditions in this particular circulation pattern, prone regioncold vortex rainstorm.And the results obtained after the simulation of water vapor transport trace in the case of cold vortex rainstorm and other rainstorm in summer via an airflow trajectory model based on Lagrangian method over Northeastern China also indicated that water vapor source of cold vortex rainstorm mainly contained Lake Baikal, the Atlantic Ocean, Bay of Bengal, the south China sea and the West Pacific. Regional cold vortex rainstorm rainstorm and regional non-cold eddy water vapor channel can be summarized as the Northwest Passage, the Western Pacific channels and the channel of the South China Sea, but the three channels, the contribution rate is significantly different regional cold eddy rainstorm water vapor by the Northwest Passage and the Western Pacific channel to provide heavy rain the water vapor of the regional non-cold vortex provided by the South China Sea, channel and the Western Pacific channel.5. Two common features of northeastern cold vortex circulation anomalies were investigated including: the high incidence rate over mid and high latitudes and negative anomalies over high latitudes but positive over mid latitudes probably due to the close correlation with the main spatial model of atmospheric circulations over mid and high latitudes that could be determined as the illustration of interdecadal variances; and the dipoles structure of teleconnection pattern formulated between Northeast Asia and Eastern Siberia. And indeed, such dipoles structure in the site was indicated after EOF analysis and most of the months or seasons were the first dominant mode. With these discoveries, the NE index with teleconnection pattern formulated between Northeast Asia and Eastern Siberia was introduced to describe the temporal variance of northeastern cold vortex days since significant positive correlation between NE index and the days.Furthermore, the impact of the West Pacific subtropical high and East Asia major trough on northeastern cold vortex mainly appeared as the same variance steps in their locations. Days of the northeast cold vortex and the Sea of Okhotsk blocking high pressure, the region of the polar vortex area index, the polar vortex strength, the zonal circulation index, East Asia and Pacific EAP index, Northern Annular Mode, the western Pacific WP index in a number of seasonThe presence of significant correlation. The northeast cold vortex with the same period in the Arctic sea ice, global sea surface temperature on the relationship between the months of international and regional differences.Northeast Cold Vortex with the previous significantly related to the month up to the sea ice in the Kara and Barents Sea district, Greenland Sea, the northern part of Eurasia and the western waters near the East Siberia Sea. Cold eddy pre-global sea surface temperature in October was significantly related regional, July and October, the cold eddy days and many months of pre-Nino3District and Nino4SST significantly associated.