Possible Influence Of The Northeast Cold Vortex On The North Pacific Storm Track During Winter

Based on the daily and monthly reanalysis data of the National Center for Atmospheric Research (NCAR) and the United States Center for environmental prediction (NCEP) and the northeast cold vortex (NECV) calendar from the meteorological research institutes of Jilin province, we make a contrastive analysis of space-time evolution of the north Pacific storm track (NPST) to the previous research. On that basis, we analyze the possible influence of NECV on NPST during winter for58years through1951/1952to2008/2009, and the important roles of some typical atmospheric teleconnection patterns play through the process. Results are summarized as follows:(1) The possible influence of NECV on NPST:there is a significantly negative relationship between the NECV day’s change and the north Pacific storm track intensity during winter, so the more (less) NECV happen, the weaker (stronger) the storm track over the North Pacific will be. The Wavelet cross spectrum analysis shows that the quasi three years periods in interannual variation is existed when expresses the influence of the NECV interannual day’s change on the north Pacific storm track during winter. During more NECV years, the major lower level cooling is located in the western parts of both the subtropical jet and the storm track in longitudes and between the two central axes in latitudes, NECV induced lower level cooling brings about the reverse relationship:a southward stronger and narrow jet but with weaker storm track activities. It is because the wave seeding from East Asia to the North Pacific storm track is weakened owing to the anomalous lower level cooling in the northwestern Pacific, which also results in reduction of eddy generation and storm track activities. And vice versa.(2) The correlation coefficient is the highest (-0.47) between the WP index and the NECV day’s change compare with the other typical atmospheric teleconnection patterns during winter, and the regression of the geopotential height and zonal wind anomaly field to the WP index are just as same as those with NECV day’s change. That is:when the WP pattern is on its negative phase, the geopotential height anomaly shows two opposite centers locate zonally on other side of the east Asian-north Pacific jet stream, and the zonal wind anomaly shows southward of the north Pacific jet stream, which are all favorable for the formation of the NECV. Therefor, the WP pattern is possible the primary teleconnection pattern for the NECV activity during winter.(3) There have good relationships between the typical atmospheric teleconnection patterns with the NECV activity, they can be summarize as follows: When the Eurasia (EU) pattern is on the positive phase and the Arctic oscillation (AO) pattern is on the negative phase, the east asian winter monsoon is stronger and the east Asian and north Pacific jet stream southward, which are favorable for the formation of NECV. The EU patern comes to the second place to fit for the NECV pattern. Therefore, those patterns which have a good relationship with NECV play important roles in the process of the influence of the NECV activity on the north Pacific stormtrack.