Temporal and Spatial Characteristics of Climate Changes in the Urumqi River Basin of Tianshan Mountain over 50 years

Based on the meteorological data during 1959-2008 from five representative weather stations in the Urumqi River Basin and surrounding areas,the regional characteristics of temperature and precipitation in the basin featuring multi-climatic zones were studied by means of some methods including wavelet analysis.As was shown in the results,the temperature in the whole Urumqi River Basin demonstrated a significant upward trend.The temperature increase particularly in autumn and winter made the greatest contribution to the marked ascent.The interdecadal temperature in the basin showed a tendency to decline before the period during 1970s-1980s while it was on the rise after 1990s on the whole.The most concentrated period of temperature mutations was in the late 1990s.At the same time,the precipitation also showed an escalating trend,which experienced a stage of unanimous upward trend after 1990s.The most concentrated period of precipitation mutations was in the early 1990s.

The Interdecadal Changes of South Pacific Sea Surface Temperature in the Mid-1990s and Their Connections with ENSO

The characteristic changes of South Pacific sea surface temperature anomalies （SSTAs） for the period January 1979 to December 2011, during which the 1990s Pacific pan-decadal variability （PDV） interdecadal regime shifts occurred, were examined. Empirical Orthogonal Function （EOF） analysis was applied to the monthly mean SSTA for two sub-periods： January 1979 to December 1994 （P 1） and January 1996 to December 2011 （P2）. Both the spatial and temporal features of the leading EOF mode for P1 and P2 showed a remarkable difference. The spatial structure of the leading EOF changed from a tripolar pattern for P 1 （EOF-P 1） to a dipole-like pattern for P2 （EOF-P2）. Besides, EOF-P 1 （EOF-P2） had significant spectral peaks at 4.6 yr （2.7 yr）. EOF-P2 not only had a closer association with E1 Nifio-Southern Oscillation （ENSO）, but also showed a faster response to ENSO than EOF-P1 based on their lead-lag relationships with ENSO. During the development of ENSO, the South Pacific SSTA associated with ENSO for both PI and P2 showed a significant eastward propagation. However, after the peak of ENSO, EOF-P1 showed a stronger persistence than EOF-P2, which still showed eastward propagation. The variability of the SSTA associated with the whole process of ENSO evolution during P1 and the SSTA associated with the development of ENSO during P2 support the existence of ocean-to-atmosphere forcing, but the SSTA associated with the decay of ENSO shows the phenomenon of atmosphere-to-ocean forcing.

LOW FREQUENCY VARIABILITY OF INTERANNUAL CHANGE PATTERNS FOR GLOBAL MEAN TEMPERATURE DURING THE RECENT 100 YEARS

The TEEOF method that expands temporally is used to conduct a diagnostic study of the variation patterns of 1, 3, 6 and 10 years with regard to mean air temperature over the globe and Southern and Northern Hemispheres over the course of 100 years. The results show that the first mode of TEEOF takes up more than 50% in the total variance, with each of the first mode in the interannual oscillations generally standing for annually varying patterns which are related with climate and reflecting long-term tendency of change in air temperature. It is particularly true for the first mode on the 10-year scale, which shows an obvious ascending trend concerning the temperature in winter and consistently the primary component of time goes in a way that is very close to the sequence of actual temperature. Apart from the first mode of all time sections of TEEOF for the globe and the two hemispheres and the second mode of the 1-year TEEOF, interannual variation described by other characteristic vectors are showing various patterns, with corresponding primary components having relation with long-term variability of specific interannual quasi-periodic oscillation structures. A 2T test applied to the annual variation pattern shows that the abrupt changes for the Southern Hemisphere and the globe come closer to the result of a uni-element t test for mean temperature than those for the Northern Hemisphere do. It indicates that the 2Ttest, when carried out with patterns of multiple variables, seems more reasonable than the t test with single elements.

The Characteristics of Changes in Sunshine Hours of Jimusi Region in Sanjiang Plain

Based on the data of sunshine hours from the four stations in Jiamusi region in Sanjiang Plain from 1961 to 2011, we analysed the changing tend and the abnormal year of sunshine hours in this region. The results showed that annual sunshine hours reduced extremely significantly in three stations of Jiamusi region in Sanjiang Plain in recent 50 years, especially in spring and winter, and the decrease of annual sunshine hours was the largest in the middle of Jiamusi region, followed by the west, while it was the smallest in the east. On the contrary, annual sunshine hours increased extremely significantly in Fuyuan in the northeast. Monthly sunshine hours of this area changed from 134.1 to 246.0 h, and the maximum data appeared in March, and the next was June, while the minimum one appeared in December. Total monthly sunshine hours reached the maximum in Tangyuan in the west, followed by middle Jiamusi and Fujin in the east, while the minimum appeared in Fuyuan in the northeast. Sunshine hours showed an increasing tendency only in July and August. From 2001 to 2011, annual sunshine hours showed a decreasing tendency in Jiamusi, while there was an obvious increase in Tangyuan, Fujin and Fuyuan; in the 20th century, annual average sunshine hours from the 1980s to 1990s decreased by 267.7 h compared with that from 1960s to 1970s. Among them, sunshine hours were the fewest in the 1990s. In recent 50 years, there was an abnormal increase in annual sunshine hours in Jiamusi in 1975 and 1982; while there were abnormal decreases in Tangyuan and Fujin in 1993, Fujin in 1995, and Fuyuan in 1982 and 1987.