共查询到10条相似文献,搜索用时 78 毫秒
1.
Acacia S. Pepler Lisa V. Alexander Jason P. Evans Steven C. Sherwood 《Climate Dynamics》2016,46(1-2):123-133
Southeast Australia is a region of high rainfall variability related to major climate drivers, with a long-term declining trend in cool-season rainfall. Projections of future rainfall trends are uncertain in this region, despite projected southward shifts in the subtropical ridge and mid-latitude westerlies. This appears to be related to a poor representation of the spatial relationships between rainfall variability and zonal wind patterns across southeast Australia in the latest Coupled Model Intercomparison Project ensemble, particularly in the areas where weather systems embedded in the mid-latitude westerlies are the main source of cool-season rainfall. Downscaling with regional climate models offers improvements in the mean rainfall climatology, and shows some ability to correct for poor modelled relationships between rainfall and zonal winds along the east coast of Australia. However, it provides only minor improvements to these relationships in southeast Australia, despite the improved representation of topographic features. These results suggest that both global and regional climate models may fail to translate projected circulation changes into their likely rainfall impacts in southeast Australia. 相似文献
2.
Relationship between rainfall and lightning over central Indian region in monsoon and premonsoon seasons 总被引:2,自引:0,他引:2
Lightning activity and rainfall over the central Indian region (lat, 15.5° N to 25.5° N and lon, 75° E to 85° E) from the TRMM satellite have been analyzed. Ten years' data of monthly lightning and hourly averaged monthly rainfall from 1998 to 2007 have been used for analysis, which shows quite different relationships between lightning and rainfall in monsoon and premonsoon seasons in this region. Very good positive correlation is observed between rainfall and lightning during the premonsoon period, however, in the monsoon period a correlation between them is not so good. The different relationship between lightning and rainfall in the monsoon and premonsoon has been attributed to the low updraft during the monsoon period due to low cloud base height and low aerosol concentration during this period. This analysis shows that deep electrified convective systems do form over the central Indian region during active monsoon periods; however the relationship between convective rainfall and lightning frequency during this period is not as consistent as during the premonsoon period. 相似文献
3.
本研究将云闪随机放电参数化方案植入到偶极电荷结构中,固定主负电荷区的参数和位置,通过不断调整上部正电荷区的参数(电荷浓度和水平范围)和位置以此来模拟不同高度处起始的正极性云闪,进而探讨正云闪放电特征与雷暴电荷分布之间的关系。模拟结果表明在偶极电荷结构中,抬升上部正电荷区的高度,能够产生如观测所示的高海拔正云闪,不同于普通正云闪起始于向上传播的负先导及水平或稍向下延伸的正先导,高海拔处起始的正云闪以大范围向下传播的正先导及水平或轻微向上延伸的负先导为主要特征。随着上部正电荷区位置的抬升,正云闪起始高度也随之升高,当上部正电荷区抬升到一定高度后(本研究中当上部正电荷区下边界超过12 km),云闪通常起始于主正电荷区内,且上部正电荷区的浓度以及水平半径对于云闪的起始高度没有显著影响。此外,云闪正、负先导通道的长度与电荷区的浓度、水平半径以及起始点和负、正电荷区之间的距离存在显著的正相关关系。 相似文献
4.
With the EOF of reanalysis data being analyzed, a northern-
southern dipole is found in the upper troposphere geopotential height
field of over the Asian-Australian monsoon region in the winter of the
Northern Hemisphere (NH), which is defined as Asian-Australian dipole
(AAD) in this study. Its intensity index is defined as AADI.
Correlation and synthetic analysis illustrate that AADI is closely
related to the weather and climate of Asian-Australian region in boreal
winter. The index can reflect the simultaneous anomalies of temperature
and precipitation on interannual and decadal scales in the boreal
winter of Asian-Australian region. The superposition of the decadal and
interannual signals is significant for the relationship between the
AADI and climate change. The index can be used as an indicator of
intensity of the Asian-Australian monsoon. In the years of strong AADI,
the East Asia major deep trough is stronger, the Subtropical High is
weaker and the Alaska ridge and the westerly jet are stronger than
those in normal years. Enhanced meridional circulation between high and
low latitudes exists in the years of strong AADI. These relationships
reflect the intrinsic link between the anomalies in the upper
troposphere geopotential height and climate in the Asian-Australian
region. 相似文献
5.
The Northern Path of Asian Dust Transport from the Gobi Desert to North America 总被引:1,自引:0,他引:1 下载免费PDF全文
CHEN Ke-Yi 《大气和海洋科学快报》2010,3(3):155-159
The aerosol index (AI) of the Total Ozone Mapping Spectrometer (TOMS) satellite data (1979 2001) was analyzed to reveal the climatological long-distance path of dust transport from Asia to North America. The AI in the west coast of the United States is highly correlated with that in the Gobi desert. Additionally, from the TOMS satellite images, it can be seen that very strong plumes advect from Asia to the west coast of North America in typical dust storm cases. When applying the sourcereceptor relationship to detect the northern dust transport path between the Gobi source region and the west coast of the United States receptor region, it is evident that the dust plume can be transported northward beyond 60°N from its source region and that it takes 5 to 6 days to reach the west coast of the United States. The cross correlation technique shown in this work is a useful tool that can be applied in other regions to give useful insights into relationships between major dust sources and downwind receptor locations by using remotely sensed dust observations. 相似文献
6.
根据台湾省及东南亚地区高空天气图资料及探空资料,分析东风喷射气流之平均位置和特性,并就青藏高原、副热带西风喷射气流和东风喷射气流之关系,讨论东风喷射气流之成因以及对北半球天气和气候之影响,东风喷射气流之南北两侧存在着极强烈的混切现象,这种温切现象不但与东风喷射气流有关,而且对高空民航机之飞航安全有极重大的影响。 相似文献
7.
我国地闪活动和降水关系的区域差异 总被引:5,自引:2,他引:3
利用我国部分地区2005年的地闪定位资料和气象台站雨量观测资料,由南向北选取我国四个不同气候带区域(区域1~4),分析了这些区域的地闪活动与降水的相关关系。结果表明,由南向北及气候特征由潮湿趋于干旱的区域的地闪活动和降水相关性增强。闪电活动与有闪电降水(即对应闪电的降水)日变化的线性相关系数在由南向北的区域分别为0.56、0.46、0.56、0.80,旬变化的线性相关系数分别为0.73、0.86、0.89、0.92,月变化的线性相关系数分别为0.74、0.88、0.965、0.99;较干旱的区域3和区域4的地闪活动与所有降水的时间序列有较强的相关性,其线性相关系数日变化分别为0.31、0.41,旬变化分别为0.84,0.52,月变化分别为0.93、0.80;地闪与降水的空间线性关系相对复杂,但也表现出由南向北和气候趋于干旱对应关系增强的特征,区域4的闪电和降水相关性达到0.54。分析区域中较干旱地区的雷暴活动产生机制(主要受热力抬升作用)相比潮湿地区(既受热力抬升作用,又受大尺度系统相互作用)更为单一,这可能是干旱地区的闪电活动与降水有较好相关的重要原因。 相似文献
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Winter precipitation isotope slopes of the contiguous USA and their relationship to the Pacific/North American (PNA) pattern 总被引:1,自引:0,他引:1
This study compares the synoptic-dynamic relationship between two phases of the Pacific/North American (PNA) pattern and winter precipitation isotopes at 73 sites across the contiguous USA. We use the spatial pattern of isotope slope—the rate of changes in precipitation isotope ratios with distance—to identify features in the seasonal precipitation isotope fields related to climatic patterns, PNA positive and PNA negative. Our results show relationships between zones of high isotope slopes and the spatial position of the polar jet stream and juxtaposition of air masses associated with the PNA pattern. During a positive PNA winter, zones of high isotope slope in the eastern USA shift southward. This change is coincident with a southward displacement of the polar jet stream in this region, which leads to a greater frequency of polar air masses and 18O-depleted isotope values of precipitation in the region. In the western USA, zones of high slope shift eastward during the positive PNA winter, associated with more frequent penetration of tropical air masses that bring 18O-enriched precipitation to the region. Differences in δ18O/temperature relationships between the PNA-positive and -negative winters and contrasting δ18O/temperature behaviors in the eastern and western USA provide support for the role of variation in moisture source and transport as a control on the isotopic patterns. These findings highlight the importance of synoptic climate driven by PNA pattern in determining the spatial patterns of precipitation isotopes and provide constraints on paleo-water isotope interpretation and modern isotope hydrological processes. 相似文献