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21.
南海季风爆发的年代际转折与东亚副热带夏季降水的关系 总被引:1,自引:0,他引:1
利用1979—2016年NCEP再分析资料, 分析了南海季风爆发的年代际转折与东亚副热带夏季降水的关系。结果表明:南海夏季风爆发时间在1993/1994年出现年代际转变, 1979—1993年爆发时间相对偏晚, 夏季华南降水偏少, 长江中下游至日本南部降水偏多; 1994—2016年爆发时间偏早, 夏季华南降水偏多, 长江中下游到日本南部降水偏少。南海季风爆发时间年代际转折与夏季东亚副热带降水关系可能受到菲律宾越赤道气流强度的调控, 季风爆发时间与菲律宾越赤道气流有显著正相关, 且均在1993/1994年间存在年代际转变。在1994—2016(1979—1993)年南海夏季风爆发偏早(晚), 菲律宾越赤道气流偏弱(强), 澳大利亚北部有偏北(南)风异常, 将暖池的热量往赤道输送, 使得赤道对流增强(减弱), 产生异常上升(下沉)运动汇入Hadley环流上升支, 增强(减弱)的Hadley环流导致下沉主体偏北(南), 促使副高脊线偏北(南), 从西北太平洋(孟加拉湾)往华南地区(江淮到日本南部)输送水汽增强, 所以华南(江淮到日本南部)夏季降水偏多。 相似文献
22.
Having recognized that it is the tropospheric temperature (TT) gradient rather than the land–ocean surface temperature gradient that drives the Indian monsoon, a new mechanism of El Niño/Southern Oscillation (ENSO) monsoon teleconnection has been unveiled in which the ENSO influences the Indian monsoon by modifying the TT gradient over the region. Here we show that equatorial Pacific coralline oxygen isotopes reflect TT gradient variability over the Indian monsoon region and are strongly correlated to monsoon precipitation as well as to the length of the rainy season. Using these relationships we have been able to reconstruct past Indian monsoon rainfall variability of the first half of the 20th century in agreement with the instrumental record. Additionally, an older coral oxygen isotope record has been used to reconstruct seasonally resolved summer monsoon rainfall variability of the latter half of the 17th century, indicating that the average annual rainfall during this period was similar to that during the 20th century. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
23.
Ghulam Jeelani Rouf Ahmad Shah Rajendrakumar D. Deshpande Ashok P. Dimri Suraj Mal Anupam Sharma 《水文研究》2021,35(11):e14406
Western disturbances (WDs) and Indian summer monsoon (ISM) led precipitation play a central role in the Himalayan water budget. Estimating their contributions to water resource is although a challenging but essential for hydrologic understanding and effective water resource management. In this study, we used stable water isotope data of precipitation and surface waters to estimate the contribution of ISM and WDs to the water resources in three mountainous river basins - Indus, Bhagirathi and Teesta river basins of western, central and Eastern Himalayas. The study reveals distinct seasonality in isotope characteristics of precipitation and surface waters in each river basin is due to changes in moisture source, hydrometeorology and relief. Despite steady spatial variance in the slope and intercept of regression lines from the Teesta to Indus and the Bhagirathi river basins, the slope and intercept are close to the global meteoric water line and reported local meteoric water line of other regions in the Himalayas and the Tibetan Plateau. The two-component end-member mixing method using d-excess as tracer were used to estimate the contribution from ISM and WD led precipitation to surface water in aforementioned river basins. The results suggest that the influence of the ISM on the water resources is high (>72% to annual river flow) in Teesta river basin (eastern Himalayas), while as the WDs led precipitation is dominantly contributing (>70% average annual river flow) to the surface waters in the Indus river basin (western Himalayas). The contribution of ISM and WD led precipitation in Bhagirathi river basin is 60% and 40%, respectively. The findings demonstrate that the unusual changes in the ISM and WD moisture dynamics have the potential to affect the economy and food security of the region, which is dependent on the availability of water resources. The obtained results are of assistance to policy makers/mangers to make use of the information for better understanding hydrologic response amid unusual behaviour of the dual monsoon system over the region. 相似文献
24.
Abstract Ecohydrology is the science that studies the mutual interaction between the hydrological cycle and ecosystems. Such an interaction is especially intense in water-controlled ecosystems, where water may be a limiting factor, not only because of its scarcity, but also because of its intermittent and unpredictable appearance. Soil moisture is the key variable modulating the complex dynamics of the climate-soil-vegetation system and controlling the spatial and temporal patterns of vegetation. In this note the authors' perspective to the field is discussed and some open questions are outlined. 相似文献
25.
China's Loess Plateau was formed under special conditions. The tectonic movement, topographical characteristics, and monsoon patterns combined to create a favourable environment for the accumulation of thick loessic deposits. The Loess Plateau itself is part of the ‘Monsoon Triangle’ of China, a region very susceptible to climatic changes. Throughout the Upper Pleistocene the palaeoenvironment on the Loess Plateau alternated from steppe, to deciduous forest and coniferous forest, in response to shifts in the atmospheric circulation. Three monsoon patterns appear to be indicated: (1) a full glacial monsoon pattern (18000–15000 yr BP) which induced a cold and dry climate favouring loess accumulation in steppe conditions; (2) an interglacial monsoon pattern (last interglacial and Holocene) in which a warm humid climate prevailed with deciduous forests, leaving palaeosols interbedded within the loess sequence; and (3) a transitional or interstadial monsoon pattern (50 000–23 000 yr BP) in which the climate was cold and humid in the Loess Plateau, encouraging the development of coniferous forest. 相似文献
26.
Ionospheric scintillation observations of VHF radio signals from FLEETSAT satellite (73°E longitude) at Bhopal from January
1990 to December 1990 have been used to study the characteristic variations of scintillation activity. It is found that scintillation
occurrence is essentially a night-time phenomenon and day-time scintillations are very rare. Annual average nocturnal variation
of percentage occurrence of scintillations shows maximum at around 2100–2200 hours LT. Seasonally, scintillations are most
prominent during equinoxes and least during summer. Geomagnetic disturbances tend to decrease the occurrence of scintillations
in the pre-midnight period. 相似文献
27.
EvaluationofForecastPerformanceofanEconomicalExplicitTimeIntegrationSchemeinaLimitedAreaModeloverIndianRegionA.Bandyopadhyaya... 相似文献
28.
29.
The paper deals with the application of the telluric method and of magnetotelluric soundings including experimental and model
data on the localization of tectonic disturbances in connection with the selection of appropriate sites for nuclear plants. 相似文献
30.
斜压半地转模式中的非频散周期解 总被引:2,自引:0,他引:2
给出了3个通量矢量,从而将非线性平流项表示为3个通量矢量的旋度和散度,它们分别对纬向风和经向风的低频加速产生贡献。经过卷积运算,还建立了低频变化的动力学模型。给出了通量矢量E.、G1.、G2.等的空间分布及其相应的流函数与势函数的水平分布和时间演变,从而指出,瞬变扰动间的相互作用对流动具有低频加速作用。 相似文献