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41.
利用国家气象信息中心提供的1951~2004年全国160个测站月平均降水资料和欧洲中心提供的ERA-40再分析资料,对近50多年东北地区夏季降水、东北冷涡与前期北半球环状模和海温的关系进行了统计分析,定义了一个夏季(6~8月)东北冷涡强度指数(NECVI)。结果表明:NECVI能够较好表征东北低涡的气候效应;夏季东北冷涡强度与降水存在显著的正相关,东北冷涡强年,降水偏多,前期2月北半球环状模(NAM)偏弱;东北冷涡偏弱年,降水偏少,前期2月NAM偏强。此外,夏季东北冷涡与前期的中国近海海温存在显著的负相关,前期NAM和中国近海海温的异常可以作为夏季东北冷涡异常的一个前兆信号,进而为东北地区夏季降水异常的预测提供参考依据。 相似文献
42.
43.
本研究采取苗种强化培育、坑道培育大规格苗种、湖间带鲍参混养等相结合,并配套适当技术措施,促进鲍快速生长,缩短养殖周期一年左右,提高成活率15%以上,增加经济效益200%左右,形成鲍高效养殖的较理想模式。 相似文献
44.
The temporal and spatial distributions of Antarctic sea ice play important roles in both the generation mechanisms and the signal characteristics of microseisms. This link paves the way for seismological investigations of Antarctic sea ice. Here we present an overview of the current state of seismological research about microseisms on Antarctic sea ice. We first briefly review satellite remote-sensing observations of Antarctic sea ice over the past 50 years. We then systematically expound upon the generation mechanisms and source distribution of microseisms in relation to seismic noise investigations of sea ice, and the characteristics of Antarctic microseisms and relationship with sea ice variations are further analyzed. We also analyze the continuous data recorded at seismic station BEAR in West Antarctica from 2011 to 2018 and compare the microseism observations with the corresponding satellite remote-sensing observations of Antarctic sea ice. Our results show that:(1) the microseisms from the coastal regions of West Antarctica exhibit clear seasonal variations, SFM with maximum intensities every April-May and minimum intensities around every October-November; while DFM intensities peak every February-March, and reach the minimum around every October. Comparatively, the strong seasonal periodicity of Antarctic sea ice in better agreement with the observed DFM; and (2) microseism decay is not synchronous with sea ice expansion since the microseism intensity is also linked to the source location, source intensity (e.g., ocean storms, ocean wave field), and other factors. Finally, we discuss the effect of Southern Annular Mode on Antarctic sea ice and microseisms, as well as the current limitations and potential of employing seismological investigations to elucidate Antarctic sea ice variations and climate change. 相似文献
45.
46.
利用1961—2013年NCEP/NCAR再分析资料和Had ISST月平均海表面温度资料,分析了夏半年热带太平洋中部型海温异常与热带印度洋海盆模(Indian Ocean Basin M ode,IOBM)的特征,并研究了不同位相配置时二者对同期中国东部气候的共同影响。结果表明:1)太平洋中部型海温异常指数与印度洋海盆模指数几乎相互独立。太平洋中部型海温异常与IOBM同位相变化(记为PPNN事件)和反位相变化(记为PNNP事件)时,热带印太地区海温异常分别呈三级型和偶极型分布。2)不同位相配置对中国东部地区降水异常的影响及其影响机制存在显著差异:当发生PPNN事件时,水汽从海洋性大陆(Maritime Continent,MC)地区向江淮流域输送;热带海温异常引起大气产生Gill型响应,维持了中国东部的环流异常;M C地区通过经向三圈异常垂直环流引起江淮流域降水异常增多。发生PNNP事件时,Gill型环流响应中心西移,长江流域降水偏少,水汽辐散;同时MC地区对流层低层准定常Rossby波能传播也有利于长江流域扰动的维持。这些结果对深刻认识中国东部地区夏半年降水异常成因和印度洋/太平洋海温异常不同分布的作用具有重要意义。 相似文献
47.
Evidence has been found for the teleconnection of Indian Ocean Dipole mode (IOD) events in the southern high latitude sea
surface pressure field, although the mechanisms that might lead to such far-reaching links remain unresolved. Based on the
teleconnection pattern between IOD and the climate anomaly in the upper troposphere, we propose one such mechanism here: the
energy propagation theory of the atmospheric planetary wave. Ray traces of the atmospheric planetary waves suggest that the
energy propagation of the waves could be responsible for the teleconnection between IOD and tropospheric climate anomalies
in southern high latitudes. 相似文献
48.
Long-Term Variability of North Pacific Subtropical Mode Water in Response to Spin-Up of the Subtropical Gyre 总被引:1,自引:0,他引:1
The Meteorological Research Institute's ocean general circulation model (MRI-OGCM) has been used to investigate the temperature
variability of the North Pacific Subtropical Mode Water (NPSTMW) over a time series longer than 5 years via the spin-up of
the subtropical gyre. Besides an interannual variation, the wintertime sea surface temperature in the area where the NPSTMW
is formed, and the temperature of the NPSTMW itself, both change remarkably in a >5-year time scale. An analysis of heat budgets
showed that the long-term changes in NPSTMW temperature are due mainly to a leading advection of heat by the Kuroshio Extension
and compensating surface heat flux. As a result of a dynamical adjustment to the wind stress fields, the transports of the
Kuroshio and the Kuroshio Extension increased in the mid 1970s with a lag of 3 years after the wind stress curl in the central
North Pacific. The increased heat advection by the Kuroshio Extension induces a warming in the mixed layer in the NPSTMW formation
area, followed by a warming of the NPSTMW itself. Both these warming actions increase the heat release to the atmosphere.
These results imply that the surface heat flux over the Kuroshio Extension area varies in response to the change in the ocean
circulation through the spin-up of the subtropical gyre.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
49.
Vinu Valsala 《Journal of Oceanography》2008,64(4):479-494
The combined and individual responses of the first and second baroclinic mode dynamics of the tropical Indian Ocean to the
well-known Indian Ocean Dipole mode (IOD) wind anomalies are investigated. The IOD forced first baroclinic Rossby waves arrive
at the western boundary in three months, while the reflected component from the eastern boundary with opposite phase arrives
in five to six months, both carry input energy to the west. The inclusion of the second baroclinic mode slows down the wave
propagation by mode coupling and stretches the energy spectrum to a relatively longer time scale. The total energy exists
in the equatorial wave guide for at least five months from the forcing, as much as 10% of that of the atmospheric input, which
mainly dissipates at the western boundary. The individual responses of the ocean to IOD interannual wind anomaly show that
the significant modes of oceanic anomalies are confined to a wave guide of 10° on either side of the equator. 相似文献
50.
On Multi-Timescale Variability of Temperature in China in Modulated Annual Cycle Reference Frame 总被引:2,自引:0,他引:2
The traditional anomaly (TA) reference frame and its corresponding anomaly
for a given data span changes with the extension of data length. In this study, the
modulated annual cycle (MAC), instead of the widely used climatological mean annual
cycle, is used as an alternative reference frame for computing climate anomalies to
study the multi-timescale variability of surface air temperature (SAT) in China based
on homogenized daily data from 1952 to 2004. The Ensemble Empirical Mode Decomposition
(EEMD) method is used to separate daily SAT into a high frequency component, a MAC
component, an interannual component, and a decadal-to-trend component. The results
show that the EEMD method can reflect historical events reasonably well, indicating
its adaptive and temporally local characteristics. It is shown that MAC is a temporally
local reference frame and will not be altered over a particular time span by an extension
of data length, thereby making it easier for physical interpretation. In the MAC reference
frame, the low frequency component is found more suitable for studying the interannual to
longer timescale variability (ILV) than a 13-month window running mean, which does not
exclude the annual cycle. It is also better than other traditional versions (annual or
summer or winter mean) of ILV, which contains a portion of the annual cycle. The analysis
reveals that the variability of the annual cycle could be as large as the magnitude of
interannual variability. The possible physical causes of different timescale variability
of SAT in China are further discussed. 相似文献