Some Aspects of the Characteristics of Monsoon Disturbances Using a Combined Barotropic－Baroclinic Model

ＳｏｍｅＡｓｐｅｃｔｓｏｆｔｈｅＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＭｏｎｓｏｏｎＤｉｓｔｕｒｂａｎｃｅｓＵｓｉｎｇａＣｏｍｂｉｎｅｄＢａｒｏｔｒｏｐｉｃ－ＢａｒｏｃｌｉｎｉｃＭｏｄｅｌ￥Ｎ．Ｒ．ＰａｒｉｊａａｎｄＳ．Ｋ．Ｄａｓｈ（ＣｅｎｔｒｅｆｏｒＡ...     

The Effect of Weak Shear－induced Motion on Brownian Coagulation of Aerosol Particles

ＴｈｅＥｆｆｅｃｔｏｆＷｅａｋＳｈｅａｒ－ｉｎｄｕｃｅｄＭｏｔｉｏｎｏｎＢｒｏｗｎｉａｎＣｏａｇｕｌａｔｉｏｎｏｆＡｅｒｏｓｏｌＰａｒｔｉｃｌｅｓＷｉｎｊｉｎｇｓｏｎｓ（Ｃ．Ｓ．Ｗｉｎ）（温景嵩）（Ｄｅｐａｒｔｍｅｎｔｏｆｐｈｙｓｉｃｓ，Ｎａｎｋａｉ...     

Multivariate Objective Analysis of Wind and Height Fields in the Tropics

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Diurnal Variation of Southwest Monsoon Rainfall at Indian Stations

ＤｉｕｒｎａｌＶａｒｉａｔｉｏｎｏｆＳｏｕｔｈｗｅｓｔＭｏｎｓｏｏｎＲａｉｎｆａｌｌａｔＩｎｄｉａｎＳｔａｔｉｏｎｓＪ．Ｍ．Ｐａｔｈａｎ（ＩｎｄｉａｎＩｎｓｔｉｔｕｔｅｏｆＴｒｏｐｉｃａｌＭｅｔｅｏｒｏｌｏｇｙ，Ｐａｓｈａｎ，Ｐｕｎｅ－４１１００８，...     

Regional and Synoptic-scale Features Associated with Inactive Periods of the Summer Monsoon over South China

ＲｅｇｉｏｎａｌａｎｄＳｙｎｏｐｔｉｃ－ｓｃａｌｅＦｅａｔｕｒｅｓＡｓｏｃｉａｔｅｄｗｉｔｈＩｎａｃｔｉｖｅＰｅｒｉｏｄｓｏｆｔｈｅＳｕｍｍｅｒＭｏｎｓｏｏｎｏｖｅｒＳｏｕｔｈＣｈｉｎａ①Ｃ．Ｈ．ＳｏａｎｄＪｏｈｎｎｙＣ．Ｌ．ＣｈａｎＤｅｐａｒｔｍｅ...     

Medium Range Prediction of Summer Monsoon Activities over India vis-a-vis Their Correspondence with the Observational Features

１．ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｉｎｉｔｉａｔｉｏｎｏｆｔｈｅｃｒｏｓｅｑｕａｔｏｒｉａｌｆｌｏｗｏｆｔｈｅＳｏｍａｌｉａｃｏａｓｔｄｕｒｉｎｇＭａｙｉｎｒｅｓｐｏｎｓｅｔｏｔｈｅｈｅａｔｉｎｇｏｖｅｒｔｈｅＳｏｕｔｈＡｓｉａｎｃｏｎｔｉｎｅｎｔｍ...     

Effect of the Interaction of Different Scale Vortices on the Structure and Motion of Typhoons

ＥｆｆｅｃｔｏｆｔｈｅＩｎｔｅｒａｃｔｉｏｎｏｆＤｉｆｆｅｒｅｎｔＳｃａｌｅＶｏｒｔｉｃｅｓｏｎｔｈｅＳｔｒｕｃｔｕｒｅａｎｄＭｏｔｉｏｎｏｆＴｙｐｈｏｏｎｓＣｈｅｎＬｉａｎｓｈｏｕ（陈联寿）（ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＭｅｔ６ｏｒｏｌｏｇｉｃ...     

Some Unique Characteristics of Atmospheric Interannual Variability in Rainfall Time Series over India and the United Kingdom

ＳｏｍｅＵｎｉｑｕｅＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＡｔｍｏｓｐｈｅｒｉｃＩｎｔｅｒａｎｎｕａｌＶａｒｉａｂｉｌｉｔｙｉｎＲａｉｎｆａｌｌＴｉｍｅＳｅｒｉｅｓｏｖｅｒＩｎｄｉａａｎｄｔｈｅＵｎｉｔｅｄＫｉｎｇｄｏｍ￥（Ａ．ＭａｒｙＳｅｌｖａｍ，Ｊ．...     

Solar Multi-Spectral Radiometric Observations of Atmospheric Optical Thickness over Passarlapudi Gas Well Blow-Out Site in India

ＳｏｌａｒＭｕｌｔｉ－ＳｐｅｃｔｒａｌＲａｄｉｏｍｅｔｒｉｃＯｂｓｅｒｖａｔｉｏｎｓｏｆＡｔｍｏｓｐｈｅｒｉｃＯｐｔｉｃａｌＴｈｉｃｋｎｅｓｏｖｅｒＰａｓａｒｌａｐｕｄｉＧａｓＷｅｌＢｌｏｗ－ＯｕｔＳｉｔｅｉｎＩｎｄｉａＧ．Ｐａｎｄｉｔｈｕｒａｉａｎ...     

Climatology and Interannual Variability of the Southeast Asian Summer Monsoon

ＣｌｉｍａｔｏｌｏｇｙａｎｄＩｎｔｅｒａｎｎｕａｌＶａｒｉａｂｉｌｉｔｙｏｆｔｈｅＳｏｕｔｈｅａｓｔＡｓｉａｎＳｕｍｍｅｒＭｏｎｓｏｏｎＫ．－Ｍ．ＬａｕＬａｂｏｒａｔｏｒｙｆｏｒＡｔｍｏｓｐｈｅｒｅｓ，Ｃｏｄｅ９１３，ＮＡＳＡ－ＧｏｄｄａｒｄＳｐａｃ...     

Medium-range oscillations in the summer tropical easterlies at 200 hPa

By the use of space-time spectral analysis and band-pass filter, some of the features of the medium-range Oscillations in the summer tropical easterlies (10oS-20o) at 200 hPa are investigated based on a two-year (1980 and 1982) wind (u, v) data set for the period from May to September. Space-time power spectral analysis shows that the total energy of the westward moving waves was the largest and that of the standing waves and eastward moving waves was relatively small in the 200 hPa easterlies; the total energy of the eastward moving waves was at minimum at 10oN. Three kind of the medium-range oscillations with about 50 day, 25 day and quasi-biweekly periods were found in the easterlies, which all show a remarkable interannual variation and latitudinal differences in these two years. The wave energy of zonal wind is mainly associated with the planetary waves (1-3), which all may make important contributions to the 50 day and 25 day oscillations in different years or different latitudes. The quasi-biweekly oscillation is mainly related to the synoptic waves (4-6). In equatorial region, the 50 day oscillation was dominant with a eastward phase propagation in 1982 while the dominant oscillation in 1980 was of 25day period with a westward phase propagations in 1980. Both of them are of the mode of zonal wavenumber 1. Strong westward 50 day oscillation was found in 10oN-20oN in these two years. Regular propagations of the meridional wind 50 day oscillation were also found in the easterlies.The 50 day and 25 day oscillation of zonal wind all demonstrate southward phase propagation over the region of the South Asia monsoon and northward phase propagation near interational date line, where are the climatic mean position of the tropical upper-tropospheric easterly jet and the tropical upper tropospheric trough (TUTT), respectively.     

Temperature changes over Eurasia during the late summer of 1979

During the late summer of 1979, massive changes occurred in the distribution of temperature over Eur asia north of 15oN. At 300 hPa, zonal mean temperature averaged over Eurasia along 20o－25oN de-creased sharply around 23 August. An abrupt decrease in 300 hPa zonal mean temperature also occurred over extensive mid-latitude zones (40o－55oN) around 18 August, i. e., about 5 days prior to the monsoon withdrawal over South Asia.The intensity and location of N－S oriented, vertical overturning underwent significant changes over Eurasia during the transition from summer to fall. Near 20o－25oN, zonal mean updrafts weakened con-siderably during the transition period (18－27 August). Around 45oN, zonal mean downdrafts and the asso-ciated cooling (radiative) rate increased considerably during the transition period.Near 15oN, 300 hPa zonal mean temperature fluctuated nearly periodically with an approximate 40-day period. These fluctuations appear to be associated with a small imbalance between 40-day filtered adiabatic cooling (heating) and diabatic heating (cooling).     

Topographically forced three-wave quasi-esonant and non-resonant interactions among barotropic rossby waves on an infinnite beta-plane

In this paper, we first apply the assumption h = εh′ of topographic variation (h is the nondimensional topographic height and is a small parameter) to obtain nonlinear equations describing three-wave quasi-resonant and non-resonant interactions among Rossby waves for zonal wavenumbers 1—3 over a wavenumber-two bottom topography (WTBT). Some numerical calculations are made with the fourt-order Rung-Kutta Scheme. It is found that for the case without topographic forcing, the period of three-wave quasi-resonance (TWQR) is found to be independent of the zonal basic westerly wind, but dependent on the meridional wavenumber and the initial amplitudes. For the fixed initial data, when the frequency mismatch is smaller and the meridional wavelength is moderate, its period will belong to the 30–60-day period band. However, when the wavenumber-two topography is included, the periods of the forced quasi-resonant Rossby waves are also found to be strongly dependent on the setting of the zonal basic westerly wind. Under the same conditions, only when the zonal basic westerly wind reaches a moderate extent, intraseasonal oscillations in the 30–60-day period band can be found for zonal wavenumbers 1–3. On the other hand, if three Rossby waves considered have the same meridional wavenumber, three-wave non-resonant interaction over a WTBT can occur in this case. When the WTBT vanishes, the amplitudes of these Rossby waves are conserved. But in the presence of a WTBT, the three Rossby waves oscillate with the identical period. The period, over a moderate range of the zonal basic westerly wind, is in the intraseasonal, 30–60-Day range.     

热带和中高纬地区季节内振荡的特征及其动力学诊断

使用5年低阶全球谱模式资料,对中高纬大气和热带大气季节内振荡的动力学性质和传播特征进行了诊断研究。分析发现模式再现了大气中季节内振荡在热带和中高纬地区的传播特性以及它们之间的差异。热带大气30—60天振荡在速度势场上表现为纬向—波结构和行波特性,而在散度风场上反映了赤道西太平洋—印度洋东西向偶极子型的振荡。中高纬大气30—60天振荡表现为定常波位相和振幅的变化,即波包络的传播特征。它与中高纬地区遥相关型的转换有关,通过遥相关位相和振幅的变化,不仅完成了热带和中高纬地区之间以及热带不同区域之间的能量输送,而且通过这种能量输送过程把南、北半球中高纬地区季节内振荡联系起来。      

春季热带地区OLR低频振荡及其与长江中下游连阴雨

本文应用NOAA卫星接收的1975—1983年向外长波辐射(OLR)资料研究了春季热带地区低频振荡的基本特征,得出东半球热带地区盛行周期为30天左右的低频振荡,这种振荡最显著的区域在0—10°S、70—90°E的印度洋地区。文章阐述了过渡季节这种低频振荡的经向和纬向传播特征。 本文还进一步指出,在热带低频振荡的不同阶段,ITCZ、北半球副热带以及西风带环流系统也呈现出显著的周期变化,并查证了低频振荡作为长江中下游连阴雨和连晴过程的背景事实。因此本研究工作也为长江中下游连阴雨和连晴天气的中、长期可预报性提供     

Nonlinear kinetic energy interactions and their contributions to the growth and decay of atmospheric waves in the lower troposphere during summer monsoon, 1979

Summary Lower tropospheric (1000–500) hPa kinetic energy (KE), temporal variations of KE and nonlinear KE transfer of rotational and divergent flows and energy conversion between them, partitioning further into stationary and transient components in the Fourier spectral domain and the mechanism for the evolution of significant transient waves for the month July 1979 in the latitudinal belt 10° S–30° N are studied.Divergent zonal and eddy KE show their maxima at the lowest level 1000 hPa. Lower tropospheric monsoon motion provides a non-divergent level close to 850 hPa. The daily flow patterns bear little resemblence to the climatology over tropics at 500 hPa. Although the transient mode of synoptic scale waves is stronger than that of planetary scale waves they are comparable. Analysis of energetics over global tropics can get signature of transient activities embedded in the large scale system. Summer momentum flux in the lower troposphere is essentially associated with stationary planetary and transient synoptic scale waves. Waves 1, 3 and 6 are the most preferred transient waves. Divergent to rotational KE conversion is the most dominating mechanism for the maintenance of planetary and synoptic scale waves. All categories of waves contribute towards the maintenance of zonal flows. The primary source of energy for transient synoptic scale waves is the transient divergent rotational KE transfer whereas the interaction between zonal stationary and transient wave is likely to be secondary source. Transient KE and all transient interactions, stationary KE and all stationary interactions are found to be strongest at 500 hPa and 850 hPa respectively. Growth and decay of transient waves 1 and 3 are mainly controlled by divergent-rotational KE conversions whereas those of transient wave 6 are controlled by KE transfer due to zonal-wave interaction.With 13 Figures     

Space-time structures of earthquakes

Using the United States Geological Survey global daily data sets for 31 years, we have tabulated the earthquake intensities on a global latitude longitude grid and represented them as a finite sum of spherical harmonics. An interesting aspect of this global view of earthquakes is that we see a low frequency modulation in the amplitudes of the spherical harmonic waves. There are periods when these waves carry larger amplitudes compared to other periods. A power spectral analysis of these amplitudes clearly shows the presence of a low frequency oscillation in time with a largest mode around 40 days. That period also coincides with a well-know period in the atmosphere and in the ocean called the Madden Julian Oscillation. This paper also illustrates the existence of a spatial oscillation in strong earthquake occurrences on the western rim of the Pacific plate. These are like pendulum oscillations in the earthquake frequencies that swing north or south along the western rim at these periods. The spatial amplitude of the oscillation is nearly 10,000 km and occurs on an intraseasonal time scale of 20–60 days. A 34-year long United States Geological Survey earthquake database was examined in this context; this roughly exhibited 69 swings of these oscillations. Spectral analysis supports the intraseasonal timescale, and also reveals higher frequencies on a 7–10 day time scale. These space-time characteristics of these pendulum-like earthquake oscillations are similar to those of the MJO. Fluctuations in the length of day on this time scale are also connected to the MJO. Inasmuch as the atmospheric component of the MJO will torque the solid earth through mountain stresses, we speculate the MJO and our proposed earthquake cycle may be connected. The closeness of these periods calls for future study.     

永暑礁夏季风期间海气要素的谱特征

本文通过南沙群岛永暑礁海洋气象观测站1989年夏季（5—8月）的海气要素功率谱和交叉谱分析，得出气象要素变化普遍存在30—40天和15.38天两种低频波；对于这两种低频波，海平面气压与海面风速两要素有显著的相关，风速的变化落后于气压0.34天（30—40天振荡）和0.68天（准双周振荡）；低云量与风速也有显著的相关，30—40天振荡风速落后于低云量0.86天，准双周振荡风速超前于云量0.37天。表层水温也具有准双周振荡规律，与低云量有显著相关，且落后低云量0.47天。     

长江中游和下游夏季降水季节内振荡的差异

利用1979~2013年中国站点逐日降水资料和NCEP/NCAR再分析资料,对长江中下游夏季降水的季节内振荡最显著周期进行了分析研究。结果表明长江中游最显著周期为10~30天,长江下游最显著周期为30~60天。为了揭示这种差异产生的物理原因,进一步利用位相合成的方法对这两个区域不同周期的季节内振荡降水、高低空风场和高度场以及垂直结构和水汽等循环过程的演变特征进行分析。在200 hPa环流场上,长江中游的降水主要受到高纬度自西向东传播的波列影响,而长江下游的降水与鄂霍次克海的高度场的变化相关。在风场的垂直涡度和散度的位相结构演变过程中,10~30天的垂直涡度和散度有自北向南的移动,30~60天的垂直涡度和散度在长江以南地区有自南向北的传播。水汽输送的位相发展过程表明,长江中游的水汽分别来自于南海的向北输送和长江以北地区向南的水汽输送;长江下游地区的水汽则主要来自于热带东印度洋经孟加拉湾的向东输送并在南海的北向输送,以及西太平洋水汽向西输送到南海再向长江下游的输送。从高层大尺度环流场和整层积分的水汽通量输送上解释了长江中游10~30天降水的自北向南移动,和长江下游30~60天降水自南向北传播的原因。