共查询到20条相似文献，搜索用时 406 毫秒
1.
本年四月十六日中央研究院评议会举行第二届年会时,以我国科学研究应特别注重於国家及社会实际急需之问题,并以此事徵询气象研究所之意见。炯因凝定气象方面对於目下我国社会急需建设之六项问题,送交评议会,再由中央研究院根据意见书之内容,向有关系各方建议。嗣得各方覆函,大体均表示赞同,且有一部分已见之实行矣。兹将当时送达评议会之意见书披露於后。 相似文献
2.
FAN Ke 《大气和海洋科学快报》2009,2(3):159-164
To examine the zonal asymmetry of the Antarctic oscillation （AAO）, different portions of the AAO from June to October （JJASO） in the interannual variability of the Atlantic tropical hurricanes number （ATHN） are documented in this research. It follows that the AAO in the Western Hemisphere （AAOWH） is positively correlated with the ATHN, at 0.36 during the period of 1871-1998 and 0.42 during the period of 1949-98. After removing the linear regressions on the Southern Oscillation Index （SOI） in all time series, the above correlation coefficients are 0.25 and 0.30, respectively. The underlying mechanisms are studied through analyses of the atmospheric general circulation variability associated with the AAOWH. It turns out that the positive （negative） phase of JJASO AAOWH corresponds with several factors： decreased （increased） vertical zonal wind shear magnitude, low-level anomalous convergence （divergence）, high-level anomalous divergence （convergence）, and warmed （cooled） sea surface temperature in the tropical Atlantic. Therefore, the positive （negative） phase of JJASO AAOWH is favorable （unfavorable） to the tropical hurricane genesis. 相似文献
3.
In this study, the TOMS/SBUV (Total Ozone Mapping Spectrometer/Solar Backscatter Ultraviolet Radiometer) data and SAGE (Stratospheric Aerosol and Gas Experiment) II data were employed to calculate the monthly total zonal ozone deviations over the Tibetan Plateau and the 150?C50-hPa zonal ozone variations. The results show that there is a significant correlation between the two, with a correlation coefficient of 0.977. From 150 to 50 hPa, the ozone valley over the Tibetan Plateau (OVTP) becomes the strongest based on the SAGE II data, and the South Asian high (SAH) is the most active according to the 40-yr reanalysis data of the European Centre for Medium-Range Weather Forecasts (ERA40), so a correlation between the SAH and the OVTP may exist. The WACCM3 (Whole Atmosphere Community Climate Model version 3) simulation results show that both SAH and OVTP could still present within 150?C50 hPa with reduced strength even when the height of the Tibetan Plateau was cut down to 1500 m. It is also shown that the seasonal variation of SAH would result in a matched seasonal variation of the OVTP, which suggests a meaningful effect of SAH on the OVTP. Meanwhile, it is found that the atmospheric circulation would impose different effects on the OVTP, depending on the SAH??s evolution stages and movement directions. At 150?C50 hPa, as the SAH approaches the plateau, the SAH zonal (meridional) transport would make the OVTP deeper (shallower), while the vertical transport of ozone produces a deeper (shallower) OVTP at the lower (higher) level; the combined dynamic effects lead to a weakened OVTP. When the SAH stabilizes over the plateau, the zonal (meridional) transport results in a shallower (deeper) OVTP while the vertical transport would create a deeper (shallower) OVTP at the middle (bottom and top) levels; the combined dynamic effects produce a deeper OVTP. As the SAH retreats from the plateau, the OVTP becomes deeper (shallower) under the zonal (meridional) effect or shallower under the vertical effect; the combined dynamic effects contribute to a deeper (shallower) OVTP at the middle (bottom and top) levels. The SAH would have a weak effect on the OVTP over the plateau when positioned over the tropical Pacific. 相似文献
4.
采用美国国家环境预测中心的CFSR(Climate Forecast System Reanalysis)再分析资料和QuickSCAT(Quick Scatterometer)、AVHRR(Advanced Very High Resolution Radiometer)、TRMM(Tropical Rainfall Measuring Mission)高分辨率卫星资料,研究了大气对春季东海黑潮锋响应的气压调整机制及其年际变化。结果表明,春季东海黑潮锋位于黑潮暖舌的西北侧,呈西南-东北走向,与大尺度气压背景场的等压线走向一致,锋区东南侧暖水与西北侧冷水之间产生的局地气压梯度与大尺度气压梯度形成同向叠加,使得锋区附近西北指向东南的气压梯度达到最大,造成该处的海表面10 m矢量风速也最大,在摩擦作用下形成东北偏北风(NNE)。锋区与其东南侧的NNE风之间沿锋区走向(跨锋区走向)的分量差,会在暖舌附近产生气旋性切变涡度(风速辐合),由此产生上升运动和强降水;而在锋区西北侧的冷水区情况正好相反,有反气旋性切变涡度(风速辐散),并伴有下沉运动和弱降水,从而形成跨锋区的次级环流圈。东海黑潮锋区偏强(弱)年,锋区东南侧暖水与西北侧冷水之间的局地气压梯度也偏强(弱),与大尺度气压梯度同向叠加后形成偏强(弱)的NNE风,造成锋区东南侧暖舌附近的气旋性切变涡度、风速辐合、上升运动和降水均偏强(弱),而锋区西北侧冷水区的反气旋性切变涡度、风速辐散和下沉运动均偏强(弱),跨锋区次级环流圈偏强(弱),这表明在年际时间尺度上气压调整机制仍起作用。 相似文献
5.
During 1979–2015, the intensity of the Siberian high(SH) in November and December–January(DJ) is frequently shown to have an out-of-phase relationship, which is accompanied by opposite surface air temperature and circulation anomalies.Further analyses indicate that the autumn Arctic sea ice is important for the phase reversal of the SH. There is a significantly positive(negative) correlation between the November(DJ) SH and the September sea ice area(SIA) anomalies. It is suggested that the reduction of autumn SIA induces anomalous upward surface turbulent heat flux(SHF), which can persist into November, especially over the Barents Sea. Consequently, the enhanced eddy energy and wave activity flux are transported to mid and high latitudes. This will then benefit the development of the storm track in northeastern Europe. Conversely, when downward SHF anomalies prevail in DJ, the decreased heat flux and suppressed eddy energy hinder the growth of the storm track during DJ over the Barents Sea and Europe. Through the eddy–mean flow interaction, the strengthened(weakened)storm track activities induce decreased(increased) Ural blockings and accelerated(decelerated) westerlies, which makes the cold air from the Arctic inhibited(transported) over the Siberian area. Therefore, a weaker(stronger) SH in November(DJ) occurs downstream. Moreover, anomalously large snowfall may intensify the SH in DJ rather than in November. The ensemble-mean results from the CMIP5 historical simulations further confirm these connections. The different responses to Arctic sea ice anomalies in early and middle winter set this study apart from earlier ones. 相似文献
6.
Interannual variability in the onset of the summer monsoon over the Eastern Bay of Bengal 总被引：3，自引：0，他引：3
Summary Climatological characteristics associated with summer monsoon onset over the eastern Bay of Bengal (BOB) are examined in terms
of the westerly-easterly boundary surface (WEB). The vertical tilt of the WEB depends on the horizontal meridional temperature
gradient (MTG) near the WEB, under the constraint of the thermal wind balance. The switch in the WEB tilt firstly occurs between
90 and 100°E during the first pentad of May. At this time the 850 hPa ridgeline splits over the BOB and heavy rainfall commences
over the eastern BOB, indicating the onset of the BOB summer monsoon (BOBSM). The area-averaged MTG (200–500 hPa) is proposed
as an index to define the BOBSM onset. A comparison of the onset determined by the MTG, 850 hPa zonal wind, and outgoing longwave
radiation (OLR) shows that the MTG index is the most effective in characterizing the interannual variability of the BOBSM
onset.
Strong precursor signals are found prior to an anomalous BOBSM onset. Composite results show that early (late) BOBSM onset
follows excessive (deficient) rainfall over the western Pacific and anomalous lower tropospheric cyclonic circulation which
extends zonally from the northern Indian Ocean into the western Pacific, and strong (weak) equatorial westerly anomalies in
the preceding winter and spring. Prior to an early (late) BOBSM onset, significant positive (negative) thickness anomalies
exist around the Tibetan Plateau, accompanied by anomalous upper tropospheric anticyclonic (cyclonic) circulation. The interannual
variations of the BOBSM onset are significantly correlated with anomalous sea surface temperature related to ENSO. These occurs
through changes in the Walker circulation and local Hadley circulation, leading to middle and upper tropospheric temperature
anomalies over the Asian sector. The strong precursor signals around the Tibetan Plateau may be partly caused by local snow
cover anomalies, and an early (late) BOBSM onset is preceded by less (more) snow accumulation over the Tibetan Plateau during
the preceding winter. 相似文献
7.
The impact of eddies on the Kuroshio Current in the Luzon Strait (LS) area is investigated by using the sea surface height anomaly (SSHA) satellite observation data and the sea surface height (SSH) assimilation data. The influence of the eddies on the mean current depends upon the type of eddies and their relative position. The mean current is enhanced (weakened) as the cyclonic (anticyclonic) eddy becomes slightly far from it, whereas it is weakened (enhanced) as the cyclonic (anticyclonic) eddy moves near or within the position of the mean current; this is explained as the eddy-induced meridional velocity and geostrophic flow relationship. The anticyclonic (cyclonic) eddy can increase (decrease) the mean meridional flow due to superimposition of the eddy-induced meridional flow when the eddy is within the region of the mean current. However, when the eddy is slightly far from the mean current region, the anticyclonic (cyclonic) eddy tends to decrease (increase) the zonal gradient of the SSH, which thus results in weakening (strengthening) of the mean current in the LS region. 相似文献
8.
Motivated in part by the mathematical problems associated with the application of open boundary conditions to the hydrostatic primitive equations (PE), Browning et al. (1990, Dyn. Atmos. Oceans, 14: 303–332) proposed the use of the reduced system (RS) of equations to replace PE for oceanographic problems. The RS are essentially the Boussinesq equations (BO) with the non-hydrostatic terms in the vertical momentum equation multiplied by a constant δ2 ? 1. This artificially alters the physics (e.g. changing the intemal-inertial wave properties) to facilitate numerical integration, but the changes are assumed to have negligible effects on the dynamics of interest. We assess the accuracy and utility of the RS (following the guidelines for the choice of δ) by comparing numerical finite difference solutions of RS, PE and BO for initial-value problems involving three-dimensional instability of an ocean front and atmospheric frontal development in a two-dimensional Eady wave. Both explicit (BO, PE) and semi-implicit (BOSI, PESI) time-difference schemes are used for the Boussinesq and primitive equations. For RS, the same explicit scheme as for BO is used where δ ? 1 allows larger time steps than with the other explicit models. It is found that relative to BO solutions, the errors for RS are small but increase rapidly and monotonically with increasing δ (over a range consistent with the guidelines) and are greater than the errors for the other models. The use of BOSI allows time steps at least as large as those for RS and results in smaller errors than RS. For these problems, BOSI is the preferable model to replace PE. 相似文献
9.
中南半岛对流对南海夏季风建立过程的影响 总被引：14，自引：1，他引：13
利用RegCM2模式进行数值试验,得到中南半岛对流对北半球副高带断裂、进而对孟加拉湾对流建立具有重要影响,而孟加拉湾对流建立后激发的Rossby波列又是南海夏季风建立的主要因子之一.进一步分析中南半岛对流、副高带断裂及南海夏季风建立的年际变化,得到中南半岛对流的强弱(活跃的早晚)与副高带在孟加拉湾北部断裂及南海夏季风爆发的早晚有密切关系.它们还与海温异常及纬圈环流的变化相联系:当赤道中东太平洋海温偏暖(冷)时,Walker环流偏弱(强),中南半岛对流偏弱(强),副高带断裂偏晚(早),南海夏季风建立偏迟(早). 相似文献
10.
利用NCEP/DOE的逐日再分析资料和国家气象信息中心的常规观测站温度资料,首先分析了2012/2013年冬季中国东北区域极端低温事件过程中区域平均温度的低频振荡变化特征,然后分析了北半球中高纬度对流低层和中层低频环流系统配置的变化及其与东北地区强冷空气活动过程的联系,最后进一步研究了中高纬度低频环流系统的传播特征及其对温度变化的影响。主要结果有:（1）2012/2013年冬季东北区域平均温度存在很强的30～60 d的周期振荡特征,同时伴随较强的10～30 d低频振荡,后者与实际降温过程对应关系更好;（2）对10～30 d的低频振荡而言,在东北地区低频温度变化降低最大的位相7（位相3升高最大）,500 hPa上,我国东部地区正好处于贝加尔湖地区的低频高压（低压）环流和日本海的低频低压（高压）环流型之间的低频偏北（偏南）的较强引导气流中;同时在850 hPa上,我国东部从东北到南海都是较强的偏北（偏南）低频风控制,这使得东亚冬季风环流系统加强（被抑制）,东北区域则经历一次大幅度的低频温度降低（升高）过程,这些高低空低频环流系统的配置和演变导致了2012/2013年冬季一次次强（或较强）的冷空气沿偏东偏北的路径影响我国东北地区,并导致极端低温事件的出现;（3）沿着乌拉尔山-贝加尔湖-我国东北地区-西北太平洋传播的500 hPa低频波列,是驱动2012/2013年冬季东亚冬季风低频振荡和我国东北地区极端低温事件的环流系统。 相似文献
11.
利用美国联合台风警报中心(Joint Typhoon Warning Center,JTWC),中国气象局(China Meteorological Administration,CMA)上海台风所,日本气象厅(Japan Meteorological Agency,JMA)的台风最佳路径资料以及美国NCAR/NCEP再分析资料等,深入研究厄尔尼诺—南方涛动(El Ni1o-Southern Oscillation,ENSO)与西北太平洋强热带气旋(Tropical Cyclone,TC),即1 min最大风速大于等于114 kn相关关系的变化。结果表明,ENSO与热带西北太平洋(Western North Pacific,WNP)强TC频数之间的相关关系存在明显年代际变化。在1960—1971年期间(前一阶段),强TC年频数与Ni1o3. 4(11月—次年1月平均)相关性较弱;而在1983—2014年期间(后一阶段)两者的相关性则为强的正相关。并且强TC的年频数、生命史以及生成位置在后一阶段El Ni1o和La Ni1a年之间的差异相比前一阶段都有明显的增大。进一步分析发现:热带太平洋海温异常(Sea Surface Temperature Anomaly,SSTA)的西移是造成后一阶段Ni1o3. 4指数与强TC年频数相关性提高的关键因素。在后一阶段的El Ni1o(La Ni1a)年,SSTA的西移使得WNP东南象限的相对湿度明显增加(减少),从而有利于(不利于) TC在此象限生成。又因为位于东南象限的TC比较容易发展成强TC,因此导致后一阶段的El Ni1o(La Ni1a)年有更多(更少)的强TC在西北太平洋的东南象限生成。 相似文献
12.
Simulations of the Tropical Intraseasonal Oscillation by the Atmospheric General Circulation Model of the Beijing Climate Center 总被引：1，自引：0，他引：1 
下载免费PDF全文
下载免费PDF全文 The performance of BCC (Beijing Climate Center) AGCM 2.0.1 (Atmospheric General Circulation Model version 2.0.1) in simulating the tropical intraseasonal oscillation (TIO) is examined in this paper.The simulations are validated against observation and compared with the NCAR CAM3 (Community Atmosphere Model version 3) results.The BCC AGCM2.0.1 is developed based on the original BCC AGCM (version 1) and NCAR CAM3.New reference atmosphere and reference pressure are introduced into the model.Therefore,the origi... 相似文献
13.
An analysis of 3 years' (1967–70) radiosonde wind data on the windward (Salt Lake City, Utah) and lee (Denver, Colorado) sides of mountains indicates that at these two stations: (1) the distributions of the kinetic energy of the mean and turbulent motions are similar above the mountain top; (2) below the mountain top, on the windward side, mountains tend to divert the component of the mean motion normal to the mountains to that parallel to the mountains; (3) the meridional eddy transport of westerly momentum is affected by the presence of the mountains to a higher level to the lee of the mountains than upwind of them; (4) the production of turbulent energy is higher below the mountain top in the vicinity of mountains than it is for the zonal average; (5) high frequencies of the motion show a more pronounced contribution in the meridional motion in the windward side, but in the zonal motion in the lee of the mountains; (6) disturbances of 1–2 day periods can be maintained deep into the valley, whereas disturbances of longer periods reduce their amplitudes rapidly with decreasing height from the mountain top; (7) the cospectra of the wind velocities show that the southward/northward transport of westerly momentum results from a southward/northward contribution from most frequencies. The main contributions come from eddies with periods longer than two days. 相似文献
14.
南极涛动和北半球大气环流异常的联系 总被引：5，自引：2，他引：3
使用ECMWF逐日再分析资料分析研究了北半球冬季南极涛动和北半球大气环流异常之间的联系。资料的分析结果表明, 南极涛动和滞后其25～40天位于北大西洋地区的一个弱的类似于北大西洋涛动 (North Atlantic Oscillation, 简称NAO) 的偶极子模态, 以及伴随这一偶极子模态而出现的北半球中纬度纬向风异常之间存在着统计上的联系。处于正 (负) 位相的南极涛动对应着滞后25～40天后, 北大西洋高纬极区出现位势高度负 (正) 异常, 副热带大西洋出现位势高度正 (负) 异常; 同时, 在北半球中高纬度地区(45°N～65°N) 出现西 (东) 风异常, 中低纬度地区(25°N～40°N)出现东 (西) 风异常。文中也对资料分析结果进行了简单的动力学分析, 表明与南极涛动相联系的涡动动量异常是驱动北半球纬向平均纬向风异常的主要原因。 相似文献
15.
Traditionally,a delayed(early)onset of the South China Sea summer monsoon(SCSSM)has been observed to follow a warm(cold)El Ni?o-Southern Oscillation(ENSO)event in winter,supporting high seasonal predictability of SCSSM onset.However,the empirical seasonal forecasting skill of the SCSSM onset,solely based on ENSO,has deteriorated since 2010.Meanwhile,unexpected delayed onsets of the SCSSM have also occurred in the past decade.We attribute these changes to the Northwest Indian Ocean(NWIO)warming of the sea surface.The NWIO warming has teleconnections related to(1)suppressing the seasonal convection over the South China Sea,which weakens the impacts of ENSO on SCSSM onset and delays the start of SCSSM,and(2)favoring more high-frequency,propagating moist convective activities,which enhances the uncertainty of the seasonal prediction of SCSSM onset date.Our results yield insight into the predictability of the SCSSM onset under the context of uneven ocean warming operating within the larger-scale background state of global climate change. 相似文献
16.
利用大气环流模式模拟了赤道中印度洋海区夏季变温与海温本身异常对中国夏季降水的影响.结果表明:当该海区夏季正(负)海温距平值呈递增(递减)变化时,激发出的降水场的正(负)异常幅度比正(负)海温距平强迫下相应的降水场的正(负)异常幅度大;但当正(负)海温距平呈递减(递增)趋势变化时,激发出的降水异常场与正(负)海温距平强迫下相应的降水异常场的分布形势类似(不同),异常幅度也有所差异.夏季中印度洋不同类型的海温异常对大气加热的不同,导致东亚季风和印度季风的不同变异,暖海温异常下引起东亚季风的明显偏强,而冷海温异常下引起印度季风的明显偏强. 相似文献
17.
The impact of the simulated large-scale atmospheric circulation on the regional climate is examined using the Weather Research and Forecasting (WRF) model as a regional climate model. The purpose is to understand the potential need for interior grid nudging for dynamical downscaling of global climate model (GCM) output for air quality applications under a changing climate. In this study we downscale the NCEP-Department of Energy Atmospheric Model Intercomparison Project (AMIP-II) Reanalysis using three continuous 20-year WRF simulations: one simulation without interior grid nudging and two using different interior grid nudging methods. The biases in 2-m temperature and precipitation for the simulation without interior grid nudging are unreasonably large with respect to the North American Regional Reanalysis (NARR) over the eastern half of the contiguous United States (CONUS) during the summer when air quality concerns are most relevant. This study examines how these differences arise from errors in predicting the large-scale atmospheric circulation. It is demonstrated that the Bermuda high, which strongly influences the regional climate for much of the eastern half of the CONUS during the summer, is poorly simulated without interior grid nudging. In particular, two summers when the Bermuda high was west (1993) and east (2003) of its climatological position are chosen to illustrate problems in the large-scale atmospheric circulation anomalies. For both summers, WRF without interior grid nudging fails to simulate the placement of the upper-level anticyclonic (1993) and cyclonic (2003) circulation anomalies. The displacement of the large-scale circulation impacts the lower atmosphere moisture transport and precipitable water, affecting the convective environment and precipitation. Using interior grid nudging improves the large-scale circulation aloft and moisture transport/precipitable water anomalies, thereby improving the simulated 2-m temperature and precipitation. The results demonstrate that constraining the RCM to the large-scale features in the driving fields improves the overall accuracy of the simulated regional climate, and suggest that in the absence of such a constraint, the RCM will likely misrepresent important large-scale shifts in the atmospheric circulation under a future climate. 相似文献
18.
19.
华北雨季开始早晚与大气环流和海表温度异常的关系 总被引：2，自引：0，他引：2
本文利用国家气候中心的1961~2016年华北雨季监测资料、美国国家环境预报中心/大气研究中心（NCEP/NCAR）的大气再分析资料、NOAA海表温度资料,分析了华北雨季开始早晚的气候特征,然后利用合成分析、回归分析等方法,研究了华北雨季开始早晚与大气环流系统和关键区域海表温度的关系。结果表明,56 a来华北雨季开始最早在7月6日,最晚在8月10日,1961~2016年华北雨季开始平均日期是7月18日。华北雨季开始时间具有显著的年际变化,但雨季发生早晚的长期变化趋势不太明显。华北雨季开始早晚与西太平洋副热带高压（简称副高）、东亚副热带西风急流、东亚夏季风等环流系统的活动关系密切,当对流层高层副热带西风急流建立偏早偏强,中层西太平洋副高第二次北跳偏早,低层东亚夏季风北进提前时,华北雨季开始偏早,反之华北雨季开始偏晚。华北雨季开始早晚与春、夏季热带印度洋、赤道中东太平洋海表温度关系显著且稳定,当Ni?o3.4指数和热带印度洋全区海表温度一致模态（IOBW）为正值时,贝加尔湖大陆高压偏强,副高偏强偏南,东亚夏季风偏弱,导致华北雨季开始偏晚;当海表温度指数为负值时,则华北雨季开始偏早。 相似文献
20.
基于条件非线性最优扰动的目标观测中瞄准区
不同引导性变量的影响试验研究 总被引：3，自引：0，他引：3
基于GRAPES区域业务预报模式,采用一种快速算法计算出来的条件非线性最优扰动对实际台风个例麦莎(No.0509)开展了目标观测研究,应用数值模式,进行一系列的敏感性试验,讨论了与目标观测设计相关的一些问题,包括确定瞄准区时使用不同的引导性变量对目标观测效果的影响、及瞄准区范围变化对预报效果的影响。文中分别以提高麦莎在检验区(20.125°—35.3125°N,116.8125°—129.75°E)内的24 h海平面气压预报和24 h累积降水量预报为目的,基于条件非线性最优扰动使用了3种不同的引导性变量寻找敏感区(又称瞄准区),对这些敏感区的分布特点和有效性进行了比较和讨论。试验结果表明,在使用的3种引导性变量中,用不同的引导性变量识别的敏感区是有差别的,总体上说,文中使用的3种引导性变量识别的瞄准区对提高预报都是有效的,特别是第2和第3种的效果更好些,且两者识别的瞄准区常显示出类似的特点。文中进一步针对检验区内24 h累积降水量预报误差问题,将前面确定的瞄准区范围扩大相同的幅度,讨论瞄准区范围变化对改进预报的影响。试验结果表明,增加瞄准格点数,有可能使预报效果得到改善,但是试验结果同时也暗示了单纯靠扩大瞄准... 相似文献