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1.
北半球温带气旋活动和风暴路径的年代际变化 总被引：12，自引：3，他引：9
基于欧洲中心再分析数据ERA40的海平面气压场和高度场,本文分别采用拉格朗日和欧拉方法研究分析了1958～2001年北半球的不同季节温带气旋活动和风暴路径的年代际变化,以及可能的原因.以客观判定和追踪温带气旋为基础的拉格朗日方法得到了北半球的两个温带气旋主要活动中心,即北太平洋地区和北大西洋/北美地区,同时以500 hPa位势高度天气尺度滤波方差为基础的欧拉方法得到了同主要气旋活动中心相吻合的两条风暴轴.研究表明,44年中北大西洋/北美地区温带气旋活动北移加强,以春季最为显著.风暴轴也同样存在着向极移动并加强的特征,并且温带气旋和风暴路径两者移动趋势的相关性很高.作为一个典型地区,北大西洋/北美地区的气旋活动体现了风暴路径的北移,以及温带地区向极地的扩展.但有意思的是北太平洋的情况完全不同,即北太平洋地区的温带气旋活动和风暴轴向低纬度偏移并加强,以春季的南移趋势最为显著.对于此结论,两种方法也有很高的统计相关性.虽然大量研究表明北半球整体上呈现出风暴路径北移的变化特征,但对于具体地区情况有明显差异.另外,400 hPa最大Eady增长率和气旋活动频率的经验正交展开函数 (EOF) 第一模态的空间分布和时间序列非常相似,北太平洋地区和北大西洋地区风暴路径相反的变化趋势很可能同其大气斜压性的同位相的变化有着密切的关系.这也从另一个方面支持了本文对温带气旋和风暴路径年代际变化的分析. 相似文献
2.
ENSEMBLE PREDICTION EXPERIMENTS OF TRACKS OF TROPICAL CYCLONES BY USING MULTIPLE CUMULUS PARAMETERIZATION SCHEMES 总被引：1，自引：1，他引：0
Ensemble prediction experiments of the tracks of eight tropical cyclones occurring between 2004 -2006 over the western Pacific have been performed by using MM5 with five cumulus parameterizations chemes. The results show that the predictions of the tracks of the tropical cyclones are sensitive to the selection of cumulus parameterization schemes. Each scheme has its own advantage and disadvantage, and the predications without cumulus parameterization schemes are not the worst, sometimes even better than the others. And all of the three ensemble methods improve the predictions of the tracks significantly, among which the ensemble method without parameterization schemes, the Grell, Betts-Miller and Kain-Fritsch schemes are the best. 相似文献
3.
The impact of cumulus parameterizations and microphysics schemes under different combinations on typhoon track prediction 总被引：2，自引：1，他引：1
This study examines the effects of cumulus parameterizations and microphysics schemes on the track forecast of typhoon Nabi using the Weather Research Forecast model. The study found that the effects of cumulus parameterizations on typhoon track forecast were comparatively strong and the typhoon track forecast of Kain-Fritsch (KF) was superior to that of Betts-Miller (BM). When KF was selected, the simulated results would be improved if microphysics schemes were selected than otherwise. The results from Ferrier, WSM6, and Lin were very close to those in the best track. KF performed well with the simulations of the western extension and eastern contraction changes of a North Pacific high as well as the distribution and strength of the typhoon wind field. 相似文献
4.
Summary From 1994 to 2003, fifty-five tropical cyclones entered the Canadian Hurricane Centre (CHC) Response Zone, or about 42% of
all named Atlantic tropical cyclones in this ten-year period, and 2003 was the fourth consecutive year for a tropical cyclone
to make landfall in Canada. The CHC forecasts all tropical cyclones that enter the CHC Response Zone and assumes the lead
in forecasting once the cyclone enters its area of forecast responsibility. This study acknowledges the challenges of forecasting
such tropical cyclones at extratropical latitudes. If a tropical cyclone has been declared extratropical, global models may
no longer use vortex bogussing to carry the cyclone, and even if it is modeled, large model errors often result. The purpose
of this study is to develop a new version of the Florida State University (FSU) hurricane superensemble with greater skill
in tracking tropical cyclones, especially at extratropical latitudes. This has been achieved from the development of the synthetic
superensemble, which is similar to the operational version of the multi-model superensemble that is used at FSU. The synthetic
superensemble differs in that is has a larger set of member models consisting of regular member models, synthetic versions
of these models, and the operational superensemble and its synthetic version. This synthetic superensemble is being used here
to forecast hurricane tracks from the 2001, 2002, and 2003 hurricane seasons. The track forecasts from this method have generally
less error than those of the member models, the operational superensemble, and the ensemble mean. This study shows that the
synthetic superensemble performs consistently well and would be an asset to operational hurricane track forecasting. 相似文献
5.
变性再发展热带气旋Yaji(2006)的数值模拟研究 总被引：2，自引：2，他引：0
利用中尺度模式WRF对2006年14号热带气旋Yaji的变性过程进行了双重嵌套模拟。结果表明,采用高分辨率的TRMM/TMI卫星反演SST资料,在第一重区域(网格距为15km)采用WSM3微物理方案和Betts-Miller对流参数化方案,在第二重移动嵌套区域(网格距为5km)采用Lin微物理方案,不采用对流参数化方案,模式能较好地模拟Yaji的路径和变性前后的强度演变,其中模拟的路径平均误差为64km,强度平均误差为2.5hPa,模拟的风场分布与Quickscat卫星反演的风场分布也较为吻合。利用模拟资料还研究了Yaji变性过程中的非对称流特征。 相似文献
6.
Summary Seven different microphysical sensitivity experiments were designed with an objective to evaluate their respective impacts
in modulating hurricane intensity forecasts using mesoscale model MM5. Microphysical processes such as melting of graupel,
snow and cloud ice hydrometeors, suppression of evaporation of falling rain, the intercept parameter and fall speed of snow
and graupel hydrometeors are modified in the existing NASA Goddard Space Flight Center (GSFC) microphysical parameterization
scheme. We studied the impacts of cloud microphysical processes by means of track, intensity, precipitation, propagation speed,
kinematic and thermodynamic vertical structural characteristics of hurricane inner core. These results suggest that the set
of experiments where (a) melting of snow, graupel and cloud ice were suppressed (b) melting of snow and graupel were suppressed
and (c) where the evaporation of rain water was suppressed all produced most intense storms. The major findings of this study
are the interconversion processes such as melting and evaporation among hydrometeors and associated feedback mechanism are
significantly modulate the intensity of the hurricane. In particular an experiment where the melting of graupel, snow and
cloud ice hydrometeors was eliminated from the model parameterization scheme produced the most explosively intensified storm.
In the experiment where rain water evaporation was eliminated from the model, it produced a stronger storm as compared to
the control run but it was not as strong as the storms produced from absence of melting processes. The impact on intensity
due to variations made in intercept parameters of the hydrometeors (i.e., snow and graupel) were not that evident compared
to other experiments. The weakest storm was noted in the experiment where the fall speeds of the snow hydrometeors were increased
two fold. This study has isolated some of the factors that contributed to a stronger hurricane and concludes with a motivation
that the findings from this study will help in further improvement in the design of sophisticated explicit microphysical parameterization
for the mesoscale non-hydrostatic model for realistic hurricane intensity forecasts. 相似文献
7.
The effects of storm-induced sea surface temperature (SST) cooling on hurricane intensity are investigated using a 5-day cloud-resolving simulation of Hurricane Bonnie (1998). Two sensitivity simulations are performed in which the storm-induced cooling is either ignored or shifted close to the modeled storm track. Results show marked sensitivity of the model-simulated storm intensity to the magnitude and relative position with respect to the hurricane track. It is shown that incorporation of the storm-induced cooling, with an average value of 1.3℃, causes a 25-hPa weakening of the hurricane, which is about 20 hPa per 1℃ change in SST. Shifting the SST cooling close to the storm track generates the weakest storm, accounting for about 47% reduction in the storm intensity. It is found that the storm intensity changes are well correlated with the air-sea temperature difference. The results have important implications for the use of coupled hurricane-ocean models for numerical prediction of tropical cyclones. 相似文献
8.
Comparison of observed gale radius statistics 总被引：1，自引：0，他引：1
Summary Forecasts of tropical cyclone track and intensity have long been used to characterize the evolution and expected threat from
a tropical storm. However, in recent years, recognition of the contributions of subtropical cyclogenesis to tropical storm
formation and the process of extratropical transition to latter stages of the once-tropical storm’s lifecycle have raised
awareness about the importance of storm structure. Indeed, the structure of a cyclone determines the distribution and intensity
of the significant weather associated with that storm.
In this study, storm structure is characterized in terms of significant wind radii. The radii of tropical storm, damaging,
and hurricane-force winds, as well as the radius of maximum winds are all analyzed. These wind radii are objectively derived
from the H*Wind surface wind analysis system. Initially, six years of these data are examined for consistency with previous studies.
Having ascertained that the H*Wind radii are realistic, detailed comparisons are performed between the H*Wind and NHC Best Track wind radii for two years (2004 and 2005) of North Atlantic tropical storm and hurricane cases. This
intercomparison reveals an unexpected bias: the H*Wind radii are consistently larger than the NHC Best Track for all but the smallest and least intense storms.
Further examination of the objectively-determined H*Wind tropical storm force wind radius data compared to subjectively-determined radii for the same storm times demonstrates
that the objective wind radii are underestimating the extent of the tropical storm force wind area. Since the objective H*Wind radii are large compared to the NHC Best Track – and yet underestimate the area of tropical storm force winds – this
argues for further examination of the methods used to ascertain these significant wind radii. 相似文献
9.
Equator-to-pole temperature differences and the extra-tropical storm track responses of the CMIP5 climate models 总被引：2，自引：2，他引：0
This paper aims to understand the physical processes causing the large spread in the storm track projections of the CMIP5 climate models. In particular, the relationship between the climate change responses of the storm tracks, as measured by the 2–6 day mean sea level pressure variance, and the equator-to-pole temperature differences at upper- and lower-tropospheric levels is investigated. In the southern hemisphere the responses of the upper- and lower-tropospheric temperature differences are correlated across the models and as a result they share similar associations with the storm track responses. There are large regions in which the storm track responses are correlated with the temperature difference responses, and a simple linear regression model based on the temperature differences at either level captures the spatial pattern of the mean storm track response as well explaining between 30 and 60 % of the inter-model variance of the storm track responses. In the northern hemisphere the responses of the two temperature differences are not significantly correlated and their associations with the storm track responses are more complicated. In summer, the responses of the lower-tropospheric temperature differences dominate the inter-model spread of the storm track responses. In winter, the responses of the upper- and lower-temperature differences both play a role. The results suggest that there is potential to reduce the spread in storm track responses by constraining the relative magnitudes of the warming in the tropical and polar regions. 相似文献
10.
Summary This study uses an adaptive observational strategy for hurricane forecasting. It shows the impacts of Lidar Atmospheric Sensing
Experiment (LASE) and dropsonde data sets from Convection and Moisture Experiment (CAMEX) field campaigns on hurricane track
and intensity forecasts. The following cases are used in this study: Bonnie, Danielle and Georges of 1998 and Erin, Gabrielle
and Humberto of 2001. A single model run for each storm is carried out using the Florida State University Global Spectral
Model (FSUGSM) with the European Center for Medium Range Weather Forecasts (ECMWF) analysis as initial conditions, in addition
to 50 other model runs where the analysis is randomly perturbed for each storm. The centers of maximum variance of the DLM
heights are located from the forecast error variance fields at the 84-hr forecast. Back correlations are then performed using
the centers of these maximum variances and the fields at the 36-hr forecast. The regions having the highest correlations in
the vicinity of the hurricanes are indicative of regions from where the error growth emanates and suggests the need for additional
observations. Data sets are next assimilated in those areas that contain high correlations. Forecasts are computed using the
new initial conditions for the storm cases, and track and intensity skills are then examined with respect to the control forecast.
The adaptive strategy is capable of identifying sensitive areas where additional observations can help in reducing the hurricane
track forecast errors. A reduction of position error by approximately 52% for day 3 of forecast (averaged over 7 storm cases)
over the control runs is observed. The intensity forecast shows only a slight positive impact due to the model’s coarse resolution.
Corresponding author’s address: T. N. Krishnamurti, Department of Meteorology, Florida State University, Tallahassee, FL 32306-4520,
USA 相似文献
11.
M. P. Hoerling J. W. Hurrell T. Xu G. T. Bates A. S. Phillips 《Climate Dynamics》2004,23(3-4):391-405
Ensembles of atmospheric general circulation model (AGCM) experiments are used in an effort to understand the boreal winter Northern Hemisphere (NH) extratropical climate response to the observed warming of tropical sea surface temperatures (SSTs) over the last half of the twentieth Century. Specifically, we inquire about the origins of unusual, if not unprecedented, changes in the wintertime North Atlantic and European climate that are well described by a linear trend in most indices of the North Atlantic Oscillation (NAO). The simulated NH atmospheric response to the linear trend component of tropic-wide SST change since 1950 projects strongly onto the positive polarity of the NAO and is a hemispheric pattern distinguished by decreased (increased) Arctic (middle latitude) sea level pressure. Progressive warming of the Indian Ocean is the principal contributor to this wintertime extratropical response, as shown through additional AGCM ensembles forced with only the SST trend in that sector. The Indian Ocean influence is further established through the reproducibility of results across three different models forced with identical, idealized patterns of the observed warming. Examination of the transient atmospheric adjustment to a sudden “switch-on” of an Indian Ocean SST anomaly reveals that the North Atlantic response is not consistent with linear theory and most likely involves synoptic eddy feedbacks associated with changes in the North Atlantic storm track. The tropical SST control exerted over twentieth century regional climate underlies the importance of determining the future course of tropical SST for regional climate change and its uncertainty. Better understanding of the extratropical responses to different, plausible trajectories of the tropical oceans is key to such efforts. 相似文献
12.
Atmospheric Infra Red Sounder(AIRS) measurements are a valuable supplement to current observational data, especially over the oceans where conventional data are sparse. In this study, two types of AIRS-retrieved temperature and moisture profiles, the AIRS Science Team product(Sci Sup) and the single field-of-view(SFOV) research product, were evaluated with European Centre for Medium-Range Weather Forecasts(ECMWF) analysis data over the Atlantic Ocean during Hurricane Ike(2008) and Hurricane Irene(2011). The evaluation results showed that both types of AIRS profiles agreed well with the ECMWF analysis, especially between 200 h Pa and 700 h Pa. The average standard deviation of both temperature profiles was approximately 1 K under 200 h Pa, where the mean AIRS temperature profile from the AIRS Sci Sup retrievals was slightly colder than that from the AIRS SFOV retrievals. The mean Sci Sup moisture profile was slightly drier than that from the SFOV in the mid troposphere. A series of data assimilation and forecast experiments was then conducted with the Advanced Research version of the Weather Research and Forecasting(WRF) model and its three-dimensional variational(3DVAR) data assimilation system for hurricanes Ike and Irene. The results showed an improvement in the hurricane track due to the assimilation of AIRS clear-sky temperature profiles in the hurricane environment. In terms of total precipitable water and rainfall forecasts, the hurricane moisture environment was found to be affected by the AIRS sounding assimilation.Meanwhile, improving hurricane intensity forecasts through assimilating AIRS profiles remains a challenge for further study. 相似文献
13.
The winter storm activity on the Northern Hemisphere during the last one thousand years in a global climate simulation was analyzed by determining all midlatitude storms and their tracks, then consecutively clustering them for hundred years’ segments. Storm track clusters with longest lifetime and largest deepening rates are found over the oceans. The numbers of extratropical winter storms exhibit notable yearly variability but hardly any variability on centennial time scales. The clusters of these storm tracks also show only small differences between the centuries. The numbers of members in neighboring oceanic clusters are negatively correlated. A linear relationship was found between the numbers of members per storm track clusters over the Pacific or Atlantic Ocean and seasonal mean atmospheric circulation patterns by a canonical correlation analysis. 相似文献
14.
15.
Summary The first part of the paper comprises of a control experiment and its forecasts validations with the observed. The PSU-NCAR
mesoscale model MM5 was utilized at a horizontal resolution of 4 km using the data sets for hurricane Charley of 2004. The
model configures some of the best available versions for physics and microphysical parameterizations schemes to produce forecasts
which are close to the observed trend of hurricane Charley. The basic validations of the control run were carried out in terms
of track, intensity (sea-level pressure and surface wind speed), storm propagation speed, precipitation and radar reflectivity
with that of observed. The validations were necessary because this control experiment will be considered as a benchmark forecast
for comparison with other microphysics sensitive experiments forecasts in the second part of this paper. In general, the control
run forecasts closely comply with that of observed track and intensity of the hurricane Charley. We also note that control
run manage to reproduce much of the important structural characteristics features of the hurricane as observed. 相似文献
16.
A. A. Alekseeva 《Russian Meteorology and Hydrology》2017,42(1):1-8
In contrast to the common opinion, hurricane winds in extratropical cyclones are a quite frequent phenomenon followed by huge damage, especially in densely populated areas. This phenomenon has been poorly studied and is hardly predictable so far. The features of hurricane winds in extratropical cyclones, and the similarity and difference in their structure as compared to those in tropical cyclones are revealed. 相似文献
17.
The role of the convective “trigger function” in numerical forecasts of mesoscale convective systems 总被引：1，自引：0，他引：1
Summary Three-dimensional numerical model simulations of a mesoscale convective system are performed to evaluate the sensitivity of the simulations to differences in the convective trigger function. The Penn State/NCAR mesoscale model with the Kain-Fritsch convective parameterization scheme is used as the modeling system for the study. All simulations are performed on the June 10–11, 1985 squall line from the OK PRE-STORM field experiment. Individual simulations differ only in their specification of the trigger function within the Kain-Fritsch scheme. Comparison of results from 12 hour simulations indicates that the position, timing, and intensity of convective activity and mesoscale features vary substantially as a function of the trigger function formulation. The results suggest that the convective trigger function is an integral part of the overall convective parameterization problem, and that great care must be exercised is designing realistic trigger function formulations, especially as model resolutions approach the scale of individual convective clouds.With 7 Figures 相似文献
18.
极轨气象卫星S-NPP、MetOp-A和FY-3B上搭载的微波湿度计观测资料可以反映出台风周围水汽和云雨结构。本文使用权重函数峰值在800 hPa附近的微波湿度计通道观测资料和ERA5再分析资料全天空模拟亮温,以飓风Sandy和Isaac为例,对用方位谱台风中心位置定位方法得到的观测和模拟中心位置进行了比较。利用下午星S-NPP搭载的先进技术微波探测仪(Advanced Technology Microwave Sounder,ATMS)和上午星MetOp-A搭载的微波湿度计(Microwave Humidity Sounder,MHS)观测亮温得到的飓风Sandy(Isaac)中心位置与最佳路径平均相差35.8 km(32.9 km),但用ERA5全天空模拟亮温得到的飓风Sandy(Isaac)中心位置与最佳路径平均相差73.3 km(82.1 km)。若按照热带风暴和台风等级来划分,ATMS和MHS观测和模拟亮温得到的台风中心位置与最佳路径的平均距离对热带风暴分别是36.5 km和105.9 km,对台风分别是25.8 km和56.4 km。若用FY-3B搭载的微波湿度计(以MWHS表示)替换ATMS,所得结果类似。ERA5作为全球大气再分析资料的典型代表,用方位谱台风中心位置定位方法得到的台风中心位置误差较大的原因是ERA5再分析资料全天空模拟亮温在台风中的分布结构与观测亮温相差较大,而模拟亮温与冰水路径分布结构极为相似。研究对台风数值预报中的全天空模拟亮温资料同化具有一定的参考意义。 相似文献
19.
Response of Northern Hemisphere storm tracks to Indian-western Pacific Ocean warming in atmospheric general circulation models 总被引：1，自引：1，他引：0
With 40 years integration output of two atmospheric general circulation models (GAMIL/IAP and HadAM3/UKMO) forced with identical prescribed seasonally-varying sea surface temperature, this study examines the effect of the observed Indian-western Pacific Ocean (IWP) warming on the Northern Hemisphere storm tracks. Both models indicate that the observed IWP warming tends to cause both the North Pacific storm track (NPST) and the North Atlantic storm track (NAST) to move northward. Such a consistent effect on the two storm tracks is closely associated with the changes in the low-level atmospheric baroclinicity, high-level jet stream and upper-level geopotential height. The IWP warming can excite a wavelike circum-global teleconnection in the geopotential height that gives rise to an anticyclonic anomaly over the midlatitude North Pacific and a positive-phase NAO anomaly over the North Atlantic. These geopotential height anomalies tend to enhance upper-level zonal westerly winds north of the climatological jet axes and increase low-level baroclinicity and eddy growth rates, thus favoring transient eddy more active north of the climatological storm track axes, responsible for the northward shift of the both storm tracks. The IWP warming-induced northward shift of the NAST is quite similar to the observed, suggesting that the IWP warming can be one of the key factors to cause decadal northward shift of the NAST since the 1980s. However, the IWP warming-induced northward shift of the NPST is completely opposite to the observed, implying that the observed southward shift of the NPST since the 1980s would be primarily attributed to other reasons, although the IWP warming can have a cancelling effect against those reasons. 相似文献
20.
Matthew Ranson Carolyn Kousky Matthias Ruth Lesley Jantarasami Allison Crimmins Lisa Tarquinio 《Climatic change》2014,127(2):227-241
This paper provides the first quantitative synthesis of the rapidly growing literature on future tropical and extratropical cyclone damages under climate change. We estimate a probability distribution for the predicted impact of changes in global surface air temperatures on future storm damages, using an ensemble of 478 estimates of the temperature-damage relationship from nineteen studies. Our analysis produces three main empirical results. First, we find strong but not conclusive support for the hypothesis that climate change will cause damages from tropical cyclones and wind storms to increase, with most models predicting higher future storm damages due to climate change. Second, there is substantial variation in projected changes in losses across regions. Potential changes in damages are greatest in the North Atlantic basin, where the multi-model average predicts that a 2.5 °C increase in global surface air temperature would cause hurricane damages to increase by 63 %. The ensemble predictions for Western North Pacific tropical cyclones and European wind storms (extratropical cyclones) are +28 % and +23 %, respectively. Finally, our analysis shows that existing models of storm damages under climate change generate a wide range of predictions, ranging from moderate decreases to very large increases in losses. 相似文献