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1.
An investigation of the effects of wave state and sea spray on an idealized typhoon using an air-sea coupled modeling system 总被引：1，自引：0，他引：1
In this study, the impact of atmosphere-wave coupling on typhoon intensity was investigated using numerical simulations of an idealized typhoon in a coupled atmosphere-wave-ocean modeling system. The coupling between atmosphere and sea surface waves considered the effects of wave state and sea sprays on air-sea momentum flux, the atmospheric low-level dissipative heating, and the wave-state-affected sea- spray heat flux. Several experiments were conducted to examine the impacts of wave state, sea sprays, and dissipative heating on an idealized typhoon system. Results show that considering the wave state and sea-spray-affected sea-surface roughness reduces typhoon intensity, while including dissipative heating intensifies the typhoon system. Taking into account sea spray heat flux also strengthens the typhoon system with increasing maximum wind speed and significant wave height. The overall impact of atmosphere-wave coupling makes a positive contribution to the intensification of the idealized typhoon system. The minimum central pressure simulated by the coupled atmosphere-wave experiment was 16.4 hPa deeper than that of the control run, and the maximum wind speed and significant wave height increased by 31% and 4%, respectively. Meanwhile, within the area beneath the typhoon center, the average total upward air-sea heat flux increased by 22%, and the averaged latent heat flux increased more significantly by 31% compared to the uncoupled run. 相似文献
2.
To examine effects of sea spray evaporation and dissipative heating on structure and intensity of a real tropical cyclone,the sea spray flux parameterization scheme was incorporated into the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model(MM5).Sensitivity tests were performed with varying the spray source function intensities and with and without dissipation heating.The numerical results indicate that sea spray evaporation increases the interfacial sensible heat flux,which is increased by 16% for the moderate spray and 47% for the heavy spray,but has little effect on the interfacial latent heat flux.The net effect of sea spray evaporation is to decrease the total sensible heat flux and to increase the total latent heat flux.The total enthalpy flux is increased by 1% and 12% with moderate and strong spray amounts,respectively.Consistent with these results,the intensity of the tropical cyclone is increased by 5% and 16% in maximum 10-m wind speed,respectively,due to sea spray evaporation.Sea spray evaporation and dissipative heating modify the tropical cyclone structure in important but complex ways.The effect of sea spray on the near-surface temperature and moisture depends on the spray amounts and its location within the tropical cyclone.Within the high-wind region of a tropical cyclone,the lower atmosphere becomes cooler and moister due to the evaporation of sea spray.However,the dissipative heating offsets the cooling due to sea spray evaporation,which makes the lower atmosphere warmer. 相似文献
3.
从强迫耗散无辐散正压涡度方程出发，用不同方案模拟试验得到它的数值解，它与方程解析解的特征较为一致，结果表明非绝热加热强迫强“Kelvin”猫眼强度，冷却则相反，耗散则缓和流场演变，模拟所得“猫眼”强度，移动及形状变化及涡度场等特征与副高实际演变有相似之处。 相似文献
4.
Surface heat and moisture fluxes are important to the evolution of a tropical storm after its landfall. Soil moisture is one of the essential components that influence surface heating and moisture fluxes. In this study, the impact of soil moisture on a pre-landfall numerical simulation of Tropical Storm Bill(2015), which had a much longer lifespan over land, is investigated by using the research version of the NCEP Hurricane Weather Research and Forecasting(HWRF) model. It is found that increased soil moisture with SLAB scheme before storm's landfall tends to produce a weaker storm after landfall and has negative impacts on storm track simulation. Further diagnoses with different land surface schemes and sensitivity experiments indicate that the increase in soil moisture inside the storm corresponds to a strengthened vertical mixing within the storm boundary layer, which is conducive to the decay of storm and has negative impacts on storm evolution. In addition, surface diabatic heating effects over the storm environment are also found to be an important positive contribution to the storm evolution over land, but their impacts are not so substantial as boundary layer vertical mixing inside the storm. The overall results highlight the importance and uncertainty of soil moisture in numerical model simulations of landfalling hurricanes and their further evolution over land. 相似文献
5.
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
6.
J. Wood 《Meteorology and Atmospheric Physics》2003,83(3-4):187-196
Summary ?In this study, TRMM Microwave Imager (TMI) data were used to investigate a possible relationship between the total ice contents
of Atlantic basin hurricanes to their intensities. Ice content data from the TMI was gathered for all available TRMM swaths
for the ten hurricanes. These data were then correlated to the observed maximum wind speeds and minimum central pressures
from the storms at the respective times of the TRMM swaths to examine the relationship.
Several methods of correlating the ice content data to the observed data were tried and the most successful method involved
the use of multiple linear regression to compute correlation coefficients using the observed intensity and TMI ice content
data as well as storm size. This method allowed for the inclusion of storm size, which had been found to be an important factor
in total ice content. These correlation coefficients were then used to produce regressed intensities for the hurricanes and
these regressed intensities were then correlated to the observed intensities. The result was a correlation coefficient of
0.437 for the relationship between the regressed maximum wind speeds and observed maximum wind speeds and 0.483 for the regressed
minimum central pressures and the observed minimum central pressures. Though not entirely conclusive, the results do appear
to substantiate the possibility of an ice content-intensity relationship within Atlantic basin hurricanes. With further investigation,
it may be possible to use ice content as another determinant in league with the Dvorak method and other methods of tropical
cyclone intensity in regions that are out of the range of surface or aircraft observations.
Received April 30, 2002; accepted July 18, 2002
Published online: March 20, 2003 相似文献
7.
《Atmospheric Science Letters》2001,2(1-4):86-93
Recently some indications have appeared that several purely meteorological processes in the terrestrial atmosphere are dependent upon magnetosphere variations. To analyse the possible relationship with North Atlantic hurricane intensification, the authors examine geomagnetic data for ten days prior to all hurricanes over the last 50 years (1950–1999). A significant positive correlation between the averaged Kp index of global geomagnetic activity and hurricane intensity as measured by maximum sustained wind speed is identified for baroclinically-initiated hurricanes. Results are consistent with a mechanism whereby ionization processes trigger glaciation at cloud top which leads to hurricane intensification through upper tropospheric latent heat release. 相似文献
8.
We use FLIGHT+ aircraft reconnaissance data for tropical cyclones (TCs) in the North Atlantic and Eastern Pacific from 1997 to 2015 to re-examine TC fullness (TCF) characteristics at the flight level. The results show a strong positive correlation between the flight-level TCF and the intensity of TCs, with the flight-level TCF increasing much more rapidly than the near-surface TCF with increasing intensity of the TCs. The tangential wind in small-TCF hurricanes is statistically significantly stronger near the eye center than that in large-TCF hurricanes. Large-TCF hurricanes have a ring-like vorticity structure. No significant correlation is observed between the flight-level TCF and the comparative extent of the vorticity-skirt region occupied in the outer core skirt. The proportion of the rapid filamentation zone in the outer core skirt increases with increasing flight-level TCF. The differences in entropy between the radius of the maximum wind and the outer boundary of the outer core skirt also increase with increasing flight-level TCF. 相似文献
9.
THE EFFECTS OF EXTERNAL FORCING,DISSIPATION AND NONLINEARITY ON THE SOLUTIONS OF ATMOSPHERIC EQUATIONS 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Based on the primitive equations of the atmosphere,we study the effects of external forcing.dissipation and nonlinearity on the solutions of stationary motion and non-stationary motion.Theresults show that the asymptotic behavior of solutions of the forced dissipative nonlinear system isessentially different from that of the adiabatic non-dissipative system,the adiabatic dissipativesystem,the diabatic non-dissipative system and the diabatic dissipative linear system,and that thejoint action of external forcing,dissipation and nonlinearity is the source of multiple equilibria.From this we can conclude that the important actions of diabatic heating and dissipation must beconsidered in the models of the long-term weather and the climate. 相似文献
10.
Based on the primitive equations of the atmosphere,we study the effects of external forcing.dissipation and nonlinearity on the solutions of stationary motion and non-stationary motion.The results show that the asymptotic behavior of solutions of the forced dissipative nonlinear system is essentially different from that of the adiabatic non-dissipative system,the adiabatic dissipative system,the diabatic non-dissipative system and the diabatic dissipative linear system,and that the joint action of external forcing,dissipation and nonlinearity is the source of multiple equilibria.From this we can conclude that the important actions of diabatic heating and dissipation must be considered in the models of the long-term weather and the climate. 相似文献
11.
Summary Forecasting the tracks of hurricanes is a problem of immense importance. It is a major scientific exercise in solving the
complicated set of mathematical equations that govern the behavior of atmospheric flow in general and hurricanes in particular.
Moreover, hurricanes rank as the most devastating of all natural phenomena, in terms of loss of life and destruction of property.
Hitherto, unlike many other atmospheric and oceanic systems, hurricanes have defied rapid advances in prediction of their
motion, and progress has been of the order of a mere one percent or so reduction per annum in mean 48 hour forecast position
errors over the past two decades. A research program aimed at estimating inherent and actual mean absolute forecast position
errors, has produced an apparent paradox. Despite the fact that the equations governing hurricane motion are a complex, coupled,
nonlinear set of dynamical equations, there is very strong evidence for the existence of an underlying simple, linear, invariant
behavior. The original aim of the research program was to determine the lower limits of mean hurricane forecast position errors
and to quantify them out to 72 hour leadtime. The appearance of the paradox meant that the focus shifted first to examining
and explaining the paradox. Attention then turns to showing that the mean forecasts errors are still a very large 40 to 50
percent lower than the mean position errors currently being achieved in practice by state-of-the-art models numerical weather
prediction (NWP) models.
Revised December 14, 1999 相似文献
12.
Sensitivity of MJO simulations to diabatic heating profiles 总被引：2，自引：0，他引：2
The difficulty for global atmospheric models to reproduce the Madden–Julian oscillation (MJO) is a long-lasting problem. In an attempt to understand this difficulty, simple numerical experiments are conducted using a global climate model. This model, in its full paramterization package (control run), is capable of producing the gross features of the MJO, namely, its planetary-scale, intraseasonal, eastward slow propagation. When latent heating profiles in the model are artificially modified, the characteristics of the simulated MJO changed drastically. Intraseasonal perturbations are dominated by stationary component over the Indian and western Pacific Oceans when heating profiles are top heavy (maximum in the upper troposphere). In contrast, when diabatic heating is bottom heavy (maximum in the lower troposphere), planetary-scale, intraseasonal, eastward propagating perturbations are reproduced with a phase speed similar to that of the MJO. The difference appears to come from surface and low-level moisture convergence, which is much stronger and more coherent in space when the heating profile is bottom heavy than when it is top heavy. These sensitivity experiments, along with other theoretical, numerical, and observational results, have led to a hypothesis that the difficulty for global models to produce the MJO partially is rooted in a lack of sufficient diabatic heating in the lower troposphere, presumably from shallow convection. 相似文献
13.
Recent intense hurricane response to global climate change 总被引：1，自引：0，他引：1
An Anthropogenic Climate Change Index (ACCI) is developed and used to investigate the potential global warming contribution to current tropical cyclone activity. The ACCI is defined as the difference between the means of ensembles of climate simulations with and without anthropogenic gases and aerosols. This index indicates that the bulk of the current anthropogenic warming has occurred in the past four decades, which enables improved confidence in assessing hurricane changes as it removes many of the data issues from previous eras. We find no anthropogenic signal in annual global tropical cyclone or hurricane frequencies. But a strong signal is found in proportions of both weaker and stronger hurricanes: the proportion of Category 4 and 5 hurricanes has increased at a rate of ~25–30 % per °C of global warming after accounting for analysis and observing system changes. This has been balanced by a similar decrease in Category 1 and 2 hurricane proportions, leading to development of a distinctly bimodal intensity distribution, with the secondary maximum at Category 4 hurricanes. This global signal is reproduced in all ocean basins. The observed increase in Category 4–5 hurricanes may not continue at the same rate with future global warming. The analysis suggests that following an initial climate increase in intense hurricane proportions a saturation level will be reached beyond which any further global warming will have little effect. 相似文献
14.
强迫耗散非线性发展方程准完全平方守恒格式的构造 总被引：5，自引：0，他引：5
从描述大气和海洋运动的强迫耗散非线性发展方程出发，对强迫耗散非线性大气和海洋方程组显式差分格式的计算稳定性进行了分析，构造了一类强迫耗散性发展方程的显式准完全平方守恒差分格式，理论分析和数值试验证明，这类显式准完全平方守恒差分格式是计算稳定的．值得推广应用。 相似文献
15.
The impact is studied of small land areas on the configuration and structure of the tropical cyclone as well as on the variations
of different characteristics of hurricanes (wind field, kinetic energy, and vorticity) during their passage over islands.
The results of computations based on the regional numerical atmospheric ETA model for the hurricanes of the Caribbean Sea
and typhoons of the Northwestern Pacific revealed that the disturbance of the symmetric circulation in the vortex accompanied
by significant kinetic energy losses takes place when crossing the archipelagos or separate islands. It is demonstrated that
the vortex intensity depends not on the energy loss due to the underlying surface roughness only but on the heat flux from
it as well. The kinetic energy generation in the hurricane sharply decreases as a result of the decrease in the pressure gradient
over the land that is caused, in turn, by the tropical cyclone moving away from the oceanic heat source. At the recurring
appearance of the cyclone over the warm ocean waters, its deepening and intensification recommence. 相似文献
16.
下投式探空资料对Debby飓风路径预报影响的数值试验 总被引：1，自引：0，他引：1
在飓风路径的数值预报中，对于初始场的要求很高，然而，由于初始资料的缺乏，经常导致路径预报的误差较大，尤其是当飓风处于远离陆地的海上时，这种误差更大，通过利用UM模式在Debby飓风活动期间，对下投式探空仪所获取探空资料，采用不同使用方案的三个时次共计10次数值试验的结论分析，给出一些有意义的 结论，即非实时资料对实时资料的有效补充，能够提高飓风路径预报精度，而在众多气象要素场中，风场和湿度场对飓风路径预报的影响更大。 相似文献
17.
变步长显式完全平方守恒差分格式 总被引：8，自引：0，他引：8
综合隐式完全平方守恒差分格式和显式瞬时平方守恒差分格式的优点，针对一类非线性发展方程构造了一种通过自动调节时间步长来保持平方守恒性的显式差分格式。它基于加小耗散的思想，但又与小耗散法有所不同。本文取的耗散项不是一般的人工耗散，而是取能够弥补由于时间离散所产生的截断误差的所谓（时间）协调耗散。因此，该格式具有较高的时间精度。在数值试验中，该类格式可取得满意的效果。 相似文献
18.
A case is reported, during which the Subtropical High over the Western Pacific(hereafter, SHWP in abbreviation)shifted northwestward and met-yu at Chaniiang River valley ended. Several numerical experiments on SHWP activity influenced by the heating over south Asia monsoon area are carried out, and the statistic significance of the results is checked. The results indicate that the enhancement of positive heating over South Asia will motivate a wave-like series of anomaly centers, which propagate northeastward from the maximum heating center.so that a strong positive potential height anomaly center will set up from North China to Japan at Day 3 result in the enhancement of SHWP. Comparison of the influence upon SHWP by the heating over south Asia monsoonarea with that over ITCZ area south to SHWP is also carried out. It is pointed out that the heating over South Asiamonsoon area tends to favor SHWP northward movement while the heating over ITCZ area tends to thvor SHWP westward stretching. As for the time to begin to influence on SHWP, the heating over south Asia monsoon areafavors the enhancement of SHWP atter Day 3 while that over ITCZ south to SHWP effects after Day 5. 相似文献
19.
Little is known about the influence of hurricanes on precipitation extremes (PEs) in Southern Ontario, Canada. We examine PEs and their spatial–temporal link with hurricanes events in Southern Ontario during the period of 1950–2000. On average, 5.4 PEs or 11 % of the 50 wettest days in the selected five locations occurred under the influence of hurricanes within this 51-year period. Our results indicate hurricane-influenced PEs are most frequent in September and derive from storms that had reached major hurricane status (>50 m/s) at some point during their lifetime. An absence of landfalling hurricanes in Southern Ontario during the 1960s to 1980s suggests either that the direct impact of hurricanes occurs on a multidecadal time scale or that recent years are experiencing unprecedented change. 相似文献
20.
We employ the heat engine framework to derive a simple method for assessing the strength of irreversible processes in global
climate models (GCMs). Using the explicit energy budget of an idealized GCM, we show that the thermodynamic efficiencies based
on the net heating rate and frictional work rate provides a measure of physical and numerical irreversibilities present in
either open (e.g., the Hadley circulation) or closed (e.g., the general circulation) circulations. In addition, we show that
the Carnot efficiency is useful for assessing the maximum possible efficiency attained by closed circulations. Comparison
of the work-based efficiency with that based on the net heating rate and the Carnot efficiency provides a gauge of how close
to reversible and ideal the circulations are. A series of experiments with the idealized GCM demonstrate the usefulness of
our method and show the sensitivity of an essentially reversible model to changes in physical and numerical parameters such
as rotation period and resolution. 相似文献