2010 Vol. 16, No. 3
2010, 16(3): 201-209.
Abstract:
In this study, we derived atmospheric profiles of temperature, moisture, and ozone, along with surface emissivity, skin temperature, and surface pressure, from infrared-sounder radiances under clear sky (cloudless) condition. Clouds were detected objectively using the Atmospheric Infrared Sounder under a relatively low spatial resolution and cloud-mask information from the Moderate Resolution Imaging Spectroradiometer under a high horizontal resolution; this detection was conducted using space matching. Newton’s nonlinear physical iterative solution technique is applied to the radiative transfer equation (RTE) to retrieve temperature profiles, relative humidity profiles, and surface variables simultaneously. This technique is carried out by using the results of an eigenvector regression retrieval as the background profile and using corresponding iterative forms for the weighting functions of temperature and water-vapor mixing ratio. The iterative forms are obtained by applying the variational principle to the RTE. We also compared the retrievals obtained with different types of observations. The results show that the retrieved atmospheric sounding profile has great superiority over other observations by accuracy and resolution. Retrieved profiles can be used to improve the initial conditions of numerical models and used in areas where conventional observations are sparse, such as plateaus, deserts, and seas.
In this study, we derived atmospheric profiles of temperature, moisture, and ozone, along with surface emissivity, skin temperature, and surface pressure, from infrared-sounder radiances under clear sky (cloudless) condition. Clouds were detected objectively using the Atmospheric Infrared Sounder under a relatively low spatial resolution and cloud-mask information from the Moderate Resolution Imaging Spectroradiometer under a high horizontal resolution; this detection was conducted using space matching. Newton’s nonlinear physical iterative solution technique is applied to the radiative transfer equation (RTE) to retrieve temperature profiles, relative humidity profiles, and surface variables simultaneously. This technique is carried out by using the results of an eigenvector regression retrieval as the background profile and using corresponding iterative forms for the weighting functions of temperature and water-vapor mixing ratio. The iterative forms are obtained by applying the variational principle to the RTE. We also compared the retrievals obtained with different types of observations. The results show that the retrieved atmospheric sounding profile has great superiority over other observations by accuracy and resolution. Retrieved profiles can be used to improve the initial conditions of numerical models and used in areas where conventional observations are sparse, such as plateaus, deserts, and seas.
2010, 16(3): 210-220.
Abstract:
The influences of Tropical Rainfall Measuring Mission (TRMM) precipitation products on the structure and underlying physics of intraseasonal oscillation (ISO) are investigated with the U.S. National Aeronautics and Space Administration Goddard Earth Observing System model version 3 (GEOS-3) data assimilation system (DAS). The strong ISO phase in the 1998 summer is apparently located in the Asian monsoon region and the east equatorial Pacific region. The eastward propagation is a dominant feature for the tropical ISO at 20 to 30-day oscillation while the northeastward propagation is the salient ISO at 30 to 60-day oscillation over the 10°N to 25°N belt region. It appears that the Kelvin wave structure is for the tropical 20 to 30-day oscillation. The tropical 30 to 60-day oscillation has the characteristics of the Kelvin-Rossby wave. The impact of satellite-derived precipitation (and its associated latent heating) on the ISO intensity is limited in the GEOS-3 assimilation system. However, its impact on the ISO spatial structures is obvious. Overall, the results demonstrate a better eastward propagation and a northward propagation of ISO with the TRMM precipitation simulation, indicating that latent heating is very important in exciting the equatorial ISO.
The influences of Tropical Rainfall Measuring Mission (TRMM) precipitation products on the structure and underlying physics of intraseasonal oscillation (ISO) are investigated with the U.S. National Aeronautics and Space Administration Goddard Earth Observing System model version 3 (GEOS-3) data assimilation system (DAS). The strong ISO phase in the 1998 summer is apparently located in the Asian monsoon region and the east equatorial Pacific region. The eastward propagation is a dominant feature for the tropical ISO at 20 to 30-day oscillation while the northeastward propagation is the salient ISO at 30 to 60-day oscillation over the 10°N to 25°N belt region. It appears that the Kelvin wave structure is for the tropical 20 to 30-day oscillation. The tropical 30 to 60-day oscillation has the characteristics of the Kelvin-Rossby wave. The impact of satellite-derived precipitation (and its associated latent heating) on the ISO intensity is limited in the GEOS-3 assimilation system. However, its impact on the ISO spatial structures is obvious. Overall, the results demonstrate a better eastward propagation and a northward propagation of ISO with the TRMM precipitation simulation, indicating that latent heating is very important in exciting the equatorial ISO.
2010, 16(3): 221-230.
Abstract:
Using reanalysis data provided by the U.S. National Centers for Environmental Prediction/National Center for Atmospheric Research, the potential relationship between the El Niño-Southern Oscillation (ENSO) cycle and blocking highs in three key regions of Eurasia (Ural, Baikal, and Okhotsk) from 1950 to 2008 is analyzed. Composite analysis of 500 hPa geopotential height field during different stages of ENSO reveals that in the winters of El Niño (EN) years, there is significant negative anomaly of geopotential height in the three key regions. In the winters of La Niña (LN) years, on the other hand, significant positive anomaly of geopotential height is observed in Eastern Ural, Baikal, and Okhotsk. In summer, Okhotsk exhibits positive anomaly, which is significant at a confidence level of 90% by Student’s t-test during the developing stage of an LN year. In the developing stage of an EN year, geopotential height field at 500 hPa manifests positive (negative) anomaly in Baikal (Ural and Okhotsk), while the geopotential height field at 500 hPa exhibits positive (negative) anomaly in Ural and Okhotsk (Baikal) during the decaying stage of both EN and LN years. However, these abnormities are insignificant in a developing EN year, decaying EN year, and the summer of a decaying LN year. By analyzing 500 hPa geopotential height field during different phases of the ENSO cycle, it is observed that results of the case study are consistent with those of composite analysis. Annual average blocking is likewise examined during the different stages of ENSO from 1950 to 2008. Combined with composite analysis and case study, results indicate that blockings in the three key regions are suppressed (enhanced) during the winters of EN (LN) years. In summer, the influence of ENSO on the blockings in the three key regions is not as significant as that in winter. Evidently, developing LN may enhance blockings in Okhotsk. Influence factors on blockings are various and complex. This paper indicates that the influence of ENSO on blockings cannot be neglected, and that it is crucial to related operational forecasting as a potential signal.
Using reanalysis data provided by the U.S. National Centers for Environmental Prediction/National Center for Atmospheric Research, the potential relationship between the El Niño-Southern Oscillation (ENSO) cycle and blocking highs in three key regions of Eurasia (Ural, Baikal, and Okhotsk) from 1950 to 2008 is analyzed. Composite analysis of 500 hPa geopotential height field during different stages of ENSO reveals that in the winters of El Niño (EN) years, there is significant negative anomaly of geopotential height in the three key regions. In the winters of La Niña (LN) years, on the other hand, significant positive anomaly of geopotential height is observed in Eastern Ural, Baikal, and Okhotsk. In summer, Okhotsk exhibits positive anomaly, which is significant at a confidence level of 90% by Student’s t-test during the developing stage of an LN year. In the developing stage of an EN year, geopotential height field at 500 hPa manifests positive (negative) anomaly in Baikal (Ural and Okhotsk), while the geopotential height field at 500 hPa exhibits positive (negative) anomaly in Ural and Okhotsk (Baikal) during the decaying stage of both EN and LN years. However, these abnormities are insignificant in a developing EN year, decaying EN year, and the summer of a decaying LN year. By analyzing 500 hPa geopotential height field during different phases of the ENSO cycle, it is observed that results of the case study are consistent with those of composite analysis. Annual average blocking is likewise examined during the different stages of ENSO from 1950 to 2008. Combined with composite analysis and case study, results indicate that blockings in the three key regions are suppressed (enhanced) during the winters of EN (LN) years. In summer, the influence of ENSO on the blockings in the three key regions is not as significant as that in winter. Evidently, developing LN may enhance blockings in Okhotsk. Influence factors on blockings are various and complex. This paper indicates that the influence of ENSO on blockings cannot be neglected, and that it is crucial to related operational forecasting as a potential signal.
2010, 16(3): 231-237.
Abstract:
This study examines the wave trains at 500 hPa occurring in East Asian summer by using the Empirical Orthogonal Function (EOF) analysis as a diagnostic tool. The results are summarized as follows: (1) A wave train pattern (OKJ pattern) originating from the upstream areas of the Sea of Okhotsk to the subtropical regions could display its strong signal in early and middle summer. The OKJ pattern is clearly recognized in the first EOF component in Eurasia. (2) The other wave train pattern originating from the Philippines via Japan to North America (the P-J pattern) shows quite strong signals in the whole summer. Although the P-J pattern is described as the second EOF component around the area from East Asia to Northeast Pacific Ocean, the variance contribution is the same as that of OKJ pattern in the first EOF component. (3) The composite analyses indicate that the OKJ and P-J wave trains could coexist to some extents.
This study examines the wave trains at 500 hPa occurring in East Asian summer by using the Empirical Orthogonal Function (EOF) analysis as a diagnostic tool. The results are summarized as follows: (1) A wave train pattern (OKJ pattern) originating from the upstream areas of the Sea of Okhotsk to the subtropical regions could display its strong signal in early and middle summer. The OKJ pattern is clearly recognized in the first EOF component in Eurasia. (2) The other wave train pattern originating from the Philippines via Japan to North America (the P-J pattern) shows quite strong signals in the whole summer. Although the P-J pattern is described as the second EOF component around the area from East Asia to Northeast Pacific Ocean, the variance contribution is the same as that of OKJ pattern in the first EOF component. (3) The composite analyses indicate that the OKJ and P-J wave trains could coexist to some extents.
2010, 16(3): 238-246.
Abstract:
In this paper, we discussed the features of atmospheric circulations over Eurasia as a response to sea surface temperature anomalies (SSTAs) over the tropical Indian Ocean, the equatorial Pacific, Kuroshio and the North Atlantic. Our results are shown as follows: (1) CAM3.0, driven by the combined SSTAs over the four oceanic regions, can simulate well the features of anomalous atmospheric circulations over Eurasia in January 2008, indicating that the effects of the SSTAs over these four regions were one of the key causes of the anomalous systems over Eurasia. (2) The SSTAs over each key region contributed to the intensification of blocking over the Urals Mountains and a main East Asian trough. However, the influence of the SSTAs over individual oceanic regions differed from one another in other aspects. The SSTAs over the North Atlantic had an impact on the 500-hPa anomalous height (Z500A) over the middle-high latitudes and had a somewhat smaller effect over the low latitudes. For the warm SSTAs over Kuroshio, the subtropical high was much stronger, spread farther north than usual, and had an anomalous easterly that dominated the northwest Pacific Ocean. The warm SSTAs over the tropical Indian Ocean could have caused a negative Z500A from West Asia to Middle Asia, a remarkably anomalous southwesterly from the Indian Ocean to the south of China and an anomalous anticyclone circulation over the South China Sea-Philippine Sea region. Because of the La Niña event, the winter monsoon was stronger than normal, with an anomalously cooler northerly over the southeastern coastal areas of China. (3) The combined effects of the SSTAs over the four key regions were likely more important to the atmospheric circulation anomalies of January 2008 over Eurasia than the effects of individual or partly combined SSTAs. This unique SSTA distribution possibly led to the circulation anomalies over Eurasia in January 2008, especially the atmospheric circulation anomalies over the subtropics, which were more similar to those of the winter El Niño events than to the circulation anomalies following La Niña.
In this paper, we discussed the features of atmospheric circulations over Eurasia as a response to sea surface temperature anomalies (SSTAs) over the tropical Indian Ocean, the equatorial Pacific, Kuroshio and the North Atlantic. Our results are shown as follows: (1) CAM3.0, driven by the combined SSTAs over the four oceanic regions, can simulate well the features of anomalous atmospheric circulations over Eurasia in January 2008, indicating that the effects of the SSTAs over these four regions were one of the key causes of the anomalous systems over Eurasia. (2) The SSTAs over each key region contributed to the intensification of blocking over the Urals Mountains and a main East Asian trough. However, the influence of the SSTAs over individual oceanic regions differed from one another in other aspects. The SSTAs over the North Atlantic had an impact on the 500-hPa anomalous height (Z500A) over the middle-high latitudes and had a somewhat smaller effect over the low latitudes. For the warm SSTAs over Kuroshio, the subtropical high was much stronger, spread farther north than usual, and had an anomalous easterly that dominated the northwest Pacific Ocean. The warm SSTAs over the tropical Indian Ocean could have caused a negative Z500A from West Asia to Middle Asia, a remarkably anomalous southwesterly from the Indian Ocean to the south of China and an anomalous anticyclone circulation over the South China Sea-Philippine Sea region. Because of the La Niña event, the winter monsoon was stronger than normal, with an anomalously cooler northerly over the southeastern coastal areas of China. (3) The combined effects of the SSTAs over the four key regions were likely more important to the atmospheric circulation anomalies of January 2008 over Eurasia than the effects of individual or partly combined SSTAs. This unique SSTA distribution possibly led to the circulation anomalies over Eurasia in January 2008, especially the atmospheric circulation anomalies over the subtropics, which were more similar to those of the winter El Niño events than to the circulation anomalies following La Niña.
2010, 16(3): 247-254.
Abstract:
The Weather Research Forecast model (WRF) configured with high resolution and NCEP 1°×1° reanalysis data were used to simulate the development of a tropical deep convection over the Tiwi Islands, northern Australia, and to investigate the sensitivity of model results to model configuration and parameterization schemes of microphysical processes. The simulation results were compared with available measurements. The results show that the model can reproduce most of the important characteristics of the observed diurnal evolution of the convection, including the initiation of convection along the sea-breeze front, which is then reinforced by downdraft outflows, merging of cells and the formation of a deep convective system. However, further improvement is needed to simulate more accurately the location and the time for initiation of the deep convective system. Sensitivity tests show that double-nesting schemes are more accurate than the non-nesting schemes in predicting the distribution and intensity of precipitation as far as this particular case is concerned. Additionally, microphysical schemes also have an effect on the simulated amount of precipitation. It is shown that the best agreement is reached between the simulation results and observations when the Purdue Lin scheme is used.
The Weather Research Forecast model (WRF) configured with high resolution and NCEP 1°×1° reanalysis data were used to simulate the development of a tropical deep convection over the Tiwi Islands, northern Australia, and to investigate the sensitivity of model results to model configuration and parameterization schemes of microphysical processes. The simulation results were compared with available measurements. The results show that the model can reproduce most of the important characteristics of the observed diurnal evolution of the convection, including the initiation of convection along the sea-breeze front, which is then reinforced by downdraft outflows, merging of cells and the formation of a deep convective system. However, further improvement is needed to simulate more accurately the location and the time for initiation of the deep convective system. Sensitivity tests show that double-nesting schemes are more accurate than the non-nesting schemes in predicting the distribution and intensity of precipitation as far as this particular case is concerned. Additionally, microphysical schemes also have an effect on the simulated amount of precipitation. It is shown that the best agreement is reached between the simulation results and observations when the Purdue Lin scheme is used.
2010, 16(3): 255-262.
Abstract:
With the precipitation data of 113 stations in East China during the last 50 years, the characteristics of the precipitation, including Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP) and their tendencies, are analyzed. The results show that the PCD in the northern part of the region is markedly higher than that in the southern part, but the PCP in the south is much earlier than that in the north by about one and a half months, which displays significant regional differences in precipitation. With the global warming, precipitation over East China shows an increasing tendency, but PCD displays a trend that is neither increasing nor decreasing. At the same time, the PCP is later than before, which can be mainly found in Jiangxi and southern Henan provinces. As a result, there are strong associations between the precipitation, PCD and PCP, which can be shown in the years with more precipitation, stronger PCD and later-than-usual PCP. In a word, the abnormal distribution of precipitation, PCP, and PCD over East China results in more extreme events of precipitation and more droughts and floods.
With the precipitation data of 113 stations in East China during the last 50 years, the characteristics of the precipitation, including Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP) and their tendencies, are analyzed. The results show that the PCD in the northern part of the region is markedly higher than that in the southern part, but the PCP in the south is much earlier than that in the north by about one and a half months, which displays significant regional differences in precipitation. With the global warming, precipitation over East China shows an increasing tendency, but PCD displays a trend that is neither increasing nor decreasing. At the same time, the PCP is later than before, which can be mainly found in Jiangxi and southern Henan provinces. As a result, there are strong associations between the precipitation, PCD and PCP, which can be shown in the years with more precipitation, stronger PCD and later-than-usual PCP. In a word, the abnormal distribution of precipitation, PCP, and PCD over East China results in more extreme events of precipitation and more droughts and floods.
2010, 16(3): 263-270.
Abstract:
The 2003–C2006 observations were utilized to analyze the surface characteristics of summer land-sea breezes along the coastland of Guangxi and the Weather Research and Forecast model was applied to simulate the breeze structure on August 1–C2, 2006. Results show that 1) the intensity and distributions of the breezes reproduced from improved urban underlying surface were close to observations. In the daytime the coastwise urban band was a convergent belt of sea breeze, corresponding to the centers of torrential rains; in the nighttime hours the surface of the Gulf of Tonkin (the Vietnamese name) or the Northern Bay (the Chinese name) acted as a convergent zone of land breezes, likely to produce convective cloud cluster; 2) the experiment on urbanization showed the heat island effect enhancing (weakening) the sea (land) breeze development. Furthermore, the heat island effect mitigated the atmospheric cooling via radiation over the cities in the night, weakening sinking motion correspondingly, thereby suppressing the dominant factor responsible for the steady development of temperature inversion. As a result, the inversion vigor was reduced greatly, but nevertheless no strong effect of the decreased subsidence was found upon the inversion height.
The 2003–C2006 observations were utilized to analyze the surface characteristics of summer land-sea breezes along the coastland of Guangxi and the Weather Research and Forecast model was applied to simulate the breeze structure on August 1–C2, 2006. Results show that 1) the intensity and distributions of the breezes reproduced from improved urban underlying surface were close to observations. In the daytime the coastwise urban band was a convergent belt of sea breeze, corresponding to the centers of torrential rains; in the nighttime hours the surface of the Gulf of Tonkin (the Vietnamese name) or the Northern Bay (the Chinese name) acted as a convergent zone of land breezes, likely to produce convective cloud cluster; 2) the experiment on urbanization showed the heat island effect enhancing (weakening) the sea (land) breeze development. Furthermore, the heat island effect mitigated the atmospheric cooling via radiation over the cities in the night, weakening sinking motion correspondingly, thereby suppressing the dominant factor responsible for the steady development of temperature inversion. As a result, the inversion vigor was reduced greatly, but nevertheless no strong effect of the decreased subsidence was found upon the inversion height.
2010, 16(3): 271-279.
Abstract:
The basic features of climatology and interannual variations of tropical Pacific and Indian Oceans were analyzed using a coupled general circulation model (CGCM), which was constituted with an intermediate 2.5-layer ocean model and atmosphere model ECHAM4. The CGCM well captures the spatial and temporal structure of the Pacific El Niño-Southern Oscillation (ENSO) and the variability features in the tropical Indian Ocean. The influence of Pacific air-sea coupled process on the Indian Ocean variability was investigated carefully by conducting numerical experiments. Results show that the occurrence frequency of positive/negative Indian Ocean Dipole (IOD) event will decrease/increase with the presence/absence of the coupled process in the Pacific Ocean. Further analysis demonstrated that the air-sea coupled process in the Pacific Ocean affects the IOD variability mainly by influencing the zonal gradient of thermocline via modulating the background sea surface wind.
The basic features of climatology and interannual variations of tropical Pacific and Indian Oceans were analyzed using a coupled general circulation model (CGCM), which was constituted with an intermediate 2.5-layer ocean model and atmosphere model ECHAM4. The CGCM well captures the spatial and temporal structure of the Pacific El Niño-Southern Oscillation (ENSO) and the variability features in the tropical Indian Ocean. The influence of Pacific air-sea coupled process on the Indian Ocean variability was investigated carefully by conducting numerical experiments. Results show that the occurrence frequency of positive/negative Indian Ocean Dipole (IOD) event will decrease/increase with the presence/absence of the coupled process in the Pacific Ocean. Further analysis demonstrated that the air-sea coupled process in the Pacific Ocean affects the IOD variability mainly by influencing the zonal gradient of thermocline via modulating the background sea surface wind.
2010, 16(3): 280-291.
Abstract:
Storm identification and tracking based on weather radar data are essential to nowcasting and severe weather warning. A new two-dimensional storm identification method simultaneously seeking in two directions is proposed, and identification results are used to discuss storm tracking algorithms. Three modern optimization algorithms (simulated annealing algorithm, genetic algorithm and ant colony algorithm) are tested to match storms in successive time intervals. Preliminary results indicate that the simulated annealing algorithm and ant colony algorithm are effective and have intuitionally adjustable parameters, whereas the genetic algorithm is unsatisfactorily constrained by the mode of genetic operations. Experiments provide not only the feasibility and characteristics of storm tracking with modern optimization algorithms, but also references for studies and applications in relevant fields.
Storm identification and tracking based on weather radar data are essential to nowcasting and severe weather warning. A new two-dimensional storm identification method simultaneously seeking in two directions is proposed, and identification results are used to discuss storm tracking algorithms. Three modern optimization algorithms (simulated annealing algorithm, genetic algorithm and ant colony algorithm) are tested to match storms in successive time intervals. Preliminary results indicate that the simulated annealing algorithm and ant colony algorithm are effective and have intuitionally adjustable parameters, whereas the genetic algorithm is unsatisfactorily constrained by the mode of genetic operations. Experiments provide not only the feasibility and characteristics of storm tracking with modern optimization algorithms, but also references for studies and applications in relevant fields.
2010, 16(3): 292-298.
Abstract:
With high resolution (1 km), the distribution of wind energy resources in Hainan province and over its offshore waters is numerically simulated by using the Wind Energy Simulation Toolkit (WEST) model developed by Meteorological Research Branch of Environment Canada. Compared with observations from eight coastal anemometric towers and 18 existing stations in the province, the simulations show good reproduction of the real distribution of wind resources in Hainan and over its offshore waters, with the relative error of annual mean wind speed being no more than 9% at the 70-m level. Moreover, based on the simulated results of WEST grids that are closest to where the eight wind towers are located, the annual mean wind speeds are further estimated by using the Danish software WasP (Wind Atlas Analysis and Application Program). The estimated results are then compared with the observations from the towers. It shows that the relative error is also less than 9%. Therefore, WEST and WEST+WAsP will be useful tools for the assessment of wind energy resources in high resolution and selection of wind farm sites in Hainan province and over its offshore waters.
With high resolution (1 km), the distribution of wind energy resources in Hainan province and over its offshore waters is numerically simulated by using the Wind Energy Simulation Toolkit (WEST) model developed by Meteorological Research Branch of Environment Canada. Compared with observations from eight coastal anemometric towers and 18 existing stations in the province, the simulations show good reproduction of the real distribution of wind resources in Hainan and over its offshore waters, with the relative error of annual mean wind speed being no more than 9% at the 70-m level. Moreover, based on the simulated results of WEST grids that are closest to where the eight wind towers are located, the annual mean wind speeds are further estimated by using the Danish software WasP (Wind Atlas Analysis and Application Program). The estimated results are then compared with the observations from the towers. It shows that the relative error is also less than 9%. Therefore, WEST and WEST+WAsP will be useful tools for the assessment of wind energy resources in high resolution and selection of wind farm sites in Hainan province and over its offshore waters.
2010, 16(3): 299-304.
Abstract:
Hazard factors, hazard-bear1ing objects, disaster-developing environment, and disaster-preventing capability play key roles in the formation of Tropical Cyclone (TC) disasters. Of all of these, the most important is the intensity of hazard factors (risk sources). In this study, this intensity is uniformly defined by the probability of hazard factors; then a relationship is established between disaster risk intensity and hazard factors. The exceedance probability of various hazard factors, including frequency and timing, scope of wind and rain, and maximum wind and rain of impacting TC cases, are calculated using data from TCs that impacted Shanghai from 1959–C2006. The relationship between disaster situation and risk probability of hazard factors is analyzed, and the indices and model of TC disaster assessment are established based on the results. The process maximum wind speed and maximum daily precipitation are very important in TC-related disaster formation in Shanghai. The results of disaster indices coordinate with the results of the assessment model, and both can show the extent of probability of a TC disaster. Tests using TC data in 2007 and 2008 show that disasters caused by TC Krosa (0716) would be more serious than those by TC Wipha (0713), and that TC Fung Wong (0808) would have a weak impact. Real-life situations validate these results.
Hazard factors, hazard-bear1ing objects, disaster-developing environment, and disaster-preventing capability play key roles in the formation of Tropical Cyclone (TC) disasters. Of all of these, the most important is the intensity of hazard factors (risk sources). In this study, this intensity is uniformly defined by the probability of hazard factors; then a relationship is established between disaster risk intensity and hazard factors. The exceedance probability of various hazard factors, including frequency and timing, scope of wind and rain, and maximum wind and rain of impacting TC cases, are calculated using data from TCs that impacted Shanghai from 1959–C2006. The relationship between disaster situation and risk probability of hazard factors is analyzed, and the indices and model of TC disaster assessment are established based on the results. The process maximum wind speed and maximum daily precipitation are very important in TC-related disaster formation in Shanghai. The results of disaster indices coordinate with the results of the assessment model, and both can show the extent of probability of a TC disaster. Tests using TC data in 2007 and 2008 show that disasters caused by TC Krosa (0716) would be more serious than those by TC Wipha (0713), and that TC Fung Wong (0808) would have a weak impact. Real-life situations validate these results.
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