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1.
A bottom-mounted Recording Doppler Current Profiler was placed at an offshore location (depth of 34 m) in the southeast Chukchi Sea, Alaska, from July through December 2007 (UTC) with the objective of linking observed wave activity—wind-sea and swells—to their synoptic drivers. A total of 47 intervals of elevated wave state were recorded: 29 exceeding 1 m significant wave height (SWH), 16 exceeding 2 m SWH, and 3 m exceeded on two occasions; during one of those, a SWH of 4 m was observed. Detailed analysis of the two large events, including comparison with high-resolution reanalysis wind data (North America Regional Reanalysis), showed wave direction from the east, varied about 15° to the north (counterclockwise) from the wind direction, and current flow in the opposite direction (from the west). This is thought to be the influence of a strong “wind-sea” presence. Regarding classic wave limitations, although the SE Chukchi Sea is a large embayment bordered by land to the east, fetch limitations from the northeast and southeast did not appear to be a constraint for the wind speeds indicated by reanalysis. These two events appeared to be driven by winds associated with cyclonic systems that moved into the eastern Bering Sea and stalled. Examination of smaller waves associated with these events suggested that waves of 1.5 m SWH or less are likely part of another regime and can either be swell or wind-sea, moving in from the open Chukchi Sea to the northwest or through the Bering Strait to the south.  相似文献   

2.
We studied the wave characteristics during the very severe cyclonic storm THANE which crossed the east coast of India between Puducherry and Cuddalore based on waves measured at a location in Bay of Bengal at 14 m water depth. Objective of the paper is to document the highest wave height measured in the nearshore waters of east coast of India. On 29 December 2011, cyclone passed within 77–315 km of the wave measurement location with maximum wind speed of 46.3 m/s (90 knots) and resulted in maximum wave height of 8.1 m. Maximum wave height recorded is 0.54 times the water depth, and the ratio of crest height to wave height of the highest wave recorded is 0.65. Maximum value of significant wave height estimated using the parametric wave model for deep-water conditions is 6.4 m, whereas the measured value is 6 m indicating that parametric wave model estimates the wave height reasonably well (within 8 % error) during the cyclone period.  相似文献   

3.
The rise of total water levels at the coast is caused primarily by three factors that encompass storm surges, tides and wind waves. The accuracy of total water elevation (TWE) forecast depends not only on the cyclonic track and its intensity, but also on the spatial distribution of winds which include its speed and direction. In the present study, the cyclonic winds are validated using buoy winds for the recent cyclones formed in the Bay of Bengal since 2010 using Jelesnianski wind scheme. It is found that the cyclonic winds computed from the scheme show an underestimate in the magnitude and also a mismatch in its direction. Hence, the wind scheme is suitably modified based on the buoy observations available at different locations using a power law which reduces the exponential decay of winds by about 30%. Moreover, the cyclonic wind direction is also corrected by suitably modifying its inflow angle. The significance of modified exponential factor and inflow angle in the computation cyclonic winds is highlighted using statistical analysis. A hydrodynamic finite element-based Advanced Circulation 2D depth integrated (ADCIRC-2DDI) model is used here to compute TWE as a response to combined effect of cyclonic winds and astronomical tides. As contribution of wave setup plays an important role near the coast, a coupled ADCIRC + SWAN is used to perceive the contribution of wind waves on the TWE. The experiments are performed to validate computed surge residuals with available tide gauge data. On comparison of observed surge residuals with the simulations using modified winds from the uncoupled and coupled models, it is found that the simulated surge residuals are better compared, especially with the inclusion of wave effect through the coupled model.  相似文献   

4.
For the very first time, the mesoscale circulation patterns and synoptic-dynamic structure of the atmospheric systems that led to the dust emission to the south coast region of Caspian Sea (SCRCS) were identified and classified using the region synoptic stations’ observations of 2005–2013. Satellite measurements and images, NCEP/NCAR reanalysis data, and Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF-CHEM) model products were also used in this study. Results showed that in 49 % of cases, cyclonic circulations over the Middle East deserts were the main transporter of dust particles into the atmosphere where then transferred to the SCRCS by southerly winds over the Alborz mountains in the lower troposphere and by westerly waves in the middle and upper troposphere. During the warm seasons, the surface heating lead to the development of mesoscale thermal low pressures over the hot deserts on the eastern regions of the Caspian Sea, like Turkmenistan and Qura Qum. Those heat lows were responsible for the 38 % of the occurred events. Turbulence and instabilities in the lower troposphere were identified as the second important dust emitter to the atmosphere where those dust particles transported to the SCRCS with the strong northeasterly wind. The third pattern by 13 % of cases was belonging to the mesoscale thermal low pressure that was developed over the arid regions of Iran like Dasht-é-Kavir. Because of the nature of the turbulence in the lower troposphere and heat lows, the ascent of dust particles by these two mechanisms was limited to a shallow layer in the troposphere. The results of simulation with the WRF-CHEM model, analysis of moderate resolution imaging spectroradiometer (MODIS) images, and spatial zoning of atmospheric optical depth (AOD) confirmed the results of the synoptic study.  相似文献   

5.
The Ministry of Shipping desires to revise the inland vessels’ limit (IVL) notification based on scientific rationale to improve the safety of vessels and onboard personnel. The Mormugao port region extending up to the Panaji was considered for this pilot study. Measured winds and wave parameters (AWS and moored buoy) as well as NCEP re-analysis and NCMRWF winds were used for the analysis and input to regional and local models. The results of wave model were validated with measured significant wave heights (SWHs) and the comparison shows a good match. The analysis indicates that SWHs do not exceed 2.0 m during non-monsoon months, and in monsoon months exceed 5.0 m, and even 7.0 m, especially during extreme events. In order to draw IVL contours for Goa coastal region, local model was set up and nearshore waves were simulated for the period May 2004–May 2005. Based on the nearshore SWH distribution, IVL contours have been fixed for the Mormugao port and Panaji coastal regions.  相似文献   

6.
A mathematical model has been developed to forecast or hindcast wind, waves, and longshore currents during the passage of a coastal storm. Storm intensity is a function of the barometric pressure gradient which is modeled by rotating an inverted normal curve around the center of an ellipse. The length and orientation of the major and minor axes of the ellipse control the size and shape of the storm. The path of the storm is determined by a sequence of storm positions for the hindcast mode, and by interpolated positions assuming constant speed and direction for the forecast mode. The site location, shoreline orientation, and nearshore bottom slope provide input data for the shore position. The geostrophic wind speed and direction at the shore site are computed from the latitude and barometric pressure gradient. The geostrophic wind is converted into surface wind speed and direction by applying corrections for frictional effects over land and sea. The surface wind speed and direction, effective fetch, and wind duration are used to compute wave period, breaker height, and breaker angle at the shore site. The longshore current velocity is computed as a function of wave period, breaker height and angle, and nearshore slope. The model was tested by comparing observed data for several coastal locations with predicted values for wind speed, wave period and height, and longshore current velocity. Forecasts were made for actual storms and for hypothetical circular and elliptical storms.  相似文献   

7.
A tropical cyclone was formed over central northern Africa near Egypt, Libya and Crete, and it moved and deepened toward the north–northeast; meanwhile, the storm destroyed many regions in the west, southwest and central of Turkey. The cyclone carried huge dust from the north of Africa to Turkey and reduced the visibility to less than 1 km and raised the wind speed. As a result of severe storm, some meteorological stations have new extreme values that the strongest wind speed measured was 81 knots in the central region of Turkey. Medicane with wind speed 81 knots especially over Turkey is a rare event. This devastating cyclone carried exceptionally very strong winds (>80 kts) with favorable conditions to follow windstorm conceptual model. The cyclone caused adverse conditions such as excessive injuries, fatal incidents and forest fires. Mesoscale vortex formed and affected particularly the middle and western regions of Turkey. The vertical thermodynamic structure of storm is compared with April values of 40 years of datasets over Istanbul. Moreover, four different winds {measurement masts} of Istanbul Atatürk Airport are used for the microscale analysis of different meteorological parameters during deepened pressure level. In addition, divergence and vorticity of stormy weather are discussed in details during the effective time period of storm by solving equations and validated using ERA-40 reanalysis. We obtained many monitoring data sources such as ground base, radar, radiosonde and satellite display the values of the intensity of wind speed caused by cyclones of tropics have revealed similarities.  相似文献   

8.
The paper presents comprehensive statistical analyses of winds and water levels in Mobile Bay, Alabama, based on long-term meteorological and tidal observations at several locations. A procedure has been developed to select the most probable parent distribution function from a list of candidate distributions. The theoretical functions that fit the data best enable us to predict the extreme values of winds and water levels at different return periods. We have demonstrated the importance of dividing the winds into hurricane and nonhurricane seasons and separating astronomical tides from weather-driven water level changes. The statistical analysis suggests that the wind speed averaged over 8 min at Dauphin Island, Alabama, at the 100-year return period would be 48.9 m/s, which is equivalent to a sustained 1-min wind of 205 km/h, a very strong category 3 hurricane on the Saffir-Simpson scale. The probability distribution models predict that the 100-year maximum water level would be 3.23 m above the mean lower low water (MLLW) level at the bay entrance and 3.41 m above the MLLW level near the head of the bay, respectively. Extremely low water levels important to navigation are also found. Application of the predicted extreme winds and surges is illustrated through the development of a storm wave atlas in the estuary. It is expected that the methodology and results presented in this paper will benefit the management and preservation of the ecosystems and habitats in Mobile Bay.  相似文献   

9.
Response of the coastal regions of eastern Arabian Sea (AS) and Kavaratti Island lagoon in the AS to the tropical cyclonic storm `Phyan??, which developed in winter in the south-eastern AS and swept northward along the eastern AS during 9?C12 November 2009 until its landfall at the northwest coast of India, is examined based on in situ and satellite-derived measurements. Wind was predominantly south/south-westerly and the maximum wind speed (U10) of ~16 m/s occurred at Kavaratti Island region followed by ~8 m/s at Dwarka (Gujarat) and ~7 m/s at Diu (located south of Dwarka) as well as two southwest Indian coastal locations (Mangalore and Malpe). All other west Indian coastal sites recorded maximum wind speed of ~5?C6 m/s. Gust factor (i.e., gust-to-speed ratio) during peak storm event was highly variable with respect to topography, with steep hilly stations (Karwar and Ratnagiri) and proximate thick and tall vegetation-rich site (Kochi) exhibiting large values (~6), whereas Island station (Kavaratti) exhibiting ~1 (indicating consistently steady wind). Rainfall in association with Phyan was temporally scattered, with the highest 24-h accumulated precipitation (~60 mm) at Karwar and ~45 mm at several other west Indian coastal sites. Impact of Phyan on the west Indian coastal regions was manifested in terms of intensified significant waves (~2.2 m at Karwar and Panaji), sea surface cooling (~5°C at Calicut), and moderate surge (~50 cm at Verem, Goa). The surface waves were south-westerly and the peak wave period (T p) shortened from ~10?C17 s to ~5?C10 s during Phyan, indicating their transition from the long-period `swell?? to the short-period `sea??. Reduction in the spread of the mean wave period (T z) from ~5?C10 s to a steady period of ~6 s was another manifestation of the influence of the cyclone on the surface wave field. Several factors such as (1) water piling-up at the coast supported by south/south-westerly wind and seaward flow of the excess water in the rivers due to heavy rains, (2) reduction of piling-up at the coast, supported by the upstream penetration of seawater into the rivers, and (3) possible interaction of upstream flow with river run-off, together resulted in the observed moderate surge at the west Indian coast. Despite the intense wind forcing, Kavaratti Island lagoon experienced insignificantly weak surge (~7 cm) because of lack of river influx and absence of a sufficiently large land boundary required for the generation and sustenance of wave/wind-driven water mass piling-up at the land?Csea interface.  相似文献   

10.
《Sedimentology》2018,65(2):461-491
Gravelly beach ridges, which are formed solely by swash processes, may accurately reflect past wave conditions. The thickness (or height) of a gravelly beach ridge approximately equals the height of wave inundation, which is the sum of the surge and wave run‐up. Their ancient counterparts, if well‐preserved and identified, can be used to estimate palaeowave conditions, which can later be converted to palaeowind intensities based on wind–wave relationships. A technique is described for estimating the palaeowind speed in this paper, which is referred to as the gravelly beach‐ridge thickness technique. By comparing these estimates with instrumental wind records obtained at a modern lake, Qinghai Lake in north‐western China, the beach‐ridge thickness technique is shown to be useful for estimating the average wind speed (V avg). When applying this method to ancient fetch‐limited basins, five parameters are necessary: (i) the thickness of the isolated gravelly beach ridge; (ii) the average depth of the water body; (iii) the palaeofetch; (iv) the angle between the palaeowind direction and the normal to the shoreline; and (v) the particle size. This technique was applied to an ancient example in the Eocene Dongying Depression, located in eastern China. The results indicate that the average wind speed of the northern wind ranged between 2·27 m sec−1 and 8·36 m sec−1 from 45·0 Ma to 42·0 Ma, and displayed a generally decreasing trend that included early strengthening followed by weakening and later strengthening during this period. The beach‐ridge thickness technique provides a new perspective on delineating palaeowind conditions and can be applied to ancient fetch‐limited basins with gravelly beach ridges worldwide. Generally, if a water body is sufficiently large (fetch exceeding 40 km), deep (average depth exceeding 10 m) and waves (or winds) are determined to approach the shoreline with high angles (angle of incidence <35°), then the calculation errors will be small to negligible.  相似文献   

11.
Cyclone-generated surface waves are simulated using state-of-art SWAN (Simulating WAves Nearshore) model coupled with hydrodynamic model inputs. A severe cyclonic storm passed over the Arabian Sea during 4–9th November 1982 is selected from UNISYS track records. The cyclone lasted for nearly 6 days and subsided with a land fall at Gujarat coast, west coast of India. In this study, cyclonic wind fields are generated using a well-established relationship suggested by Jelesnianski and Taylor (1973). The associated water level variations due to storm surge and surge generated currents are simulated using POM (Princeton Ocean Model). The outputs are one-way coupled with the wave model SWAN for simulating wave parameters off Gujarat, north-east basin of Arabian Sea. An extensive literature review is carried out on the progress and methodology adopted for storm wave modelling and analysis. The results presented in this paper reveal the severity of the storm event and would be highly useful for assessing the extreme wave event/climate especially for the south coast of Gujarat.  相似文献   

12.
Among the semi-enclosed basins of the world ocean, the South China Sea (SCS) is unique in its configuration as it lies under the main southwest-northeast pathway of the seasonal monsoons. The northeast (NE) monsoon (November–February) and southwest (SW) monsoon (June–August) dominate the large-scale sea level dynamics of the SCS. Sunda Shelf at the southwest part of SCS tends to amplify Sea Level Anomalies (SLAs) generated by winds over the sea. The entire region, bounded by Gulf of Thailand on the north, Karimata Strait on the south, east cost of Peninsular Malaysia on the west, and break of Sunda Shelf on the east, could experience positive or negative SLAs depending on the wind direction and speed. Strong sea level surges during NE monsoon, if coincide with spring tide, usually lead to coastal floods in the region. To understand the phenomena, we analyzed the wind-driven sea level anomalies focusing on Singapore Strait (SS), laying at the most southwest point of the region. An analysis of Tanjong Pagar tide gauge data in the SS, as well as satellite altimetry and reanalyzed wind in the region, reveals that the wind over central part of SCS is arguably the most important factor determining the observed variability of SLAs at hourly to monthly scales. Climatological SLAs in SS are found to be positive, and of the order of 30 cm during NE monsoon, but negative, and of the order of 20 cm during SW monsoon. The largest anomalies are associated with intensified winds during NE monsoon, with historical highs exceeding 50 cm. At the hourly and daily time-scales, SLA magnitude is correlated with the NE wind speed over central part of SCS with an average time lag of 36–42 h. An exact solution is derived by approximating the elongated SCS shape with one-dimensional two-step channel. The solution is utilized to derive simple model connecting SLAs in SS with the wind speeds over central part of SCS. Due to delay of sea level anomaly in SS with respect to the remote source at SCS, the simplified solutions could be used for storm surge forecast, with a lead time exceeding 1 day.  相似文献   

13.
A cyclone genesis parameter, termed the genesis potential parameter (GPP), for the Indian Sea is proposed. The parameter is defined as the product of four variables, namely vorticity at 850 hPa, middle tropospheric relative humidity, middle tropospheric instability, and the inverse of vertical wind shear. The variables are calculated using the National Centers for Environmental Prediction (NCEP), USA, reanalysis data, averaged within a circle of 2.5° radius around the centre of cyclonic system. The parameter is tested with a sample dataset of 35 nondeveloping and developing low-pressure systems that formed over the Indian Sea during the period 1995–2005. The result shows that there is a distinction between GPP values for nondeveloping and developing systems in more than 85% cases. The composite GPP value is found to be around three to five times greater for developing systems than for nondeveloping systems. The analysis of the parameter at early development stage of a cyclonic storm appears to provide a useful predictive signal for intensification of the system.  相似文献   

14.
Historically, Leyte Gulf in central eastern Philippines has received catastrophic damage due to storm surges, the most recent of which was during Typhoon Haiyan in 2013. A city-level risk assessment was performed on Leyte Gulf through synthetic storm generation, high-resolution ocean modeling, and decision tree analyses. Cyclones were generated through a combination of a Poisson point process and Monte Carlo simulations. Wind and pressure fields generated from the cyclones were used in a storm surge model of Leyte Gulf developed on Delft3D. The output of these simulations was a synthetic record of extreme sea level events, which were used to estimate maximum surge heights for different return periods and to characterize surge-producing storm characteristics using decision tree analyses. The results showed that the area most prone to surges is the Tacloban–Basey area with a 2.8?±?0.3 m surge occurring at a frequency of every 50 years. Nearby Palo area will likely receive a surge of 1.9?±?0.4 m every 50 years while Giporlos–Salcedo area a surge of 1.0?±?0.1 m. The decision tree analysis performed for each of these areas showed that for surges of 3–4 m, high-velocity winds (>?30 m/s) are consistently the main determining factor. For the areas, Tacloban, Basey, and Giporlos–Salcedo, wind speed was also the main determining factor for surge?>?4 m.  相似文献   

15.
Estimating palaeowind strength from beach deposits   总被引：1，自引：0，他引：1  
Abstract The geological record of past wind conditions is well expressed in the coarse gravel, cobble and boulder beach deposits of Quaternary palaeolakes in the Great Basin of the western USA and elsewhere. This paper describes a technique, using the particle‐size distribution of beach deposits, to reconstruct palaeowind conditions when the lakes were present. The beach particle technique (BPT) is first developed using coarse beach deposits from the 1986–87 highstand of the Great Salt Lake in Utah, combined with instrumental wind records from the same time period. Next, the BPT is used to test the hypothesis that wind conditions were more severe than at present during the last highstand of Lake Lahontan (≈ 13 ka), which only lasted a decade or two at most. The largest 50 beach clasts were measured at nine beach sites located along the north, west and south sides of Antelope Island in the Great Salt Lake, all of which formed in 1986–87. At these sites, the largest clast sizes range from 10 to 28 cm (b‐axis), and fetch lengths range from 25 to 55 km. Nearshore wave height was calculated by assuming that the critical threshold velocity required to move the largest clasts represents a minimum estimate of the breaking wave velocity, which is controlled by wave height. Shoaling transformations are undertaken to estimate deep‐water wave heights and, ultimately, wind velocity. Wind estimates for the nine sites, using the BPT, range from 6·5 to 17·4 m s?1, which is in reasonable agreement with the instrumental record from Salt Lake City Airport. The same technique was applied to eight late Pleistocene beaches surrounding the Carson Sink sub‐basin of Lake Lahontan, Nevada. Using the BPT, estimated winds for the eight sites range from 9·7 to 27·1 m s?1. The strongest winds were calculated for a cobble/boulder beach with a fetch of 25 km. Instrumental wind records for the 1992–99 period indicate that wind events of 9–12 m s?1 are common and that the strongest significant wind event (≥ 9 m s?1 for ≥ 3 h) reached an average velocity of 15·5 m s?1. Based on this preliminary comparison, it appears that the late Pleistocene western Great Basin was a windier place than at present, at least for a brief time.  相似文献   

16.
The disastrous effects of numerous winter storms on the marine environment in the North Sea and the Baltic Sea during the last decade show that wind waves generated by strong winds actually represent natural hazards and require high quality wave forecast systems as warning tools to avoid losses due to the impact of rough seas. Hence, the operational wave forecast system running at the German Weather Service including a regional wave model for the North Sea and the Baltic Sea is checked extensively whether it provides reasonable wave forecasts, especially for periods of extraordinary high sea states during winter storms. For two selected extreme storm events that induced serious damage in the area of interest, comprehensive comparisons between wave measurements and wave model forecast data are accomplished. Spectral data as well as integrated parameters are considered, and the final outcome of the corresponding comparisons and statistical analysis is encouraging. Over and above the capability to provide good short-term forecast results, the regional wave model is able to predict extreme events as severe winter storms connected with extraordinary high waves already about 2 days in advance. Therefore, it represents an appropriate warning tool for offshore activities and coastal environment.  相似文献   

17.
Yin  Chao  Huang  Haijun  Wang  Daoru  Liu  Yanxia 《Natural Hazards》2022,113(1):103-123

With the rapid expansion of the scale of deep sea net-cage use in the nearshore area of Hainan Island, tropical cyclone-induced wave hazard assessment is urgently needed. In this study, the wind-wave-current coupled ADCIRC?+?SWAN model, which considers the effects of tidal and storm surges, was used to simulate tropical cyclone events over the last 33 years. This model adopts an unstructured high-resolution grid with a nearshore resolution of up to 100 m. The compared simulated results and observations during typhoons JEBI (2013), HAIYAN (2013) and KALMAEGI (2014) were in agreement. This study statistically analyzed maximum significant wave heights on the basis of a large set of simulated storm wave level maps to derive the wave heights of different return periods. Then, the results of nearshore wave hazard classification were obtained by applying the affinity propagation (AP) clustering method to dozens of nearshore profiles. The results demonstrate that the risk at any point in the nearshore area of Hainan Island is dominated by the wave hazard type and water depth condition. The wave hazard assessment method developed for Hainan Island will be significant in assisting government decision-making in the rational planning of deep sea net-cage aquaculture.

  相似文献   

18.
The Jeddah coast lies in the central eastern Red Sea, which is characterized by the predominant northwest winds and the associated wind waves throughout the year. A detailed investigation on the spectral wave characteristics in the nearshore regions of the Jeddah coast has not been carried out yet, primarily due to the lack of data. In the present study, we have analyzed the available wave spectra measured at two nearshore locations along the Jeddah coast using wave gauges. The wave spectra were separated into wind sea and swell components using a frequency-based algorithm, and the integral wave parameters corresponding to each component were derived. Although the measurements were limited to the summer season, notable features such as the diurnal variability and the superimposition of wind seas and swells have been identified from the spectra. The superimposition is mainly due to the interaction of the young swells propagated from the northern Red Sea and the local breezes prevailing along the coast at certain periods in a diurnal cycle. Based on the wave speed calculations and the estimated time shifts between the wind and waves, the potential swell regions have been backtracked.  相似文献   

19.
The spectral characteristics of shallow water waves were studied at two locations along the eastern Arabian Sea during 2011. Wave spectra were single-peaked from June to October and predominantly double-peaked during the rest of the year. Even though both locations were subjected to open sea conditions, the percentage of single-peaked spectra was large (63 %) in the southern location compared to a location 350 km north (46 %), because of variation in local winds. Throughout the year, the double-peaked spectra were mostly swell dominated in the southern location. In the northern location, the double-peaked spectra during January to May and December were sea dominated due to the strong local winds blowing from north-west. For the double-peaked wave spectra, the average difference between the spectral peaks was 0.11 Hz, and the average ratio of the spectral energy density at the two peaks was 0.5. Significant wave heights up to 4.2 m and a maximum wave height of 7 m were observed during the south-west monsoon period. Fifty per cent of the waves recorded had spectral peak wave periods between 6 and 12 s. The narrowest directional spectra were found for waves with 10–12-s peak wave periods. Inverse wave age values were biased towards lower values with peaks in the range of 0.2–0.6, indicating a swell-driven wave regime along the eastern Arabian Sea.  相似文献   

20.
Extreme sea storms are dangerous and a potential source of damage. In this study, we examine storm events in the Black Sea and Caspian Sea, the atmosphere circulation patterns associated with the sea storm events, and their changes in the present (1961–2000) and future (2046–2065) climates. A calendar of storms for the present climate is derived from results of wave model SWAN (Simulating WAves Nearshore) experiments. On the basis of this calendar, a catalog of atmospheric sea level pressure (SLP) fields was prepared from the NCEP/NCAR reanalysis dataset for 1961–2000. The SLP fields were subjected to a pattern recognition algorithm which employed empirical orthogonal decomposition followed by cluster analysis. The NCEP/NCAR reanalysis data is used to evaluate the occurring circulation types (CTs) within the ECHAM5-MPI/OM Atmosphere and Ocean Global Circulation Model (AOGCM) for the period 1961–2000. Our analysis shows that the ECHAM5-MPI/OM model is capable of reproducing circulation patterns for the storm events. The occurrence of present and future ECHAM5-MPI/OM CTs is investigated. It is shown that storm CTs are expected to occur noticeably less frequently in the middle of the 21st century.  相似文献   

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