Mesoscale Wind Fields Research Articles

Mesoscale wind field patterns conducive to the high-PM2.5 episodes over South Korea: Cluster analysis

Mesoscale wind field patterns play important roles in episodes of high particulate matter (PM2.5). Previous studies have reported the main synoptic meteorological features associated with high-PM2.5 days with two primary modes: long-range transport (LRT) and stagnation or local contribution (STL). However, due to the lack of more small-scale analyses spanning across multiple administrative regions, statistical quantification of representative mesoscale wind patterns with elevated PM2.5 episodes is needed to explore region-specific emissions reduction strategies in South Korea. This study applied k-means clustering to NCEP FNL reanalysis data from 2016 to 2020 to identify mesoscale wind field patterns associated with high-PM2.5 episodes across all 17 administrative regions of South Korea. Our statistical approach yielded region-specific wind fields for 17 individual administrative regions, and also empirically yielded a total of eight representative patterns, four patterns each for both LRT and STL modes, which were applicable across all regions. The eight patterns were consistent with most previous studies. In addition, we quantified the LTP and STL modes in all 17 regions, and showed that they were more prevalent in the western and southeastern administrative regions of South Korea, respectively. Our results serve as a reference for region-specific mitigation strategies in all administrative regions of South Korea, and will also be useful for analyzing relations between meteorology and high-PM2.5 episodes in the SIJAQ and ASIA-AQ studies.

The Effects of Topography and Urban Agglomeration on the Sea Breeze Evolution over the Pearl River Delta Region

Sea breezes are one of the most important weather processes affecting the environmental and climatic features over coastal areas, and the sea breeze from the Pearl River Estuary (PRE) has significant effects on the Pearl River Delta (PRD) region. We simulated a typical sea breeze process that occurred on 27 December 2020 in the PRD region using the Weather Research and Forecasting (WRF) model to quantify the effects of topography and city clusters on the development of the sea breeze circulation. The results show that: (1) the topography on the west coast of the PRD tends to block the intrusion of the sea breeze and detour it along the eastern part of the terrain in the southeast of Jiangmen. The depth of sea breeze along the position of the detour is increased by 120 m, the penetration distance is increased by 40 km, the maximum intensity of sea breeze decreases by ~0.4 m/s, and the time of maximum speed delays for 4 h. However, on the east coast, the topography promotes the sea breeze, resulting in an occurrence about 4 h earlier due to the heating effects. The depth and the speed of the sea breeze are increased by 466 m and 1.2 m/s, respectively. (2) Under the influence of Urban Heat Island Circulation (UHIC), the sea breezes reach cities near the coast an hour earlier and are later inhibited from propagating further inland. Moreover, a wind convergence zone with a speed of 3–5 m/s and a width of about 25 km is formed along the boundary of suburbs and cities in the PRD region. As a result, two important convergence areas: Foshan–Guangzhou, and Dongguan–Shenzhen are formed. (3) Overall, the topography has a more remarkable impact on the mesoscale wind field especially in the mountain and bay areas, resulting in an average speed disturbance of 2.8 m/s. The urban heat island effect is relatively small and on average it causes only ± 0.9–1.8 m/s wind speed perturbations in the periphery of two convergence areas and over PRE.

Simulation of extreme waves using coupled atmosphere-wave modeling system over the South China Sea

A real-time two-way coupled atmosphere-wave model in the South China Sea (SCS) has been established based on the atmosphere model WRF and the wave model SWAN in this study. We implement a nested computational grid along the SCS in the SWAN model and utilize the WRF model to provide high-resolution mesoscale wind field and pressure field over the SCS under the influence of typhoons. The numerical simulation of the typhoon waves generated by typhoon Kai-tak (1213), Rammasun (1409) and Hato (1713) had been carried out. The results of the numerical simulation are compared with the results of the field observation and the satellite altimeter. The verification results show that the coupled WRF-SWAN model has a high accuracy in the simulation of typhoon waves under the influence of typhoons in the SCS. The results of the simulation reveal the asymmetrical distribution of wind speed and typhoon wave height generated by typhoons in the space. The intensity of the typhoon on the right is greater than that on the left of the typhoon track. The real-time two-way coupled atmosphere-wave model based on the WRF model and the SWAN model can accurately simulate the dynamic process of typhoon and the temporal and spatial distribution of the typhoon waves generated by typhoons. According to the results of the coupled WRF and SWAN model, a corresponding relationship between typhoon wind speed and wave height was obtained, which was combined with the statistical data of typhoon occurring in the SCS during 1949–2019, the distribution characteristics of typhoon wave in the SCS had been simulated. The statistical data grid with a spatial accuracy of 0.5 degree of typhoon waves in the SCS had been established, and then the statistical wave height of typhoon in the SCS based on the Pearson-III distribution had been simulated. Eight characteristic locations have been identified in the SCS, the highest frequency and the hugest height of typhoon wave is near the Luzon Strait, the average of typhoon wave height is reached 9.2 m. The second is southern Taiwan in the eight different selected positions, and the statistical average value of typhoon wave height is close to 8.0 m. Comparison of the Paracel Islands, Spratly Islands and Dongsha Islands, the smallest statistical value of the typhoon wave height is the waves in Spratly Islands, with a mean value of 3.0 m, and the statistical mean value of typhoon wave height near the Paracel Islands and Dongsha Islands are about 6.0 m. Based on the statistical results, combined with the frequency of typhoon in the region, the distribution of typhoon wave height can be calculated at any location in the SCS, and it can be provide to some references for the design of the coastal and ocean engineering.

Exploring the wakes of large offshore wind farms

Offshore meteorological characteristics set specific conditions for the operation of offshore wind farms. One specific feature is low turbulence intensity which on the one hand reduces loads on turbines but on the other hand is the reason for much longer turbine and farm wakes than over land. The German Government is presently funding a research project called WIPAFF (Wind PArk Far Field) which heads for the analysis of properties and impacts of offshore wind park far fields. The focus is on the analysis of wind farm wakes, their interaction among each other and their regional climate impact. This is done by in-situ, extensive aircraft and satellite measurements and by operating meso-scale wind field models and an analytical wind farm model.

A multiscale modelling methodology applicable for regulatory purposes taking into account effects of complex terrain and buildings on pollutant dispersion: a case study for an inner Alpine basin

Dispersion modelling in complex terrain always has been challenging for modellers. Although a large number of publications are dedicated to that field, candidate methods and models for usage in regulatory applications are scarce. This is all the more true when the combined effect of topography and obstacles on pollutant dispersion has to be taken into account. In Austria, largely situated in Alpine regions, such complex situations are quite frequent. This work deals with an approach, which is in principle capable of considering both buildings and topography in simulations by combining state-of-the-art wind field models at the micro- (<1 km) and mesoscale γ (2-20 km) with a Lagrangian particle model. In order to make such complex numerical models applicable for regulatory purposes, meteorological input data for the models need to be readily derived from routine observations. Here, use was made of the traditional way to bin meteorological data based on wind direction, speed, and stability class, formerly mainly used in conjunction with Gaussian-type models. It is demonstrated that this approach leads to reasonable agreements (fractional bias < 0.1) between observed and modelled annual average concentrations in an Alpine basin with frequent low-wind-speed conditions, temperature inversions, and quite complex flow patterns, while keeping the simulation times within the frame of possibility with regard to applications in licencing procedures. However, due to the simplifications in the derivation of meteorological input data as well as several ad hoc assumptions regarding the boundary conditions of the mesoscale wind field model, the methodology is not suited for computing detailed time and space variations of pollutant concentrations.

Study on the Relationship Between Mesoscale Wind Field Changes and Rainstorm Using Windprofiler Data

By using the windprofiler data,this paper studies the relationship betw een mesoscale wind field changes and rainstorm. Firstly,it is indicated that the high spatial and temporal resolution data can clearly reveal the effect of mesoscale wind filed changes such as low-level jet and low-level wind shear before the heavy precipitation happens. Before the heavy precipitation happens,the strong wind field and the momentum continuously go dow nstream,making the low-level positive vorticity increase,with the warm and humid air,trigger the precipitation. Secondly,an index I is designed to represent the intensity and height of the low-level jet,the index will increase rapidly before the heavy precipitation. Thirdly,the low-level vertical wind shear increases significantly,and it plays a significant role in triggering the generation of heavy precipitation.

Sensitivity of Landsat‐Scale Energy Balance to Aerodynamic Variability in Mountains and Complex Terrain

AbstractThe speed and direction of air flow through complex terrain are difficult to define. Both impact sensible and latent heat flux exchanges at the surface. Evapotranspiration (ET) models such as Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC™) estimate ET as a residual of the surface energy process and are thus sensitive to aerodynamics, including terrain‐induced impacts on roughness governing convective heat transfer (H). There is a need to explore the sensitivities of H estimation and thereby ET estimation to wind speed and terrain roughness in mountainous areas and to determine the merit of operating complex mesoscale wind field models in conjunction with the energy balance process. A sensitivity analysis is explored in METRIC where we increased wind speed in proportion to a relative elevation parameter and we increased aerodynamic roughness to assimilate impacts of relative terrain roughness, estimated in proportion to standard deviation of elevation within a 3 km locality. These aerodynamic modifications increased convective heat transfer in complex terrain and reduced estimated ET. In other sensitivity runs, we reduced estimated wind speed on estimated leeward slopes. Estimated ET with and without these sensitivity adjustments is shown for mountainous areas of Montana and Nevada. Changes in ET ranged from little change (&lt;5%) for lower slopes to about 30% reductions on windward slopes and 25% increases on leeward slopes for some mid to high elevations in the Montana application.

Mesoscale wind speed simulation using CALMET model and reanalysis information: An application to wind potential

Abstract This work presents a simple methodology to simulate the mesoscale wind field using dynamic modeling and complementary meteorological data. Meteorological information obtained from the project developed by the National Center of Environmental Research (NCEP) and the National Center of Atmospheric Research (NCAR), meteorological stations, a digital elevation model and a land use data were used in this study. All these data were input for the simulation of wind fields at three different heights (20, 30 and 40 m) through the CALMET model. Simulations were made for an area corresponding to the south central region of Chile, known as the Maule Region. The results show that the simulated spatial resolution (1 × 1 km) in the CALMET model yields good results, yielding an RMSE value near 1 m s−1 for all the heights simulated, with a greater RMSE at 40 m (1.15 m s−1) and a lesser RMSE at 20 m (1.10 m s−1). The direction of the simulated wind fields was also evaluated, yielding an RMSE near 31° at 40 m. The determination of the wind potential is presented as a direct application of the method shown in this work.

Environmental process and convergence belt of atmospheric NO2 pollution in North China

Both surface environmental monitoring and satellite remote sensing show that North China is one of the regions that are heavily polluted by NO2. Using the NO2 monitoring data from 18 major cities in the region, the tropospheric NO2 column density data from the Ozone Monitoring Instrument (OMI) on the Aura satellite, and the observations from the China Meteorological Administration network, this paper analyzes a regional NO2 pollution event in February 2007 over North China, examines the convergence of the pollutant, and identies its correlation with the atmospheric background conditions. The results show that daily mean NO2 concentrations derived from surface observations are consistent with the mean values of the OMI measurements, with their correlation coeficient reaching 0.81. The correlations of NO2 concentration with general weather patterns and sequential changes of temperature structure from 925 hPa down to the surface indicate that the weather fronts, high pressure and low pressure systems in the atmosphere play a role in changing the temporal and spatial evolutions of NO2 through removing, accumulating or converging of the pollutant, respectively. It is also found that the eastern Taihang Mountains is most heavily polluted by NO2 in North China. Based on a model that correlates NO2 column density with surface wind vector, the relation of the NO2 concentrations in six major cities in North China to the surrounding wind field is analyzed. The results show that the maximum wind field is associated with the highest frequency of pollution events, and under certain large-scale atmospheric conditions together with the topographic effect, small- and meso-scale wind fields often act to transport and converge pollutants, and become a major factor in forming the heaviest NO2 pollution event in North China. Analysis of the causes for the severe NO2 pollution event in this study may shed light on understanding, forecasting, and mitigating occurrences of heavy NO2 pollution.

Sensitivity of planetary boundary layer atmosphere to historical and future changes of land use/land cover, vegetation fraction, and soil moisture in Western Kentucky, USA

Changes in land use land cover (LULCC), vegetation fraction (FV), and soil moisture affects land surface atmosphere interactions, characteristics of planetary boundary layer (PBL), and near surface atmospheric moisture content. Previous studies have investigated impacts of LULC, FV, and soil moisture changes on atmosphere separately. The present study investigates the combined impacts of changes in LULC, FV, and soil moisture, on PBL atmosphere and near surface atmospheric moisture content. The study is set in western region of Kentucky, USA. We have used the Noah land surface scheme and MM5 model for this purpose. The study used two nested domains. The current land use land cover of the inner domain was changed to grass, forest, and bare soil to represent historical changes and potential near future modifications. Subsequently, FV and soil moisture were systematically changed for each of the land uses. The simulations have found that changes of current land use to grass within the inner domain increases latent heat flux, dew point temperature, relative humidity, and equivalent potential temperature. It was found that height of the PBL was reduced and development of circulation cells was visible along land use land cover discontinuity. Changes in horizontal and vertical wind field were also reported. FV changes for grass further magnified these impacts. For example, decrease or increase in FV has decreased or increased latent heat flux. Similar response of other PBL parameters could be found for changes in FV along with LULC. It was also found that if we replaced forest with lower FV by grass with higher FV, the impacts could cancel each other. Changes to forest and bare soil land use types and lower FV for forest also produced generally similar types of responses. Soil moisture changes, particularly drying, further impacted these responses. This study finds that increase in FV counteracts impacts of soil moisture reduction up to a level. Overall, grass produced moister PBL and lowered the height of PBL and LCL. It is interesting to note that during nighttime the impacts of LULC, FV and soil moisture changes were diminished. These changes not only modified meso-scale wind fields but also potential for convective development. It was concluded that similar experiments needed to be undertaken for convectively conducive environments to better understand the combined impacts of changes in LULC, FV and soil moisture.

A climatology of mid-tropospheric mesoscale strong wind events as observed by the MST radar, Aberystwyth

Continuous sounding of the troposphere by the NERC Mesosphere-Stratosphere-Troposphere (MST) wind profiling radar, mid-Wales, since late 1997 provides a unique dataset with which to study the mesoscale wind field of the mid-troposphere over the United Kingdom. A wind speed probability density function (PDF) generated from 7 years of data is used to design a feature-finding algorithm to identify mesoscale strong wind events in the radar dataset. The resulting 117 events form a climatology of mesoscale strong wind features at mid-tropospheric heights over the British Isles, defined as peak wind speeds at or above the top 1% of the PDF, wind speeds exceeding the top 5% for at least 1 h, and extending over at least 1 km in depth. Plotting the location of the peak winds of these features on schematic charts of the Norwegian and Shapiro–Keyser models of cyclogenesis show these to be mainly warm sector and cold frontal in nature, with smaller numbers of tropopause folds and sting jets. Wind roses indicate a prevailing westerly direction for mid-tropospheric winds generally, but the strong wind events are distinctly different: cold frontal and warm sector events prevail from the south to southwest, tropopause folds from the northwest and sting jets from the west. The wider applicability of the results to the British Isles is established through comparison with radiosonde data from five sites covering the British Isles. Copyright © 2010 Royal Meteorological Society

Observational Study of Wind Channeling within the St. Lawrence River Valley

Abstract The presence of orography can lead to thermally and dynamically induced mesoscale wind fields. The phenomenon of channeling refers to the tendency for the winds within a valley to blow more or less parallel to the valley axis for a variety of wind directions above ridge height. Channeling of surface winds has been observed in several regions of the world, including the upper Rhine Valley of Germany, the mountainous terrain near Basel, Switzerland, and the Tennessee and Hudson River Valleys in the United States. The St. Lawrence River valley (SLRV) is a primary topographic feature of eastern Canada, extending in a southwest–northeast direction from Lake Ontario, past Montreal (YUL) and Quebec City (YQB), and terminating in the Gulf of St. Lawrence. In this study the authors examine the long-term surface wind climatology of the SLRV and Lake Champlain Valley (LCV) as represented by hourly surface winds at Montreal, Quebec City, and Burlington, Vermont (BTV). Surface wind channeling is found to be prominent at all three locations with strong bidirectionalities that vary seasonally. To assess the importance of the various channeling mechanisms the authors compared the joint frequency distributions of surface wind directions versus 925-hPa geostrophic wind directions with those obtained from conceptual models. At YUL, downward momentum transport is important for geostrophic wind directions ranging from 240° to 340°. Pressure-driven channeling is the dominant mechanism producing northeasterly surface winds at YUL. These northeasterlies are most prominent in the winter, spring, and autumn seasons. At YQB, pressure-driven channeling is the dominant physical mechanism producing channeling of surface winds throughout all seasons. Of particular importance, both YUL and YQB exhibit countercurrents whereby the velocity component of the wind within the valley is opposite to the component above the valley. Forced channeling was found to be prominent at BTV, with evidence of diurnal thermal forcing during the summer season. Reasons for the predominance of pressure-driven channeling at YUL and YQB and forced channeling at BTV are discussed.

Simulating mesoscale transport and diffusion of radioactive noble gases using the Lagrangian particle dispersion model

In order to simulate the impact of mesoscale wind fields and to assess potential capability of atmospheric Lagrangian particle dispersion model (LPDM) as an emergency response model for the decision supports, two different simulations of LPDM with the mesoscale prognostic model MM5 (Mesoscale Model ver. 5) were driven. The first simulation of radioactive noble gas ( 85Kr exponent) emitted during JCO accident occurred from 30 September to 3 October 1999 at Tokai, Japan showed that the first arriving short pulse was found in Tsukuba located at 60 km away from the accidental area. However, the released radioactive noble gas was transported back to the origin site about 2 days later due to the mesoscale meteorological wind circulation, enhancing the levels of 85Kr with the secondary peak in Tsukuba. The second simulation of atmospheric dilution factors (the ratio of concentration to the emission rate, χ/ Q), during the underground nuclear test (UNT) performed by North Korea showed that high χ/ Q moved to the eastward and extended toward southward in accordance with the mesoscale atmospheric circulations generated by mesoscale prognostic model MM5. In comparison with the measurements, the simulated horizontal distribution patterns of 85Kr during the JCO are well accord with that of observation in Tsukuba such as the existence of secondary peak which is associated with the mesoscale circulations. However, the simulated level of 85Kr anomaly was found to be significantly lower than the observations, and some interpretations on these discrepancies were described. Applications of LPDM to two mesoscale emergency response dispersion cases suggest the potential capability of LPDM to be used as a decision support model provided accurate emission rate of accident in case of a large accident.

Comparison of offshore wind park sites using SAR wind measurement techniques

AbstractWind farming has grown rapidly in Europe over the last decade. All European countries with shallow coastal waters and strong mean coastal wind speeds are planning or already constructing offshore wind farms. Large parts of the North Sea and Baltic Sea are being investigated to see whether they are suitable for offshore wind parks. In this study we show how satellite images taken by space‐borne radar sensors can be used to determine mesoscale wind fields and thus help in the task of planning offshore wind farms. High‐resolution synthetic aperture radar (SAR) images acquired by the European remote sensing satellite ERS‐2 showing single wind turbines are investigated. The methods for retrieving high‐resolution wind fields from SAR images are explained and statistical comparisons of wind speed and wind direction at the two offshore wind park sites in the North Sea, Horns Rev and Butendiek, are given. Copyright © 2005 Royal Meteorological Society

Mesoscale wind and wave field modeling in the area of the Odra Lagoon

The Odra lagoon is a small inner lagoon of the western Baltic Sea which is almost completely landlocked. The wind field in this area is influenced by the formation of atmospheric boundary layers, which generate highly inhomogeneous wind fields, which can be detected by means of in situ measurements and remote sensing techniques. Different numerical wind field estimation techniques were tested within the lagoon and validated against in situ measurements. The output of a coarse-grid standard model of the DWD (Deutscher Wetterdienst) for Europe, as well as a “nested-grid” model run of a mesoscale atmospheric model, was used to estimate the local wind field structure. Two data interpolation techniques employing a set of preprocessed wind fields, generated by the mesoscale atmospheric model, and in situ measurements at pile stations within the area gave best results regarding the reconstruction of the wind field variability in space and time. Subsequent model runs with a shallow-water wave model gave better hi...

Retrieval of Kinematic Fields from Dual-Beam Airborne Radar Data Gathered in Circular Trajectories during the FASTEX Experiment

Abstract The present paper describes the vertical structure of the wind field obtained by analysis of “purls,” that is, circular trajectories regularly performed by airborne dual-beam Doppler radars within the FASTEX frontal cyclones. Kinematic information on these systems are obtained using a new analysis scheme named DAVAD (Dual-Beam Antenna Velocity Azimuth Display). Using this scheme, it is possible to obtain the mesoscale wind field and its first-order derivatives, that is, the horizontal divergence (thus the vertical velocity), the stretching and shearing deformations, and the vertical component of vorticity. A unique advantage of this analysis is that it also provides a direct estimate of the terminal fall velocity of the hydrometeors. All these parameters are crucial for validation and initialization of mesoscale and large-scale models. The capabilities of this method and the best conditions for its application are assessed through simulations. Finally, an example of application of the scheme on t...

A Modeling Diagnosis of the Development of Mesoscale Convective Systems over the South China Sea during the Summer Monsoon Onset in 1998

In this study, PSU/NCAR MM5 is used to simulate the evolution of the 1998 East Asian summer monsoon onset over the South China Sea (SCS). Simulation outputs are further utilized to study the development of mesoscale convective systems (MCSs) and their interactions with the synoptic/large-scale environment in the SCS region. During the monsoon onset, over southern China and the SCS, high equivalent potential temperature, convective instability, and the southwesterly confluence in the lower troposphere provided favorable large-scale thermodynamic and dynamic conditions for the MCS development. Model simulated results reveal that, in a warm-moist and unstable atmosphere, the downdraft outflows as a result of the MCS development could become a possible mesoscale triggering mechanism for the formation of a new MCS. Sensitivity tests depict the effect of latent heat release playing a significant role in the establishment of monsoon circulation. The terrain effect is significant for local cloud formation over land. For well organized MCSs occurring over the SCS, the influence of the mesoscale wind field is more important. The latent heat release in MCSs heats the atmosphere, reduces the surface pressure, and therefore enhances the low-level wind convergence and cyclonic circulation. The mesoscale adjustment of wind field and mass field, on one hand, enhances the MCS development or initiates the formation of a new MCS, and the organization of MCSs, on the other hand, integrates the mesoscale disturbances into a synoptic structure and forms the local monsoon trough. Without the latent heat release, monsoon circulation cannot establish itself even if the model provides favorable large-scale boundary forcing.

MANDOP Analysis over Complex Orography in the Context of the MAP Experiment

Abstract The present paper deals with the adaptation of the Multiple Analytical Doppler (MANDOP) analysis to Doppler radar observations over complex orography. The objective, in the context of the Mesoscale Alpine Programme (MAP), is to design a reliable and flexible tool able to process any kind of radar data (airborne/ground based) in order to retrieve mesoscale three-dimensional wind fields over complex terrain with a convective-scale resolution. The various effects of the orography on the wind field (slope winds) and on the radar sampling (ground clutter, shadowing effect) are considered and taken into account in each step of the wind synthesis. In addition to these specific aspects, some numerical improvements are presented that make the method quicker and more objective. The method is validated with quasi-real simulated data, and three different boundary conditions are compared (bottom, top, and both). The analysis is eventually applied to real data gathered during IOP2b of the MAP special observing...

Ecology and variability of chemical mediators from Plumbago species

SUMMARY OF COMMUNICATIONS STORMSURGEMODELINGANDFORECASTFORTHESOUTH-WESTERN ATLANTIC OCEAN RicardodeCamargo 1 ,JosephHarari 2 andPedroL.S.Dias 11 Department of Atmospheric Sciences, Institute of Astronomyand Geophysics of University of Sao Paulo. 2 Department of Physical Oceanography, Institute of Oceanogra-phy of University of Sao Paulo.Presented by IgorG.Pacca StormsurgesovertheAtlanticCoastofSouthAmer-ica have important effects in terms of coastal erosion,sediment dynamics and harbor activities, among manyothers. The aim of this project is to present a numeri-cal system for storm surge forecasts in the South-WesternAtlantic Ocean, basically from the northern Argentineanshelf (42 ◦ S) to the Rio de Janeiro coast (21 ◦ S), hereaftercalled SWAO region. The idealized system would be ableto provide disturbances in the surface elevation and shelfcurrents fields related to the passage of meteorologicalsystems over the studied area. It is very important to men-tion the cyclogenetic characteristics of the region of inter-est, which play an important role for storm surge events.Mesoscale meteorological forecasts for the studyarea can be supplied by operational runs of the RegionalAtmospheric Modelling Systems (RAMS) at the Depart-mentofAtmosphericSciencesofUniversityofSaoPaulo.The model assimilates large scale analysed and predictedfields provided by global models (normally NCEP andCPTEC, and occasionally ECMWF) and improves theforecast considering regional aspects in a 32km grid.The oceanic part of the proposed system is basedon the Princeton Ocean Model (POM) simulations for theSWAO area with approximately 10km resolution, whichwillbeforcedbypredictedwindfieldsprovidedbyRAMSas described above. The use of mesoscale wind fields inprevious hindcasting simulations shown better results incomparison to wind fields directly from global models.—( November 19, 1999 ).

Chemical and biological investigations on Nidularium innocentii Lemaire

SUMMARY OF COMMUNICATIONS STORMSURGEMODELINGANDFORECASTFORTHESOUTH-WESTERN ATLANTIC OCEAN RicardodeCamargo 1 ,JosephHarari 2 andPedroL.S.Dias 11 Department of Atmospheric Sciences, Institute of Astronomyand Geophysics of University of Sao Paulo. 2 Department of Physical Oceanography, Institute of Oceanogra-phy of University of Sao Paulo.Presented by IgorG.Pacca StormsurgesovertheAtlanticCoastofSouthAmer-ica have important effects in terms of coastal erosion,sediment dynamics and harbor activities, among manyothers. The aim of this project is to present a numeri-cal system for storm surge forecasts in the South-WesternAtlantic Ocean, basically from the northern Argentineanshelf (42 ◦ S) to the Rio de Janeiro coast (21 ◦ S), hereaftercalled SWAO region. The idealized system would be ableto provide disturbances in the surface elevation and shelfcurrents fields related to the passage of meteorologicalsystems over the studied area. It is very important to men-tion the cyclogenetic characteristics of the region of inter-est, which play an important role for storm surge events.Mesoscale meteorological forecasts for the studyarea can be supplied by operational runs of the RegionalAtmospheric Modelling Systems (RAMS) at the Depart-mentofAtmosphericSciencesofUniversityofSaoPaulo.The model assimilates large scale analysed and predictedfields provided by global models (normally NCEP andCPTEC, and occasionally ECMWF) and improves theforecast considering regional aspects in a 32km grid.The oceanic part of the proposed system is basedon the Princeton Ocean Model (POM) simulations for theSWAO area with approximately 10km resolution, whichwillbeforcedbypredictedwindfieldsprovidedbyRAMSas described above. The use of mesoscale wind fields inprevious hindcasting simulations shown better results incomparison to wind fields directly from global models.—( November 19, 1999 ).