Showing papers on "Sea breeze published in 2011"

Offshore wind power development in Europe and its comparison with onshore counterpart

Abstract: Wind power, as a renewable source of energy, produces no emissions and is an excellent alternative in environmental terms to conventional electricity production based on fuels such as oil, coal or natural gas. At present, the vast majority of wind power is generated from onshore wind farms. However, their growth is limited by the lack of inexpensive land near major population centers and the visual pollution caused by large wind turbines. Comparing with onshore wind power, offshore winds tend to flow at higher speeds than onshore winds, thus it allows turbines to produce more electricity. Estimates predict a huge increase in wind energy development over the next 20 years. Much of this development will be offshore wind energy. This implies that great investment will be done in offshore wind farms over the next decades. For this reason, offshore wind farms promise to become an important source of energy in the near future. In this study, history, current status, investment cost, employment, industry and installation of offshore wind energy in Europe are investigated in detail, and also compared to its onshore counterpart.

Diurnal and seasonal variability of surface ozone and NOx at a tropical coastal site: Association with mesoscale and synoptic meteorological conditions

Abstract: [1] Simultaneous measurements of near-surface ozone, NOx (NO + NO2), and meteorological parameters were carried out at the tropical coastal location of Trivandrum (8.55°N, 77°E) in India from November 2007 to May 2009. The data have been used to investigate the diurnal and seasonal patterns of ozone and its precursor, NOx, and also the interdependence of these two chemical species. The diurnal pattern is found to be closely associated with the mesoscale circulation (sea breeze and land breeze) and the availability of NOx. The daytime peak in ozone extends until the onset of land breeze, which brings in NOx for titration of ozone. Near-surface ozone concentration reaches peak values during the postmonsoon or winter months and shows minima during the summer or monsoon season. The high ozone concentration during winter is due to the presence of northeasterly winds that transport precursor gases to the site. The daytime concentration of ozone is found to be directly linked to the nighttime level of NOx. The present analysis reveals that one molecule of NOx or NO2 is responsible for the formation of about seven to nine molecules of ozone. A study of satellite-derived tropospheric ozone and total ozone has shown that tropospheric ozone contributes 8%–15% of total ozone over this site and near-surface ozone contributes 34%–83% of tropospheric ozone. The seasonal pattern of tropospheric column ozone is similar to that of tropospheric NO2.

A numerical study of interactions between surface forcing and sea breeze circulations and their effects on stagnation in the greater Houston area

Abstract: [1] High-resolution simulations from the Advanced Research Weather Research and Forecasting (ARW-WRF) model, coupled to an urban canopy model (UCM), are used to investigate impacts of soil moisture, sea surface temperature (SST), and city of Houston itself on the development of a stagnant wind event in the Houston-Galveston (HG) area on 30 August 2000. Surface and wind profiler observations are used to evaluate the performance of WRF-UCM. The model captures the observed nocturnal urban-heat-island intensity, diurnal rotation of surface winds, and the timing and vertical extent of sea breeze and its reversal in the boundary layer remarkably well. Using hourly SST slightly improves the WRF simulation of offshore wind and temperature. Model sensitivity tests demonstrate a delicate balance between the strength of sea breeze and prevailing offshore weak flow in determining the duration of the afternoon-evening stagnation in HG. When the morning offshore flow is weak (3–5 m s−1), variations (1°–3°C) in surface temperature caused by environmental conditions substantially modify the wind fields over HG. The existence of the city itself seems to favor stagnation. Extremely dry soils increase daytime surface temperature by about 2°C, produced more vigorous boundary layer and faster moving sea breeze, favoring stagnation during late afternoon. The simulation with dry soils produces a 3 h shorter duration stagnation in the afternoon and 4 h longer duration in the evening, which may lead to more severe nighttime air pollution. Hourly variations of SST in shallow water in the Galveston Bay substantially affect the low-level wind speed in HG.

Selection, Design and Construction of Offshore Wind Turbine Foundations

Abstract: In the past twenty five years, European nations have led the way in the development of offshore wind farms. However, development in offshore wind energy is picking speed in other continents as well. More recently, there has been explosive growth in investment in the clean energy sector, with onshore and offshore wind power taking by far the largest share of that investment. About 50 billion US dollars were invested each year since 2007. Although economic crises may have impeded investment in 2010. In the last few years nearly 30 to 40 percent of all new installed power generation capacity in Europe and the United States is attributed to wind energy. The European Wind Energy Association estimates that between 20 GW and 40 GW of offshore wind energy capacity will be operating in the European Union by 2020. The US Department of Energy predicts that 50 GW of installed offshore wind energy will be developed in the next 20 years (NWTC, 2006). This means at least US$100 billion of capital investment with about US$50 billion going to offshore design and construction contracts. In the United States, offshore wind power development has not been a focus area because there is great potential for wind power on land. However, high quality onshore wind resources are mostly located in the Midwest and Central United States while the demand centers are located along the coasts, thereby making the cost of transmission high. On the northeast coast of the United States, offshore development is an attractive alternative because electricity costs are high and transmission line construction from the mid-west faces many obstacles. Higher quality wind resources, proximity to coastal population centers, potential for reducing land use, aesthetic concerns, and ease of transportation and installation are a few of the compelling reasons why power companies are turning their attention to offshore development. Offshore turbines are being made larger to economize in the foundation and power collection costs. As the technology for wind turbines improves, the industry has developed wind turbines with rotor diameters as large as 150 m and power ratings of over 7.5 MW to 10 MW. As increasing number of wind farms are being planned 15 to 50 km from shore in water depths of over 50 m, the combination of water depth, the increasing wind tower heights and rotor blade diameters create loads that complicate the foundation design and consequently place a greater burden on the engineer to develop more innovative and cost-effective foundations and support structures. Moreover, offshore foundations are exposed to additional loads such as ocean currents, storm wave loading, ice loads and potential ship impact loads. All of these factors pose significant challenges in the

Variability of aerosol optical properties in the Western Mediterranean Basin

Abstract: . Aerosol light scattering, absorption and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Mean scattering and hemispheric backscattering coefficients (@ 635 nm) were 26.6±23.2 Mm−1 and 4.3±2.7 Mm−1, respectively and the mean aerosol absorption coefficient (@ 637 nm) was 2.8±2.2 Mm−1. Mean values of Single Scattering Albedo (SSA) and Angstrom exponent (a) (calculated from 450 nm to 635 nm) at MSY were 0.90±0.05 and 1.3±0.5 respectively. A clear relationship was observed between the PM1/PM10 and PM2.5/PM10 ratios as a function of the calculated Angstrom exponents. Mass scattering cross sections (MSC) for fine mass and sulfate at 635 nm were 2.8±0.5 m2 g−1 and 11.8±2.2 m2 g−1, respectively, while the mean aerosol absorption cross section (MAC) was 10.4±2.0 m2 g−1. The variability in aerosol optical properties in the WMB were largely explained by the origin and ageing of air masses over the measurement site. The MAC values appear dependent of particles aging: similar to the expected absorption cross-section for fresh emissions under Atlantic Advection episodes and higher under aerosol pollution episodes. The analysis of the Angstrom exponent as a function of the origin the air masses revealed that polluted winter anticyclonic conditions and summer recirculation scenarios typical of the WMB led to an increase of fine particles in the atmosphere (a = 1.5±0.1) while the aerosol optical properties under Atlantic Advection episodes and Saharan dust outbreaks were clearly dominated by coarser particles (a = 1.0±0.4). The sea breeze played an important role in transporting pollutants from the developed WMB coastlines towards inland rural areas, changing the optical properties of aerosols. Aerosol scattering and backscattering coefficients increased by around 40 % in the afternoon when the sea breeze was fully developed while the absorption coefficient increased by more than 100 % as a consequence of the increase in the equivalent black carbon concentration (EBC) observed at MSY under sea breeze circulation.

A multi-year study of sea breezes in a Mediterranean coastal site: Alicante (Spain)

Abstract: Using 6-year data collected in a high-resolution network of 19 stations in the province of Alicante (Spain), the characteristics of sea breezes for the period 2000–2005 were studied This study attempts to develop a multi-year climatology of sea breeze flows focusing on a Western Mediterranean coastal site We used half-hourly meteorological records from a reference station in Alicante and sea surface temperature measurements at Albufereta beach to identify past sea breeze episodes, on the basis of an objective selection technique A total of 475 sea breeze events during the 6-year period were identified and the following parameters were determined: mean time of onset, mean wind speed and direction at the time of onset, mean time of cessation, mean temporal dimension (duration), mean maximum velocity, mean time of maximum velocity and mean wind path of the sea breeze The mean onset and cessation times are 0940 UTC and 2009 UTC (local standard time = UTC + 0100 h, or + 0200 h with daylight-saving time), respectively, with a mean duration of 1029 h The mean wind speed at the time of the passage of sea breeze fronts is low (207 m s−1), but sea breeze gust intensities range from 36 to 116 m s−1 and they generally occur during 1200–1300 UTC Southerly and southeasterly onset flows dominate in winter, whereas more easterly onsets occur in spring and summer The mean inland directed wind path of the sea breezes is 977 km with noteworthy differences throughout the year; a case study showed onshore wind peaks of 111 m s−1, 50-km inland of the Vinalopo river valley in the late afternoon The spatial and temporal change in wind speed and direction were also analysed, using multi-year wind hodographs for the 19 stations and eight well-defined synoptic patterns favouring the development of sea breezes Copyright © 2009 Royal Meteorological Society

Moisture Sources and Life Cycle of Convective Systems over Western Colombia

Abstract: This paper describes life cycle and moisture sources of mesoscale convective systems (MCSs) observed over western Colombia. Results show that, in general, MCS are more frequent during boreal summer and autumn, and particularly, systems observed in summer season present longer life and larger extension. On the continent, MCS genesis is strongly affected by sea breeze and diurnal heating and presents a peak from 15 to 18 LST. For oceanic systems, the main genesis period is later, from 00 to 03 LST. Continental and oceanic systems present a tendency of westward displacement. Analysis using a Lagrangian approach implemented to estimate air parcel trajectories suggests that, during boreal winter, the main moisture sources are from the Caribbean Sea and tropical north Atlantic, possibly resulting from the moisture-laden trade winds and the land-ocean temperature contrast over northern South America. In summer, it is clear the influence of ITCZ positioning with moisture particles traveling from the tropical Atlantic over Amazonian river basin. In Autumn, Chilean-Peruvian Pacific is the main moisture source, confirming the importance of Choco low level jet to MCS genesis.

Diurnal Convection Peaks over the Eastern Indian Ocean off Sumatra during Different MJO Phases

Abstract: The authors investigated diurnal convection peak characteristics over the eastern Indian Ocean off the island of Sumatra during different phases of the Madden-Julian oscillation (MJO). During MJO phases 2 to 3 (P2 and P3) defined by Wheeler and Hendon (2004), prominent diurnal variation in convection was observed by satellites when moderate low-level westerly winds were dominant over the eastern Indian Ocean. The diurnal convection peaks were prominent over the island of Sumatra in the evening, while migrations of the convection toward the Indian Ocean were observed in the early morning. By using the Global Positioning System around the western region offshore of Sumatra, a significant reduction in water vapor was observed from evening until midnight, compensating for the upward motion over the island. During midnight to early morning, the water vapor in-creased in the western offshore region as the convections migrated from the island. This prominent diurnal varia-tion confirmed the result from a numerical experiment by Miura et al. (2007) using the Nonhydrostatic ICosahe-dral Atmospheric Model (NICAM).During P2 to P3, the atmosphere over the eastern Indian Ocean contains abundant water vapor, while the Maritime Continent is fairly well heated by solar radiation under calm conditions. This situation should be favor-able for the development of two diurnal convection peaks: the evening convection over the land induced by solar radiative heating and the midnight convection over the ocean triggered by convergence of the low-level westerly wind and the land breeze.

Generation mechanisms for mesoscale eddies in the Gulf of Lions: radar observation and modeling

Abstract: Coastal mesoscale eddies were evidenced during a high-frequency radar campaign in the Gulf of Lions (GoL), northwestern Mediterranean Sea, from June 2005 to January 2007. These anticyclonic eddies are characterized by repeated and intermittent occurrences as well as variable lifetime. This paper aims at studying the link between these new surface observations with similar structures suggested at depth by traditional acoustic Doppler current profiler measurements and investigates the eddy generation and driving mechanisms by means of an academic numerical study. The influence of the wind forcing on the GoL circulation and the eddy generation is analyzed, using a number of idealized configurations in order to investigate the interaction with river discharge, buoyancy, and bathymetric effects. The wind forcing is shown to be crucial for two different generation mechanisms: A strong northerly offshore wind (Mistral) generates a vortex column due to the bathymetric constraint of a geostrophic barotropic current, which can surface after the wind relaxes; a southerly onshore wind generates a freshwater bulge from the Rhone river discharge, which detaches from the coast and forms a well-defined surface anticyclonic eddy based on buoyancy gradients. These structures are expected to have important consequences in terms of dispersion or retention of biogeochemical material at local scales.

The Growth of the Planetary Boundary Layer at a Coastal Site: a Case Study

Abstract: A lidar system is used to determine the diurnal evolution of the planetary boundary layer (PBL) height on a summer day characterized by anticyclonic conditions. The site is located some 15 km distant from the sea, on a peninsula in south-east Italy. Contrary to expectations, the PBL height, after an initial growth consequent to sunrise, ceases to increase about 2 h before noon and then decreases and stabilizes in the afternoon. An interpretation of such anomalous behaviour is provided in terms of trajectories of air parcels towards the lidar site, which are influenced by the sea breeze, leading to a transition from a continental boundary layer to a coastal internal boundary layer. The results are analyzed using mesoscale numerical model simulations and a simple model that allows for a more direct interpretation of experimental results.

Influence of meteorological conditions on summer ozone levels in the central Kanto area of Japan

Abstract: We investigated the influence of meteorological factors that affect ozone in summer using both measurement analysis and numerical simulation. The results show that there is a close relationship between changes in meteorological conditions and variations in ozone concentrations over the central Kanto area. In summer, up to 84% of long-term variations in peak ozone concentrations may be accounted for by changes in the seasonally averaged daily maximum temperatures and seasonally averaged wind speeds. The ozone episodes in the Kanto region are dominated by three major patterns, of which Patterns I and II are regular summertime pressure patterns with a 26% and 16% frequency of occurrence, respectively. A detailed process analysis of ozone formation under urban heat island (UHI) at two areas in the Kanto region – urban and rural area – indicates that ozone formation is mainly controlled by chemistry, dry deposition, vertical transport, and horizontal transport processes. The groundlevel ozone concentrations are enhanced mainly by the vertical mixing of ozone-rich air from aloft, whereas dry deposition process mainly depletes ozone. Horizontal transport and chemistry processes play opposite roles in the net change of ozone concentration between the two areas. The results of numerical simulations also indicate that the sea breeze has significant effects on the ozone accumulation and distribution in the Kanto area. The high ozone was first observed in urban area and then was transported to the rural area by sea breeze. At rural area, the highest ozone concentrations were found in late afternoon, about two hours later in comparison with the urban area.

Development of selection algorithms and databases for sea breeze studies

Abstract: We present an automated and manual algorithm for identifying past sea breeze episodes in the Bay of Alicante (southeastern coast of the Iberian Peninsula, IP, Spain) for a 6-year study period (2000–2005). The main goal was to provide databases for better understanding the functioning of sea breezes, which have a crucial influence on weather and climate in both coastal and inland areas and therefore affect human life in many ways. The algorithms apply a well-defined set of criteria based on meteorological and sea surface temperature measurements in order to detect past occurrences. The automated and manual identification techniques successfully identified a total of 475 and 1414 sea breeze events, respectively. A large database containing the significant characteristic parameters measured (onset time, cessation time, duration time, maximum wind speed, inland penetration, etc.) for these 475 sea breeze days is presented. We evaluated the accuracy of both selection techniques by means of comparison with independent objective and subjective techniques. Both databases are the major contribution of this paper and have been used in some climatological sea breeze studies and are also presented here for any coastal expert interested in numerical–theoretical, observational–experimental and climatological wind studies.

Numerical simulations of local circulations and pollution transport over Reunion Island

Abstract: . A series of high-resolution (1 km) numerical simulations with a limited-area numerical model has been performed over Reunion Island. In the dynamical context of a regular maritime flow perturbed by a major topographic obstacle such as Reunion Island, the objectives are to identify the main atmospheric circulations at local-scale over the island and to improve the understanding of local-scale transport and dispersion of pollutants emitted from local sources. To investigate the effects of topography and land surface heating on low-level flows over the island, simulations representative of austral winter were performed in idealized conditions keeping the radiative forcing plus a background east-south-easterly synoptic flux of varying strengths, typical of the prevailing trade-wind conditions. The numerical experiments show mainly that flow splitting of the trade-wind occurs around the island, with enhanced winds blowing along the coast lines parallel to the synoptic flux, due to the lateral constriction of the flow by the island and resulting Venturi effect. Blocking occurs on the island side facing the trade-wind. The north-western area on the leeside is screened from the trade-wind by high mountains, and this enables the development of diurnal thermally-induced circulations, combining downslope and land-breeze at night, and upslope and sea breeze at daytime. Flow splitting is modulated by radiative convergence toward the island at daytime, and divergence from the island at night. Stronger winds than the large-scale trade-wind occur along the coast at daytime (Venturi effect), whereas at night, the trade-wind flow is pushed few kilometres offshore by divergence of cooled air from the land. At night, the trade-wind flow is pushed few kilometres offshore by divergence of cooled air from the land. Consequently, a number of processes of pollution transport and dispersion have been identified. Vortices in the wake of the island were found to cause counterflow circulation and trapping of polluted air masses near the north-western coast. These air masses may in turn be sucked by anabatic wind systems during daytime (upslope and sea breezes) in the cirques and up to the summits of the island, and especially to Piton Maido (2200 m) where a new observatory of the Indian Ocean background atmosphere is being built. A "cap effect" above the mountains downstream from the volcano (to the south-east of the island), and especially above Piton Maido, might occur in case of development of inland and upslope breezes on the west coast. In this case, air pumped from lower layers may protect the observatory from the volcanic plume forced to pass over a "cap" of low-level air clean of volcanic emissions.

The influence of the summer sea breeze on thermal comfort in Funchal (Madeira): a contribution to tourism and urban planning

Abstract: To urism plays a crucial role for the development of coastal areas. Despite the mildness of Madeira’s climate, very hot days can occur during summer, a situation to which most tourists from northern Europe (the majority of foreign tourists) are poorly adapted. As sea breezes strongly contribute to moderate heat stress in urban environments, their influence on the thermal comfort on the island has been studied. Sea breezes occurred on 84 % of the days during the period under study (May to October 2006). They usually start around 09:30 h and end after 22:00 h, with an average duration of about 12:50 hours and a mean velocity of 2.9 m/s. Physiologically Equivalent Temperature (PET) was used to evaluate the thermal comfort of a sample of days during the summer of 2006. It was concluded that most of the sites in the city are “slightly comfortable” during normal days with sea breeze, but only shore sites and the highest green areas offer some comfort during hot days. Inside the city, the thermal perception is generally “hot” and strong heat stress can occur. As sea breezes are important to mitigate heat stress, some basic guidelines were presented: urban planners should take advantage of this wind system avoiding dense construction near the shoreline that would act as a barrier to the renewal of the air inside the city. In terms of tourism, planners and local authorities should provide solutions to mitigate the negative effects during hot periods, creating a system to warn and relocate more vulnerable tourists to places near the shore line, to the mountains, to gardens and air-conditioned buildings. In combination with other components (beauty of the island, gastronomy, cultural values and safety), climate information can be a factor of attractiveness to tourists. Zusammenfassung

Characterization of the Vertical Structure of Coastal Atmospheric Boundary Layer over Thumba (.∘N, .∘E) during Different Seasons

Abstract: Vertical profiles of meteorological parameters obtained from balloon-borne GPS Radiosonde for a period of more than two years are analyzed for characterization of the coastal atmospheric boundary layer (CABL) over Thumba (8.5∘N, 76.9∘E, India). The study reports seasonal variability in the thickness of three different sublayers of the CABL, namely, mixed layer, turbulent flow, and sea breeze flow. Among the three, the vertical thickness of sea breeze flow showed considerable dominance on the other two throughout the year. Mixed layer heights derived through gradients in virtual potential temperature (𝜃𝑣) showed large seasonal variability with a peak in the Summer and Post-Monsoon. On the other hand, the vertical thickness of turbulent flow remained steady all through the year. Results from the present study indicate that the magnitudes of mixed layer heights are often larger than the turbulent flow thickness.

The influence of the Atlantic Warm Pool on the Florida panhandle sea breeze

Abstract: [1] In this paper we examine the variations of the boreal summer season sea breeze circulation along the Florida panhandle coast from relatively high resolution (10 km) regional climate model integrations. The 23 year climatology (1979–2001) of the multidecadal dynamically downscaled simulations forced by the National Centers for Environmental Prediction–Department of Energy (NCEP-DOE) Reanalysis II at the lateral boundaries verify quite well with the observed climatology. The variations at diurnal and interannual time scales are also well simulated with respect to the observations. We show from composite analyses made from these downscaled simulations that sea breezes in northwestern Florida are associated with changes in the size of the Atlantic Warm Pool (AWP) on interannual time scales. In large AWP years when the North Atlantic Subtropical High becomes weaker and moves further eastward relative to the small AWP years, a large part of the southeast U.S. including Florida comes under the influence of relatively strong anomalous low-level northerly flow and large-scale subsidence consistent with the theory of the Sverdrup balance. This tends to suppress the diurnal convection over the Florida panhandle coast in large AWP years. This study is also an illustration of the benefit of dynamic downscaling in understanding the low-frequency variations of the sea breeze.

Observations over an annual cycle and simulations of wind-forced oscillations near the critical latitude for diurnal-inertial resonance

Abstract: Sea breezes are characteristic features of coastal regions that can extend large distances from the coastline. Oscillations close to the inertial period are thought to account for around half the kinetic energy in the global surface ocean and play an important role in mixing. In the vicinity of 30°N/S, through a resonance between the diurnal and inertial frequencies, diurnal winds could force enhanced anti-cyclonic rotary motions that contribute to near-inertial energy. Observations of strong diurnal anti-cyclonic currents in water of depth 175 m off the Namibian coastline at 28.6°S are analysed over the annual cycle. Maxima in the diurnal anti-cyclonic current and wind stress amplitudes appear to be observed during the austral summer. Both the diurnal anti-cyclonic current and wind stress components have approximately constant phase throughout the year. These observations provide further evidence that these diurnal currents may be wind forced. Realistic General Ocean Turbulence Model (GOTM) 1-D simulations of diurnal wind forcing, including the first order coast-normal surface slope response to diurnal wind forcing, represent the principal features of the observed diurnal anti-cyclonic current but do not replicate the observed vertical diurnal current structure accurately. Cross-shelf 2-D slice simulations suggest that the first order surface slope response approximation applies away from the coast (>140 km). However, nearer to the coast, additional surface slope variations associated with spatial variations in the simulated velocity field (estimated from Bernoulli theory) appear to be significant and also result in transfer of energy to higher harmonics. Evidence from 3-D simulations at similar latitude in the northern hemisphere suggests that 3-D variations, including propagating near-inertial waves, may also need to be considered.

Analyzing coastal precipitation using TRMM observations

Abstract: . The interaction between breezes and synoptic gradient winds, and surface friction increase in transition from sea to land can create persistent convergence zones nearby coastlines. The low level convergence of moist air promotes the dynamical and microphysical processes responsible for the formation of clouds and precipitation. Our work focuses on the winter seasons of 1998–2011 in the Eastern Mediterranean. During the winter the Mediterranean sea is usually warmer than the adjacent land, resulting in frequent occurrence of land breeze that opposes the common synoptic winds. Using rain-rate vertical profiles from the Tropical Rainfall Measurement Mission (TRMM) satellite, we examined the spatial and temporal distribution of average hydrometeor mass in clouds as a function of the distance from coastlines. Results show that coastlines in the Eastern Mediterranean are indeed favored areas for precipitation formation. The intra-seasonal and diurnal changes in the distribution of hydrometeor mass indicate that the land breeze may likely be the main responsible mechanism behind our results.

Local versus remote wind effects on the coastal circulation of a microtidal bay in the

Abstract: Article history:Received 26 January 2011Received in revised form 13 April 2011Accepted 24 May 2011Available online 2 June 2011Keywords:Coastal circulationWind-driven currentsIsland trapped wavesBaysMediterranean Sea Coastal currents inmicrotidal baysareassumed tobeweakandrandom, promptlyresponding tovariations inwind forcing. However wind effects can act at scales that vary from local to large scales. With the aim ofexamining the response of coastal flow to local and regional wind forcing and their relative importance asdrivers of coastal circulation, current data were collected during five months during the summer 2009 inPalma Bay (western Mediterranean Sea). The data set is jointly analyzed with a primitive-equation model tocharacterize the circulation in the bay. Moored acoustic Doppler current profiler (ADCP) data shows thatcurrents in the bay fluctuate widely in direction resulting in an almost negligible mean current (b1.5 cm/s).This strong variability is mainly attributed to two major wind forced mechanisms interacting in the bay:island trapped waves (ITWs) propagating at an island scale and locally wind-induced mass balance. Windforced oscillations at periods of 60 and 24 h dominate current variability. The fluctuations at 60 h areassociated with the first radial and rst azimuthal mode of ITWs generated by remote wind. Weak ITWs areassociated with currents flowing parallel to the coast, whereas more intense ITWs form an anticyclonic gyreover the southeastern part of the bay due to flow separation at Enderrocat Cape. At the period of 24 h, thewind has two effects: the first radial and second azimuthal mode of ITWs and a local wind-induced massbalance in response to the sea breeze. Variations in wind and consequent changes in coastal circulation are amajor contributor to coastal water renewal, and hence critically influence key environmental aspects such aswater quality or marine organism dispersal in Palma Bay.© 2011 Elsevier B.V. All rights reserved.

Swell Propagation over Indian Ocean Region

Abstract: Swells are the ocean surface gravity waves that have propagated out of their generating fetch to the distant coasts without significant attenuation. Therefore they contain a clear signature of the nature and intensity of wind at the generation location. This makes them a precursor to various atmospheric phenomena like distant storms, tropical cyclones, or even large scale sea breeze like monsoon. Since they are not affected by wind once they propagate out of their generating region, they cannot be described by regional wave models forced by local winds. However, their prediction is important, in particular, for ship routing and off shore structure designing. In the present work, the propagation of swell waves from the Southern Ocean and southern Indian Ocean to the central and northern Indian Ocean has been studied. For this purpose a spectral ocean Wave Model (WAM) has been used to simulate significant wave height for 13 years from 1993-2005 using NCEP blended winds at a horizontal spatial resolution of ...

Modeled large‐scale warming impacts on summer California coastal‐cooling trends

Abstract: [1] Regional Atmospheric Modeling System (RAMS) meso-meteorological model simulations with a horizontal grid resolution of 4 km on an inner grid over the South Coast Air Basin of California were used to investigate effects from long-term (i.e., past 35 years) large-scale warming impacts on coastal flows. Comparison of present- and past-climate simulations showed significant increases in summer daytime sea breeze activity by up to 1.5 m s−1 (in the onshore component) and a concurrent coastal cooling of average-daily peak temperatures of up to −1.6°C, both of which support observations that the latter is an indirect “reverse reaction” to the large-scale warming of inland areas.