Sea Breeze Events Research Articles

Toward Producing the Chukchi–Beaufort High-Resolution Atmospheric Reanalysis (CBHAR) via the WRFDA Data Assimilation System

Abstract The Weather Research and Forecasting Model (WRF) and its variational data assimilation system (WRFDA) are applied to the Chukchi–Beaufort Seas and adjacent Arctic Slope region for high-resolution regional atmospheric reanalysis study. To optimize WRFDA performance over the study area, a set of sensitivity experiments are carried out to analyze the model sensitivity to model background errors (BEs) and the assimilation of various observational datasets. Observational data are assimilated every 6 h and the results are verified against unassimilated observations. In the BE sensitivity analyses, the results of assimilating in situ surface observations with a customized, domain-dependent BE are compared to those using the WRF-provided global BE. It is found that the customized BE is necessary in order to achieve positive impacts from WRFDA assimilation for the study area. When seasonal variability is incorporated into the customized BE, the impacts are minor. Sensitivity analyses examining the assimilation of different datasets via WRFDA demonstrate that 1) positive impacts are always seen through the assimilation of in situ surface and radiosonde measurements, 2) assimilating Quick Scatterometer (QuikSCAT) winds improves the simulation of the 10-m wind field over ocean and coastal areas, and 3) selectively assimilating Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved profiles under clear-sky and snow-free conditions is essential to avoid degradation of assimilation performance, while assimilation of Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) retrievals has little impact, most likely due to limited data availability. Based on the sensitivity results, a 1-yr (2009) experimental reanalysis is conducted and consistent improvements are achieved, particularly in capturing mesoscale processes such as mountain barrier and sea-breeze effects.

Ecosystem Regulatory Services and Human Comfort in an Outdoor Environment of Lokoja, Nigeria

Aims: To determine the effect of land cover change and local temperature variation on the thermal comfort of inhabitants of the town while carrying out their outdoor activities. Study Design: Application of satellite imageries, meteorological data and questionnaire for the study. Place and Duration of Study: Department of Geography and Planning, Kofi State University, Antigua, Nigeria between June and October, 2012. Methodology: Computation of 12 months humidor values from temperature and humidity data for the year 1987, 2001 and 2011. Satellite image processing, classification, victimization and interpretation for land use and land cover change for 1987, 2001 and 2012; extraction of NDVI values and map for 2012 using Arc GIS 9.2. Land use and Land cover change rate were calculated. Temporary installation of thermo-hygrometers in 10 identified neighborhoods for a daily humidor values for the months of July, August and September 383 copies of questionnaire was retrieved and analyses using principal component analysis method of SPPS 17 software. Results: The least humidor values of 34.7 in December 1987, 34.4 in January 2001 and 35.8 in December 2011 indicated that discomfort is a common feature. The increasing change in rate in built up (0.95km2/yr) and the corresponding decline in rate of vegetation Original Research Article British Journal of Applied Science & Technology, 4(18): 2576-2589, 2014 2577 (1.73km2/yr) is the responsible for the near dryness in the built up area indicated by the NDVI values are attest to the increasing level of discomfort in the area of study. The perception level is significant s the KMO value of 0.602 which suggest a strong positive correlation among the variables. Effect of Land and sea breezes accounted for 22.7% of the variation in discomfort, urbanization 16.4% and Exposure 10%, while improper mitigation processes accounted for 8.8% and 11.4% for health implication. Conclusion: The rapid response to urban green economy will enhance the proper benefits of ecosystem services to Lakota environment. The governmental and nongovernmental agencies are sensitize the general public on the role of vegetation in the environment, as this contribute to regulating air temperature.

Effects of meteorological conditions on the concentration and dispersion of an accidental release of H2S in Canada

This study aims to determine the effects of the land's meteorological conditions on the dispersion of an accidental release of H2S using the CALPro software. The three Canadian cities or towns of Edmonton, Yarmouth and Whitehorse, which are all of different meteorological conditions, were chosen as the domains of study. Hourly geophysical, surface and upper air meteorological data were used with CALMET to model the wind field of the three domains for the modeling period of March 11, 2012 from 00h00 to 23h00 LST. Individual 5-h modeling periods where the wind field showed the most significant variations were chosen for each region of study. CALPUFF was used to model the dispersion effects of an accidental release of H2S from a single point source due to an accidental vessel puncture using time-varying emission data modified to suit each region's modeling period. Despite the wind reversal encountered in Edmonton, its relatively flat terrain allowed H2S to disperse outwards, causing concentrations to accumulate lower than the other two regions but still to sever levels and a much greater population. Differences between the effect of land and sea breeze on H2S dispersion in Yarmouth's coastal region caused concentrations to accumulate higher than the other two regions and to life threatening levels around the source. The mountainous terrain of Whitehorse shaped the plume trajectory, causing H2S concentrations to accumulate to levels that can cause irreversible health effects at various times and locations. Results show that each area's meteorological conditions will have different impacts on dispersion.

Characteristics of annual, seasonal, and diurnal precipitation in the Southeastern United States derived from long-term remotely sensed data

The objective of this paper is to investigate long-term inter-annual, seasonal, and diurnal rainfall characteristics in the Southeastern United States. In order to capture precipitation features at high resolution, we use precipitation estimates from the Tropical Rainfall Measuring Mission (TRMM); the TRMM Precipitation Radar (TPR 2A25: 0.05°×0.05°/daily) and the TRMM Multi-satellite Precipitation Analysis (TMPA 3B42: 0.25°×0.25°/3-h) datasets to create a 13-year rainfall climatology. The higher resolution climatology (2A25) displays a greater ability to capture more localized landform precipitation features when compared with 3B42. On an annual basis, the Southeastern US is characterized by a succession of cold and warm precipitation regimes. The cold season is characterized by higher rain intensity West of 82°W (roughly Atlanta, GA) and the warm season is characterized by higher rain intensity over the coastal areas. The cold/warm rainfall regime duality is modulated by local topographic characteristics that prevail along a W–E direction. During the cold season, the diurnal cycle of precipitation is characterized by a quasi-constant repartition of rain events throughout the day and an absence of land/ocean contrast. On the contrary for summertime there is a strong land/ocean signature with a predominance of late morning/early afternoon (12:00–15:00LST) rainfall over ocean and afternoon/early evening (15:00–18:00LST) precipitation events over land that account for more than 25% of the daily events along the coasts. Differences are observed for the Florida peninsula, where the diurnal cycle displays an afternoon maximum of variable intensity due to sea breeze effects regardless of the season.

A Numerical Modeling Study of the Propagation of Idealized Sea-Breeze Density Currents

AbstractSea breezes are often modeled as a wave response to transient heating in a stratified environment. They occur, however, as density currents with well-defined fronts, the understanding of which rests primarily on experiments and theory that do not include the stratification within and above the current and the steady heat input at the land surface. These gaps are investigated here via a sequence of idealized 2D density current simulations, progressing from the simplest classical case to more realistic surface heating and stratification.In the classical situation where the entire horizontal density contrast is imposed initially, the front quickly attains a constant speed determined by traditional formulas based on the density contrast across the front and the current depth, or by the amount of heat needed to produce it from an initially barotropic fluid. However, these diagnostic and prognostic tools fail completely if the current is driven by a gradual input of heat, analogous to a real sea-breeze situation. In this case the current accelerates slowly at first, remaining much slower than would be expected based on classical formulas.The motion of a classical density current is mostly inertial, with accelerations occurring at the current head; while in the continuously heated case, the entire current accelerates, requiring interior body forces to develop slowly owing to heating of the density current itself. This explains why observed sea-breeze fronts propagate more slowly than predicted from classical formulas, and may help to explain why larger landmasses, where fronts have more time to accelerate, often experience stronger convective storms when triggered by sea-breeze effects.

Simulation of local atmospheric dynamics in the coastal region of Dunkerque

The structure of the lower troposphere has been studied during the sea-breeze and post sea-breeze events in an industrialized coastal area of the North Sea. Atmospheric dynamics and dispersion of pollutants in the lower troposphere have been analyzed by the experimental results of the 3D nonhydrostatic Meso-NH model in Dunkerque area (51°N, 2.20°E), in the north of France. The simulations were verified and extended by data of the measurement campaign. Ground-based remote sensing systems (lidar and sodar), surface meteorology and air quality network stations data have been employed. We illustrate the different pollution scenarios and breeze structure by the analysis of Lagrangian tracers and back trajectories.

The Effect of Sea Breezes on Air Pollution Dispersion

The Effect of Sea Breezes on Air Pollution Dispersion

THE INFLUENCE OF CALCARENITE LIMESTONE REEFS ON BEACH EROSION AND RECOVERY, FROM SECONDS TO YEARS

Mechanisms through which natural rock and coral landforms interact with waves, currents, sediment transport and beach morphology are still poorly understood. Therefore, interactions between sediment transport and calcarenite limestone landforms at Yanchep Lagoon in southwestern Australia were investigated over a cascade of spatial and temporal scales: from single waves, through sea breeze and storm events, to seasonal and inter-annual variability. The hypotheses that were confirmed included: (1) hard landforms with higher elevations relative to sea level are more likely to reduce beach erosion but also to inhibit recovery; and (2) the placement and continuity of landforms in the nearshore can generate current jets, and hence local sediment sources and sinks. These hypotheses were consistently confirmed at all scales, however results show that to fully explain changes at broader scales (such as inter-annual and seasonal changes) an understanding at finer scales (such as during sea breezes, storm event and single waves) was necessary.

The impact of sea breeze under different synoptic patterns on air pollution within Athens basin

Air quality in densely populated urban coastal areas is directly related to the coupling of the synoptic and the local scale flows. The dispersion conditions within Athens basin, under the influence of different meteorological forcings, lead to distinct spatio-temporal air pollution patterns. The aim of the current observational research is to identify and examine the effect of sea breeze under different atmospheric circulation patterns on air pollution levels for a one-year study period (2007). The study employs surface pressure maps, routine meteorological observations at two coastal sites and nitrogen monoxide (NO), nitrogen dioxide (NO2) and ozone (O3) concentrations from a network of four air quality stations within the Athens basin. A three-step methodology is applied that incorporates a set of criteria for classifying atmospheric circulation and identifying sea breeze events under each circulation pattern. Two types of sea breeze development are identified (pure sea breeze-PSB and modified sea breeze-MSB) with distinct characteristics. Sea breeze is found to develop more frequently under offshore compared to onshore and parallel to the shoreline background flows. Poor dispersion conditions (high nitrogen oxides-NOx and O3 concentrations) are connected to the pure sea breeze cases and to those cases where sea breeze interacts with a moderate northerly flow during the warm period. The levels of NOx and O3 for the northern Athens basin area are found to be significantly higher during the sea breeze days compared to the Etesian days. Regarding the diurnal variation of ozone for the sea breeze days, peak concentrations and higher intra-daily ranges are observed. Day-to-day pollution accumulation (build-up effect) is measured for O3 at the northern stations in the Athens basin.

High-Resolution ASCAT Scatterometer Winds Near the Coast

The European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) Ocean and Sea Ice Satellite Application Facility delivers operational wind products from the Advanced Scatterometer (ASCAT) at 25 km and 12.5 km Wind Vector Cell (WVC) spacing. In these products, based on the backscatter processing performed at EUMETSAT, data closer than ~ 70 km (25 km products) or ~ 35 km (12.5 km products) to the coast are flagged because of land contamination. An alternative wind product is presented here which uses a different way of averaging the full resolution (FR) backscatter measurements from ASCAT. The FR backscatter measurements are screened for land contamination in the coastal zone, thus allowing the construction of WVCs that follow the coast line. The implied alternative spatial averaging allows good quality winds over sea as close as 15-20 km to the shore. The alternative (coastal) and nominal products are compared, and the resulting winds are validated with buoy winds, both in coastal and open sea regions. In regions far away from the coast, the ASCAT coastal and nominal products appear to be of identical quality, but fewer WVCs pass the quality control steps for the nominal product, indicating that the coastal product better resolves sub-WVC wind variability. In the coastal region, we anticipate enhanced wind variability due to katabatic and sea breeze effects, among others. However, the quality of the coastal winds in terms of buoy wind component difference standard deviation is almost as good as for the open sea winds.

Surface ozone at a coastal suburban site in 2009 and 2010: Relationships to chemical and meteorological processes

Air quality and meteorological measurements were conducted at the Chemistry and Physics of the Atmospheric Boundary Layer Experiment (CAPABLE) site during the summers of 2009 and 2010 in Hampton, Virginia. Significant differences in surface ozone mixing ratios were observed between the two years and are correlated with meteorological parameters such as temperature, humidity, and cloud cover. The number of exceedance days for ozone set by the U.S. Environmental Protection Agency within this region has been decreasing for the past decade, especially in urban areas. There were no exceedance days with respect to ozone in 2009, and there were four exceedance days in 2010. The four highest ozone daily maxima and the two exceedance days observed during the 2010 measurement period were coincident with sea breeze phenomena. In one case, surface ozone increased at a rate of 14.6 ppb h−1 with the passage of a sea breeze front. A comprehensive multilinear regression model as well as an operational forecast was unable to resolve the high ozone observed during sea breeze events. As the number of exceedance days per year within this region continues to decrease, accurately forecasting sea breezes may become more important for the forecasting of pollution events.

Impact of sea breeze on vertical structure of aerosol optical properties in Dunkerque, France

During July 2008, we used an elastic backscattering LIDAR to monitor the aerosol vertical distribution at the coastal area of Dunkerque, France. Here we report the sea breeze event which was observed with more highlighted effect of aerosol on 25 July. By combining LIDAR measurements with Sun photometer-retrieved aerosol optical thickness, we estimated an average LIDAR ratio of 33 sr (± 14 sr) for the estimation of aerosol extinction profiles during the sea breeze. The LIDAR derived aerosol extinction in the first 200 m is clearly affected by the sea breeze and increases by more than 100% at the time of sea breeze arrival. A sharp convective boundary layer height decrease is observed in the LIDAR data due to the formation of the thermal internal boundary layer in the lowest part of the sea-to-land flow. PM2.5 concentration increases due to the thermal internal boundary layer formation and reaches its maximum between 1 and 2h after the front overpass. Except during the front overpass, the PM2.5 is well correlated to the inverse of the mixing height detected by the LIDAR.

Characterization of typical coastal circulations with high-resolution measurements in the Gulf of Valencia

Measurements from 27 stations taken in the coastal area of the Gulf of Valencia are utilized to characterize the typical coastal circulation systems observed in this area. The wind measurements are available in a resolution of 15 s at daytime and 5 min at nighttime and cover the period of May 2006–April 2007. The analysis of median daily cycles shows that the meteorological situation in the Gulf of Valencia is dominated by a distinguished sea breeze. The observed development of local circulation systems varies within a distance of just a few kilometres, not only over land but also over water. These variations can be explained by the local influences of a pronounced coastal orography, land use and shape of the coastline. The measurements are classified in days with and days without pronounced sea breeze effects. This classification allows a refined discussion on spatial and temporal characteristics of the observed circulation systems. The classification shows an occurrence of sea breezes at 2 out of 3 days. Copyright © 2011 Royal Meteorological Society

Development of selection algorithms and databases for sea breeze studies

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.

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

AbstractUsing 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 (2.07 m s−1), but sea breeze gust intensities range from 3.6 to 11.6 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 97.7 km with noteworthy differences throughout the year; a case study showed onshore wind peaks of 11.1 m s−1, 50‐km inland of the Vinalopó 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

Mixing Depth Estimation from Operational JMA and KMA Wind-Profiler Data and its Preliminary Applications: Examples from Four Selected Sites

In this study, mixed layer (ML) height information is extracted from the range-corrected signal-to-noise ratio (SNR) data of wind profilers operated by the Japan Meteorological Agency (JMA) and the Korea Meteorological Administration (KMA). The altitude where the maximum backscattered power is received by a wind profiler is regarded as ML height. Four sites (Kumagaya and Mito in Japan; Munsan and Gangneung in Korea) were tested on clear sky days, which were chosen using a sunshine ratio. The ML height information obtained was utilized to analyze the spatiotemporal variations of ML heights over Japan and to qualitatively evaluate the model mixing depth predicted by a KMA regional numerical weather prediction model. The frequency of the wind profiler is 1.36 GHz (1.29 GHz for sites in Korea), and the temporal resolution of the SNR data is 10 min. In the vertical, the operating resolutions are 300 m for the sites in Japan and 70 m for Korea. The quantitative analysis of the mixing depths estimated by JMA shows day-to-day, seasonal, and spatial variations in the measured mixing depths. Comparison with nearby radiosonde observations, as well as surface station and satellite observations, is conducted. The estimated ML height tended to be somewhat high in the early morning presumably due to the minimum detectable range and a residual layer (RL) effect. Mean ML heights at the Kumagaya site in July and October 2001 show a seasonal difference of about 500 m. The sea breeze effect can be seen in ML heights at the Mito site located near the sea coast. On the other hand, the evaluation of model-predicted ML heights against KMA SNR data reflected the nonlocal K-profile boundary layer scheme's well-known feature of having faster development with greater depth for an ML. It is proposed in this paper that the ML heights estimated from the Munsan and Gangneung sites can be applied to the observational analysis of mixing depths and be employed as an auxiliary tool for evaluating model ML heights on an operational basis.

Radial diffusive samplers for determination of 8-h concentration of BTEX, acetone, ethanol and ozone in ambient air during a sea breeze event

The radial diffusive sampler Radiello® filled with Carbograph 4 was evaluated for monitoring BTEX, ethanol and acetone concentrations for 8-hour exposure time. The sampling rates were first evaluated in an exposure chamber under standard conditions. Benzene and toluene showed the highest sampling rates with satisfactory standard deviations. Ethylbenzene and xylenes showed medium sampling rates but higher standard deviations that can be attributed to a low affinity of these compounds with the adsorbent medium for short sampling time. Acetone has a fair result because of the increase of its partial pressure in the vicinity of the adsorbent surface in the course of sampling. The Carbograph 4 adsorbent does not seem to be suitable for sampling ethanol, likely because of its high volatility. The influences of three environmental factors (temperature (T), relative humidity (RH) and concentration level (C)) on the sampling rates were also evaluated, following a fractional factorial design at two factor levels (low and high). Results were only investigated on benzene, toluene and acetone. Temperature and relative humidity are found to be the most important factors leading to variability of the benzene and toluene sampling rates. The applicability of the sampler for 8-hour sampling was demonstrated by the results of a measurement campaign carried out during a sea breeze event. Mapping of benzene, toluene and acetone concentrations showed the highest concentrations in the industrial zone following the wind direction coming from the North. Nevertheless, the sea breeze tends to reduce the spread of the industrial plumes. On the contrary, the ozone map presents the lowest concentrations at the same industrial area indicating a net consumption of ozone. The highest ozone concentrations were found in the southeastern zone suggesting a local ozone formation.

Numerical Simulations of the Impacts of Land-Cover Change on a Southern Sea Breeze in South-West Western Australia

A sea-breeze event in south-west Western Australia is simulated using the Regional Atmospheric Modelling System (RAMS) version 6.0. The model is evaluated against high resolution soundings as well as station observations and is shown to reproduce the qualitative features of the sea breeze well. Sensitivity tests are carried out to investigate the effects of historical land-cover change and changes in soil moisture on the dynamics of the sea breeze. It is found that land-cover change alone, i.e., a change from wooded grasslands to bare soil, with no change in soil moisture initialisation, does not significantly alter the overall structure of the sea breeze but results in higher surface winds due to the reduced vegetation roughness length, which leads to enhanced surface moisture advection inland. On the other hand, land-cover change in conjunction with increased soil moisture results in a considerably weaker, shallower, and less penetrative sea breeze, and delays its onset and duration. A sea-breeze scaling analysis highlights the impact of increasing soil moisture on reducing the sea-breeze volume flux scale.

한반도 동남연안지역의 냉수대 영향과 해풍의 상호관련성 연구

The characteristic of cold water by upwelling in the southeast of the Korean Peninsula and the effect of sea breeze in this region are investigated. The coastal upwelling around the southeast coast of the Korea Peninsula is analyzed by using Coastal Oceanographic Data statistical analyses for 5 years were carried out. The period of an cold water event, on the average, was observed southwesterly wind events. The analysis suggests that strong and persistent southwesterly winds in period of an cold water play an important role of bring the moisture to the surface, generating persistent cyclone as jangma. In order to investigate the effect of cold water on sea breeze, we considered two case. First, Exp. 1 is not occurred coastal upwelling on sea breeze. Second, Exp. 2 is occurred cold water on sea breeze. Two experiments were completed separately to the effects of cold water by upwelling. The results show the sea breeze is stronger in Exp. 2, when the cold water occurs, and weaker in Exp. 1, when there is no cold water. In order to verify the effect of the sea breeze on the cold water by upwelling, on the intensification and change of direction of the prevailing wind, the sea breeze effectively intensify cold water condition.

Diurnal sea breeze effects on inner-shelf cross-shore exchange

Cross-shore exchange by strong (cross-shore wind stress, τ sx >0.05 Pa) diurnal (7–25 h) sea breeze events are investigated using two years of continuous wind, wave, and ocean velocity profiles in 13 m water depth on the inner-shelf in Marina, Monterey bay, California. The diurnal surface wind stress, waves, and currents have spectral peaks at 1, 2, and 3 cpd and the diurnal variability represents about 50% of the total variability. During sea breeze relaxation (−0.05< τ sx <0.05 Pa), a background wave-driven inner-shelf Eulerian undertow profile exists, which is equal and opposite to the Lagrangian Stokes drift profile, resulting in a net zero Lagrangian transport at depth. In the presence of a sea breeze ( τ sx >0.05 Pa), a uniform offshore profile develops that is different from the background undertow profile allowing cross-shore Lagrangian transport to develop, while including Lagrangian Stokes drift. The diurnal cross-shore current response is similar to subtidal (>25 h) cross-shore current response, as found by Fewings et al. (2008). The seasonality of waves and winds modify the diurnal sea breeze impact. It is suggested that material is not transported cross-shore except during sea breeze events owing to near zero transport during relaxation periods. During sea breeze events, cross-shore exchange of material appears to occur onshore near the surface and offshore near the sea bed. Since sea breeze events last for a few hours, the long-term cross-shore transport is incremental each day.