Note on the CO2 air–sea gas exchange at high temperatures

The temperature dependency of ocean–atmosphere gas transfer velocities is commonly estimated in terms of Schmidt numbers, i.e. the ratio of kinematic viscosity to diffusivity. In numerical models least square regressions are used to fit the limited number of experimentally derived Schmidt numbers to a function of temperature. For CO₂ a well established fit can be found in the literature. This fit constitutes an integral part in standardized carbon cycle simulation projects (e.g. C4MIP, OC4MIP, Friedlingstein et al., 2006). However, the fit is valid only in the range where diffusivity measurements exist, i.e., from 0 to about 30 °C. In many climate warming simulations like e.g. the MPI contribution to the fourth Intergovernmental Panel on Climate Change Assessment Report (IPCC AR 4), sea surface temperatures largely exceed the validated range and approach or even reach the range, where the standard fits leave the physically meaningful range. Thus, this paper underlines the demand for new measurements of seawater diffusivities for CO₂ and other trace gases especially for the temperature range >30 °C.In this paper we provide improved fits for the temperature dependence of the Schmidt number. For carbon dioxide our fit is compared to the established fit under identical climate change simulations carried out with the 3D-carbon cycle model HAMOCC. We find that in many tropical and subtropical high temperature regions the established fit leads to unrealistically short adaption times of the surface water pCO₂ to altered atmospheric pCO₂. In regions where the local oceanic pCO₂ is not primarily controlled by the atmospheric boundary pCO₂ but by other processes such as biological activity, the atmosphere ocean pCO₂ gradient is clearly underestimated when using the established fit. The effect on global oceanic carbon uptake in a greenhouse world is rather small and the potential climate feedback introduced by this bias seems to be negligible. However, the bias will clearly gain in significance the more regions warm up to over 30 °C. On a regional scale, especially in coastal regions at low latitudes, the effect is not negligible and a different steady state is approached.     

Barnacle larval transport in the Mandovi–Zuari estuarine system, central west coast of India

A two-dimensional hydrodynamic and particle tracking model was used to estimate the dispersion and retention of barnacle larvae from their possible spawning sites in a tropical monsoon-influenced estuarine system (central west coast of India). Validation of the hydrodynamic simulations yielded a good match with field measurements. The pattern of larval dispersal in the region varied with the winds and currents. The seasonal changes in abundance could be attributed to physical forcing and weather conditions. The extent of barnacle larval dispersal from spawning sites varied from 10 to 78 km for different sites and seasons. During a 24-h cycle, the larval abundance showed one to two peaks in the estuarine area. The increased larval abundance is favored by the flood currents, pushing the larvae into the estuary. Physical forcing in the region helps in transport of the larvae from their spawning sites hugging to the coast and contributing to the population within the estuary. Field observations and numerical experiments suggest the occurrence of higher larval abundance in the estuary during post-monsoon. The dispersal pattern indicated that the barnacle population present in the estuary is well mixed, and with a seasonally changing pattern.     

Interannual variability in the wintertime air–sea flux of carbon dioxide in the northern North Atlantic, 1981–2001

Gridded fields of sea surface temperature (SST), sea level pressure (SLP), and wind speed were used in combination with data for the atmospheric mole fraction of CO₂ and an empirical relationship between measured values of the fugacity of carbon dioxide in surface water and SST, to calculate the air–sea CO₂ flux in the northern North Atlantic. The flux was calculated for each of the months October–March, in the time period 1981 until 2001, allowing for an assessment of the interannual variations in the region. Locally and on a monthly time scale, the interannual variability of the flux could be as high as ±100% in regions seasonally covered by sea ice. However, in open-ocean areas the variability was normally between ±20% and ±40%. The interannual variability was found to be approximately halved when fluxes averaged over each winter season were compared. Summarised over the whole northern North Atlantic, the air to sea carbon flux over winter totalled 0.08 Gton, with an interannual variability of about ±7%. On a monthly basis the interannual variations were slightly higher, about ±8% to ±13%. Changes in wind speed and atmospheric fCO₂ (the latter directly related to SLP variations) accounted for most of the interannual variations of the computed air–sea CO₂ fluxes. A tendency for increasing CO₂ flux into the ocean with increasing values of the NAO index was identified.     

Modelling the carbon export and air–sea flux of CO2 in the Greenland Sea

We have developed a 3D model for the carbon cycle and air–sea flux of CO₂ in the Greenland Sea that consists of three submodels for hydrodynamics, carbon chemistry and plankton ecology. The hydrodynamical model, based on the primitive Navier–Stokes equations, simulates the physical environment that is used for the chemical and biological models. The chemical model calculates the pCO₂ as a function of the total inorganic carbon, alkalinity, temperature and salinity. The ecological model has eight state variables and simulates the transformation of CO₂ into organic carbon, vertical transport, and the respiration processes that convert the organic carbon back into inorganic form. The model gives an average annual primary production of 68 g C m⁻² y⁻¹, of which 44.7 g C m⁻² y⁻¹ is new production. In the eastern part of the Greenland Sea, the average annual new production is above 50 g C m⁻² y⁻¹. Simulated, annual flux of CO₂ from the atmosphere is 53 g C m⁻² y⁻¹, which sums up to 0.026 Gt for the whole Greenland Sea. Of this, 9 g C m⁻² y⁻¹ is exported by sinking particles, 6 g C m⁻² y⁻¹ by migrating zooplankton (mainly Calanus hyperboreus), and 38 g C m⁻² y⁻¹ by advection.     

The dynamics of the nanophytoplankton community in the coastal ecosystem of the Southern Bight (North Sea) during the winter–spring period

The seasonal dynamics of the nanophytoplankton community (pelagic algae 2–20 μm) was studied at a location in the Southern Bight (North Sea) from October 1993 through May 1994. During the study period the cell number and biomass of the nanoalgae varied between 10⁵–10⁶ cells dm⁻³ and 16–300 μg wet weight dm⁻³. Several ecological events seem common to the boreal coastal nanophytoplankton communities in the winter–spring period. These are: (1) abrupt fall in abundance at the beginning of winter (late October–early November); (2) winter minimum (December–March); (3) steady increase in cell number and biomass (April–May); followed by (4) the spring maximum occurring usually in May.     

The sea/land breeze in the northern coastal area of Shandong Peninsula

In this paper the seasonal variation and structural characteristics of the sea/ land breeze in the northern coastal area of" Shandong Peninsula are studied in two ways: one is the analysis of the observed wind data, and the other is numerical simulation and experiments. Firstly, the hour to hour wind data through the year 1984 at Longkou Meteorological Station and Yantai Oceanographic Station are analysed through energy spectra and hodograph. It is revealed from the analysed results that the effects of the sea/ land breeze in the area are notable in spring, summer and fall, especially in May. However, in winter the effects of sea / land breeze are not obvious. because the cold noitherly is prevailing. Secondly, a two-dimensional non- linear model of primitive equations is used to study the sea / land breeze circulation in May in the area. The results of numerical simulation consist basically with the analysed results of the observed sea / land breeze. A reasonable theoretical structure of the sea / land     

Formation of methane-related authigenic carbonates in a highly dynamic biogeochemical system in the Krishna–Godavari Basin,Bay of Bengal

We report the abundant occurrence of authigenic Fe-rich carbonate, high Mg-calcite (HMC) and low Mg-calcite from 11 cores recovered from the Krishna–Godavari Basin (K–G Basin), Bay of Bengal. The cores were collected as part of the Indian gas hydrate exploration program on board R/V Marion Dufresne (MD-161: May, 2007) in different environments, including mounds (mud diapirs), mass flows, and hemipelagic sediments over a range of water depths from 647 to 2079 m. Authigenic carbonates range in size from 1 mm to 12 cm and display various morphologies like roundish or platy (micro-) nodules and tube-like forms. From the cores, 173 carbonate samples have been investigated for their depth distribution, mineralogy, geochemical and stable isotopic composition. The stable carbon isotopic composition of 46 out of 88 measured carbonate samples are around −50‰ which allows the differentiation into methane-related carbonates (HMC), especially at Sites 8 and 15, but also in low abundance at Sites 1, 5, 9 and 12. Results indicate that the carbonates at Site 8 and 15 represent paleo methane seepage locations. The Fe-rich carbonates occur abundantly at many sites in the K–G Basin. Their varying carbon isotopic composition indicates that probably not only sulfate reduction through organic matter degradation but also methanogenesis are the responsible processes for their formation.     

Biological versus physical processes as drivers of large oscillations of the air–sea CO2 flux in the Antarctic marginal ice zone during summer

The fugacity of CO₂ and abundance of chlorophyll a (Chla) were determined in two long transects from the Polar Front to the Antarctic Continent in austral summer, December 1995–January 1996. Large undersaturations of CO₂ in the surface water were observed coinciding with high Chla content. In the major hydrographic regions the mean air–sea fluxes were found to range from −3 to +7 mmol m⁻² d⁻¹ making these regions act as a sink as well as a source for CO₂. In the total 40-d period, the summation of the several strong source and sink regions revealed an overall modest net source of 0.3 mmol m⁻² d⁻¹, this based on the Wanninkhof (J. Geophys. Res. 97 (1992) 7373) quadratic relationship at in situ windspeed. A simple budget approach was used to quantify the role of phytoplankton blooms in the inorganic carbonate system of the Antarctic seas in a time frame spanning several weeks. The major controlling physical factors such as air–sea flux, Ekman pumping and upwelling are included. Net community production varies between −9 and +7 mmol m⁻² d⁻¹, because of the large oscillations in the dominance of autotrophic (CO₂ fixation) versus heterotrophic (CO₂ respiration) activity. Here the mixed layer depth is the major controlling factor. When integrated over time the gross influx and efflux of CO₂ from air to sea is large, but the net residual air/sea exchange is a modest efflux from sea to atmosphere.     

Seasonal and inter-annual variability in properties of surface water off Santander,Bay of Biscay, 1991–1995

The annual cycle of temperature, salinity and nutrients of surface waters (up to 100 m depth) was studied from June 1991 to December 1995 in a cross-shelf section over the continental shelf waters off Santander (southern Bay of Biscay). The time series showed that the temperature followed the expected seasonal warming and cooling pattern, which determines a seasonal process of stratification and mixing of the water column. The stratification period occurs annually between May and October in a layer of about 50 m depth from the neritic station beyond to the shelf-break. In the period between November and April the water column remained mixed. During spring and summer low salinity values were found in the surface due to continental runoff and advection from oceanic waters. In late autumn and winter, the salinity pattern was governed by an influx of salty water associated with the poleward current. As in other temperate latitudes, nitrates showed the highest values in winter throughout the water column and the lowest values at the surface during the stratified period. Wind-induced upwelling events were observed mainly in summer, which are characterised by low temperatures (< 12°C), high salinity and nutrient concentrations. The inter-annual variability of temperature showed a warming trend in the upper layers but this sign was not found at 100 m depth. In salinity a decreasing trend was observed throughout the water column, and this feature corresponds to the relaxing of the high salinity anomaly detected in the North Atlantic at the beginning of the 1990s. Both trends were coherent in the cross-shelf section from the coast to the slope.     

Effects of surface waves and sea spray on air–sea fluxes during the passage of Typhoon Hagupit

Air–sea exchange plays a vital role in the development and maintenance of tropical cyclones(TCs). Although studies have suggested the dependence of air–sea fluxes on surface waves and sea spray, how these processes modify those fluxes under TC conditions have not been sufficiently investigated based on in-situ observations.Using continuous meteorological and surface wave data from a moored buoy in the northern South China Sea,this study examines the effects of surface waves and sea spray on air–sea fluxes during the passage of Typhoon Hagupit. The mooring was within about 40 km of the center of Hagupit. Surface waves could increase momentum flux to the ocean by about 15%, and sea spray enhanced both sensible and latent heat fluxes to the atmosphere,causing Hagupit to absorb 500 W/m~2 more heat flux from the ocean. These results have powerful implications for understanding TC–ocean interaction and improving TC intensity forecasting.     

The atmospheric cycling and air–sea exchange of mercury species in the South and equatorial Atlantic Ocean

Measurements of gas-, particle- and precipitation-phases of atmospheric mercury (Hg) were made in the South and equatorial Atlantic Ocean as part of the 1996 IOC Trace Metal Baseline Study (Montevideo, Uruguay to Barbados). Total gaseous mercury (TGM) ranged from 1.17 to 1.99 ng m⁻³, with a weighted mean of 1.61±0.09 ng m⁻³. These values compare well with Pacific Ocean data and earlier results from the Atlantic. The open-ocean samples recorded a distinctive inter-hemispheric gradient, which is consistent with a long-lived trace gas emitted to a greater extent from the Northern than from the Southern Hemisphere. Correlations with surface ²²²Rn measurements indicate an influence of regional terrestrial sources on open-ocean TGM concentrations. Total Hg in precipitation ranged from 10 to 99 pM (volume-weighted average: 17.8±2.9 pM). On average, about 72% of the total Hg was “reactive” (i.e., reducible by SnCl₂). The data showed an apparent rapid nonlinear decrease in concentration with event size (“washout curve”). The wet depositional flux was estimated at 18–36 nmol m⁻² yr⁻¹ (4–7 μg m⁻² yr⁻¹), which is slightly lower than that found in mid-continental locations of North America (6–12 μg m⁻² yr⁻¹). ²¹⁰Pb analyses indicate a strong impact of particles on rain Hg concentrations. Particle-phase Hg (range 5–25 fmol m⁻³; mean 12±1 fmol m⁻³; 66% “reactive”) was comparable to values over the equatorial Pacific. The dry depositional flux is ca. 0.4 nmol m⁻² yr⁻¹, or 0.4–1.0% of the wet flux. Particle-phase Hg concentrations did not change significantly when African dust was present during sampling. However, the Hg/Al ratios were consistent with crustal values during the dust periods. The residence time of TGM was calculated to be 1.3–3.4 yr in this region, based on standing stock estimates. Incubation of rainwater added to surface seawater gave reduction rates [i.e., production of elemental Hg (Hg°); 1.6–4.3% d of total Hg added] comparable to additions of inorganic ionic standards, indicating that Hg⁺² from precipitation is reduced in a similar manner in surface waters. Thus, precipitation-phase Hg is generally available for evasion to the atmosphere following deposition to the surface ocean, effectively enhancing the mobility and residence time of Hg at the Earth's surface.     

Seasonal and inter-annual variability of air–sea CO2 fluxes and seawater carbonate chemistry in the Southern North Sea

A 3D coupled biogeochemical–hydrodynamic model (MIRO-CO₂&CO) is implemented in the English Channel (ECH) and the Southern Bight of the North Sea (SBNS) to estimate the present-day spatio-temporal distribution of air–sea CO₂ fluxes, surface water partial pressure of CO₂ (pCO₂) and other components of the carbonate system (pH, saturation state of calcite (Ω_ca) and of aragonite (Ω_ar)), and the main drivers of their variability. Over the 1994–2004 period, air–sea CO₂ fluxes show significant inter-annual variability, with oscillations between net annual CO₂ sinks and sources. The inter-annual variability of air–sea CO₂ fluxes simulated in the SBNS is controlled primarily by river loads and changes of biological activities (net autotrophy in spring and early summer, and net heterotrophy in winter and autumn), while in areas less influenced by river inputs such as the ECH, the inter-annual variations of air–sea CO₂ fluxes are mainly due to changes in sea surface temperature and in near-surface wind strength and direction. In the ECH, the decrease of pH, of Ω_ca and of Ω_ar follows the one expected from the increase of atmospheric CO₂ (ocean acidification), but the decrease of these quantities in the SBNS during the considered time period is faster than the one expected from ocean acidification alone. This seems to be related to a general pattern of decreasing nutrient river loads and net ecosystem production (NEP) in the SBNS. Annually, the combined effect of carbon and nutrient loads leads to an increase of the sink of CO₂ in the ECH and the SBNS, but the impact of the river loads varies spatially and is stronger in river plumes and nearshore waters than in offshore waters. The impact of organic and inorganic carbon (C) inputs is mainly confined to the coast and generates a source of CO₂ to the atmosphere and low pH, of Ω_ca and of Ω_ar values in estuarine plumes, while the impact of nutrient loads, highest than the effect of C inputs in coastal nearshore waters, also propagates offshore and, by stimulating primary production, drives a sink of atmospheric CO₂ and higher values of pH, of Ω_ca and of Ω_ar.     

Retrieval of remotely sensed air–sea carbon flux in the Chinese Bohai Sea

ABSTRACT

Having a reliable ocean carbon flux (f(CO₂)) retrieval model is essential to monitoring the global carbon cycle and to evaluating the climate change. Remote sensing techniques provide alternatives for f(CO₂) retrieval with its advantages of wide area surveys and real-time monitoring. In the present study, a semianalytical f(CO₂) estimation model was developed based on remote sensing data and in situ measurements in the Chinese Bohai Sea. The used model performed well (R²?=?0.84) in deriving f(CO₂) based on the collected remotely sensed dataset, including sea surface temperature, estimated sea surface salinity, wind speed, Chl-a concentration. The results showed that the distribution of partial pressure of carbon dioxide (p(CO₂)) and f(CO₂) varied spatially and temporally during the 12 months in 2009. The spatial fluctuations of p(CO₂) and f(CO₂) in Bohai Sea in summer and autumn were more obvious than that in Spring and Winter. The highest values of p(CO₂) and f(CO₂) generally appeared in coastal regions. Moreover, the average f(CO₂) value of the 12 months showed that the Bohai Sea performed as a weak carbon source in 2009. The results provided technical and data support for carbon management and climate negotiation in the Bohai Sea.     

A statistical analysis of mesoscale eddies in the Bay of Bengal from 22–year altimetry data

本文使用一种基于SLA数据的涡旋识别方法,通过22年的AVISO高度计测高数据对孟加拉湾的中尺度涡特征进行了研究。本文主要分析了孟加拉湾涡旋的地理分布、涡旋极性、涡旋生命周期和传播距离、涡旋产生和消失位置、涡旋传播方向和移动轨迹、涡旋运动特征、涡旋属性的演化以及涡旋活动的季节和年际变化等特性。涡旋主要分布在孟加拉湾西部海域,并且大部分涡旋向西移动。涡旋极性分布显示气旋涡更经常出现在湾的西北部和南部,而反气旋涡主要出现在湾的东部。在22年间,共追踪探测到生命周期超过30天的气旋涡565个、反气旋涡389个;对所有生命周期和传播距离而言都是气旋涡数量居多。所有观测到的涡旋的运动属性分析显示气旋涡的涡旋平均振幅大于反气旋涡;对平均半径和平均移动速度而言,气旋涡和反气旋涡相差不大。而且,涡旋属性演化显示生命周期超过90天的涡旋具有明显的双阶段演化特征,包括一个前50天的涡旋成长阶段和一个50天之后的涡旋消亡阶段。针对涡旋活动的季节变化,气旋涡在春季居多而反气旋涡在夏季较多;长生命周期的涡旋季节分布显示在孟加拉湾涡旋活动具有明显的季节分布特征。涡旋数量的年际变化与EKE变化有一个明显的负相关。     

Importance of microzooplanktonic crustaceans in the coastal food chain: Bay of Marennes-Oléron,France

Modelling biological processes in marine ecosystems requires a good knowledge of the relationships between the different compartments of the ecosystems. Microzooplanktonic crustaceans are often neglected in field feeding studies, due to the difficulties in identification and to their small size. In coastal areas, difficulties are enhanced by the great quantities of particulate organic matter in the water column.Euterpina acutifrons is the major component of the zooplankton community in the Bay of Marennes-Oléron (south-west France) during the algal spring bloom (nauplii strongly dominate the copepod community). The grazing impact of the copepod Euterpina acutifrons (microzooplanktonic and mesozooplanktonic fractions) on the algal standing stock was estimated in the Marennes-Oléron Bay during this period by means of both laboratory experiments and field data. The results suggest that grazing pressure of the microzooplanktonic stages was similar to the pressure exerted by the mesozooplanktonic ones, underlining the significant role of small copepod stages in marine systems in terms of grazing impact. Our results indicate that the daily grazing pressure exerted by the whole population is quite low in the Marennes-Oléron Bay (about 15 % of the algal standing stock).     

Changes of seawater quality in Ofunto Bay,Iwate, after the 2011 off the Pacific coast of Tohoku Earthquake

Ofunato Bay was a semi-closed area because of the breakwater effect at the entrance; however, the breakwater was destroyed by a massive tsunami generated by the 2011 off the Pacific coast of Tohoku Earthquake. Consequently, the physical environment of Ofunato Bay has been changed significantly, i.e., the modification of the stratified structure of seawater inside the bay and the intermittent intrusion of seawater outside the bay. These alterations of physical environment are considered to have an influence on the chemical and biological environment in Ofunato Bay. To elucidate the influence of the tsunami on the aquatic environment, we measured dissolved nutrients, chlorophyll a and dissolved oxygen concentrations, and heterotrophic bacteria abundance inside and outside of Ofunato Bay from 2012 to 2014, and compared these data with those obtained before the earthquake. As compared with before the earthquake, significant changes after the earthquake were (1) decrease of ammonium and phosphate concentrations, (2) increase of chlorophyll a concentration, (3) increase of dissolved oxygen concentration in the bottom, and (4) decrease of heterotrophic bacteria abundance. The collapse of the breakwater and consequential enhanced water exchange were considered to have brought the decrease of nutrient concentration inside the bay. Furthermore, washout of shellfish mariculture rafts by the tsunami decreased the shellfish biodeposits along with the elution of nutrients by heterotrophic bacteria. Decrease of cultivated shellfish further caused a decline in feeding pressure on phytoplankton and, subsequently, increased the phytoplankton biomass that contributed to the decrease of nutrients inside the bay.     

Trends of sea surface temperature and sea surface temperature fronts in the South China Sea during 2003–2017

The trends of the sea surface temperature(SST) and SST fronts in the South China Sea(SCS) are analyzed during2003–2017 using high-resolution satellite data. The linear trend of the basin averaged SST is 0.31°C per decade,with the strongest warming identified in southeastern Vietnam. Although the rate of warming is comparable in summer and winter for the entire basin, the corresponding spatial patterns of the linear trend are substantially different between them. The SST trend to the west of the Luzon Strait is characterized by rapid warming in summer, exceeding approximately 0.6°C per decade, but the trend is insignificant in winter. The strongest warming trend occurs in the southeast of Vietnam in winter, with much less pronounced warming in summer. A positive trend of SST fronts is identified for the coast of China and is associated with increasing wind stress. The increasing trend of SST fronts is also found in the east of Vietnam. Large-scale circulation, such as El Ni?o, can influence the trends of the SST and SST fronts. A significant correlation is found between the SST anomaly and Ni?o3.4 index, and the ENSO signal leads by eight months. The basin averaged SST linear trends increase after the El Ni?o event(2009–2010), which is, at least, due to the rapid warming rate causing by the enhanced northeasterly wind. Peaks of positive anomalous SST and negatively anomalous SST fronts are found to co-occur with the strong El Ni?o events.     

Seabed morphology and gas venting features in the continental slope region of Krishna–Godavari basin,Bay of Bengal: Implications in gas-hydrate exploration

Increased oil and gas exploration activity has led to a detailed investigation of the continental shelf and adjacent slope regions of Mahanadi, Krishna–Godavari (KG) and Cauvery basins, which are promising petroliferous basins along the eastern continental margin of India. In this paper, we analyze the high resolution sparker, subbottom profiler and multibeam data in KG offshore basin to understand the shallow structures and shallow deposits for gas hydrate exploration. We identified and mapped prominent positive topographic features in the bathymetry data. These mounds show fluid/gas migration features such as acoustic voids, acoustic chimneys, and acoustic turbid layers. It is interesting to note that drilling/coring onboard JOIDES in the vicinity of the mounds show the presence of thick accumulation of subsurface gas hydrate. Further, geological and geochemical study of long sediment cores collected onboard Marion Dufresne in the vicinity of the mounds and sedimentary ridges shows the imprints of paleo-expulsion of methane and sulfidic fluid from the seafloor.     

The depth-varying response of coastal circulation and water levels to 2D radiation stress when applied in a coupled wave–tide–surge modelling system during an extreme storm

During storm events wave setup in shallow regions can contribute significantly to the total water elevation, and radiation stress can also generate alongshore drift influencing sediment transport. In low lying coastal regions this generates the potential for flood inundation and morphological change. A coupled tide–surge–wave modelling system is therefore required for accurate forecasting. Liverpool Bay, UK, is taken as a case study because it has a resource of observations and incorporates three estuaries, thus providing conditions to assess the model performance both at the open coast and within estuarine environments. The model covers a region encompassing depths from about 50 m below the mean tidal level to shallow wetting and drying regions, and has previously given good wave and surge hindcasts both for individual storm events and multi-year studies.The present study builds on an already accepted model, to include and assess the spatial influence of 2D radiation stress when implemented in a 3D circulation model. The results show that the method is computationally efficient, so relevant for operational use, and also provides a plausible solution. The varied influence of radiation stress across a coastal domain is demonstrated, with larger impact at an estuary mouth and along the open coast, while having lesser impact within an estuary and further offshore.