Surface Radiative Fluxes Research Articles

Sensitivity of Summertime Convection to Aerosol Loading and Properties in the United Arab Emirates

The Weather Research and Forecasting (WRF) model is used to investigate convection–aerosol interactions in the United Arab Emirates (UAE) for a summertime convective event. Both an idealized and climatological aerosol distributions are considered. The convection on 14 August 2013 was triggered by the low-level convergence of the cyclonic circulation associated with the Arabian Heat Low (AHL) and the daytime sea-breeze circulation. Numerical experiments reveal a high sensitivity to aerosol properties. In particular, replacing 20% of the rural aerosols by carbonaceous particles has a comparable impact on the surface radiative fluxes to increasing the aerosol loading by a factor of 10. In both cases, the UAE-averaged net shortwave flux is reduced by ~90 W m−2 while the net longwave flux increases by ~51 W m−2. However, when the aerosol composition is changed, WRF generates 20% more precipitation than when the aerosol loading is increased, due to a broader and weaker AHL. The surface downward and upward shortwave and upward longwave radiation fluxes are found to scale linearly with the aerosol loading. An increase in the amount of aerosols also leads to drier conditions and a delay in the onset of convection due to changes in the AHL.

A decade of surface meteorology and radiation fluxes at Brewster Glacier in the Southern Alps of New Zealand

AbstractHigh‐altitude observations of mountain meteorology remain extremely rare in the Southern Alps despite their importance for detecting changes in seasonal snow and glacier extent. To address this, we present a unique in situ analysis of surface meteorology, including radiative forcing from clouds, using automatic weather station data obtained near the terminus of Brewster Glacier in the Southern Alps of New Zealand over the period 2010–2020. The average air temperature is 2.1°C at an altitude of 1,650 m above sea level, and seasonal cycles of surface temperature and albedo indicate the automatic weather station (AWS) site is typically snow‐covered between June and November. Snowfall can occur anytime of the year, but rainfall accounts for more than half of the total precipitation (56%). In the absence of strong gradient airflow, a katabatic wind often develops on the glacier, which is strongest at night time and early morning. Partly cloudy conditions are most frequent (43%) at a daily time scale, followed by overcast (34%) and clear‐sky conditions (23%). A distinct diurnal and seasonal cycle of cloud cover is observed, with clouds most frequent in the afternoon during spring. Daily clear‐sky conditions are most common during winter, in particular in June, while the atmospheric transmission of shortwave radiation is lowest in summer. For 4 months of the year (May–August), the increase in incoming longwave radiation by clouds exceeds the decrease in incoming shortwave radiation. Interannual extremes in melt on Brewster Glacier cannot be fully attributed to summer air temperature anomalies and future work should seek to examine the influence of clouds and atmospheric moisture fluxes on seasonal mass balance variations.

Quantifying the local and remote impacts of sub‐grid physical processes on the Southeast Pacific sea surface fluxes in the Community Atmosphere Model version 5 by a limited‐area parameter perturbation approach

AbstractThe Southeast Pacific (SEP) has distinct climate features that are governed by interactions among processes at multiple spatial scales and thus are hard to represent in climate models. This study investigates the local and remote impacts of various physical processes on surface fluxes over SEP in the Community Atmosphere Model version 5 by using a limited‐area parameter perturbation approach. In this approach, physical parameters from the Zhang‐McFarlane (ZM) convection scheme and the turbulence parameterization scheme of Cloud Layers Unified by Binormals (CLUBB) are perturbed in specific regions, but fixed outside. Three limited‐area perturbed parameter ensembles are performed over SEP, the Intertropical Convergence Zone (ITCZ) and the South Pacific convergence zone (SPCZ), respectively, with the simulations over SEP the primary focus that can respond to both local impacts and remote impacts from ITCZ and SPCZ. Results show that most of the variability of surface radiative fluxes is explained by the local impacts of sub‐grid physical processes and those related to shallow convection are most important. By contrast, a considerable portion of the variability of the surface latent heat flux is attributed to the remote effects from ITCZ and SPCZ, which are mainly contributed by the ZM parameters that can affect the large‐scale circulation by modulating the diabatic heating related to precipitation. Both the latent heat flux and shortwave radiative flux over SEP increase with the eastern‐ITCZ precipitation due to the stronger surface wind and less clouds, respectively. Overall, our results help better understand the sources of uncertainties in the simulated SEP climate.

Predicting large-scale pool fire dynamics using an unsteady flamelet- and large-eddy simulation-based model suite

A low-Mach, unstructured, large-eddy-simulation-based, unsteady flamelet approach with a generalized heat loss combustion methodology (including soot generation and consumption mechanisms) is deployed to support a large-scale, quiescent, 5-m JP-8 pool fire validation study. The quiescent pool fire validation study deploys solution sensitivity procedures, i.e., the effect of mesh and time step refinement on capturing key fire dynamics such as fingering and puffing, as mesh resolutions approach O(1) cm. A novel design-order, discrete-ordinate-method discretization methodology is established by use of an analytical thermal/participating media radiation solution on both low-order hexahedral and tetrahedral mesh topologies in addition to quadratic hexahedral elements. The coupling between heat losses and the flamelet thermochemical state is achieved by augmenting the unsteady flamelet equation set with a heat loss source term. Soot and radiation source terms are determined using flamelet approaches for the full range of heat losses experienced in fire applications including radiative extinction. The proposed modeling and simulation paradigm are validated using pool surface radiative heat flux, maximum centerline temperature location, and puffing frequency data, all of which are predicted within 10% accuracy. Simulations demonstrate that under-resolved meshes predict an overly conservative radiative heat flux magnitude with improved comparisons as compared to a previously deployed hybrid Reynolds-averaged Navier–Stokes/eddy dissipation concept-based methodology.

Subtropical Eastern North Pacific SST Bias in Earth System Models

AbstractThis study systematically evaluates the warm sea surface temperature (SST) bias in the Subtropical Eastern North Pacific, a problem plaguing most Coupled Model Intercomparison Project Phase 6 models, using the Energy Exascale Earth System Model version 1 (E3SM). In the model at its standard resolution (1° atmosphere, 30–60 km ocean), the SST bias, exceeding several degrees, is mainly concentrated along the coast between 25°N and 40°N. In the high‐resolution (0.25° atmosphere, 18–6 km ocean) version of the model, the nearshore SST bias improves considerably with a better representation of coastal upwelling. However, the offshore SST bias, approximately centered at 125°W and 25°N, is relatively stronger in the high‐resolution version. To better understand the offshore warm bias in the model, a mixed‐layer heat budget analysis is performed. While errors in surface radiative fluxes occur at both resolutions, positive biases in horizontal heat advection also play a role in the SST bias at high‐resolution. Analysis of HighResMIP models indicates that the shift in the location of the prominent SST bias from nearshore to offshore with an increase in model spatial resolution, is not native to E3SM alone.

Validation of Landsat-8 satellite-derived radiative energy fluxes using wireless sensor network data over Beas River basin, India

ABSTRACT In the present paper, spatio-temporal variability in surface radiative energy fluxes has been estimated for snow/ice-covered Beas River basin, lower Western Himalaya, India using remote sensing technology and evaluated with wireless sensor network (WSN) collected data at various elevation levels. Surface energy fluxes are derived using Landsat-8 satellite images and digital elevation model (DEM) at fine spatial resolution (~30-m) during clear-sky days of the year 2016–2017. RMSE have been estimated in incoming shortwave, incoming longwave, outgoing longwave, net shortwave and net radiation flux and observed to be ~5%, ~ 6.3%, ~2.4%, ~18.9%, and ~28.3% of the respective mean values. Landsat-8 images in conjunction with DEM have shown the potential to retrieve variability in surface radiative energy fluxes at fine resolution in mountain terrain. Additionally, temporal variability in radiative radiation fluxes have also been explored on different elevation ranges and aspects slopes. The high energy fluxes have been estimated on southern slopes during analysis as compared to northern slopes in the present study. The paper appears to be the first for reporting net radiation flux for Himalayan snow cover at 30-m spatial resolution. The satellite-derived energy fluxes may be valuable in various applications associated with climatology, hydrology, wet-snow avalanche detection, land use land cover, mass balance, ecology, etc., especially in the absence of in situ data.

FIRE HAZARDS IN LITHIUM-ION BATTERIES UNDER OVERCHARGING AND SAFETY STRATEGIES

Various Li-ion battery (LIB) fire and blasts have raised real worries about the safety issues connected with LIBs, some of those occurrences were in the main brought about by overcharging of LIBs. Thus, to possess a superior comprehension of the fire dangers brought about by LIB overcharging, 2 broadly utilised industrial LIBs, nickel manganese cobalt oxide (NMC) and lithium iron phosphate (LFP), were tried during this work. a couple of boundaries together with the surface temperature, the flame temperature, voltage, and radiative heat flux were calculable and investigated. The outcomes demonstrate that the underlying cathartic voltage increments with the event of charge cut-off voltage. AN overcharged LIB can undergo a additional vicious burning cycle and has lower steadiness than a typical one, and therefore the increasing cut-off voltage bothers the seriousness. Furthermore, this work examines the thermal runaway mechanism and presents completely different thermal runaway mitigation process, together with separators, flame retardants, and safety vents. The work then outlines measures for stifling Fires, and lands up with a bunch of suggestions for future innovative work. Quercetin, an organic antioxidant, has been utilized as an additive in Li-ion cells to boost the chemistry performance to enhance the cycle life and also the overcharging characteristics. The quercetin -containing lithium battery showed an improvement in its electrochemical properties with 92% capacity retention after 350 cycles. the advance would possibly result from the formation of a passivation microstructure (from quercetin oxidation) on the electrode’s surface. The quercetin-containing batteries provided long term cycling and a high safety performance, creating them a viable power supply for applications involving electrical devices with important safety requirements.

Effects of Incorporating Measured Leaf Optical Properties in Land Surface Models

Leaf optical properties (LOPs, i.e., leaf reflectance and transmittance), as a fundamental property of vegetation, are a key parameter in the canopy radiative transfer process. LOPs have a direct impact on the surface solar radiation partition and further affect surface flux exchanges. Recent works have provided reliable LOP data and mentioned that notable differences exist between the prescribed LOP values in current land surface models and measured LOP values, especially in the near-infrared (NIR) band. To evaluate the effects of different LOP values in land surface modeling, we ran two land surface models (the Community Land Model and the Common Land Model) with their default prescribed and measured values to examine the differences in simulated surface radiation partitions and fluxes. Our analyses show that differences in LOP values can lead to a large discrepancy in albedo, radiation partition, sensible heat flux and net radiation simulations. By using the measured LOP values, in the boreal forest zone, Southeast China, and the eastern United States, both models have a significantly increased surface albedo in the NIR band, with the difference exceeding 10% during JJA. Thus, the measured LOP values can improve the negative albedo bias in the boreal forest zone during summertime. Moreover, both models simulate less net radiation with a maximum reduction of 11 W/m2 when incorporating the measured LOP values. Therefore, the total sensible heat flux can be reduced by as much as 11 W/m2. The results of this study emphasize that different LOP values can have a considerable effect on the surface radiation budget and sensible heat flux simulations which need attention in land surface model development. However, in current offline simulations, the measured LOP values cause slight changes in land surface temperatures and gross primary productivity (GPP).

Saharan Dust Effects on North Atlantic Sea‐Surface Skin Temperatures

AbstractSaharan dust outbreaks frequently propagate westward over the Atlantic Ocean; accurate quantification of the dust aerosol scattering and absorption effect on the surface radiative fluxes (SRF) is fundamental to understanding critical climate feedbacks. By exploiting large sets of measurements from many ship campaigns in conjunction with reanalysis products, this study characterizes the sensitivity of the SRF and skin Sea‐Surface Temperature (SSTskin) to the Saharan dust aerosols using models of the atmospheric radiative transfer and thermal skin effect. Saharan dust outbreaks can decrease the surface shortwave radiation up to 190 W/m2, and an analysis of the corresponding SSTskin changes using a thermal skin model suggests dust‐induced cooling effects as large as −0.24 K during daytime and a warming effect of up of 0.06 K during daytime and nighttime respectively. Greater physical insight into the radiative transfer through an aerosol‐burdened atmosphere will substantially improve the predictive capabilities of weather and climate studies on a regional basis.

Surface Radiative Flux Bias Reduction Through Regionally Varying Cloud Fraction Parameter Nudging in a Global Coupled Forecast System

AbstractA simple parameter nudging procedure is described that systematically reduces near‐analysis time errors in the surface net shortwave flux in the Navy ESPC (Earth System Prediction Capability) system, a global coupled forecast system that is the product of a continuing development effort at the U. S. Naval Research Laboratory. The procedure generates geographically varying perturbations to one of the cloud fraction parameters in the atmospheric model component of the system during the data assimilation cycle, resulting in large improvements in near‐analysis time surface net shortwave flux biases. After a several week spin‐up period, the global RMSE of the succeeding 10‐day mean bias computed for lead times of 6–12 hours is reduced by 40 percent. Results from application of the approach in a series of 45‐day integrations show that improvements are realized at longer forecast lead times as well. The global RMSE of the surface net shortwave flux averaged over these integrations improves by 37 percent for lead times from 1–5 days, decreasing to 18 percent for lead times from 31–45 days. The corresponding longwave flux errors are slightly degraded, ranging from a 2 percent increase for lead times from 1–5 days to a 0.5 percent increase for lead times from 31–45 days. Global‐mean reductions in ground and sea surface temperature errors are obtained through most of the 45‐day integration period due to improvements over ocean and polar regions. Potential steps for extension and operational application of the method are discussed.

Surfer: A fast simulation algorithm to predict surface temperatures and mean radiant temperatures in large urban models

Outdoor thermal comfort simulation simulations rely on the mean radiant temperature (MRT) seen by pedestrians as an important input that remains difficult to compute. Especially for large urban models, computing relevant surface temperatures and radiation fluxes that make up the MRT is a daunting task in terms of simulation setup and the computational overhead. We propose a new algorithm to estimate exterior surface temperatures of building facades, roofs, and ground surfaces in an arbitrary urban 3D model. The algorithm discretizes all model surfaces and clusters them by material properties and sky and sun exposure to reduce computational complexity. The model setup is fully automated, and the algorithm is implemented in the popular Rhino3d CAD environment. We demonstrate the accuracy of the algorithm by comparing both the resulting external surface temperatures against a high-fidelity simulation and the final MRT against real-world measurements. We report an RMSE of 1.8 °C and 2.0 °C, respectively, while reducing simulation times by a factor of ~80. Envisioned applications of the algorithm range from rapid microclimate simulations in fast-paced urban design processes to large scale urban comfort evaluation of existing cities.

Two-color pyrometry based flame to fuel surface radiative heat flux diagnostic using flamelets

In this study, a non-intrusive two-color pyrometry based radiative heat flux diagnostic is presented that accounts for the self-absorption effects. This diagnostic relies on looking up the flame temperature and soot volume fraction using the ratio of color intensities obtained from digital cameras and numerical solutions of 1D steady-state diffusion flames. Virtual two color pyrometry of computed flame show a unique one-to-one mapping of strained flames with intensity ratio; thereby allowing flames to be indexed and creation of a two-color flamelet manifold (TCFM). The TCFM is a function of two variables; the ratio of red to green intensities (flame index) and physical distance to the stoichiometric surface defined using a level-set function. The developed diagnostic is used in upward flame spread experiments where an approximate flame hull reconstruction method is applied to provide the 3D level-set function and intensity ratio for use of TCFM to provide radiative absorption properties for 3D ray tracing. Accounting for self-absorption effects provide improved soot volume fraction estimates. The radiative heat flux estimates are found to be in very good agreement with literature and improved results are obtained near the flame base.

Effects of Cropland Expansion on the Regional Land Surface Radiative Energy Balance and Heat Fluxes in Northern China

Land use change can impact the land surface radiation budget and energy balance by changing surface biophysical processes. Based on satellite remote sensing data and land use data from 2000 to 2015, we quantitatively estimated radiative forcing induced by cropland expansion during the early 21st century in northern China. The results showed that heat flux from the land surface to the atmosphere due to cropland expansion was quite variable in different climate zones. The heat flux increased in humid North China, whereas it decreased in arid Northwest China, semiarid Inner Mongolia, and humid Northeast China. Cropland expansion from woodland areas led to a general decline in the land surface heat flux to the atmosphere, which led to a cooling effect on the climate. The surface heat flux to the atmosphere due to cropland expansion in grassland areas displayed significant variations in different climate zones. The surface heat flux decreased only in humid Northeast China and arid Northwest China. The net surface radiation and latent heat flux both increased when grasslands were changed into cropland, but to different extents, which produced the differences in the surface heat flux to the atmosphere between different zones.

Impacts of low cloud and fog on surface radiation fluxes for ecosystems in coastal California

Advection fog processes produce frequent low cloud and fog (LCF) during summer along the coast of central and northern California. Four radiometer datasets from sites in San Francisco and Monterey Bay as well as fog-drip and meteorological observations were used to characterize the role of LCF on surface radiation budget components and scattering of solar radiation. LCF produced distinct and consistent impacts on surface radiation relative to clear skies including large reductions (approximately half) in solar irradiance but large increases (approximately 180%) in the diffuse beam component, consistent increases of approximately 70 W m−2 in down-welling longwave radiation (L↓), as well as reductions in net radiation and leaf surface temperature by day and increases at night. L↓ can be a useful and accurate tool for monitoring the presence of LCF, using simple thresholds: LCF = L↓ > 360 W m−2 and clear-sky = L↓ 0.0059β + 0.3, where β is the solar elevation angle. We also present a model to partition the diffuse and direct beam fractions of solar irradiance specifically for coastal LCF, which improved accuracy by more than 10% relative to existing universal models. These radiation characteristics are important for understanding energy balance and sunlight conditions experienced by coastal ecosystems.

A new WSGGM considering CO in oxy-fuel combustion: A theoretical calculation and numerical simulation application

The HITEMP 2010 databases was employed in line by line (LBL) method to calculate an accurate total emissivity benchmark for oxy-fuel combustion atmosphere. This paper focuses on the effect of CO in the oxy-fuel gas mixture on the total emissivity. CO is significant in the primary combustion zone of boiler, generating from incomplete combustion and gasification reactions in oxy-fuel combustion mode. Based on the total emissivity benchmark from LBL, the new correlation coefficients for weighted sum of gray gases model (WSGGM) are fitted for mole fraction of CO from 0% to 45%, molar ratio of H2O to CO2 between 0.01 and 4, temperature range of 400 K–3000 K and path length varying from 0.01 m to 60 m. Radiative heat flux and radiative source term results from solving the radiation transfer equation (RTE) in one-dimensional slab system are used to evaluate the accuracy and effectiveness of new correlation coefficients for WSGGM. By comparing with the results from LBL and models in other literature, new correlation coefficients for WSGGM are validated no matter in non-isothermal and non-homogenous conditions considering CO in gas mixture. At last, the new correlation coefficients are implemented in the numerical simulation of oxy-natural gas furnace to show the effect of gas radiation model on the wall surface radiative heat flux.

Meteorological Conditions and Cloud Effects on Surface Radiation Balance Near Helheim Glacier and Jakobshavn Isbræ (Greenland) Using Ground-Based Observations

The surface radiation budget is an essential component of the total energy exchange between the atmosphere and the Earth’s surface. Measurements of radiative fluxes near/on ice surfaces are sparse in the polar regions, including on the Greenland Ice Sheet (GrIS), and the effects of cloud on radiative fluxes are still poorly studied. In this work, we assess the impacts of cloud on radiative fluxes using two metrics: the longwave-equivalent cloudiness, derived from long-wave radiation measurements, and the cloud transmittance factor, obtained from short-wave radiation data. The metrics are applied to radiation data from two automatic weather stations located over the bare ground near the ice front of Helheim (HG, 66.3290°N, 38.1460°W) and Jakobshavn Isbræ(JI, 69.2220°N, 49.8150°W) on the GrIS. Comparisons of meteorological parameters, surface radiation fluxes, and cloud metrics show significant differences between the two sites. The cloud transmittance factor is higher at HG than at JI, and the incoming short-wave radiation in the summer at HG is about 50.0 W m−2 larger than at JI. Cloud metrics derived at the two sites reveal partly cloudy conditions were frequent (42 and 65% of the period at HG and JI) with a high dependency on the wind direction. The total cloud radiative effect (CREnet) generally increases during melt season at the two stations due to long-wave CRE enhancement by cloud fraction. CREnet decreases from May to June and increases afterward, due to the strengthened short-wave CRE. The annually averaged CREnet were 3.0 ± 7.4 W m−2 and 1.9±15.1 W m−2 at JI and HG. CREnet estimated from AWS indicates that clouds cool the JI and HG during melt season at different rates.

A multi-year short-range hindcast experiment with CESM1 for evaluating climate model moist processes from diurnal to interannual timescales

Abstract. We present a multi-year short-range hindcast experiment and its experimental design for better evaluation of both the mean state and variability of atmospheric moist processes in climate models from diurnal to interannual timescales and facilitate model development. We used the Community Earth System Model version 1 as the base model and performed a suite of 3 d hindcasts initialized every day starting at 00:00 Z from 1997 to 2012. Three processes – the diurnal cycle of clouds during different cloud regimes over the central US, precipitation and diabatic heating associated with the Madden–Julian Oscillation (MJO), and the response of precipitation, surface radiative and heat fluxes, as well as zonal wind stress to sea surface temperature anomalies associated with the El Niño–Southern Oscillation – are evaluated as examples to demonstrate how one can better utilize simulations from this experiment to gain insights into model errors and their connection to physical parameterizations or large-scale state. This is achieved by comparing the hindcasts with corresponding long-term observations for periods based on different phenomena. These analyses can only be done through this multi-year hindcast approach to establish robust statistics of the processes under well-controlled large-scale environment because these phenomena are either a result of interannual climate variability or only happen a few times in a given year (e.g., MJO, or cloud regime types). Furthermore, comparison of hindcasts to the typical simulations in climate mode with the same model allows one to infer what portion of a model's climate error directly comes from fast errors in the parameterizations of moist processes. As demonstrated here, model biases in the mean state and variability associated with parameterized moist processes usually develop within a few days and manifest within weeks to affect the simulations of large-scale circulation and ultimately the climate mean state and variability. Therefore, model developers can achieve additional useful understanding of the underlying problems in model physics by conducting a multi-year hindcast experiment.

An evaluation of the Arctic clouds and surface radiative fluxes in CMIP6 models

To assess the performances of state-of-the-art global climate models on simulating the Arctic clouds and surface radiation balance, the 2001–2014 Arctic Basin surface radiation budget, clouds, and the cloud radiative effects (CREs) in 22 coupled model intercomparison project 6 (CMIP6) models are evaluated against satellite observations. For the results from CMIP6 multi-model mean, cloud fraction (CF) peaks in autumn and is lowest in winter and spring, consistent with that from three satellite observation products (CloudSat-CALIPSO, CERES-MODIS, and APP-x). Simulated CF also shows consistent spatial patterns with those in observations. However, almost all models overestimate the CF amount throughout the year when compared to CERES-MODIS and APP-x. On average, clouds warm the surface of the Arctic Basin mainly via the longwave (LW) radiation cloud warming effect in winter. Simulated surface energy loss of LW is less than that in CERES-EBAF observation, while the net surface shortwave (SW) flux is underestimated. The biases may result from the stronger cloud LW warming effect and SW cooling effect from the overestimated CF by the models. These two biases compensate each other, yielding similar net surface radiation flux between model output (3.0 W/m2) and CERES-EBAF observation (6.1 W/m2). During 2001–2014, significant increasing trend of spring CF is found in the multi-model mean, consistent with previous studies based on surface and satellite observations. Although most of the 22 CMIP6 models show common seasonal cycles of CF and liquid water path/ice water path (LWP/IWP), large inter-model spreads exist in the amounts of CF and LWP/IWP throughout the year, indicating the influences of different cloud parameterization schemes used in different models. Cloud Feedback Model Intercomparison Project (CFMIP) observation simulator package (COSP) is a great tool to accurately assess the performance of climate models on simulating clouds. More intuitive and credible evaluation results can be obtained based on the COSP model output. In the future, with the release of more COSP output of CMIP6 models, it is expected that those inter-model spreads and the model-observation biases can be substantially reduced. Longer term active satellite observations are also necessary to evaluate models’ cloud simulations and to further explore the role of clouds in the rapid Arctic climate changes.

Impact of fine atmospheric scales on ocean eddies and deep convection in the Subpolar Northern Atlantic

In this study we examine the sensitivity of the high-resolution regional ocean model solution to the atmospheric forcing of low (70 km - LoRes) and high (14 km - HiRes) spatial resolutions over the North Atlantic. To force the regional set up of NEMO ocean general circulation model (OGCM) we use the North Atlantic Atmospheric Downscaling (NAAD) product, which is the result of the Weather Research and Forecasting (WRF) atmospheric GCM with ERA-Interim as a boundary condition. Increase of the of the resolution of the atmospheric forcing and thus, representation of the surface turbulent heat and radiative fluxes in HiRes and LoRes atmospheric forcing, cause the 1.5° negative difference between sea surface temperature and -0.15 PSU in sea water salinity over the whole domain. The output of the OGCM forced by the high-resolution atmosphere is almost equal to the observational datasets. More intensive turbulent heat loss from the ocean surface and ventilation processes result in lower ocean heat content in the upper ocean (0-700 m) and at intermediate depth (700-1500 m) when the model is forced by HiRes. HiRes-driven experiment shows more intense coastal currents and less intensive large-scale currents. Ventilation processes are sensitive to the mesoscale atmospheric events representation: HiRes experiment provides deeper by 100 m mixed layer depths and its later in time deepening and restratification.

Improvement in the prediction of gasoline pool fire behaviour: CFD modelling and validation

The development and implementation of mathematical models through Computational Fluid Dynamics (CFD) techniques has been acknowledged as a promising tool for the prediction of hydrocarbon pool fires behaviours. In this sense, different approaches, with different assumptions and simplifications, and accounting for different phenomena, have been developed in the literature. However, the deviations in the predictions of the experimentally determined parameters, such as temperatures profiles, flame heights and radiative heat flux, by the implemented models are still high. Therefore, the implementation of these models to predict combustion phenomena and flame behaviours for various scenarios is limited. In this work, the software C3D is used to model gasoline pool fires of different diameters, and under different wind conditions, in order to improve the quality of the predictions of the flame behaviour. The modelled cases correspond to the experimental studies reported in literature. The results from the implemented model show an improved predictive quality when compared with other modelling works reported on literature for the same experimental cases. The deviations in the time averaged temperature, flame height, surface emissive power and radiative heat flux, has been calculated to be 5.0%, 0.05%, 6.32% and 3.82%, respectively.