scholarly journals The Impact of Wave Model Source Terms and Coupling Strategies to Rapidly Developing Waves across the North-West European Shelf during Extreme Events

2021 ◽  
Vol 9 (4) ◽  
pp. 403
Author(s):  
Nieves G. Valiente ◽  
Andrew Saulter ◽  
John M. Edwards ◽  
Huw W. Lewis ◽  
Juan M. Castillo Sanchez ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Stress ◽  
Wave Model ◽  
Wave Growth ◽  
North West ◽  
Wind Speeds ◽  
The North ◽  
European Shelf ◽  
The Impact ◽  
Coupling Strategies

Prediction of severe natural hazards requires accurate forecasting systems. Recently, there has been a tendency towards more integrated solutions, where different components of the Earth system are coupled to explicitly represent the physical feedbacks between them. This study focuses on rapidly developing waves under extratropical storms to understand the impact of different wave source term parameterisations in the WAVEWATCH III (WWIII) model (ST4 and ST6) and coupling strategies (surface roughness closure versus surface stress closure) on the accuracy of the Met Office regional atmosphere-ocean-wave coupled research system for the north-west (NW) European shelf (UKC4). Results of a study focused on simulations during winter 2013/14 demonstrate that ST6 allows for a faster wave growth than the ST4 parameterisation but might degrade low to mid energy wave states. The difference between ST6 and ST4 in wave growth is larger for higher wind speeds and short fetches. The experiment with ST4 and roughness closure consistently under-predicts the wave growth in those locations where fetch dependence is an important factor (i.e., seas at the East (E) of Ireland and the UK for storms coming from the NW-WNW). The implementation in the wave model of ST6 physics with the stress closure coupling strategy appears to improve growth of young wind-seas, reducing bias in those locations where the storms are underestimated. The slower wave growth when using surface roughness closure seems to be related to an underestimation of the momentum transfer computed by the wave model when coupling the wind speeds. For very young to young wind seas, this can be overcome when the surface stress is computed by the atmospheric model and directly passed to the ocean.

The impact of wave source terms and coupling strategies on the accuracy of the UKC4 regional coupled atmosphere–ocean–wave forecasting system during extreme events

2021 ◽  
Author(s):  
Nieves G. Valiente ◽  
Andrew Saulter ◽  
John Edwards ◽  
Huw Lewis ◽  
Juan M. Castillo ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Momentum Transfer ◽  
Wave Model ◽  
Atmospheric Model ◽  
Source Terms ◽  
Wave Source ◽  
Wave Growth ◽  
Wind Speeds ◽  
Coupling Strategy ◽  
The Impact

<p>Prediction of severe natural hazards requires accurate forecasting systems. Recently, there is a tendency to move towards more integrated solutions, where different components of the Earth system are coupled to better reproduce the physical feedbacks between them. Atmosphere–wave coupling should, in principle, improve the momentum flux because there is more detail in the two-way feedback due to the atmosphere receiving a more realistic picture of the surface roughness. However, the coupling between the ocean surface and the wind might become less efficient at transferring momentum during large storms.</p><p>This study focuses on rapidly developing waves under extratropical storms to understand the sensitivity in atmosphere–wave present generation source terms and coupling strategies. Here, we analyse the effect of momentum transfer to fast growth waves during both long and fetch limited conditions using the Met Office regional atmosphere–ocean–wave coupled research system for the northwestern (NW) European shelf (UKC4).</p><p>Two different sets of numerical experiments are conducted focusing on the atmosphere–wave components. The first one explores the sensitivity to two different wave source parameterizations, ST4 and ST6, and uses a two-way feedback coupling strategy (A2W) where a sea-state dependent surface roughness modifies the atmospheric momentum budget. In the second set of simulations, the impact of the coupling strategy is assessed. The A2W approach using ST6 physics is compared against a simpler one-way strategy (A1W) where no wave feedback on the atmospheric model exists and the wind stress is directly passed to the wave model (WAVEWATCHIII) ensuring conservation of momentum.</p><p>Results demonstrate that ST6 physics allows for a faster wave growth than the currently used ST4 parameterization but might degrade low to mid energy wave states for the NW shelf. ST6 versus ST4 difference in wave growth is larger for higher wind speeds and short fetches. The experiment with ST4 and A2W consistently under-predicts the wave growth in those locations across the NW shelf where fetch dependence is an important factor (i.e., seas at the E of Ireland and the UK for storms coming from the NW-WNW). The implementation in the wave model of physics that depend solely in the wind input (ST6) with the A1W coupling strategy appears to improve growth of young wind-seas, reducing bias in those locations where the storms are underestimated. The analysis of the transfer of momentum across the air-sea boundary layer shows that forecasts of large wave events may require a different coupling approach. The slower wave growth seems to be related to an underestimation of the momentum transfer computed by the wave model when coupling the wind speeds (A2W). This suggests that coupling the wind speeds to the wave model and allowing this to calculate the momentum transfer from the atmosphere to waves and ocean underestimates the transfer by a few percent. For very young to young wind seas, this can be overcome when the surface stress is computed by the atmospheric model and directly passed to the ocean (A1W).</p>

scholarly journals Impacts of some meteorological parameters on the SO2 concentrations in the city of Obrenovac, Serbia

2010 ◽  
Vol 75 (5) ◽  
pp. 703-715 ◽  
Author(s):  
Snezana Nenadovic ◽  
Ljiljana Matovic ◽  
Misko Milanovic ◽  
Sava Janicevic ◽  
Jasmina Grbovic-Novakovic ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Power Plants ◽  
Meteorological Parameters ◽  
North West ◽  
Wind Speeds ◽  
The North ◽  
West Part ◽  
Measuring Site ◽  
The Impact ◽  
The City

In this paper, the impacts of some meteorological parameters on the SO2 concentrations in the City of Obrenovac are presented. The City of Obrenovac is located in the north-west part of Serbia on the banks of the River Sava. The observed source emission, the power plants TENT A and TENT B are situated on the bank of the Sava River in the vicinity of Obrenovac. During the period from January to November 2006, the concentrations of sulfur dioxide in the air at 4 monitoring sites in Obrenovac were measured. It was noticed that the maximal measured daily concentrations of sulfur dioxide ranged from 1 ?g/m3 (16th November, 2006) to 98 ?g/m3 (29th January 2006) and lie under the maximal allowed concentration value according to the Serbian Law on Environmental Protection. The measured sulfur dioxide concentrations mostly showed characteristics usual for a daily acidification sulfur dioxide cycle, excluding the specificities influenced by the measuring site itself. Sulfur dioxide transport was recorded at increased wind speeds, primarily from the southeast direction. Based on the impact of meteorological parameters on the sulfur dioxide concentration, a validation of the monitoring sites was also performed from the aspect of their representivity.

scholarly journals Can wave coupling improve operational regional ocean forecasts for the North-West European Shelf?

2018 ◽  
Author(s):  
Huw W. Lewis ◽  
Juan Manuel Castillo Sanchez ◽  
John Siddorn ◽  
Robert R. King ◽  
Marina Tonani ◽  
...  
Keyword(s):  
Mixed Layer ◽  
Sea Surface ◽  
Ocean Wave ◽  
Prediction System ◽  
Wave Coupling ◽  
North West ◽  
The North ◽  
European Shelf ◽  
Ocean Prediction ◽  
The Impact

Abstract. Operational ocean forecasts are typically produced by modelling systems run using a forced mode approach. The evolution of the ocean state is not directly influenced by surface waves, and the ocean dynamics are driven by an external source of meteorological data which is independent of the ocean state. Model coupling provides one approach to increase the extent to which ocean forecast systems can represent the interactions and feedbacks between ocean, waves and the atmosphere seen in nature. This paper demonstrates the impact of improving how the effect of waves on the momentum exchange across the ocean-atmosphere interface is represented through ocean-wave coupling on the performance of an operational regional ocean prediction system. This study focuses on the eddy-resolving (1.5 km resolution) Atlantic Margin Model (AMM15) ocean model configuration for the North-West European Shelf (NWS) region. A series of two-year duration forecast trials of the Copernicus Marine Environment Monitoring Service (CMEMS) North-West Shelf regional ocean prediction system are analysed. The impact of including ocean-wave feedbacks via dynamic coupling on the simulated ocean is discussed. The main interactions included are the modification of surface stress by wave growth and dissipation, Stokes–Coriolis forcing and wave height dependent ocean surface roughness. Given the relevance to operational forecasting, trials with and without ocean data assimilation are considered. Summary forecast metrics demonstrate that the ocean-wave coupled system is a viable evolution for future operational implementation. When results are considered in more depth, wave coupling was found to result in an annual cycle of relatively warmer winter and cooler summer sea surface temperatures for seasonally stratified regions of the NWS. This is driven by enhanced mixing due to waves, and a deepening of the ocean mixed layer during summer. The impact of wave coupling is shown to be reduced within the mixed layer with assimilation of ocean observations. Evaluation of salinity and ocean currents against profile measurements in the German Bight demonstrates improved simulation with wave coupling relative to control simulations. Further, evidence is provided of improvement to simulation of extremes of sea surface height anomalies relative to coastal tide gauges.

scholarly journals Can wave coupling improve operational regional ocean forecasts for the north-west European Shelf?

Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 669-690 ◽  
Author(s):  
Huw W. Lewis ◽  
Juan Manuel Castillo Sanchez ◽  
John Siddorn ◽  
Robert R. King ◽  
Marina Tonani ◽  
...  
Keyword(s):  
Sea Surface ◽  
Ocean Wave ◽  
Prediction System ◽  
Wave Coupling ◽  
North West ◽  
The North ◽  
European Shelf ◽  
Ocean Prediction ◽  
The Impact ◽  
West European

Abstract. Operational ocean forecasts are typically produced by modelling systems run using a forced mode approach. The evolution of the ocean state is not directly influenced by surface waves, and the ocean dynamics are driven by an external source of meteorological data which are independent of the ocean state. Model coupling provides one approach to increase the extent to which ocean forecast systems can represent the interactions and feedbacks between ocean, waves, and the atmosphere seen in nature. This paper demonstrates the impact of improving how the effect of waves on the momentum exchange across the ocean–atmosphere interface is represented through ocean–wave coupling on the performance of an operational regional ocean prediction system. This study focuses on the eddy-resolving (1.5 km resolution) Atlantic Margin Model (AMM15) ocean model configuration for the north-west European Shelf (NWS) region. A series of 2-year duration forecast trials of the Copernicus Marine Environment Monitoring Service (CMEMS) north-west European Shelf regional ocean prediction system are analysed. The impact of including ocean–wave feedbacks via dynamic coupling on the simulated ocean is discussed. The main interactions included are the modification of surface stress by wave growth and dissipation, Stokes–Coriolis forcing, and wave-height-dependent ocean surface roughness. Given the relevance to operational forecasting, trials with and without ocean data assimilation are considered. Summary forecast metrics demonstrate that the ocean–wave coupled system is a viable evolution for future operational implementation. When results are considered in more depth, wave coupling was found to result in an annual cycle of relatively warmer winter and cooler summer sea surface temperatures for seasonally stratified regions of the NWS. This is driven by enhanced mixing due to waves, and a deepening of the ocean mixed layer during summer. The impact of wave coupling is shown to be reduced within the mixed layer with assimilation of ocean observations. Evaluation of salinity and ocean currents against profile measurements in the German Bight demonstrates improved simulation with wave coupling relative to control simulations. Further, evidence is provided of improvement to simulation of extremes of sea surface height anomalies relative to coastal tide gauges.

scholarly journals A Novel Sea Surface Roughness Parameterization Based on Wave State and Sea Foam

2021 ◽  
Vol 9 (3) ◽  
pp. 246
Author(s):  
Difu Sun ◽  
Junqiang Song ◽  
Xiaoyong Li ◽  
Kaijun Ren ◽  
Hongze Leng
Keyword(s):  
Surface Roughness ◽  
Wind Speed ◽  
Drag Coefficient ◽  
Sea Surface ◽  
High Wind Speed ◽  
Wave State ◽  
Wind Speeds ◽  
Sea Surface Roughness ◽  
Extreme Wind ◽  
The Impact

A wave state related sea surface roughness parameterization scheme that takes into account the impact of sea foam is proposed in this study. Using eight observational datasets, the performances of two most widely used wave state related parameterizations are examined under various wave conditions. Based on the different performances of two wave state related parameterizations under different wave state, and by introducing the effect of sea foam, a new sea surface roughness parameterization suitable for low to extreme wind conditions is proposed. The behaviors of drag coefficient predicted by the proposed parameterization match the field and laboratory measurements well. It is shown that the drag coefficient increases with the increasing wind speed under low and moderate wind speed conditions, and then decreases with increasing wind speed, due to the effect of sea foam under high wind speed conditions. The maximum values of the drag coefficient are reached when the 10 m wind speeds are in the range of 30–35 m/s.

scholarly journals Effect of tropical cyclones on the Stratosphere-Troposphere Exchange observed using satellite observations over north Indian Ocean

2016 ◽  
Author(s):  
M. Venkat Ratnam ◽  
S. Ravindra Babu ◽  
S. S. Das ◽  
Ghouse Basha ◽  
B. V. Krishnamurthy ◽  
...  
Keyword(s):  
Water Vapor ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Lower Stratosphere ◽  
North Indian Ocean ◽  
Satellite Observations ◽  
Upper Troposphere ◽  
North West ◽  
The North ◽  
The Impact

Abstract. Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere-troposphere exchange (STE) process in the Upper Troposphere and Lower Stratosphere (UTLS) region. In the present study, the impact of cyclones that occurred over the North Indian Ocean during 2007–2013 on the STE process is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS) Radio Occultation (RO) measurements and ozone and water vapor concentrations in UTLS region are obtained from Aura-Microwave Limb Sounder (MLS) satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km from the centre of cyclone. In our earlier study we have observed decrease (increase) in the tropopause altitude (temperature) up to 0.6 km (3 K) and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL) thickness of 3 km within the 500 km from the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from cyclone centre whereas the enhancement in the water vapor in the lower stratosphere is more significant on south-east side extending from 500–1000 km away from the cyclone centre. We estimated the cross-tropopause mass flux for different intensities of cyclones and found that the mean flux from stratosphere to troposphere for cyclonic stroms is 0.05 ± 0.29 × 10−3 kg m−2 and for very severe cyclonic stroms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed in the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget and consequentially the STE in the UTLS region.

scholarly journals 'Greenfields' and 'Brownfields': automotive industrial development in the UK and in Portugal

Finisterra ◽  
2012 ◽  
Vol 31 (62) ◽  
Author(s):  
Andrew Pike ◽  
Mário Vale
Keyword(s):  
Industrial Policy ◽  
Automobile Industry ◽  
Industrial Development ◽  
Development Strategies ◽  
North West ◽  
Demonstration Effect ◽  
North East ◽  
The North ◽  
The Uk ◽  
The Impact

The industrial policy in the UK and in Portugal, as in most EU countries, seeks to attract new investment capacity, to create jobs and to promote the impact of the so-called "demonstration efect" of "greenfield" development strategies pursued in the new plants of inward investors on existing or "brownfield" plants. This industrial policy focus is particularly evident in the automobile industry.This paper compares the industrial policy oriented towards the automobile industry in the UK and in Portugal. Two recent "greenfield" investments are analised: Nissan in the North-East region (UK) and Ford/VW in the Setúbal Peninsula (Portugal), as well as three "brownfield" plants: Ford Halewood and GM Vauxhall Ellesmere Port in the North-West region (UK) and Renault in Setúbal (Portugal). The first part starts with a discussion of industrial policy in the automobile sector, the role of "greenfield" development strategies and the "demonstration effect" on "brownfield" plants. Then, the limits of new inward investment are pointed out, basically their problems and restrictions. Afterwards, the structural barriers to the "demonstration effect" within "brownfield" plants are outlined and some possabilities for alternative "brownfield" development strategies are presented.

Pashtun and Punjabi Taliban

Pakistan ◽  
2020 ◽  
pp. 131-144
Author(s):  
Mariam Abou Zahab
Keyword(s):  
North West ◽  
Competition And Cooperation ◽  
Sectarian Violence ◽  
The North ◽  
North West Frontier Province ◽  
Tribal Areas ◽  
The Impact

This chapter attempts to analyse the dynamics of the Pashtun–Punjabi nexus and the areas of competition and cooperation between Sunni sectarian groups and the Pakistani Taliban. It outlines the links between Sunni sectarian groups and the Afghan Taliban, the impact of the collapse of the Taliban regime in Afghanistan and the implications of the relocation of Punjabi jihadi/sectarian groups in the North West Frontier Province (NWFP) and the Federally Administered Tribal Areas (FATA). It also focuses on the consequences of the storming of Islamabad's Lal Masjid in July 2007, and it investigates the re-emergence of sectarian groups in Karachi and in the Punjab and its implications for Pakistan. The Punjab and Karachi have been the primary hubs of sectarian violence in Pakistan since the 1980s, but in the post-9/11 environment the Sunni-Shia conflict has assumed a new dimension.

scholarly journals Impact of Satellite Observations on the Tropical Cyclone Track Forecasts of the Navy Operational Global Atmospheric Prediction System

2009 ◽  
Vol 137 (1) ◽  
pp. 41-50 ◽  
Author(s):  
James S. Goerss
Keyword(s):  
Tropical Cyclone ◽  
Precipitable Water ◽  
Satellite Observation ◽  
Satellite Observations ◽  
Prediction System ◽  
Wind Speeds ◽  
The North ◽  
Percent Improvement ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Impact

Abstract The tropical cyclone (TC) track forecasts of the Navy Operational Global Atmospheric Prediction System (NOGAPS) were evaluated for a number of data assimilation experiments conducted using observational data from two periods: 4 July–31 October 2005 and 1 August–30 September 2006. The experiments were designed to illustrate the impact of different types of satellite observations on the NOGAPS TC track forecasts. The satellite observations assimilated in these experiments consisted of feature-track winds from geostationary and polar-orbiting satellites, Special Sensor Microwave Imager (SSM/I) total column precipitable water and wind speeds, Advanced Microwave Sounding Unit-A (AMSU-A) radiances, and Quick Scatterometer (QuikSCAT) and European Remote Sensing Satellite-2 (ERS-2) scatterometer winds. There were some differences between the results from basin to basin and from year to year, but the combined results for the 2005 and 2006 test periods for the North Pacific and Atlantic Ocean basins indicated that the assimilation of the feature-track winds from the geostationary satellites had the most impact, ranging from 7% to 24% improvement in NOGAPS TC track forecasts. This impact was statistically significant at all forecast lengths. The impact of the assimilation of SSM/I precipitable water was consistently positive and statistically significant at all forecast lengths. The improvements resulting from the assimilation of AMSU-A radiances were also consistently positive and significant at most forecast lengths. There were no significant improvements/degradations from the assimilation of the other satellite observation types [e.g., Moderate Resolution Imaging Spectroradiometer (MODIS) winds, SSM/I wind speeds, and scatterometer winds]. The assimilation of all satellite observations resulted in a gain in skill of roughly 12 h for the NOGAPS 48- and 72-h TC track forecasts and a gain in skill of roughly 24 h for the 96- and 120-h forecasts. The percent improvement in these forecasts ranged from almost 20% at 24 h to over 40% at 120 h.

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