Upwelling along the western barrier reef of New Caledonia

2005 ◽  
Vol 56 (7) ◽  
pp. 1005 ◽  
Author(s):  
Christian Hénin ◽  
G. R. Cresswell
Keyword(s):  
Cold Water ◽  
New Caledonia ◽  
Water Layer ◽  
Tidal Mixing ◽  
Warm Water ◽  
Outer Reef ◽  
Easterly Wind ◽  
Wind Speeds ◽  
The North ◽  
Wind Events

Temperature decreases of up to 5°C at an automatic station at ~10 m depth at the outer reef of western New Caledonia signalled the occurrence of upwelling. The decreases are related to south-easterly wind events and they can take up to 5 days to develop. Successive wind events can depress the temperature for as much as 1 month. An upwelling shows in thermal satellite imagery as a band of cold water ~10 km wide and as long as several hundred kilometres just outside the reef. The cold water frequently spreads out to sea. The upwellings are more common in summer (October to March) than in winter. During lengthy periods of low wind speeds, the waters outside the reef appear to be overrun by warm water from farther north. The frequent occurrence of the warm water layer in the north may partly explain why upwellings are more common along the southern half of the reef. The entire lagoon cools in winter; most of the lagoon warms in summer, except at the southern end where the waters are cool, perhaps from tidal mixing.

scholarly journals Western Iberian winter wind indices based on significant wind events

2005 ◽  
Vol 2 (2) ◽  
pp. 105-127 ◽  
Author(s):  
E. Mason ◽  
A. M. P. Santos ◽  
Á J. Peliz
Keyword(s):  
Negative Impact ◽  
Significant Negative Correlation ◽  
Hybrid Index ◽  
Easterly Wind ◽  
Annual Variations ◽  
Wind Speeds ◽  
Wind Event ◽  
Wind Events ◽  
Environmental Prediction ◽  
Offshore Transport

Abstract. Wind speed data obtained from the National Centers for Environmental Prediction (NCEP) Reanalysis project are used to construct winter (November–March) wind indices for the western Iberian Peninsula. The data used represent a 2.5&deg square area, centred at 41.0&deg N, 9.4&deg W, over the period 1948-2003. The NCEP data are well correlated with a time-series (1980–2001) of wind measurements from the Cape Carvoeiro lighthouse on the western Portuguese coast (39.4&deg N, 9.4&deg W). The new indices, of which there are four corresponding to northerlies, easterlies, southerlies and westerlies, constitute measures of numbers of significant wind event days, where a significant wind event is defined to be 4 or more consecutive days of wind speeds exceeding 4 m s-1. Results show both intra- and inter-annual variations in the numbers of significant wind event days, as well as clear decadal trends. A comparison between a hybrid index, composed of the numbers of significant northerly and easterly wind event days - both promote offshore transport, which is thought to have a negative impact on pelagic fish recruitment - and western Iberian sardine catch data, reveal an extensive period of significant negative correlation. The relationship over the most recent period, ~1999–2000, is unclear.

scholarly journals Norwegian hindcast archive (NORA3) – A validation of offshore wind resources in the North Sea and Norwegian Sea

2021 ◽  
Author(s):  
Ida Marie Solbrekke ◽  
Asgeir Sorteberg ◽  
Hilde Haakenstad
Keyword(s):  
Wind Power ◽  
Power Production ◽  
Offshore Wind ◽  
Norwegian Sea ◽  
Offshore Wind Power ◽  
Wind Speeds ◽  
The North ◽  
The North Sea ◽  
Wind Events ◽  
Simulated Wind

Abstract. A new high-resolution (3 km) numerical mesoscale weather simulation spanning the period 2004–2018 is validated for offshore wind power purposes for the North Sea and Norwegian Sea. The NORwegian hindcast Archive (NORA3) was created by dynamical downscaling, forced with state-of-the-art hourly atmospheric reanalysis as boundary conditions. A validation of the simulated wind climatology has been carried out to determine the ability of NORA3 to act as a tool for planning future offshore wind power installations. Special emphasis is placed on evaluating offshore wind power-related metrics and the impact of simulated wind speed deviations on the estimated wind power and the related variability. The general conclusion of the validation is that the NORA3 data is rather well suited for wind power estimates, but gives slightly conservative estimates on the offshore wind metrics. Wind speeds are typically 5 % (0.5 ms−1) lower than observed wind speeds, giving an underestimation of offshore wind power of 10 %–20 % (equivalent to an underestimation of 3 percentage point in the capacity factor), for a selected turbine type and hub height. The model is biased towards lower wind power estimates because of overestimation of the frequency of low-speed wind events (< 10 ms−1) and underestimation of high-speed wind events (> 10 ms−1). The hourly wind speed and wind power variability are slightly underestimated in NORA3. However, the number of hours with zero power production (around 12 % of the time) is fairly well captured, while the duration of each of these events is slightly overestimated, leading to 25-year return values for zero-power duration being too high for four of the six sites. The model is relatively good at capturing spatial co-variability in hourly wind power production among the sites. However, the observed decorrelation length was estimated to be 432 km, whereas the model-based length was 19 % longer.

scholarly journals Drivers of Extreme Wind Events in Mexico for Wind Power Applications

2020 ◽  
Author(s):  
Simon Thomas ◽  
Oscar Martinez-Alvarado ◽  
Dan Drew ◽  
Hannah Bloomfield
Keyword(s):  
Gulf Of Mexico ◽  
Wind Power ◽  
Baja California ◽  
Southern Oscillation ◽  
Wind Farms ◽  
Reanalysis Data ◽  
Baja California Sur ◽  
Wind Speeds ◽  
The North ◽  
Wind Events

&lt;p&gt;In this talk, we investigate the causes of the strongest and weakest winds observed across Mexico and explore the consequences of these to current and future wind energy production in the country. Using 40 years of the ERA-5 atmospheric reanalysis data, we find that the strongest winds in this region are caused by cold surges, where an anticyclone moves South from the Central United States of America resulting in strong Northerly winds across the Gulf of Mexico which channel through the gap in the mountains to the South of Mexico. Other regions have different drivers for high and low wind speed events. The strongest winds across the East coast of Mexico originate from Easterly trade winds propagating across the Gulf of Mexico, whereas those in Baja California Sur are influenced by the proximity of the North Pacific High. These regions in Mexico have&amp;#160;peak (and sustained low) wind speeds at different times of year&amp;#160;which suggests that wind farms in different regions could compliment one another to&amp;#160;optimise wind power generation. However, all stations but&amp;#160;Baja California Sur see the same weather patterns associated with weak wind events, meaning that low wind power production may be unavoidable at these times. The conditions that proceed these sustained periods of strong and weak winds are explored to gain some predictability for wind power applications. The El Nino Southern Oscillation is found to influence wind speeds at some locations across Mexico at sub-seasonal time-scales.&lt;/p&gt;

scholarly journals Evaluation of a Wind-Wave System for Ensemble Tropical Cyclone Wave Forecasting. Part II: Waves

2013 ◽  
Vol 28 (2) ◽  
pp. 316-330 ◽  
Author(s):  
Steven M. Lazarus ◽  
Samuel T. Wilson ◽  
Michael E. Splitt ◽  
Gary A. Zarillo
Keyword(s):  
Tropical Cyclone ◽  
Wind Wave ◽  
Wave Model ◽  
Wave System ◽  
Wave Direction ◽  
Wind Speeds ◽  
The North ◽  
Wave Forecast ◽  
Wind Events ◽  
The Right

Abstract A wind-wave forecast system, designed with the intention of generating unbiased ensemble wave forecasts for extreme wind events, is assessed. Wave hindcasts for 12 tropical cyclones (TCs) are forced using a wind analysis produced from a combination of the North American Regional Reanalysis (NARR) and a parametric wind model. The default drag parameterization is replaced by one that is more in line with recent studies where a cap at weak-to-moderate wind speeds is applied. Quadrant-based significant wave height (Hs) statistics are composited in a storm-relative reference frame and stratified by the radius of maximum wind, storm speed, and storm intensity. Improvements in Hs are gleaned from both downscaling the NARR winds and tuning the wave model. However, the paradigm whereby the drag coefficient depends solely on the wind speed is limiting. Results indicate that Hs is biased low in the right quadrants (for all statistical subcategories). Conversely, Hs is high biased in the left-rear quadrant even though the analysis wind field is underforecast there. At radii less than 100 nautical miles, the model peak wave direction is offset from the observed, with the model (buoy) peak more in line with (to the left of) the direction of the tropical cyclone motion. As a result, the predominant storm-relative wind direction, which is northwesterly in the left-rear quadrant, opposes that of the buoy peak wave direction, while the model peak is more crosswise with respect to the wind. This will likely reduce the magnitude of the wind stress in the model.

Temperature and the recruitment of Atlantic cod (Gadus morhua)

1999 ◽  
Vol 56 (11) ◽  
pp. 2069-2077 ◽  
Author(s):  
B Planque ◽  
T Frédou
Keyword(s):  
North Atlantic ◽  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
The Other ◽  
Warm Water ◽  
The North ◽  
The North Atlantic ◽  
Interannual Fluctuations ◽  
The Relationship

Variability in the recruitment of fish has been attributed to either changes in the environment or variations in the size of reproductive stocks. Disentangling the effects of environment and stock has proven to be problematic and has resulted in recurrent controversy between studies supporting either hypothesis. In the present study, we examine the relationship between interannual changes in temperature and variation in recruitment for nine Atlantic cod (Gadus morhua) stocks in the North Atlantic. We show that for individual stocks, the relationship often appears weak and statistically not significant. On the other hand, by combining in a single metaanalysis the results from individual stocks, we demonstrate that recruitment of Atlantic cod is linked to interannual fluctuations in temperature in such a way that for stocks located in warm water the relationship is negative, for stocks located in cold water the relationship is positive, and there is no relationship for stocks located in the middle of the temperature range.

scholarly journals The Influence of Wind Direction during Storms on Sea Temperature in the Coastal Water of Muping, China

2021 ◽  
Vol 9 (7) ◽  
pp. 710
Author(s):  
Xiangyang Zheng ◽  
Yana Ding ◽  
Yandong Xu ◽  
Tao Zou ◽  
Chunlei Wang ◽  
...  
Keyword(s):  
Coastal Water ◽  
Cold Water ◽  
Vertical Mixing ◽  
Ocean Model ◽  
Storm Events ◽  
Sea Temperature ◽  
Easterly Wind ◽  
The North ◽  
Summer Storm ◽  
Lower Temperature

Sea temperature structures are important for water stratification and marine ecosystems. In the coastal water of Muping, China, stationary measurements of sea temperature captured temporal temperature changes during two summer storm events. The north component of the wind during the two storms was opposite. The temperature responded differently to wind directions in the two storm events. A well-validated numerical ocean model was used to investigate the mechanism of sea temperature variation of the coast of Muping. The model revealed that the southerly and easterly wind was upwelling-favorable in the study area. They generated the shoreward transport of bottom cold water, which induced bottom water cooling, enhanced stratification, and weakened vertical mixing. On the other hand, the northerly and westerly wind was downwelling-favorable and enhanced turbulent mixing. The alongshore upwelling-favorable wind caused more cross-shore transport than cross-shore upwelling-favorable wind, which resulted in stronger bottom cooling. Similarly, alongshore downwelling-favorable wind generated lower temperature than cross-shore wind. A surface cold-water band was formed in the second storm. Although it was formed during upwelling-favorable wind, the temperature balance analysis indicated that vertical mixing and westward horizontal advection were the two dominant processes compared to upwelling.

scholarly journals Sting-Jet Windstorms over the North Atlantic: Climatology and Contribution to Extreme Wind Risk

2017 ◽  
Vol 30 (14) ◽  
pp. 5455-5471 ◽  
Author(s):  
Neil C. G. Hart ◽  
Suzanne L. Gray ◽  
Peter A. Clark
Keyword(s):  
North Atlantic ◽  
Storm Track ◽  
Relative Vorticity ◽  
Strong Wind ◽  
Socioeconomic Impacts ◽  
Wind Speeds ◽  
The North ◽  
Extreme Wind ◽  
Strong Surface ◽  
Wind Events

Extratropical cyclones with damaging winds can have large socioeconomic impacts when they make landfall. During the last decade, studies have identified a mesoscale transient jet, the sting jet, that descends from the tip of the hooked cloud head toward the top of the boundary layer in the dry intrusion region as a cause of strong surface winds, and especially gusts, in some cyclones. While many case studies have focused on the dynamics and characteristics of these jets, there have been few studies that assess the climatology of the associated cyclones and their importance for wind risk. Here the climatological characteristics of North Atlantic cyclones are determined in terms of the possibility that they had sting jets using a previously published sting-jet precursor diagnostic applied to ERA-Interim data over 32 extended winter seasons from 1979 to 2012. Of the 5447 cyclones tracked, 32% had the precursor (42% in the 22% of cyclones that developed explosively). Precursor storms have a more southerly and zonal storm track than storms without the precursor, and precursor storms tend to be more intense as defined by 850-hPa relative vorticity. This study also shows that precursor storms are the dominant cause of cyclone-related resolved strong wind events over the British Isles for 850-hPa wind speeds exceeding 30 m s−1. Hence, early detection of a sting-jet storm could give advance warning of enhanced wind risk. However, over continental northwestern Europe, precursor cyclone-related windstorm events occur far less often.

scholarly journals Circulação de ar na península de Tróia e costa da Galé

Finisterra ◽  
2012 ◽  
Vol 35 (70) ◽  
Author(s):  
Carlos Silva Neto
Keyword(s):  
High Frequency ◽  
Air Flow ◽  
Warm Water ◽  
Western Coast ◽  
The West ◽  
Wind Speeds ◽  
The North ◽  
North Wind ◽  
The Difference

AIR FLOW OVER THE TRÓIA PENINSULA AND THE COSTA DA GALÉ – In the summer, the Portuguese western coast is characterised by an evident dominance of north and northwest wind directions. Due the influence of the Arrábida mountain, the north wind suffers a deflection and blows from the west, southwest or even south over the Tróia Peninsula, where in the summer months there is a high frequency of wind directions between west and south. This deflection is much more frequent and better marked at night than at daylight. At daylight the strong north wind is channelled through a valley between Palmela hill and the Louro mountain and frequently blows over the Tróia Peninsula, in directions between north-northeast and north-northwest. At night, north and northwest wind speeds are generally lower and west and south winds blow all over the Tróia Peninsula towards Carvalhal, as result of the deflection caused by the Arrábida and Cabo Espichel. The wind directions between west and south, frequent at night on the Tróia Peninsula, are also intensified by the difference of temperature between the cool ocean and the warm water of the estuary.

scholarly journals A climatology of wintertime low-level jets in Nares Strait

2021 ◽  
Vol 40 ◽  
Author(s):  
Svenja H.E. Kohnemann ◽  
Günther Heinemann
Keyword(s):  
Wind Speed ◽  
Climate Model ◽  
Horizontal Resolution ◽  
Strong Impact ◽  
Strong Wind ◽  
Low Level ◽  
Wind Speeds ◽  
Nares Strait ◽  
The North ◽  
Wind Events

Intense, southward low-level winds are common in Nares Strait, between Ellesmere Island and northern Greenland. The steep topography along Nares Strait leads to channelling effects, resulting in an along-strait flow. This research study presents a 30-year climatology of the flow regime from simulations of the COSMO-CLM climate model. The simulations are available for the winter periods (November–April) 1987/88 to 2016/17, and thus, cover a period long enough to give robust long-term characteristics of Nares Strait. The horizontal resolution of 15 km is high enough to represent the complex terrain and the meteorological conditions realistically. The 30-year climatology shows that LLJs associated with gap flows are a climatological feature of Nares Strait. The maximum of the mean 10-m wind speed is around 12 m s-1 and is located at the southern exit of Smith Sound. The wind speed is strongly related to the pressure gradient. Single events reach wind speeds of 40 m s-1 in the daily mean. The LLJs are associated with gap flows within the narrowest parts of the strait under stably stratified conditions, with the main LLJ occurring at 100–250 m height. With increasing mountain Froude number, the LLJ wind speed and height increase. The frequency of strong wind events (>20 m s-1 in the daily mean) for the 10 m wind shows a strong interannual variability with an average of 15 events per winter. Channelled winds have a strong impact on the formation of the North Water polynya.

Predicting cold-water bleaching in corals: role of temperature, and potential integration of light exposure

2020 ◽  
Vol 642 ◽  
pp. 133-146
Author(s):  
PC González-Espinosa ◽  
SD Donner
Keyword(s):  
Coral Bleaching ◽  
Cold Water ◽  
Light Exposure ◽  
Light Attenuation ◽  
Florida Keys ◽  
Cold Temperature ◽  
Warm Water ◽  
Coral Tissue ◽  
Effect Of Temperature ◽  
Type I

Warm-water growth and survival of corals are constrained by a set of environmental conditions such as temperature, light, nutrient levels and salinity. Water temperatures of 1 to 2°C above the usual summer maximum can trigger a phenomenon known as coral bleaching, whereby disruption of the symbiosis between coral and dinoflagellate micro-algae, living within the coral tissue, reveals the white skeleton of coral. Anomalously cold water can also lead to coral bleaching but has been the subject of limited research. Although cold-water bleaching events are less common, they can produce similar impacts on coral reefs as warm-water events. In this study, we explored the effect of temperature and light on the likelihood of cold-water coral bleaching from 1998-2017 using available bleaching observations from the Eastern Tropical Pacific and the Florida Keys. Using satellite-derived sea surface temperature, photosynthetically available radiation and light attenuation data, cold temperature and light exposure metrics were developed and then tested against the bleaching observations using logistic regression. The results show that cold-water bleaching can be best predicted with an accumulated cold-temperature metric, i.e. ‘degree cooling weeks’, analogous to the heat stress metric ‘degree heating weeks’, with high accuracy (90%) and fewer Type I and Type II errors in comparison with other models. Although light, when also considered, improved prediction accuracy, we found that the most reliable framework for cold-water bleaching prediction may be based solely on cold-temperature exposure.

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