Forcing of the Summertime Low-Level Jet along the California Coast

Parish, Thomas R.

doi:10.1175/1520-0450(2000)039<2421:fotsll>2.0.co;2

Cited by 94 publications

(85 citation statements)

References 37 publications

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“…During summer the wind-speed pattern in the area is substantially different, with the highest wind speeds occurring closer to the coast, particularly along Morocco until Cape Blanc, with two distinct high wind-speed areas (close to 9 m•s −1 ) north and south of Canary Islands. These mesoscale intensifications of the surface wind speed along the coast in the EBCCS area, on the north-west African coast, occur due to the sharpening of the pressure gradient there through a positive feedback process triggered by upwelling and by the low SST at the coast [64][65][66][67]. The low SST decreases the air temperature within the MABL at the coast, and a sharp inversion develops due to warm subsiding air above [68,69].…”

Section: Wind Sea and Swell Wave Heights And Periodsmentioning

confidence: 99%

Seasonal Variability of Wind Sea and Swell Waves Climate along the Canary Current: The Local Wind Effect

Semedo

2018

JMSE

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A climatology of wind sea and swell waves along the Canary eastern boundary current area, from west Iberia to Mauritania, is presented. The study is based on the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis ERA-Interim. The wind regime along the Canary Current, along west Iberia and north-west Africa, varies significantly from winter to summer. High summer wind speeds generate high wind sea waves, particularly along the coasts of Morocco and Western Sahara. Lower winter wind speeds, along with stronger extratropical storms crossing the North Atlantic sub-basin up north lead to a predominance of swell waves in the area during from December to February. In summer, the coast parallel wind interacts with the coastal headlands, increasing the wind speed and the locally generated waves. The spatial patterns of the wind sea or swell regional wave fields are shown to be different from the open ocean, due to coastal geometry, fetch dimensions, and island sheltering.

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Section: Wind Sea and Swell Wave Heights And Periodsmentioning

confidence: 99%

Seasonal Variability of Wind Sea and Swell Waves Climate along the Canary Current: The Local Wind Effect

Semedo

2018

JMSE

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“…The barrier jet (Schwerdtfeger, 1979;Parish, 1982;Li and Chen, 1998) is another example of an LLJ; here the wind is in a direction parallel to the barrier and is near-geostrophic. Another type of LLJs are the ones found offshore in coastal regions (Zemba and Friehe, 1987;Doyle and Warner, 1991;Douglas, 1995;Burk and Thompson, 1996;Holt, 1996;Parish, 2000). These are generally termed Coastal Low-Level Jets (CLLJs) and are the focus of this article.…”

Section: Introductionmentioning

confidence: 99%

Global distribution and seasonal variability of coastal low-level jets derived from ERA-Interim reanalysis

Ranjha

Svensson

Tjernström

et al. 2013

Tellus A: Dynamic Meteorology and Oceanography

157

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A B S T R A C TA low-level wind maximum is often found over the oceans near many coasts around the world. These Coastal Low-Level Jets (CLLJs) play an important role in the coastal weather and have significant impacts on regional climate and ecology as well as on a number of human activities. The presence of CLLJs is related to various local circumstances such as land-sea temperature contrasts, upwelling, coastal terrain, orientation of the coast, and so on, but also to the large-scale atmospheric dynamics. This makes studies of CLLJs not only interesting but also challenging. In this study, based on ERA-Interim reanalysis data, the global distribution, spatiotemporal structure and the seasonal variability of CLLJs are documented. Seasonal data from 1980 to 2011 are used to identify areas where CLLJs are frequently found in the lowest 2 km, following criteria based on the vertical profiles of wind speed and temperature. The results are analysed to highlight the fundamental aspects and distinctive features of the CLLJs across the globe, including their occurrence rate, jet height, maximum wind speed and horizontal extent. Global maps of CLLJs are constructed for the summer and winter seasons. The west coasts of North America, the Iberian Peninsula, north-western Africa and the south-eastern coast of the Arabian Peninsula make up the Northern Hemispheric CLLJ regions, while the west coasts of South America, Australia, and southern Africa comprise the South Hemispheric equivalents. The existence and characteristics of CLLJs along the southern coast of Oman and the western coast of the Iberian Peninsula regions are also discussed, not fully envisaged before in the context of CLLJs. The highest occurrence of CLLJs is found during the summer in both hemispheres, and the coast of Oman has the globally highest CLLJ frequency, with also the highest maximum wind speeds. The most commonly found CLLJ has a maximum wind speed between 9 and 15 m s(1 , and occurs at heights between 500 and 700 m a.s.l.

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“…Due to the synoptic forcing, the large-scale flow in the MABL is equatorward and coast-parallel. The strong baroclinic structure between the warm land and the cold ocean leads to a pressure gradient maximum near the coast, decreasing both offshore and inshore (Holt, 1996;Parish, 2000). Through thermal wind considerations, as the equatorward wind speed decreases towards the surface due to friction; a low-level wind maximum is generated.…”

Section: Introductionmentioning

confidence: 99%

Climatology of the Iberia coastal low-level wind jet: weather research forecasting model high-resolution results

Soares

Cardoso²,

Semedo

et al. 2014

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C T Coastal low-level jets (CLLJ) are a low-tropospheric wind feature driven by the pressure gradient produced by a sharp contrast between high temperatures over land and lower temperatures over the sea. This contrast between the cold ocean and the warm land in the summer is intensified by the impact of the coastal parallel winds on the ocean generating upwelling currents, sharpening the temperature gradient close to the coast and giving rise to strong baroclinic structures at the coast. During summertime, the Iberian Peninsula is often under the effect of the Azores High and of a thermal low pressure system inland, leading to a seasonal wind, in the west coast, called the Nortada (northerly wind). This study presents a regional climatology of the CLLJ off the west coast of the Iberian Peninsula, based on a 9 km resolution downscaling dataset, produced using the Weather Research and Forecasting (WRF) mesoscale model, forced by 19 years of ERA-Interim reanalysis (1989Á2007). The simulation results show that the jet hourly frequency of occurrence in the summer is above 30% and decreases to about 10% during spring and autumn. The monthly frequencies of occurrence can reach higher values, around 40% in summer months, and reveal large inter-annual variability in all three seasons. In the summer, at a daily base, the CLLJ is present in almost 70% of the days. The CLLJ wind direction is mostly from north-northeasterly and occurs more persistently in three areas where the interaction of the jet flow with local capes and headlands is more pronounced. The coastal jets in this area occur at heights between 300 and 400 m, and its speed has a mean around 15 m/s, reaching maximum speeds of 25 m/s.

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Forcing of the Summertime Low-Level Jet along the California Coast

Cited by 94 publications

References 37 publications

Seasonal Variability of Wind Sea and Swell Waves Climate along the Canary Current: The Local Wind Effect

Seasonal Variability of Wind Sea and Swell Waves Climate along the Canary Current: The Local Wind Effect

Global distribution and seasonal variability of coastal low-level jets derived from ERA-Interim reanalysis

Climatology of the Iberia coastal low-level wind jet: weather research forecasting model high-resolution results

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