Yoccoz1,2, geir ottersen3, and rolf langvatn4 climatic factors influence a variety of ecological processes determining patterns. Hurrell yochanan kushnir geir ottersen martin visbeck editors american geophysical union washington, dc geophysical monograph 4. Climatic significance and environmental impact geophysical monograph series on free shipping on qualified orders. North atlantic oscillation nao we will go into more detail about the concur. Department of environmental sciences, university of virginia. The north atlantic oscillation is the dominant mode of atmospheric variability in the north atlantic sector. The north atlantic oscillation nao is one of the major modes of variability of the northern hemisphere atmosphere hurrell, 1995. The nao can occur on a yearly basis, or the fluctuations can take place decades apart. The impact of the north atlantic oscillation nao on the atlantic meridional overturning circulation amoc and largescale climate is assessed using simulations with three different climate models. A possible impact of the north atlantic oscillation on the. Hurrell, yochanan kushnir, geir ottersen, and martin visbeck, investigates the. The north atlantic oscillation climatic significance and. Based measures of the north atlantic oscillation nao. North atlantic oscillation nao, an irregular fluctuation of atmospheric pressure over the north atlantic ocean that has a strong effect on winter weather in europe, greenland, northeastern north america, north africa, and northern asia.
To understand these changes, including the relative roles of natural variability and anthropogenic effects, and to predict the future state of marine ecosystems requires quantitative understanding of the physics, biogeochemistry and ecology of oceanic systems at mechanistic levels. The atmospheric pressure gradient known as the north atlantic oscillation nao has been shown to in. The role of atlantic oceanatmosphere coupling in affecting north atlantic oscillation variability arnaud czaja. Through eastwest oscillation motions of the icelandic low and the azores high, it controls the strength and direction of westerly winds. Marine ecosystems are undergoing rapid change at local and global scales. A reversal of climatic trends in the north atlantic since. Impact of the north atlantic oscillation on southern europe water.
The north atlantic oscillation nao plays an important role in the. Hurrell north atlantic oscillation nao index station. The north atlantic oscillation nao is the most important single mode for interpreting winter climate variability in the north atlantic european sector. Impact of the north atlantic oscillation on middle eastern. Impact of the maddenjulian oscillation on the intraseasonal forecast skill of the north atlantic. Oceanic influence on the north atlantic oscillation and associated northern hemisphere climate variations. Predictability and prediction of the north atlantic. The role of the north atlantic oscillation in european climate. These patterns have a big influence on winter weather in the eastern u. Published by the american geophysical union as part of the geophysical monograph series, volume 4.
Is there an influence of solar activity on the north. Using high and low nao index composites, anomaly fields of climate vari. Climate variations over the northern hemisphere are to a substantial proportion associated with the north atlantic oscillation nao. Effects of climate warming, north atlantic oscillation. Relation between the northatlantic oscillation and hydroclimatic. It is particularly important in winter, when it exerts a strong control on the climate of the northern hemisphere osborn, 2011. The north atlantic oscillation has varied markedly on multidecadal timescales. Basin scale changes in the atmospheric forcing significantly affect the oceans properties and circulation.
Impact, leading atmospheric scientists, oceanographers, paleoclimatologists, and biologists offer a focused, stateoftheart assessment of current understanding of the most prominent and recurrent pattern of atmospheric variability over the middle and high latitudes of the northern hemisphere. Demenocal2 1national center for atmospheric research, p. This prominent pattern of climate variability has a strong influence on weather over northeastern north america, greenland, and europe. When the pressure difference is large, the nao is positive and the westerly winds are strong and storms tend to be stronger, more frequent and travel across northwestern europe. North atlantic oscillation the nao is a largescale fluctuation in atmospheric pressure between the subtropical high pressure system located near the azores in the atlantic ocean and the subpolar low pressure system near iceland and is quantified in the nao index. One of the most prominent is the north atlantic oscillation nao, which refers to changes in the atmospheric sea level pressure. Climatic significance and environmental impact, edited by james w. Oceanic influence on the north atlantic oscillation and. Over the middle and high latitudes of the northern hemisphere the most prominent and recurrent pattern of atmospheric variability is the north atlantic oscillation nao. Impacts of the north atlantic oscillation on the probability of dry and. Climate significance and environmental impact, geophysical monograph 4, american geophysical union.
The relationship between the nao and seasonal climate in the uk is illustrated by the diagrams below, with seasonal average temperatures and rainfall amount for the uk as a whole plotted against nao indices for winter, and then. Pdf climate change and the north atlantic oscillation. Climatic significance and environmental impact james w. The north atlantic oscillation nao is a largescale alternation of atmospheric mass between subtropical high surface pressure, centred on the azores, and subpolar low surface pressures, centred on iceland. North atlantic oscillation model projections and influence on. Pdf the north atlantic oscillation climatic significance.
North atlantic oscillation nao university of east anglia. Predictability and prediction of the north atlantic oscillation hai lin meteorological research division, environment canada. Climatic significance and environmental impact, volume 4. The north atlantic oscillation nao is one of the most prominent and recurrent patterns of atmospheric circulation variability. A comparison and an assessment of changes in the strength of the nao and in its influence on. National centers for environmental prediction, and an observed rainfall data set produced by. The largescale environment dehai luo and yao yao rcetea, institute of atmospheric physics, chinese academy of science, beijing, china aiguo dai department of atmospheric and environmental sciences, university at albany, state. An overview of the north atlantic oscillation james w.
The interpretation of short climate records with comments on the north atlantic and southern oscillations. The north atlantic oscillation nao, the dominant mode of. We aim to demonstrate that these circulation phenomena play an important role in synchronising changes among lake ecosystems over great distances, if climatic influences are not masked by anthropogenic impacts or differences in lake morphology. An overview of the north atlantic oscillation opensky. International journal of geomagnetism and aeronomy. Variability of the north atlantic oscillation and the tropical atlantic dominate the climate of the north atlantic. The positive phase of the nao reflects belownormal heights and pressure across the high latitudes of the north atlantic and abovenormal heights and pressure over the central north. Interannual to decadal variations in middle eastern temperature, precipitationand streamflow reflect the farfield influence of the north atlantic oscillation nao, a dominant mode of atlantic sector climate variability. A multivariable analysis of the influence of the north atlantic oscillation nao on the climate of the north atlantic and european sectors is presented using the 40 yr 19581997 consistent data set from ncep. North atlantic oscillation an overview sciencedirect.
Climate significance and environmental impact download. The surface pressure drives surface winds and wintertime storms from west to. The northsouth pressure difference determines the strength of the westerly winds across the atlantic and is known as the north atlantic oscillation nao. Visbeck m et al 2003 the north atlantic oscillation, climatic significance and environmental impact ed j w hurrell et al washington, dc.
Ecological effects of the north atlantic oscillation. Using a new sea surface temperature sst based index of the nao and availablestreamflow data from five middle eastern rivers, we show that the first principal. The north atlantic oscillation nao is a climatic phenomenon in the north atlantic ocean of fluctuations in the difference of atmospheric pressure at sea level between the icelandic low and the azores high. A reversal of climatic trends in the north atlantic since 2005. The positive north atlantic oscillation with downstream. The north atlantic oscillation nao index is based on the surface sealevel pressure difference between the subtropical azores high and the subpolar low. Part of the oceans response is local and rapid surface temperature, mixed layer depth, upper ocean heat content, surface ekman. The nao is not a regional, north atlantic phenomenon, however. Analyses of climate simulations show that these variations have contributed to arctic sea ice loss, northern. Is there an influence of solar activity on the north atlantic oscillation a literature study of the forcing factors behind the north atlantic oscillation dissertations in geology at lund university, no. Pdf the north atlantic oscillation nao is one of the most prominent and recurrent patterns of atmospheric circulation variability. The impact of the north atlantic oscillation on climate.
The impact of north atlantic wind and cyclone trends on. North atlantic oscillation pdf the north atlantic oscillation nao is the most important mode of variability in the northern. This study explores the changes induced by the north atlantic oscillation nao on the probability of. Phenomena, impacts and mechanisms john marshalla, yochanan kushnirb, david battistic. The north atlantic oscillation and the uk met office. The outcomes show the presence of significant connections between the. North atlantic oscillation, climate variability, cmip5. The nao determines the speed and direction of the westerly winds across the north atlantic, as well as winter sea surface temperature. The north atlantic oscillation influence on europe. The north atlantic oscillation climatic significance and environmental impact.
The positive north atlantic oscillation with downstream blocking and middle east snowstorms. Hurrell1, yochanan kushnir 2, geir ottersen3, and martin visbeck2 the north atlantic oscillation nao is one of the most prominent and recurrent patterns of atmospheric circulation variability. Combined effects of the north atlantic oscillation and the. Agu geophysical monograph the oceans response to north atlantic oscillation variability 145 pp. An analysis of weather station data shows significant correlations between the december nao index and precipitation over korea and china in the subsequent summer. Impact of the december north atlantic oscillation on the. It dictates climate variability from the eastern seaboard of the united states to siberia and from the arctic to the subtropical atlantic, especially during boreal winter, so variations in the nao are important to. Perturbation experiments are conducted in which a pattern of anomalous heat flux corresponding to the nao is added to the model ocean. North atlantic oscillation signatures in aquatic and terrestrial ecosystemsa meta. Impact of the december north atlantic oscillation on the following february east asian trough shaobo qiao1 and guolin feng2,3 1college of atmospheric sciences, lanzhou university, lanzhou, china, 2college of physical science and technology, yangzhou university, yangzhou, china, 3national climate center, china meteorological administration, beijing, china. It is expressed as changes in westerly winds over the north atlantic region and as a result is the primary determinant of temperatures and storminess in the european winter. This is also the season that exhibits strong interdecadal variability osborn, 2004.
Largescale shifting of the weight of the atmosphere between mid and high latitudes creates climate patterns known as the arctic and north atlantic oscillations. North atlantic oscillation signatures in aquatic and. The north atlantic oscillation climatic significance and environmental impact james w. The north atlantic oscillation as a driver of rapid. The severeversusmild phenomenon he described is now recognized as an impact of the north atlantic oscillation or nao. Climatic oscillations as reflected in atmospheric modes such as the north atlantic oscillation nao may be seen as a proxy for regulating forces in aquatic and terrestrial ecosystems. The book is the first on this important phenomenon, the most prominent and recurring weather pattern over the northern hemisphere. Chinese journal of geophysics 20002018 earth interactions.
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