Comparison of NINO1+2 and NINO3.4 indices in terms of ENSO effects over the Euro-Mediterranean Region

2021 ◽  
Author(s):  
Ece Yavuzsoy ◽  
Yasemin Ezber ◽  
Omer Lutfi Sen
Keyword(s):  
Middle East ◽  
Climate Variability ◽  
Air Temperature ◽  
Mediterranean Region ◽  
Surface Air Temperature ◽  
La Niña ◽  
Negative Phase ◽  
La Nina ◽  
Dipole Pattern ◽  
The Mediterranean

<p>El Nino Southern Oscillation (ENSO) is a phenomenon in the equatorial Pacific that could have profound effects on climate around the world. Although ENSO impacts are fairly well-defined for south and north America, Australia and south-eastern Asia, they are not very clear for Euro-Mediterranean region. Some studies indicate that the negative phase of ENSO in Nino3 and Nino3.4 indices have similar effects in the negative phase of North Atlantic Oscillation (NAO).  ENSO impacts and teleconnection patterns are mostly studied using the Nino3.4 index. However, some recent studies indicate that the Nino1+2 index has higher correlation with climate variability over the Euro-Mediterranean region.</p><p>In this study, we investigate impacts of ENSO over the Euro-Mediterranean climate variability and atmospheric dynamics using the Nino1+2 and Nino3.4 indices. Additionally, we also tried to understand if there is any relation between ENSO and the Mediterranean and East Asian troughs. NCEP/NCAR Reanalysis surface air temperature, precipitation and 500 hPa geopotential height datasets and SST-based ENSO indices from ERSSTv4 were used in the analysis for boreal winter (December-January-February) for a period of 1950 - 2019. We utilized the Pearson correlation analysis to reveal the relation between these indices and climate parameters and the composite analysis  to define the pattern differences between the cold and warm phases of the indices.</p><p>Our preliminary findings show that there is a distinct correlation pattern between Nino indices and surface air temperature over the region of interest. Nino1+2 index has a more distinct dipole pattern with a significant positive correlation pole over central Europe and negative pole over north-eastern Africa. However, Nino3.4 indicates a rather zonal correlation dipole pattern whose poles are over northwest Africa (strongly positive) and northeast Africa (negative). It is also found that the Mediterranean trough location is sensitive to the phase of ENSO for both indices. Namely, the Mediterranean trough tends to be in the west of its climatological location for La Nina phases of Nino1+2 and Nino3.4, which affects the distribution of surface temperature and precipitation over the Euro-Mediterranean and Middle East and Northern Africa (MENA) regions. We concluded that the La Nina phase of Nino1+2 seems to play a more distinctive role in the dipole pattern. The surface air temperature is colder over the entire Europe while it is opposite in the Middle East region including Turkey. This dipole pattern is also detected for the La Nina phase of Nino3.4, but it is mostly observed over southwestern Europe and northern Africa. Comparison between the La Nina and El Nino phases of the Nino1+2 index indicates that for the La Nina phase precipitation is larger over the Aegean Sea and Italy and smaller in northern Europe.</p>

scholarly journals Influence of ENSO on North American subseasonal surface air temperature variability

2021 ◽  
Vol 2 (2) ◽  
pp. 395-412
Author(s):  
Patrick Martineau ◽  
Hisashi Nakamura ◽  
Yu Kosaka
Keyword(s):  
North America ◽  
Air Temperature ◽  
North American ◽  
Surface Air Temperature ◽  
Tropical Pacific ◽  
La Niña ◽  
Western North America ◽  
The North ◽  
Subseasonal Variability ◽  
La Nina

Abstract. The wintertime influence of tropical Pacific sea surface temperature (SST) variability on subseasonal variability is revisited by identifying the dominant mode of covariability between 10–60 d band-pass-filtered surface air temperature (SAT) variability over the North American continent and winter-mean SST over the tropical Pacific. We find that the El Niño–Southern Oscillation (ENSO) explains a dominant fraction of the year-to-year changes in subseasonal SAT variability that are covarying with SST and thus likely more predictable. In agreement with previous studies, we find a tendency for La Niña conditions to enhance the subseasonal SAT variability over western North America. This modulation of subseasonal variability is achieved through interactions between subseasonal eddies and La Niña-related changes in the winter-mean circulation. Specifically, eastward-propagating quasi-stationary eddies over the North Pacific are more efficient in extracting energy from the mean flow through the baroclinic conversion during La Niña. Structural changes of these eddies are crucial to enhance the efficiency of the energy conversion via amplified downgradient heat fluxes that energize subseasonal eddy thermal anomalies. The enhanced likelihood of cold extremes over western North America is associated with both an increased subseasonal SAT variability and the cold winter-mean response to La Niña.

scholarly journals Percolation Phase Transition of Surface Air Temperature Networks: A new test bed for El Niño/La Niña simulations

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Lijuan Hua ◽  
Zhenghui Lu ◽  
Naiming Yuan ◽  
Lin Chen ◽  
Yongqiang Yu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Air Temperature ◽  
El Niño ◽  
El Nino ◽  
Surface Air Temperature ◽  
La Niña ◽  
Test Bed ◽  
La Nina

scholarly journals Influence of ENSO on North American subseasonal surface air temperature variability

2020 ◽  
Author(s):  
Patrick Martineau ◽  
Hisashi Nakamura ◽  
Yu Kosaka
Keyword(s):  
North America ◽  
Air Temperature ◽  
North Pacific ◽  
Surface Air Temperature ◽  
La Niña ◽  
Western North America ◽  
The North ◽  
Subseasonal Variability ◽  
La Nina ◽  
The North Pacific

Abstract. The wintertime influence of El Niño-Southern Oscillation (ENSO) on subseasonal variability is revisited by identifying the dominant mode of covariability between 10–60 day band-pass-filtered surface air temperature (SAT) variability over the North American continent and winter-mean sea surface temperature (SST) over the North Pacific sector. We find, in agreement with previous studies, that La Niña conditions tend to enhance the subseasonal SAT variability over western North America. This modulation of subseasonal variability is achieved through interactions between subseasonal eddies and La Niña-related changes in the winter-mean circulation. Specifically, eastward-propagating quasi-stationary eddies over the North Pacific are more efficient in extracting energy from the mean flow through the baroclinic conversion of energy over the North Pacific sector during La Niña. Changes in the vertical structure of these wave anomalies are crucial to enhance the efficiency of energy conversion via amplified downgradient heat fluxes that energize subseasonal eddy thermal anomalies. The combination of increased subseasonal SAT variability and the cold winter-mean response to La Niña both contribute to enhancing the likelihood of cold extremes over western North America.

scholarly journals WAVELET ANALYSIS OF THE El NIÑO - LA NIÑA PHENOMENON DYNAMICS AND ITS FORECASTING

2018 ◽  
Vol 14 (3) ◽  
pp. 75-87
Author(s):  
V I Alekseev
Keyword(s):  
Air Temperature ◽  
El Niño ◽  
El Nino ◽  
Surface Air Temperature ◽  
La Niña ◽  
Frequency Content ◽  
Time Intervals ◽  
Instantaneous Phase ◽  
La Nina ◽  
Phase Differences

Having calculated the frequency content of a solar constant, solar activity from the time series in (1610-2012), the El Niño curve in both (1470-1984) and (1950-2075), it has been found that the frequency content of an El Niño - La Niña curve is induced by frequency contents of solar variables. The frequency contents of the variables have been calculated by developing their wavelet phase-frequency responses. Instantaneous phase differences of the solar variables curves CO2(t), global surface air temperature, El Niño in the two time intervals, in (1891-1950) and (1950-2009), have been calculated; linear approximations with coefficients of instantaneous phase differences between variables in these time intervals have been obtained. Based on relational approximation coefficient analysis of the two time intervals, it has been identified that rising surface air temperature and El Niño alike had been markedly influenced by solar variables variations during the first time interval, with the El Niño rise being affected by that of the surface air temperature amid the global climate change in 1950-2009. The predicted El Niño curves have been obtained from the 2015/16 to 2050 time period by the trained data curve in 1950-2015/16 in two versions as the sum of predicted wavelet approximating and detailing components of the original signal according to the Mallat rule. The accuracy of the predictive El Niño curve values is » 83%. On the obtained curves, coordinates of local maximum and minimum are nearly matching. Wavelet phase-frequency response imaging of one curve reflects an impact on El Niño - La Niña variations of the Earth's solar and climatic variables in the past and the future alike.

Testing of the Tropically Excited Arctic Warming Mechanism (TEAM) with Traditional El Niño and La Niña

2012 ◽  
Vol 25 (12) ◽  
pp. 4015-4022 ◽  
Author(s):  
Sukyoung Lee
Keyword(s):  
Air Temperature ◽  
El Niño ◽  
Energy Transport ◽  
El Nino ◽  
Surface Air Temperature ◽  
La Niña ◽  
The Arctic ◽  
Convective Heating ◽  
Arctic Warming ◽  
La Nina

Abstract By analyzing El Niño and La Niña composites with 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data, evidence is presented here that the surface air temperature of the Arctic winter (December–February) is anomalously warm during La Niña and cold during El Niño. Surface and top-of-the-atmosphere energy fluxes were used to calculate the composite zonal-mean poleward moist static energy transport. The result shows that the La Niña warming in the Arctic is associated with an increased poleward energy transport in the extratropics. The opposite characteristics are found for El Niño. Because the total tropical convective heating is more localized during La Niña than El Niño, these findings suggest that the Arctic surface air temperature anomalies associated with ENSO may be attributed to the tropically excited Arctic warming mechanism (TEAM). In the tropics, consistent with previous studies, the anomalous poleward energy transport is positive during El Niño and negative during La Niña. Given the debate over whether a warmer world would take on more El Niño–like or La Niña–like characteristics, the findings of this study underscore the need for further investigation of tropical influence on polar climate.

scholarly journals The Seasonal Development of an SST Anomaly in the Indian Ocean and Its Relationship to ENSO

2007 ◽  
Vol 20 (1) ◽  
pp. 38-52 ◽  
Author(s):  
Motoki Nagura ◽  
Masanori Konda
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Surface Wind ◽  
La Niña ◽  
Seasonal Development ◽  
La Nina ◽  
The Indian Ocean ◽  
Dipole Pattern ◽  
Sst Anomaly

Abstract The seasonal development of the sea surface temperature (SST) anomaly in the Indian Ocean is investigated in relation to El Niño–Southern Oscillation (ENSO), using NOAA optimally interpolated SST and NCEP reanalysis data. The result shows that the onset season of El Niño affects the seasonal development of surface wind anomalies over the equatorial eastern Indian Ocean (EEIO); these surface wind anomalies, in turn, determine whether the SST anomaly in the EEIO evolves into the eastern pole of the dipole pattern. In years when the dipole pattern develops, surface zonal wind anomalies over the EEIO switch from westerly to easterly in spring as La Niña switches to El Niño. The seasonal zonal wind over the EEIO also switches from westerly to easterly in spring, and the anomalous wind strengthens seasonal wind from winter to summer. Stronger winds and resultant thermal forcings produce the negative SST anomaly in the EEIO in winter, and its amplitude increases in summer. The SST anomaly becomes the eastern pole of the dipole pattern in fall. In contrast, if the change from La Niña to El Niño is delayed until late summer/fall or if La Niña persists throughout the year, a westerly anomaly persists from winter to summer over the EEIO. The persistent westerly anomaly strengthens the wintertime climatological westerlies and weakens the summertime easterlies. Therefore, negative SST anomalies are produced in the EEIO in winter, but the amplitude decreases in summer, and the eastern pole is not present in fall. The above explanation also applies to onset years of La Niña if the signs of the anomalies are reversed.

Trends in the Use of Perfumes and Incense in the Near East after the Muslim Conquests

2013 ◽  
Vol 23 (1) ◽  
pp. 11-30 ◽  
Author(s):  
AMAR ZOHAR ◽  
EFRAIM LEV
Keyword(s):  
Middle East ◽  
Material Culture ◽  
East Africa ◽  
Case Studies ◽  
Mediterranean Region ◽  
Medical Literature ◽  
New Crops ◽  
The World ◽  
The Mediterranean ◽  
Level Of Importance

AbstractPerfumes have been known as utilizable but exclusive products since antiquity. Use of aromatic substances was first mentioned in archaic sources of the ancient world. The origin of such fragrant substances was mainly vegetable and animal. Throughout history, the use of subtle perfumes increased and some of the exotic materials became expensive and valuable commodities. They were the source of wealth for cultures and rulers. The contribution of the Arabs to the distribution of new crops, knowledge, industrial techniques and substances is a well-known phenomenon. In our article we intend to focus on the new perfumes that were distributed throughout the world thanks to the Arab conquests and the knowledge of their other uses, mainly medicinal, that was handed down along with the products themselves. About 20 common perfumes are known to have been used in the medieval world, though half of them were not mentioned in earlier sources.These phenomena will be dealt with and presented in a profile we built up for four perfumes: agarwood, camphor, musk and ambergris. The theoretical and practical uses of these perfumes that are presented in detail (based on various sources including traders’ documents, medical literature and practical Genizah fragments, dealing mainly with medicine) will serve as case studies for the understanding of new trends in the uses of perfumes after the Muslim conquest. Arab perfumes can be divided into three groups, according to their level of importance:A. New perfumes, mainly from the vast region named “India”; most of which (such as camphor, ambergris and sandalwood and a compound made out of them known as nadd and ghāliya) were not known in the Middle East and the Mediterranean region until the Muslim conquests.B. Perfumes that kept their popularity including: a variety of cinnamon, costus, spikenard, frankincense, saffron and rose.C. Perfumes that lost their worth like balsam and myrrh.It seems that camphor was the best and most cherished perfume that substituted balsam. Like balsam, the importance of myrrh that was imported from Arabia and East Africa also declined and it seems that its substitute was musk. Transformations in perfume fashion were in fact only part of a wider revolution of the Arabic material culture which the Middle East, the Mediterranean region and even many European countries experienced due to the Arab conquests.

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