Heat Events in the Indian Subcontinent under a warming climate scenario: Detection and its Drivers 

2021 ◽  
Author(s):  
Ritika Kapoor ◽  
Carmen Alvarez-Castro ◽  
Enrico Scoccimarro ◽  
Stefano Materia ◽  
Silvio Gualdi
Keyword(s):  
North Atlantic ◽  
Heat Waves ◽  
Heat Index ◽  
World Population ◽  
Western Coast ◽  
Positive Correlation ◽  
Preliminary Results ◽  
The North ◽  
The North Atlantic ◽  
Heat Events

<p>Rising global temperatures are a potential cause for increase of extreme climate events, such as heat waves, both in severity and frequency. Under an increasing extreme event scenario, the world population of mid- and low-latitude countries is more vulnerable to heat related mortality and morbidity.</p><p>In India, the events occurred in recent years have made this vulnerability clear, since the numbers of heat-related deaths are on a rise, and heat waves can impact various sectors including health, agriculture, ecosystems and the national economy.</p><p>Preliminary results show the prevalence of heat events in seven different regions of India during the pre-monsoon (March, April, May) and transitional (May, June, July) months. We consider daily maximum temperatures (Tmax) and the NOAA’s Heat Index (HI), a combination of temperature and relative humidity that gives an insight into the discomfort because of increment in humidity.</p><p>We look into various drivers behind the heat events in the seven different clusters, in particular ENSO and the North Atlantic Regimes that have been linked to the generation of heat waves in different parts of India. The preliminary results indicate Nino 3.4 SST anomalies show positive correlation with Tmax anomalies only in the western coast during pre-monsoon season, while in the transitional months positive correlation extends to central and east India. The Tmax composite anomalies for the cold, warm and neutral phases of ENSO show positive anomalies for only warm years and negative anomalies for the cool and neutral years. Heat Index shows similar spatial patterns for correlation analysis and composite anomaly analysis. The Mean Sea Level Pressure (MSLP) composite associated with heat waves (days exceeding 95th percentile=>3 days) show a persistent ridge over the North Atlantic region.</p><p> </p>

scholarly journals Dominant Modes of China Summer Heat Waves Driven by Global Sea Surface Temperature and Atmospheric Internal Variability

2019 ◽  
Vol 32 (12) ◽  
pp. 3761-3775 ◽  
Author(s):  
Kaiqiang Deng ◽  
Song Yang ◽  
Mingfang Ting ◽  
Ping Zhao ◽  
Zunya Wang
Keyword(s):  
North Atlantic ◽  
High Pressures ◽  
Heat Waves ◽  
Southern China ◽  
Wave Train ◽  
Internal Variability ◽  
Northwest Pacific ◽  
The North ◽  
Summer Heat ◽  
The North Atlantic

AbstractThis study applies the maximum temperatures at more than 2000 Chinese stations to investigate the dominant modes of China summer heat waves (HWs). The first empirical orthogonal function (EOF) mode of the HW days reflects an increased frequency of HWs in northern China (NC), while the second and third modes represent two distinct interannual modes, with key regions over the Yangtze River valley (YRV) and southern China (SC), respectively. The NC HWs are possibly associated with the Atlantic–Eurasian teleconnection, showing zonally propagating wave trains over the North Atlantic and Eurasian continent. The YRV HWs are proposed to be linked to the North Atlantic Oscillation, which may trigger a southeastward-propagating wave train over northern Russia and East Asia that results in a high pressure anomaly over the YRV. The SC HWs are obviously dominated by the Indian Ocean and northwest Pacific warm SSTs owing to the transition from the preceding El Niño to La Niña, which excites above-normal highs over SC. The anomalously high pressures over NC, the YRV, and SC are usually accompanied by descending air motions, clear skies, decreased precipitation, and increased solar radiation, which jointly cause a drier and hotter soil condition that favors the emergence of HWs. The GFDL HiRAM experiments are able to reproduce the historical evolution of NC and SC HWs, but fail to capture the YRV HWs. The correlation coefficient between model PC1 (PC2) and observed PC1 (PC3) for the period of 1979–2008 is 0.65 (0.38), which significantly exceeds the 95% (90%) confidence level, indicating that this model has a more faithful representation for the SST-forced HWs.

scholarly journals THALASSARACHNA BASTERI AND T. AFFINIS (ACARI, HALACARIDAE), HISTORY, CHARACTERS, BIOLOGY, AND DISTRIBUTION

2015 ◽  
Vol 2 (3) ◽  
pp. 228-241 ◽  
Author(s):  
Ilse Bartsch
Keyword(s):  
Life Cycle ◽  
Shallow Water ◽  
North Atlantic ◽  
Western Coast ◽  
The North ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
Warm Temperate

Thalassarachna basteri and T. affinis are known since more than a century. Though frequently found in shallow water areas, there exist only very few descriptions of their external characters. These and distinguishing characters are outlined, data of habitat, life cycle, feeding, and distribution are given. Adults and nymphs of T. basteri and T. affinis can be discriminated on the basis of the shape of the frontal spine and number of spines on leg I. Thalassarachna basteri is regularly found in cold-temperate and polar areas, both on the eastern and western coast of the North Atlantic whereas most records of T. affinis are from the warm-temperate eastern North Atlantic.

scholarly journals Patterns of Wintertime Jet Stream Variability and Their Relation to the Storm Tracks*

2010 ◽  
Vol 67 (5) ◽  
pp. 1361-1381 ◽  
Author(s):  
Panos J. Athanasiadis ◽  
John M. Wallace ◽  
Justin J. Wettstein
Keyword(s):  
North America ◽  
North Atlantic ◽  
Zonal Wind ◽  
Wind Field ◽  
North Pacific Ocean ◽  
Winter Season ◽  
Western Coast ◽  
Dynamical Interaction ◽  
The North ◽  
The North Atlantic

Abstract A new approach is put forward for defining extratropical teleconnection patterns. The zonal wind field at 250 hPa is analyzed separately in the North Atlantic and North Pacific Ocean sectors during the winter season (December–March). Teleconnectivity of this field is found to be particularly strong. EOF analysis of the zonal wind field yields patterns that (i) are robust with respect to the range of frequencies included in the data, (ii) relate clearly to the position of the climatological-mean jets, and (iii) are broadly consistent with their traditionally defined counterparts in terms of climatic impacts. The patterns are characterized by a north–south shifting or an extension/retraction of the eddy-driven jet in its exit region and similar changes at the entrance region of the subtropical jet. The patterns also reflect the degree of separation between the subtropical and eddy-driven jets. Atlantic EOFs 1 and 2 are counterparts of the North Atlantic Oscillation (NAO) and eastern Atlantic pattern, respectively, while Pacific EOF 1 is the counterpart of the Pacific–North America (PNA) pattern. Pacific EOF 2, a pattern that has not been previously noted, has a pronounced impact on the jet configuration and precipitation over the western coast of North America. This pattern may be of particular interest for precipitation forecasting applications. Atlantic EOF 1 exhibits a long decorrelation time and strong negative skewness. The relation between these jet variability patterns and the storm-track variability is examined, including the dynamical interaction between baroclinic waves and the jets. In each sector, the eddy forcing is found to maintain the respective jet anomalies.

Summer Eurasian Heat Wave and its linkage to SST anomalies over North Atlantic and Barents-Kara Seas

2020 ◽  
Author(s):  
Hejing Wang ◽  
Dehai Luo
Keyword(s):  
Heat Wave ◽  
North Atlantic ◽  
High Latitude ◽  
Heat Waves ◽  
Wave Train ◽  
Atmospheric Circulation Patterns ◽  
The North ◽  
Summer Heat ◽  
The North Atlantic ◽  
Sst Anomalies

<p>In our study, we aim to examine what factors lead to the summer heat waves over Eurasia and their variability. The analysis reveals that the summer heat waves over Eurasia show two kinds of spatial patterns: midlatitude and high latitude types. The mid-latitude heat wave mainly occurred over west Russia in the west of 55°E and in the south of 60°N, whereas the high-latitude type mainly occurred over west Russia in the east of 55°E and in the north of 55°N. We further analyzed the relationship of the two kinds of heat waves with atmospheric circulation patterns in the Atlantic-Eurasian sector and sea surface temperature (SST) anomalies over the North Atlantic and Arctic. The results show that the cold or warm SST anomalies over Barents-Kara Seas (BKS) can significantly influence the latitude and longitude of Russian heat waves, while the heat waves are also related to the latitude of positive SST anomalies over North Atlantic.</p><p>A mid-latitude wave train propagating into Eurasia and mid-latitude Russian heat waves, which are related to the positive phase of the North Atlantic Oscillation (NAO), are seen when there are strong SST warming in the North Atlantic mid-high latitudes south of 60°N and SST cooling over BKS. In contrast, a high-latitude Russian heat wave can occur over west Russia when there are positive SST anomalies over Baffin Bay, Davis Strait and Labrador Sea north of 60°N and BKS, while this high-latitude wave train is related to the decay of Greenland blocking or the negative NAO phase via high-latitude wave train propagation.</p>

scholarly journals North Atlantic freshwater events influence European weather in subsequent summers

2021 ◽  
Author(s):  
Marilena Oltmanns ◽  
N. Penny Holliday ◽  
James Screen ◽  
D. Gwyn Evans ◽  
Simon A. Josey ◽  
...  
Keyword(s):  
North Atlantic ◽  
Heat Waves ◽  
Sea Surface ◽  
Jet Stream ◽  
North Atlantic Current ◽  
The North ◽  
Freshwater Fluxes ◽  
The North Atlantic ◽  
Arctic Ice ◽  
Atlantic Current

Abstract. Amplified Arctic ice loss in recent decades has been linked to increased occurrence of extreme mid-latitude weather. The underlying dynamical mechanisms remain elusive, however. Here, we demonstrate a novel mechanism linking freshwater releases into the North Atlantic with summer weather in Europe. Combining remote sensing, atmospheric reanalyses and model simulations, we show that freshwater events in summer trigger progressively sharper sea surface temperature gradients in subsequent winters, destabilising the overlying atmosphere and inducing a northward shift in the North Atlantic Current. In turn, the jet stream over the North Atlantic is deflected northward in the following summers, leading to warmer and drier weather over Europe. Our results suggest that growing Arctic freshwater fluxes will increase the risk of heat waves and droughts over the coming decades, and could yield enhanced predictability of European summer weather, months to years in advance.

Late Weichselian Marine 14C Reservoir Ages at the Western Coast of Norway

1999 ◽  
Vol 52 (1) ◽  
pp. 104-114 ◽  
Author(s):  
Stein Bondevik ◽  
Hilary H. Birks ◽  
Steinar Gulliksen ◽  
Jan Mangerud
Keyword(s):  
North Atlantic ◽  
Plant Material ◽  
Weighted Average ◽  
Time Interval ◽  
Western Coast ◽  
Terrestrial Plant ◽  
The North ◽  
The North Atlantic ◽  
Late Weichselian ◽  
Reservoir Age

A shallow marine Late Weichselian deposit on the outer coast of western Norway contains both terrestrial plant material and articulated marine shells. We have 14C dated both types of material from eight different stratigraphic levels covering the time interval 12,300 to 11,100 14C yr B.P. The difference between 14C-dated terrestrial plant material and marine shell material (the marine reservoir age) ranges from 200 to 525 yr, with a weighted average of 380 ± 32 yr. This is almost identical to the present reservoir age of 379 ± 20 yr for southern Norway. In the mid-Younger Dryas (YD) interval the reservoir age in the North Atlantic (55°N–65°N) was 700–800 yr, considerably greater than the present reservoir age and the age we have measured for the Bølling–Allerød interval. The reason for this increase during the YD is probably a combination of reduced inflow of surface waters to the North Atlantic and more extensive sea-ice cover. Evidence from marine cores show that the southeastern Norwegian Sea experienced rapid fluctuations in the inflow of warm Atlantic surface water during the period 12,300 to 11,000 yr B.P. However, the reservoir age apparently did not increase during these colder periods (Older Dryas I and II). The reason is probably that, in contrast to the YD, these colder periods did not last long enough and/or were of too limited extent to alter the reservoir age of the ocean. A comparison of the obtained 14C dates with the varve 14C chronology from Lake Suigetsu indicates an age of 12,770 cal yr B.P. for the AL/YD boundary.

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