scholarly journals Comparison of Atmospheric Circulation Anomalies between Dry and Wet Extreme High-Temperature Days in the Middle and Lower Reaches of the Yellow River

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1265
Author(s):  
Hangcheng Ge ◽  
Gang Zeng ◽  
Vedaste Iyakaremye ◽  
Xiaoye Yang ◽  
Zongming Wang
Keyword(s):  
High Temperature ◽  
Atmospheric Circulation ◽  
Yellow River ◽  
Wave Train ◽  
The Yellow River ◽  
South Asian High ◽  
Opposite Pattern ◽  
Extreme High Temperature ◽  
Circulation Anomalies ◽  
Atmospheric Circulation Anomalies

Many previous studies have reported that atmospheric circulation anomalies are generally the direct cause of extreme high-temperature (EHT). However, the atmospheric circulation anomalies of EHT days with different humidity and the differences between them are less often discussed, while humidity plays an important role in how people feel in a high-temperature environment. Therefore, this study uses 1961–2016 CN05.1 daily observational data and NCEP/NCAR reanalysis data to classify summer EHT days in China into dry and wet. Furthermore, we investigate the atmospheric circulation anomalies associated with the dry and wet EHT days in the middle and lower reaches of the Yellow River (MLRYR). The results reveal that dry EHT days are likely to be caused by adiabatic heating from anomalous subsidence, while wet EHT days are more likely caused by the low-latitude water vapor and heat anomalies brought by the Western Pacific Subtropical High (WPSH). This may be due to a remarkable westward/southward/narrowed extension of the Continental High (CH)/WPSH/South Asian High (SAH) accompanied by an occurrence of dry EHT day. The opposite pattern is observed for wet EHT days. Moreover, a wave train like the Silk Road pattern from the midlatitudes could affect the dry EHT days, while wet EHT days are more likely to be affected by a wave train from high latitudes. Knowing the specific characteristics of dry and wet EHT days and their associated atmospheric circulations could offer new insights into disaster risk prevention and reduction.

scholarly journals Three distinct atmospheric circulation patterns associated with high temperature extremes in South Korea

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Han-Kyoung Kim ◽  
Byung-Kwon Moon ◽  
Maeng-Ki Kim ◽  
Jong-Yeon Park ◽  
Yu-Kyung Hyun
Keyword(s):  
High Temperature ◽  
South Korea ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Negative Impact ◽  
Wave Train ◽  
Self Organizing Map ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Extreme High Temperature

AbstractThe negative impact of extreme high-temperature days (EHDs) on people’s livelihood has increased over the past decades. Therefore, an improved understanding of the fundamental mechanisms of EHDs is imperative to mitigate this impact. Herein, we classify the large-scale atmospheric circulation patterns associated with EHDs that occurred in South Korea from 1982 to 2018 using a self-organizing map (SOM) and investigate the dynamic mechanism for each cluster pattern through composite analysis. A common feature of all SOM clusters is the positive geopotential height (GPH) anomaly over the Korean Peninsula, which provides favorable conditions for EHDs through adiabatic warming caused by anomalous downward motion. Results show that Cluster 1 (C1) is related to the eastward-propagating wave train in the mid-latitude Northern Hemisphere, while Cluster 2 (C2) and 3 (C3) are influenced by a northward-propagating wave train forced by enhanced convection in the subtropical western North Pacific (WNP). Compared to C2, C3 exhibits strong and eastward-extended enhanced convection over the subtropical WNP, which generates an anomalous high-pressure system over the southern part of the Kamchatka Peninsula, reinforcing EHDs via atmospheric blocking. Our results can contribute to the understanding of East Asia climate variability because wave trains influence the climate dynamics of this region.

scholarly journals Origins of Biases in CMIP5 Models Simulating Northwest Pacific Summertime Atmospheric Circulation Anomalies during the Decaying Phase of ENSO

2018 ◽  
Vol 31 (14) ◽  
pp. 5707-5729 ◽  
Author(s):  
Weichen Tao ◽  
Gang Huang ◽  
Renguang Wu ◽  
Kaiming Hu ◽  
Pengfei Wang ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
Southern Oscillation ◽  
Coupled Model ◽  
Tropical Indian Ocean ◽  
Shortwave Radiation ◽  
Cmip5 Models ◽  
Northwest Pacific ◽  
Circulation Anomalies ◽  
Atmospheric Circulation Anomalies ◽  
Sst Anomalies

Abstract The present study documents the biases of summertime northwest Pacific (NWP) atmospheric circulation anomalies during the decaying phase of ENSO and investigates their plausible reasons in 32 models from phase 5 of the Coupled Model Intercomparison Project. Based on an intermodel empirical orthogonal function (EOF) analysis of El Niño–Southern Oscillation (ENSO)-related 850-hPa wind anomalies, the dominant modes of biases are extracted. The first EOF mode, explaining 21.3% of total intermodel variance, is characterized by a cyclone over the NWP, indicating a weaker NWP anticyclone. The cyclone appears to be a Rossby wave response to unrealistic equatorial western Pacific (WP) sea surface temperature (SST) anomalies related to excessive equatorial Pacific cold tongue in the models. On one hand, the cold SST biases increase the mean zonal SST gradient, which further intensifies warm zonal advection, favoring the development and persistence of equatorial WP SST anomalies. On the other hand, they reduce the anomalous convection caused by ENSO-related warming, and the resultant increase in downward shortwave radiation contributes to the SST anomalies there. The second EOF mode, explaining 18.6% of total intermodel variance, features an anticyclone over the NWP with location shifted northward. The related SST anomalies in the Indo-Pacific sector show a tripole structure, with warming in the tropical Indian Ocean and equatorial central and eastern Pacific and cooling in the NWP. The Indo-Pacific SST anomalies are highly controlled by ENSO amplitude, which is determined by the intensity of subtropical cells via the adjustment of meridional and vertical advection in the models.

scholarly journals On the Relationship between Winter Sea Ice and Summer Atmospheric Circulation over Eurasia

2013 ◽  
Vol 26 (15) ◽  
pp. 5523-5536 ◽  
Author(s):  
Bingyi Wu ◽  
Renhe Zhang ◽  
Rosanne D'Arrigo ◽  
Jingzhi Su
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
Rainfall Variability ◽  
Summer Rainfall ◽  
Eastern Coast ◽  
Northern Eurasia ◽  
Sea Ice Concentration ◽  
The North ◽  
Circulation Anomalies ◽  
Atmospheric Circulation Anomalies

Abstract Using NCEP–NCAR reanalysis and Japanese 25-yr Reanalysis (JRA-25) data, this paper investigates the association between winter sea ice concentration (SIC) in Baffin Bay southward to the eastern coast of Newfoundland, and the ensuing summer atmospheric circulation over the mid- to high latitudes of Eurasia. It is found that winter SIC anomalies are significantly correlated with the ensuing summer 500-hPa height anomalies that dynamically correspond to the Eurasian pattern of 850-hPa wind variability and significantly influence summer rainfall variability over northern Eurasia. Spring atmospheric circulation anomalies south of Newfoundland, associated with persistent winter–spring SIC and a horseshoe-like pattern of sea surface temperature (SST) anomalies in the North Atlantic, act as a bridge linking winter SIC and the ensuing summer atmospheric circulation anomalies over northern Eurasia. Indeed, this study only reveals the association based on observations and simple simulation experiments with SIC forcing. The more precise mechanism for this linkage needs to be addressed in future work using numerical simulations with SIC and SST as the external forcings. The results herein have the following implication: Winter SIC west of Greenland is a possible precursor for summer atmospheric circulation and rainfall anomalies over northern Eurasia.

scholarly journals Magnitude and Frequency of Temperature and Precipitation Extremes and the Associated Atmospheric Circulation Patterns in the Yellow River Basin (1960–2017), China

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2334 ◽  
Author(s):  
Xiaogang Dong ◽  
Shiting Zhang ◽  
Junju Zhou ◽  
Jianjun Cao ◽  
Liang Jiao ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
River Basin ◽  
Yellow River ◽  
Yellow River Basin ◽  
The Yellow River ◽  
Temperature Extremes ◽  
Precipitation Temperature ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
The Yellow River Basin

Since there are many destructive effects caused by extreme climate events in the Yellow River, it is of great theoretical and practical significance to explore the variations of climatic extremes in this key basin. We used a meteorological dataset from 66 stations within the Yellow River basin (YRB) for the period 1960–2017 to calculate magnitude and frequency of precipitation/temperature extremes. We also analyzed the relationships between the main large-scale atmospheric circulation patterns (ACPs) and precipitation/temperature extremes. The trends in precipitation extremes were nonsignificant, only a few stations were characterized by significantly increasing or decreasing anomalies; this indicates the precipitation intensity may have been strengthened, and the extreme rainfall duration appears to have been reduced during 1960–2017. The trends of magnitudes for “cold” extremes were larger than those for “warm” extremes, changes of trends in frost days were higher than those for summer days, and the trends in increasing warm nights were higher than those of warm days. The influence of the El Niño–Southern Oscillation (ENSO) and Arctic Oscillation (AO) on temperature extremes outweighed the influence of the North Atlantic Oscillation (NAO), Indian Ocean Dipole (IOD), and Pacific Decadal Oscillation (PDO) for the other extreme climate indices. The YRB might be at risk of increased extreme high temperature events, and more attention should be paid to this higher risk of extreme climatic events.

Drought

Geography ◽  
2020 ◽  
Author(s):  
Woonsup Choi
Keyword(s):  
Soil Moisture ◽  
Atmospheric Circulation ◽  
Agricultural Drought ◽  
Subsurface Water ◽  
Drought Indices ◽  
Human Society ◽  
Atmospheric Conditions ◽  
Spatial And Temporal Patterns ◽  
Circulation Anomalies ◽  
Atmospheric Circulation Anomalies

Drought is a natural disaster that has plagued human society throughout history. However, the meaning of drought varies by perspective and academic discipline, and the cause of drought is difficult to pinpoint. Despite the variation in its meaning, drought generally refers to the condition of an abnormally low amount of water for a given climate. Here the water can be precipitation, streamflow, soil moisture, groundwater, reservoir storage, and the like, but the lack of precipitation is a precursor for other types of drought. The lack of precipitation is often associated with anomalous atmospheric conditions such as atmospheric-circulation anomalies, higher-than-normal temperatures, and lower-than-normal relative humidity. Sea surface temperature anomalies may lead to sustained atmospheric-circulation anomalies. Drought defined as a lack of precipitation is often called meteorological or climatological drought. Other drought types can be classified within the context of the affected sectors, such as agricultural, hydrological, and socioeconomic drought. Agricultural drought generally refers to a lack of soil moisture, and hydrological drought refers to a lack of surface and subsurface water (e.g., streamflow and groundwater). Socioeconomic drought hampers human activities such as industry or water supply. As meteorological drought persists, other types of drought can follow. Such definitions of drought are regarded as conceptual definitions, but operational definitions are also necessary for quantitative understanding and management of drought events. Operational definitions use quantitative indices to identify the occurrence and characteristics of drought events such as onset, duration, termination, and deficit volume of drought. Much of existing drought research concerns developing, revising, and applying drought indices to investigate spatial and temporal patterns of drought at various geographical scales. Drought research has progressed along several directions, such as causes of drought, characteristics of drought events, impacts, and mitigation. Each of these directions is represented by the works cited in this article.

scholarly journals Significant Atmospheric Circulation Anomalies over the North Pacific Associated with the Enhanced Pacific ITCZ during the Summer–Fall of 2014

SOLA ◽  
2016 ◽  
Vol 12 (0) ◽  
pp. 282-286
Author(s):  
Shuhei Maeda ◽  
Yusuke Urabe ◽  
Kazuto Takemura ◽  
Tamaki Yasuda ◽  
Youichi Tanimoto
Keyword(s):  
Atmospheric Circulation ◽  
North Pacific ◽  
The North ◽  
Circulation Anomalies ◽  
Atmospheric Circulation Anomalies ◽  
The North Pacific
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