scholarly journals Increasing spring dust storms in the future over the Taklimakan Desert, Northwest China: implications from changes in circulation pattern frequency in CMIP6

2021 ◽  
Author(s):  
Rui Mao ◽  
Dao-Yi Gong ◽  
Seong-Joong Kim ◽  
Qi Zong ◽  
Xingya Feng ◽  
...  
Keyword(s):  
Circulation Pattern ◽  
Northwest China ◽  
Dust Storms ◽  
Cmip5 Models ◽  
Taklimakan Desert ◽  
Dust Emissions ◽  
Warming Scenario ◽  
Pattern Frequency ◽  
Circulation Patterns ◽  
The Future

Abstract Dust storms over the Taklimakan Desert (TD), Northwest China, not only influence human health but also affect regional climate through direct effects of dust aerosols on solar and longwave radiation. The Coupled Model Intercomparisons Project Phase 5 (CMIP5) models project a decrease in dust storms because of a decrease in dust emissions over the TD in the future under warming scenarios. However, inaccurate simulations of dust emissions cause the CMIP5 models to simulate dust storms poorly. Here we analyzed typical circulation patterns that initiate dust storms over the TD and examined changes in the frequency of typical circulation patterns derived from the CMIP6 models in an extreme warming scenario. The results show that there will be an increase in typical circulation pattern frequency in the latter half of the 21st century compared with 1958-2014, implying an increase in dust storms over the TD in the future under the extreme warming scenario. The increase in dust storms over the TD may be related to an increase in synoptic activities in the future from the Middle Asia to the TD, which is caused by a southern movement of subtropical westerly jet stream under the extreme warming scenario.

scholarly journals Classification of the Circulation Patterns Related to Strong Dust Weather in China Using a Combination of the Lamb–Jenkinson and k-Means Clustering Methods

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1545
Author(s):  
Ziwei Yi ◽  
Yaqiang Wang ◽  
Wencong Chen ◽  
Bin Guo ◽  
Bihui Zhang ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Cold Front ◽  
Social Economy ◽  
Circulation Pattern ◽  
Northern China ◽  
Dust Storms ◽  
Clustering Methods ◽  
Circulation Types ◽  
Circulation Patterns ◽  
Main Circulation

Sand and dust storms (SDSs) cause major disasters in northern China. They have serious impacts on human health, daily life, and industrial and agricultural production, in addition to threatening the regional ecological environment and social economy. Based on meteorological observational data and the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 dataset for spring 2000–2021, we used the Lamb–Jenkinson circulation classification method to classify the three major areas influencing SDSs in northern China. We also used the k-means clustering method to classify the overall circulation pattern in northern China. Our results show that the circulation types favoring SDSs in the southern basin of Xinjiang are southwesterly winds (SW), cyclones (C), and anticyclones (A). The circulation types favoring SDSs in western Inner Mongolia and southern Mongolia are northwesterly winds (NW), northerly winds (N), cyclones (C), and anticyclones (A). The circulation types favoring SDSs in central Inner Mongolia are northwesterly winds (NW), northerly winds (N), southwesterly winds (SW), and anticyclones (A). The 500 hPa and surface circulation patterns in China can be divided into nine types. Among them, five dominant circulation patterns favor strong SDSs: a cold high-pressure region and cold front (T1), a Mongolian cyclone (T2), a mixed type of Mongolian cyclone and cold front (T3), a thermal depression and cold front (T5), and a cold front (T8). During 2000–2004, the T8 circulation pattern occurred most frequently as the main influencing circulation. From 2005 to 2010, the T3 and T8 circulation patterns dominated. Circulation patterns T1 and T3 dominated during 2011–2015 and 2016–2020, respectively. We analyzed the main circulation patterns for four SDS events occurring in 2021 by combining the Lamb–Jenkinson and k-means methods. The SDS events in 2021 were closest to the T3 circulation pattern and were mainly influenced by Mongolian cyclones and surface cold fronts. The main propagation paths were westerly and northwesterly.

scholarly journals Effect of the El Niño Decaying Pace on the East Asian Summer Monsoon Circulation Pattern during Post-El Niño Summers

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 140
Author(s):  
Wenping Jiang ◽  
Gen Li ◽  
Gongjie Wang
Keyword(s):  
El Niño ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
El Nino ◽  
East Asian ◽  
Circulation Pattern ◽  
Northwest Pacific ◽  
Monsoon Circulation ◽  
Circulation Patterns ◽  
Sst Anomalies

El Niño events vary from case to case with different decaying paces. In this study, we demonstrate that the different El Niño decaying paces have distinct impacts on the East Asian monsoon circulation pattern during post-El Niño summers. For fast decaying (FD) El Niño summers, a large-scale anomalous anticyclone dominates over East Asia and the North Pacific from subtropical to mid-latitude; whereas, the East Asian monsoon circulation display a dipole pattern with anomalous northern cyclone and southern anticyclone for slow decaying (SD) El Niño summers. The difference in anomalous East Asian monsoon circulation patterns was closely associated with the sea surface temperature (SST) anomaly patterns in the tropics. In FD El Niño summers, the cold SST anomalies in the tropical central-eastern Pacific and warm SST anomalies in the Maritime Continent induce the anticyclone anomalies over the Northwest Pacific. In contrast, the warm Kelvin wave anchored over the tropical Indian Ocean during SD El Niño summers plays a crucial role in sustaining the anticyclone anomalies over the Northwest Pacific. In particular, the opposite atmospheric circulation anomaly patterns over Northeast Asia and the mid-latitude North Pacific are mainly modulated by the stationary Rossby wave trains triggered by the opposite SST anomalies in the tropical eastern Pacific during FD and SD El Niño summers. Finally, the effect of distinct summer monsoon circulation patterns associated with the El Niño decay pace on the summer climate over East Asia are also discussed.

scholarly journals Do CMIP5 Models Show El Niño Diversity?

2020 ◽  
Vol 33 (5) ◽  
pp. 1619-1641 ◽  
Author(s):  
Jie Feng ◽  
Tao Lian ◽  
Jun Ying ◽  
Junde Li ◽  
Gen Li
Keyword(s):  
El Niño ◽  
El Nino ◽  
Heat Budget ◽  
Equatorial Pacific ◽  
Cmip5 Models ◽  
Budget Analysis ◽  
Future Global Warming ◽  
Central Equatorial Pacific ◽  
The Future ◽  
Sst Gradient

AbstractWhether the state-of-the-art CMIP5 models have different El Niño types and how the degree of modeled El Niño diversity would be impacted by the future global warming are still heavily debated. In this study, cluster analysis is used to investigate El Niño diversity in 30 CMIP5 models. As the method does not rely on any prior knowledge of the patterns of El Niño seen in observations, it provides a practical way to identify the degree of El Niño diversity in models. Under the historical scenario, most models show a poor degree of El Niño diversity in their own model world, primarily due to the lopsided numbers of events belonging to the two modeled El Niño types and the weak compactness of events in each cluster. Four models are found showing significant El Niño diversity, yet none of them captures the longitudinal distributions of the warming centers of the two El Niño types seen in the observations. Heat budget analysis of the sea surface temperature (SST) anomaly suggests that the degree of modeled El Niño diversity is highly related to the climatological zonal SST gradient over the western-central equatorial Pacific in models. As the gradient is weakened in most models under the future high-emission scenario, the degree of modeled El Niño diversity is further reduced in the future. The results indicate that a better simulation of the SST gradient over the western-central equatorial Pacific might allow a more reliable simulation/projection of El Niño diversity in most CMIP5 models.

Six-fold increase in historical Northern Hemisphere concurrent large heatwaves driven by warming and changing atmospheric circulations

2021 ◽  
pp. 1-39
Author(s):  
Cassandra D.W. Rogers ◽  
Kai Kornhuber ◽  
Sarah E. Perkins-Kirkpatrick ◽  
Paul C. Loikith ◽  
Deepti Singh
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Warm Season ◽  
Fold Increase ◽  
Circulation Pattern ◽  
Positive Influence ◽  
Climate Risks ◽  
Circulation Patterns ◽  
Multiple Regions ◽  
Barents And Kara Seas

AbstractSimultaneous heatwaves affecting multiple regions (referred to as concurrent heatwaves), pose compounding threats to various natural and societal systems, including global food chains, emergency response systems, and reinsurance industries. While anthropogenic climate change is increasing heatwave risks across most regions, the interactions between warming and circulation changes that yield concurrent heatwaves remain understudied. Here, we quantify historical (1979-2019) trends in concurrent heatwaves during the warm-season (May-September, MJJAS) across the Northern Hemisphere mid- to high-latitudes. We find a significant increase of ~46% in the mean spatial extent of concurrent heatwaves, ~17% increase in their maximum intensity, and ~6-fold increase in their frequency. Using Self-Organising Maps, we identify large-scale circulation patterns (300 hPa) associated with specific concurrent heatwave configurations across Northern Hemisphere regions. We show that observed changes in the frequency of specific circulation patterns preferentially increase the risk of concurrent heatwaves across particular regions. Patterns linking concurrent heatwaves across eastern North America, eastern and northern Europe, parts of Asia, and the Barents and Kara Seas, show the largest increases in frequency (~5.9 additional days per decade). We also quantify the relative contributions of circulation pattern changes and warming to overall observed concurrent heatwave day frequency trends. While warming has a predominant and positive influence on increasing concurrent heatwaves, circulation pattern changes have a varying influence and account for up to 0.8 additional concurrent heatwave days per decade. Identifying regions with an elevated risk of concurrent heatwaves and understanding their drivers is indispensable for evaluating projected climate risks on interconnected societal systems and fostering regional preparedness in a changing climate.

scholarly journals Spring Extreme Precipitation Days in North China and Their Reliance on Atmospheric Circulation Patterns During 1979–2019

2022 ◽  
pp. 1-41
Keyword(s):  
Climate Variability ◽  
Atmospheric Circulation ◽  
Extreme Precipitation ◽  
Interannual Variation ◽  
North China ◽  
Circulation Pattern ◽  
Southerly Wind ◽  
Atmospheric Circulation Patterns ◽  
Rain Gauges ◽  
Circulation Patterns

Abstract The interannual variation of springtime extreme precipitation (SEP) days in North China (NC) and their reliance on atmospheric circulation patterns are studied by using the continuous daily record of 396 rain gauges and the fifth generation of the European Centre for Medium-Range Weather Forecasts atmospheric reanalysis during 1979–2019. The SEP days are defined as the days when at least 10% of rain gauges in NC record daily precipitation no less than 10.5 mm. Results show that the number of SEP days shows large interannual variability but no significant trend in the study period. Using the objective classification method of the obliquely rotated principal analysis in T-mode, we classify the atmospheric circulation into five different patterns based on the geopotential height at 700 hPa. Three circulation patterns all have fronts and are associated with strong southerly wind, leading to 88% of SEP days in NC. The strong southerly wind may provide moisture and dynamic forcing for the frontal precipitation. The interannual variation of SEP days is related with the number of the three above-mentioned dominant circulation patterns. Further analysis shows that the West Pacific pattern could be one of the possible climate variability modes related to SEP days. This study reveals that the daily circulation pattern may be the linkage between SEP days and climate variability modes in NC.

scholarly journals Africa Would Need to Import More Maize in the Future Even under 1.5°C Warming Scenario

2020 ◽  
Author(s):  
Ran Zhai ◽  
Fulu Tao ◽  
Upmanu Lall ◽  
Joshua Elliott
Keyword(s):  
Warming Scenario ◽  
The Future

scholarly journals Impact of COVID-19 Lockdown and Atmospheric Circulation on the Air Quality in Wuhan During Early 2020

2021 ◽  
Vol 299 ◽  
pp. 02011
Author(s):  
Youyong Xie ◽  
Xiefei Zhi
Keyword(s):  
Air Quality ◽  
Atmospheric Circulation ◽  
Air Pollutants ◽  
General Circulation ◽  
Circulation Pattern ◽  
Atmospheric Circulation Patterns ◽  
Atmospheric General Circulation ◽  
Circulation Patterns ◽  
The Impact

Previous studies indicated that the air quality was improved in Wuhan during COVID-19 lockdown. However, the impact of atmospheric general circulation on the changes of air quality has not been taken into account. The present study aims to discuss the improvement of air quality in Wuhan and its possible reasons during COVID-19 lockdown. The results showed that all air pollutants except O3 decreased in Wuhan during early 2020. The occurrence days of A, C, W and NW types’ circulation pattern during early 2020 are more than those during the same period of 1979-2020. The occurrence days of SW type’s circulation pattern is slightly less than those during early 1979-2020. With more occurrence days of these dominant atmospheric circulation patterns, the number of polluted days could rise in Wuhan during early 2020. Nevertheless, this scenario didn’t occur. The COVID-19 lockdown did improve the air quality in Wuhan during early 2020.

Assessing the future occurrence of severe thunderstorm environments in Europe: frequency, hotspots and impacts

2021 ◽  
Author(s):  
Flavio Pons ◽  
Davide Faranda
Keyword(s):  
Radiative Forcing ◽  
Value Theory ◽  
Severe Weather ◽  
Cmip5 Models ◽  
Dynamical System Theory ◽  
Economic Damage ◽  
Climate Change Scenarios ◽  
Severe Thunderstorms ◽  
Significant Damage ◽  
The Future

<p>We study the future frequency of atmospheric environments leading to severe thunderstorms over Europe under different climate change scenarios in CMIP5 models. Our method is founded on dynamical system theory, which makes it possible to detect future atmospheric configurations that are close analogues of past events in the class of interest.</p><p>We rely on the EM-DAT and the European Severe Weather Database to select an ensemble of past events leading to significant damage or disruption, including severe thunderstorms, hail storms, derechos and tornadoes, between 1950 and 2020. We consider the geopotential height field at 500 hPa in ERA5 data as a dynamical proxy of the corresponding configurations. Then, we leverage extreme value theory to detect close dynamic analogues in the output of CMIP5 climate projection models under two emission scenarios, namely RCP4.5 and RCP8.5.</p><p>First of all, we assess possible differences between the trends in severe weather frequency due to different radiative forcing. Then, we study the spatial structure of such trends, highlighting regions where the occurrence of such phenomena could see a sharp increase or decrease. Finally, we estimate potential future impact of such phenomena where the information about economic damage is available in EM-DAT.</p><p> </p>

A Multi-Dimensional Exploration of Future Aspect Marker "Dai" in Chinese Dialect from the Perspective of Typology — Take Gansu Tianzhu Dialect as an Example

2021 ◽  
Vol 7 (6) ◽  
pp. 5440-5452
Author(s):  
Song Shan ◽  
Min Chunfang
Keyword(s):  
Geographical Distribution ◽  
Northwest China ◽  
The Other ◽  
Semantic Features ◽  
Main Research ◽  
Regional Characteristics ◽  
Future Aspect ◽  
The Future ◽  
Aspect Marker ◽  
Chinese Dialect

Objectives: In Tianzhu dialect, the use of the future aspect marker "Dai[tɛi44]" is frequent. The grammatical meaning of the future aspect marker, "verb phrase (VP) +'Dai[tɛi44]+[lio21]'", in Tianzhu dialect can be divided into two categories according to the differences of VP: one indicates that the end of the action is about to be reached, that is, "VP +'Dai1[tɛi44]+[lio21]'"; the other indicates that the action is about to begin, that is, "VP +‘Dai2[tɛi44]+[lio21]’ ". This article takes the Tianzhu dialect aspect marker "Dai[tɛi44]" as the main research object, and focuses on the grammatical functions and semantic features of "Dai1[tɛi44]" and "Dai2[tɛi44]" by studying the actionality types of verbs in Tianzhu dialect, and compares the future aspect marker "Dai[tɛi44]" in Tianzhu dialect with the future aspect markers of other Chinese dialect in Northwest China, and generalizes the geographical distribution and regional characteristics of the future aspect marker "Dai[tɛi44]".

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