scholarly journals Development Processes of the East Asian Cyclones over the Korean Peninsula

2021 ◽  
Author(s):  
Joonsuk M. Kang ◽  
Seok-Woo Son
Keyword(s):  
Korean Peninsula ◽  
East Asian ◽  
Cold Season ◽  
Relative Vorticity ◽  
Reanalysis Data ◽  
Negative Effects ◽  
Upper Troposphere ◽  
Explicit Processes ◽  
Nonlinear Advection ◽  
Development Processes

Abstract. The development processes of the extratropical cyclones passing the Korean Peninsula during the period of 1979–2017 are quantitatively evaluated in the potential vorticity (PV) perspective. A feature tracking algorithm is applied to the ERA-Interim reanalysis data to objectively identify the distinct northern- and southern-track (NT and ST) cyclones affecting the region in the cold season. The dynamic and thermodynamic contributions to the development of these two categories of cyclones are then comparatively assessed in terms of the relative vorticity tendency resulting from the PV tendency inversion. It is quantified through inversion that the NT cyclones develop 87.9 % dynamically and 6.2 % thermodynamically. In contrast, the respective contributions to the ST cyclones are 71.8 % and 43.5 % for the ST cyclones, with negative effects from non-explicit processes. In both NT and ST cyclones, the zonal PV advection in the upper troposphere is the most influential for the dynamic development, while nonlinear advection being more important in the former. The larger thermodynamic contribution of the latter is attributed to more latent heating being involved in the development, which produces more lower-level PV and reduces damping from vertical PV advection. These results indicate that East Asian cyclones passing the Korean Peninsula have different development processes depending on their tracks.

scholarly journals Subseasonal relationship between Arctic and Eurasian surface air temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hye-Jin Kim ◽  
Seok-Woo Son ◽  
Woosok Moon ◽  
Jong-Seong Kug ◽  
Jaeyoung Hwang
Keyword(s):  
Air Temperature ◽  
Diabatic Heating ◽  
Surface Air Temperature ◽  
Significant Negative Correlation ◽  
Cold Season ◽  
Reanalysis Data ◽  
Necessary Condition ◽  
Sea Level Pressure ◽  
Blocking High ◽  
Pressure Anomaly

AbstractThe subseasonal relationship between Arctic and Eurasian surface air temperature (SAT) is re-examined using reanalysis data. Consistent with previous studies, a significant negative correlation is observed in cold season from November to February, but with a local minimum in late December. This relationship is dominated not only by the warm Arctic-cold Eurasia (WACE) pattern, which becomes more frequent during the last two decades, but also by the cold Arctic-warm Eurasia (CAWE) pattern. The budget analyses reveal that both WACE and CAWE patterns are primarily driven by the temperature advection associated with sea level pressure anomaly over the Ural region, partly cancelled by the diabatic heating. It is further found that, although the anticyclonic anomaly of WACE pattern mostly represents the Ural blocking, about 20% of WACE cases are associated with non-blocking high pressure systems. This result indicates that the Ural blocking is not a necessary condition for the WACE pattern, highlighting the importance of transient weather systems in the subseasonal Arctic-Eurasian SAT co-variability.

scholarly journals Zonal Momentum Balance in the Tropical Atmospheric Circulation during the Global Monsoon Mature Months

2013 ◽  
Vol 70 (2) ◽  
pp. 583-599 ◽  
Author(s):  
Wenchang Yang ◽  
Richard Seager ◽  
Mark A. Cane
Keyword(s):  
Angular Momentum ◽  
Pressure Gradient ◽  
Atmospheric Circulation ◽  
Coriolis Force ◽  
Gradient Force ◽  
Pressure Gradient Force ◽  
Global Monsoon ◽  
Upper Troposphere ◽  
Nonlinear Advection ◽  
Zonal Momentum

Abstract In this paper, zonal momentum balances of the tropical atmospheric circulation during the global monsoon mature months (January and July) are analyzed in three dimensions based on the ECMWF Interim Re-Analysis (ERA-Interim). It is found that the dominant terms in the balance of the atmospheric boundary layer (ABL) in both months are the pressure gradient force, the Coriolis force, and friction. The nonlinear advection term plays a significant role only in the Asian summer monsoon regions within the ABL. In the upper troposphere, the pressure gradient force, the Coriolis force, and the nonlinear advection are the dominant terms. The transient eddy force and the residual force (which can be explained as convective momentum transfer over open oceans) are secondary, yet cannot be neglected near the equator. Zonal-mean equatorial upper-troposphere easterlies are maintained by the absolute angular momentum advection associated with the cross-equatorial Hadley circulation. Equatorial upper-troposphere easterlies over the Asian monsoon regions are also controlled by the absolute angular momentum advection but are mainly maintained by the pressure gradient force in January. The equivalent linear Rayleigh friction, which is widely applied in simple tropical models, is calculated and the corresponding spatial distribution of the local coefficient and damping time scale are estimated from the linear regression. It is found that the linear momentum model is in general capable of crudely describing the tropical atmospheric circulation dynamics, yet the caveat should be kept in mind that the friction coefficient is not uniformly distributed and is even negative in some regions.

Increased frequency of Eurasian double jets linked to summer heat extremes in Europe

2021 ◽  
Author(s):  
Efi Rousi ◽  
Kai Kornhuber ◽  
Goratz Beobide Arsuaga ◽  
Fei Luo ◽  
Dim Coumou
Keyword(s):  
Zonal Wind ◽  
Large Scale ◽  
Driving Forces ◽  
Linear Regression Analysis ◽  
Reanalysis Data ◽  
Self Organizing Maps ◽  
Upper Troposphere ◽  
The North ◽  
Heat Extremes ◽  
Different Levels

<p>Persistent summer extremes, such as heatwaves and droughts, can have considerable impacts on nature and societies. There is evidence that weather persistence has increased in Europe over the past decades, in association to changes in atmosphere dynamics, but uncertainties remain and the driving forces are not yet well understood. </p><p>Particularly for Europe, the jet stream may affect surface weather significantly by modulating the North Atlantic storm tracks. Here, we examine the hypothesis that high-latitude warming and decreased westerlies in summer result in more double jets, consisting of two distinct maxima of the zonal wind in the upper troposphere, over the Eurasian sector. Previous work has shown that such double jet states are related to persistent blocking-like circulation in the mid-latitudes. </p><p>We adapt a dynamical perspective of heat extreme trends by looking at large scale circulation and in particular, changes in the zonal mean zonal wind in different levels of the upper troposphere. We define clusters of jet states with the use of Self-Organizing Maps and analyze their characteristics. We find an increase in frequency and persistence of a cluster of double jet states for the period 1979-2019 during July-August (in ERA5 reanalysis data). Those states are linked to increased surface temperature and more frequent heatwaves compared to climatology over western, central, and northern Europe. Significant positive double jet anomalies are found to be dominant in the days preceding and/or coinciding with some of the most intense historical heatwaves in Europe, such as those of 2003 and 2018. A linear regression analysis shows that the increase in frequency and persistence of double jet states may explain part of the strong upward trend in heat extremes over these European regions.</p>

scholarly journals A Synopsis of Farmland Abandonment and Its Driving Factors in Nepal

Land ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 84 ◽  
Author(s):  
Suresh Chaudhary ◽  
Yukuan Wang ◽  
Amod Mani Dixit ◽  
Narendra Raj Khanal ◽  
Pei Xu ◽  
...  
Keyword(s):  
Economic Development ◽  
Land Reform ◽  
Agricultural Landscape ◽  
Local Population ◽  
Rural Landscape ◽  
Driving Factors ◽  
Negative Effects ◽  
Farmland Abandonment ◽  
Mountainous Regions ◽  
Development Processes

Farmland abandonment is considered as an important phenomenon for changing eco-environmental and sociocultural landscapes of mountainous rural landscape. Many studies have analyzed farmland abandonment, its driving factors, geophysical processes and consequences at landscape: however, very few have focused on mountainous developing countries such as in Nepal, which is a rapidly urbanizing country suffering from serious farmland abandonment. Therefore, our study was an attempt to (i) assess the spatiotemporal extent of farmland abandonment in Nepal, (ii) explore driving factors of farmland abandonment, and (iii) discuss on the eco-environmental and sociocultural consequences in Nepal. We reviewed various literature, documents, and national reports to obtain a dataset pertaining to the overall status of farmland use and changes along with political and socioeconomic changes, economic development processes, and policy and governance in Nepal. Our results showed that farmland abandonment is widespread; however, it is more prevalent in the hilly and mountainous regions of Nepal. A total of 9,706,000 ha, accounting for 23.9% of the total cultivated farmland in Nepal, was abandoned during the period of 2001 to 2010. The driving factors included population growth, scattered distribution of settlements, urbanization, socio-economic development, poor access to physical services, and poor implementation of agriculture development policies. Furthermore, the increasing extent of natural disasters, malaria eradication, land reform and resettlement programs, the complex system of land ownership, land fragmentation, political instabilities, and the intensification of trading in agricultural products also acted as drivers of farmland abandonment in Nepal. Farmland abandonment generates negative effects on rural societies eco-environmentally and sociologically. Abandoned plots were subjected to different forms of geomorphic damage (e.g. landslide, debris flows, gully formation, sinkhole development etc.). Farmland landscape fragmented into a group of smaller interspersed patches. Such patches were opened for grassland. Furthermore, farmland abandonment also has effects on the local population and the whole society in terms of the production of goods (e.g., foods, feed, fiber), as well as services provided by the multi-functionality (e.g. sociocultural practices, values and norms) of the agricultural landscape. Therefore, this study plays an important role in planning and implementing eco-environmental management and social development processes in Nepal.

The effect of perceived ethnicity on spoken text comprehension under clear and adverse listening conditions

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Adriana Hanulíková
Keyword(s):  
Speech Perception ◽  
Language Comprehension ◽  
Text Comprehension ◽  
East Asian ◽  
Social Information ◽  
Nonnative Speakers ◽  
Cultural Environment ◽  
Negative Effects ◽  
Asian Ethnicity ◽  
Spoken Text

AbstractSocial information such as ethnicity affects metalinguistic judgments, speech perception and evaluation. This study tested whether previously reported negative effects of perceived East-Asian ethnicity on language comprehension and accentedness ratings would also be found for Moroccan ethnicity and in a socio-cultural environment with a population used to being and communicating with nonnative speakers. The results showed that accentedness ratings and comprehension scores do not depend upon the ethnicity of the speaker. We then tested whether the effect would change under adverse listening conditions and found an effect of perceived ethnicity on accentedness ratings but not on comprehension scores, suggesting that the effect of ethnicity on language comprehension is not altered under adverse listening conditions. Effects of ethnicity on accentedness ratings thus replicate previous findings, but only under suboptimal listening conditions. Although the effect of ethnicity on comprehension was not replicated in regards to Moroccan ethnicity and in a linguistically experienced population, negative correlations between accentedness ratings and the corresponding comprehension scores underlie the contribution of listeners’ characteristics to the comprehension and evaluation of nonnative speech.

East Asian Biomes

Ecology ◽  
2013 ◽  
Author(s):  
John MacKinnon
Keyword(s):  
Korean Peninsula ◽  
Forest Ecosystems ◽  
Unique Feature ◽  
Rapid Development ◽  
East Asian ◽  
Entire Region ◽  
Land Area ◽  
Important Species ◽  
Mountain Ranges ◽  
Relic Species

East Asian biomes include the major biological ecosystems that make up the land area of East Asia, specifically China with Taiwan, Mongolia, Japan, and the Korean Peninsula. These vary from northern tundra and boreal to southern tropical and subtropical ecosystems, include several major mountain ranges, and comprise forest ecosystems, grasslands, deserts, and also important wetland systems. One literally outstanding globally unique feature of the region is the Tibetan-Qinghai Plateau, which forms the source of many of Asia’s major rivers and also drives the monsoon climatic patterns of the entire region. The region includes the world’s most populated country, China, and some of the most densely populated areas but also some of the least populated areas of the planet, including Mongolia with the lowest density. The region is unusually rich in both flora and fauna and has many distinctive endemic features and relic species. The biome has been a great source of domesticated species and economically important species but faces severe conservation challenges as a result of rapid development and changing climate.

scholarly journals Upper tropospheric CO and O<sub>3</sub> budget during the Asian Summer Monsoon

2016 ◽  
Author(s):  
B. Barret ◽  
B. Sauvage ◽  
Y. Bennouna ◽  
E. Le Flochmoen
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Satellite Data ◽  
Large Scale ◽  
Transport Model ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Gangetic Plain ◽  
Upper Troposphere ◽  
Asian Summer

Abstract. During the Asian Summer Monsoon, the circulation in the Upper Troposphere-Lower Stratosphere (UTLS) is dominated by the Asian Monsoon Anticyclone (AMA). Pollutants convectively uplifted to the upper troposphere are trapped within this anticyclonic circulation that extends from the Pacific Ocean to the eastern Mediterranean basin. Among the uplifted pollutants are ozone (O3) and its precursors, such as carbon monoxide (CO) and nitrogen oxides (NOx). Many studies based on global modelisation and satellite data have documented the source regions and transport pathways of primary pollutants (CO, HCN) into the AMA. Here, we aim to quantify the O3 budget by taking into consideration anthropogenic and natural sources. We first use CO and O3 data from the Metop-A/IASI sensor to document their tropospheric distributions over Asia, taking advantage of the useful information they provide on the vertical dimension. These satellite data are used together with MOZAIC/IAGOS tropospheric profiles recorded in India to validate the distributions simulated by the global GEOS-Chem chemistry transport model. Over the Asian region, UTLS monthly CO and O3 distributions from IASI and GEOS-Chem display the same large-scale features. UTLS CO columns from GEOS-Chem are in agreement with IASI, with a low bias of 11 ± 9% and a correlation coefficient of 0.70. For O3, the model underestimates IASI UTLS columns over Asia by 14 ± 26% but the correlation between both is high (0.94). GEOS-Chem is further used to quantify the CO and O3 budget through sensitivity simulations. For CO, these simulations confirm that South-Asian anthropogenic emissions have a more important impact on enhanced concentrations within the AMA (∼25 ppbv) than East-Asian emissions (∼10 ppbv). The correlation between enhanced emissions over the Indo–gangetic–Plain and monsoon deep convection is responsible for this larger impact. Consistently, South-Asian anthropogenic NOx emissions also play a larger role in producing O3 within the AMA (∼8 ppbv) than East-Asian emissions (∼5 ppbv) but Asian lightning produced NOx are responsible for the largest O3 production (10–14 ppbv). Stratosphere to Troposphere Exchanges (STE) are also important in transporting O3 in the upper part of the AMA.

scholarly journals East Asian SO<sub>2</sub> pollution plume over Europe – Part 2: Evolution and potential impact

2009 ◽  
Vol 9 (14) ◽  
pp. 4729-4745 ◽  
Author(s):  
V. Fiedler ◽  
F. Arnold ◽  
H. Schlager ◽  
A. Dörnbrack ◽  
L. Pirjola ◽  
...  
Keyword(s):  
Water Vapor ◽  
Sulfuric Acid ◽  
Gas Phase ◽  
Fossil Fuel ◽  
East Asian ◽  
Fossil Fuel Combustion ◽  
Model Simulations ◽  
Upper Troposphere ◽  
The North ◽  
Potential Impact

Abstract. We report on the first observation-based case study of an aged East Asian anthropogenic SO2 pollution plume over Europe. Our airborne measurements in that plume detected highly elevated SO2 mole fractions (up to 900 pmol/mol) between about 5000 and 7000 m altitude. Here, we focus on investigations of the origin, dispersion, evolution, conversion, and potential impact of the observed excess SO2. In particular, we investigate SO2 conversion to gas-phase sulfuric acid and sulfuric acid aerosols. Our FLEXPART and LAGRANTO model simulations, along with additional trace gas measurements, suggest that the plume originated from East Asian fossil fuel combustion sources and, 8–7 days prior to its arrival over Europe, ascended over the coast region of central East Asia to 9000 m altitude, probably in a cyclonic system with an associated warm conveyor belt. During this initial plume ascent a substantial fraction of the initially available SO2 must have escaped from removal by cloud processes. Hereafter, while mostly descending slowly, the plume experienced advection across the North Pacific, North America and the North Atlantic. During its upper troposphere travel, clouds were absent in and above the plume and OH-induced gas-phase conversion of SO2 to gas-phase sulfuric acid (GSA) was operative, followed by GSA nucleation and condensation leading to sulfuric acid aerosol formation and growth. Our AEROFOR model simulations indicate that numerous large sulfuric acid aerosol particles were formed, which at least temporarily, caused substantial horizontal visibility degradation, and which have the potential to act as water vapor condensation nuclei in liquid water cloud formation, already at water vapor supersaturations as low as about 0.1%. Our AEROFOR model simulations also indicate that those fossil fuel combustion generated soot particles, which have survived cloud induced removal during the initial plume ascent, have experienced extensive H2SO4/H2O-coating, during upper troposphere plume travel. This coating may have dramatically altered the morphology and markedly increased the light absorption efficiency of soot particles.

scholarly journals Dynamics and Geometry of Extratropical Cyclones in the Upper Troposphere by a Neighbor Enclosed Area Tracking Algorithm

2013 ◽  
Vol 26 (21) ◽  
pp. 8641-8653 ◽  
Author(s):  
Masaru Inatsu ◽  
Shotaro Amada
Keyword(s):  
Morphological Characteristics ◽  
Major Axis ◽  
Relative Vorticity ◽  
Tracking Algorithm ◽  
The Arctic ◽  
Extratropical Cyclones ◽  
Background Flow ◽  
Upper Troposphere ◽  
The Arctic Oscillation ◽  
Hemisphere Winter

Abstract This study shows that the morphological characteristics of upper-tropospheric extratropical eddies are closely related to the background flow in the Northern Hemisphere winter. Enclosed surfaces of 300-hPa relative vorticity are identified by using the neighbor enclosed area tracking algorithm, and the periphery of these surfaces are approximated by ellipses. Eddies are classified into five categories according to the approximate ellipse. Eddies having an oblateness of less than 0.6 are classified as near circle, or are otherwise classified as northeast–southwest (NE–SW), northwest–southeast (NW–SE), north–south, or west–east, according to the direction of the major axis. In the wintertime climatology, NE–SW-oriented cyclones are collocated with the jet stream, while NW–SE-oriented cyclones mostly reside north of the jet. In interannual variability, moreover, the frequency of NE–SW cyclones is slightly correlated with the Arctic Oscillation (AO) index, while the frequency of NW–SE cyclones is highly anticorrelated with the AO index. This is consistent with positive feedback between horizontally slanted eddies and background flow, as has been shown in many previous studies.

Sign in / Sign up

Export Citation Format

Share Document