scholarly journals Sand/dust storm processes in Northeast Asia and associated large-scale circulations

2008 ◽  
Vol 8 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Y. Q. Yang ◽  
Q. Hou ◽  
C. H. Zhou ◽  
H. L. Liu ◽  
Y. Q. Wang ◽  
...  
Keyword(s):  
Dust Storm ◽  
General Circulation ◽  
Large Scale ◽  
Transition Period ◽  
Northeast Asia ◽  
Lower Troposphere ◽  
Northern China ◽  
Wind Anomaly ◽  
Cold Air ◽  
Sand Dust

Abstract. This paper introduces a definition of sand/dust storm process as a new standard and idea of sand/dust storm (SDS) groups a number of SDS-events in Northeast Asia. Based on the meteorological data from WMO/GOS network, 2456 Chinese surface stations and NCEP-NCAR reanalysis, the sand/dust storm processes in Northeast Asia in spring 2000–2006 are investigated. And the evolutions of anomalies of general circulation in the troposphere are analyzed by comparing the spring having most and least occurrences of SDS in year 2006 and 2003. Associated with the noticeably increased occurrence of SDS processes in spring 2006, the anomalies in 3-D structure of general circulation especially in the mid-and high latitudes of the Northen Hemisphere (NH) are revealed. The transition period from the winter of 2005 to spring 2006 has witnessed a fast-developed high center over the circumpolar vortex area in the upper troposphere, which pushes the polar vortex more southwards to mid-latitudes with a more extensive area over the east NH. In spring 2006, there are the significant circulation anomalies in the middle troposphere from the Baikal Lake to northern China with a stronger southward wind anomaly over Northeast Asia. Compared with a normal year, stronger meridional wind with a southward wind anomaly also in the lower troposphere prevail over the arid and semiarid regions in Mongolia and northern China during spring 2006. The positive anomalies of surface high pressure registered an abnormal high of 4–10 hPa in the Tamil Peninsular make a stronger cold air source for the repeated cold air outbreak across the desert areas in spring 2006 resulting in the most frequent SDS seasons in the last 10 years in Northeast Asia.

scholarly journals Sand/dust storms over Northeast Asia and associated large-scale circulations in spring 2006

2007 ◽  
Vol 7 (3) ◽  
pp. 9259-9281 ◽  
Author(s):  
Y. Q. Yang ◽  
Q. Hou ◽  
C. H. Zhou ◽  
H. L. Liu ◽  
Y. Q. Wang ◽  
...  
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Northeast Asia ◽  
Dust Storms ◽  
Transitional Period ◽  
Long Distance ◽  
Upper Troposphere ◽  
Zonal Winds ◽  
Sand Dust ◽  
Westerly Jets

Abstract. This paper presents a study on the meteorological conditions that accompany the sand/dust storms (SDS) of East Asia in spring 2006, based on the SDS data collected both by WMO during 2000–2006 and by 2456 Chinese surface stations, and on the meteorological reanalysis data from NCEP-NCAR . The evolution of 3-D structures of the general circulations prevailed in both winter and spring as well as their annual anomalies were investigated by comparing the years having most and least occurrences of SDS between 2000 and 2006. It is found that spring 2006 featured a noticeably increased occurrence of SDS, compared with previous years. The general circulations prevailed through both winter and spring, especially the 3-D structure of the polar circulation, show the significant anomalies compared to a normal year. This produced a range of corresponding weather phenomena, including circumpolar vortices at the upper troposphere, mid-level westerly jets, and lower zonal winds, which all favored the SDS production and transport in 2006. The study also reveals a fact that comparing with a normal year, the transitional period from the winter of 2005 to the spring of 2006 has witnessed a fast-developed high center at the upper troposphere of the northern hemisphere and the circumpolar vortex area, which pushes the area dominated by the circumpolar vortices further to mid-latitudes. The circumpolar vortices shifted southwards, and prevailed over an extensive area across the northeast hemisphere for a sustained period. The mid-high latitude areas that sit in the south of the circumpolar vortices in Asia have experienced significantly abnormal westerly jets at the mid-level of troposphere. Zonal winds prevailed at the mid and lower levels of troposphere. Sea level pressure registered an abnormal high at 4–10 hPa, compared with a normal year. The above-mentioned 3-D structures of general circulation have created thermal and dynamic conditions that favor the repeated genesis and momentous development of the Mongolian cyclones, which in turn contributes to the frequent occurrences and long distance transport of SDS.

Collaborative Effects of Cold Surge and Tropical Depression–Type Disturbance on Heavy Rainfall in Central Vietnam

2008 ◽  
Vol 136 (9) ◽  
pp. 3275-3287 ◽  
Author(s):  
Satoru Yokoi ◽  
Jun Matsumoto
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Lower Troposphere ◽  
Heavy Rainfall Event ◽  
Wind Anomaly ◽  
Southerly Wind ◽  
Cold Surge ◽  
Tropical Depression ◽  
Orographic Rainfall ◽  
Central Vietnam

Abstract This paper reveals synoptic-scale atmospheric conditions over the South China Sea (SCS) that cause heavy rainfall in central Vietnam through case study and composite analyses. The heavy rainfall event discussed in this study occurred on 2–3 November 1999. Precipitation in Hue city (central Vietnam) was more than 1800 mm for these 2 days. Two atmospheric disturbances played key roles in this heavy rainfall. First, a cold surge (CS) northerly wind anomaly in the lower troposphere, originating in northern China near 40°N, propagated southward to reach the northern SCS and then lingered there for a couple of days, resulting in stronger-than-usual northeasterly winds continuously blowing into the Indochina Peninsula against the Annam Range. Second, a southerly wind anomaly over the central SCS, associated with a tropical depression–type disturbance (TDD) in southern Vietnam, seemed to prevent the CS from propagating farther southward. Over the northern SCS, the southerly wind anomaly formed a strong low-level convergence in conjunction with the CS northeasterly wind anomaly, and supplied warm and humid tropical air. These conditions induced by the CS and TDD are favorable for the occurrence of the heavy orographic rainfall in central Vietnam. The TDD can be regarded as a result of a Rossby wave response to a large-scale convective anomaly over the Maritime Continent associated with equatorial intraseasonal variability. Using a 24-yr (1979–2002) reanalysis and surface precipitation datasets, the authors confirm that the coexistence of the CS and TDD is important for the occurrence of heavy precipitation in central Vietnam. In addition, it is observed that CSs without a TDD do not lead to much precipitation.

scholarly journals Монголия и страны Северо-Восточной Азии: торгово-экономическое и интеграционное сотрудничество (2009–2018 гг.)

2019 ◽  
Vol 3 (52) ◽  
pp. 15-28
Author(s):  
Eduard V. Batunaev ◽  
Yulia G. Grigoryeva
Keyword(s):  
East Asia ◽  
Large Scale ◽  
Transition Period ◽  
Northeast Asia ◽  
Economic Cooperation ◽  
Asia Pacific ◽  
Infrastructure Development ◽  
North East ◽  
Level Of Economic Development ◽  
Multi Stakeholder

Статья посвящена изучению характера торгово-экономического сотрудничества Монголии со странами Северо-Восточной Азии (СВА). На основе официальных статистических данных проанализирован торговый оборот, экспорт и импорт, определён характер внешнеторгового баланса Монголии со странами СВА. Показаны тенденции торгово-экономического и инвестиционного сотрудничества Монголии и СВА, участия в международных интеграционных проектах. Особое внимание уделяется новым формам и механизмам реализации многостороннего взаимодействия на региональном и мировом уровнях стран СВА и Монголии. Актуальность исследования обусловлена тем, что в условиях глобализации мировой экономики субрегион Северо-Восточная Азия характеризуется динамичным развитием и имеет большой потенциал экономического и интеграционного сотрудничества в АТР. Вместе с тем, страны, входящие в СВА, отличаются разным уровнем экономического развития и политического устройства, что создаёт определённые препятствия в достижении целей в реализации крупных совместных проектов в СВА и АТР. Монголия в переходный период провела трансформацию политической и экономической системы, ориентируется на открытую и многоопорную внешнюю политику, является членом многих международных организаций. Монголии для успешной реализации всех намеченных планов по торгово-экономичес¬кому сотрудничеству, развитию инфраструктуры, транспортно-логистических проектов, привлечения инвестиций жизненно важно участие в интеграционных проектах со странами СВА. Новизна исследования видится в том, что обозначен круг существующих проблем и пути их преодоления в торгово-экономическом и интеграционном сотрудничестве Монголии и стран Северо-Восточной Азии. The article is devoted to the study of trade and economic cooperation between Mongolia and the countries of North-East Asia (NEA). Based on official statistics, the trade turnover, export and import were analyzed, the nature of the foreign trade balance of Mongolia with the countries of Northeast Asia was determined. The trends in trade, economic and investment cooperation between Mongolia and NEA as well as participation in international integration projects were shown. Particular attention was paid to the new forms and mechanisms for the implementation of multilateral cooperation at the regional and global levels of the countries of NEA and Mongolia. The relevance of the study is confirmed by the fact that in the context of global economic globalization, the Northeast Asia subregion is characterized by dynamic development and has great potential for economic and integration cooperation in the Asia-Pacific region. At the same time, the countries that are part of NEA have a different level of economic development and political structure that creates certain obstacles to achieving the goals in implementing large-scale joint projects in NEA and Asia-Pacific. Mongolia in the transition period has transformed the political and economic system focusing on an open and multi-stakeholder foreign policy; it is a member of many international organizations. In order to successfully implement all plans for trade and economic cooperation, infrastructure development, transport and logistics projects and attracting investment call for Mongolia’s participation in integration projects with NEA countries. The novelty of the study is that it defines the circle of existing problems and ways to overcome them in the trade, economic and integration cooperation of Mongolia and the countries of North-East Asia.

scholarly journals Effects of Cloud Microphysics on Tropical Atmospheric Hydrologic Processes and Intraseasonal Variability

2005 ◽  
Vol 18 (22) ◽  
pp. 4731-4751 ◽  
Author(s):  
K. M. Lau ◽  
H. T. Wu ◽  
Y. C. Sud ◽  
G. K. Walker
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Water Cycle ◽  
Deep Convection ◽  
Intraseasonal Variability ◽  
Lower Troposphere ◽  
Circulation Model ◽  
Cloud Microphysics ◽  
Hydrologic Processes ◽  
Warm Rain

Abstract The sensitivity of tropical atmospheric hydrologic processes to cloud microphysics is investigated using the NASA Goddard Earth Observing System (GEOS) general circulation model (GCM). Results show that a faster autoconversion rate leads to (a) enhanced deep convection in the climatological convective zones anchored to tropical land regions; (b) more warm rain, but less cloud over oceanic regions; and (c) an increased convective-to-stratiform rain ratio over the entire Tropics. Fewer clouds enhance longwave cooling and reduce shortwave heating in the upper troposphere, while more warm rain produces more condensation heating in the lower troposphere. This vertical differential heating destabilizes the tropical atmosphere, producing a positive feedback resulting in more rain and an enhanced atmospheric water cycle over the Tropics. The feedback is maintained via secondary circulations between convective tower and anvil regions (cold rain), and adjacent middle-to-low cloud (warm rain) regions. The lower cell is capped by horizontal divergence and maximum cloud detrainment near the freezing–melting (0°C) level, with rising motion (relative to the vertical mean) in the warm rain region connected to sinking motion in the cold rain region. The upper cell is found above the 0°C level, with induced subsidence in the warm rain and dry regions, coupled to forced ascent in the deep convection region. It is that warm rain plays an important role in regulating the time scales of convective cycles, and in altering the tropical large-scale circulation through radiative–dynamic interactions. Reduced cloud–radiation feedback due to a faster autoconversion rate results in intermittent but more energetic eastward propagating Madden–Julian oscillations (MJOs). Conversely, a slower autoconversion rate, with increased cloud radiation produces MJOs with more realistic westward-propagating transients embedded in eastward-propagating supercloud clusters. The implications of the present results on climate change and water cycle dynamics research are discussed.

The influence of different underlying surface on sand-dust storm in northern China

2005 ◽  
Vol 15 (4) ◽  
pp. 431-438
Author(s):  
Song Yang ◽  
Quan Zhanjun ◽  
Liu Lianyou ◽  
Yan Ping ◽  
Cao Tong
Keyword(s):  
Dust Storm ◽  
Northern China ◽  
Underlying Surface ◽  
Sand Dust

scholarly journals Variations in the Frequency of Winter Extreme Cold Days in Northern China and Possible Causalities

2019 ◽  
Vol 32 (23) ◽  
pp. 8127-8141
Author(s):  
Chaoxia Yuan ◽  
Wenmao Li
Keyword(s):  
Large Scale ◽  
Polar Region ◽  
Climate Extremes ◽  
Northern China ◽  
Total Variance ◽  
Coupled Models ◽  
Cold Air ◽  
Air Temperatures ◽  
Weather And Climate ◽  
Extreme Cold

Abstract Weather and climate extremes often cause devastating disasters and motivate research to improve their understanding. Here, the spatiotemporal variations in the frequency of winter extreme cold days (WECDs) in northern China (NC) were investigated. The results show that the first EOF mode reflects the spatially consistent anomalies and explains 39% of the total variance. The second EOF mode represents the east–west contrasted anomalies and explains 17% of the total variance. In the winter, when the negative Arctic Oscillation (AO) co-occurs with the stronger Siberian high (SH), cold air from the polar region is more easily advected southward, causing the increased number of WECDs in all of NC. The co-occurrence of negative AO and stronger SH may be related to excessive snow in the preceding autumn over northeastern Eurasia through the local positive feedback between the snow and surface air temperatures and the tropospheric–stratospheric interaction. On the other hand, in the winter when the negative AO co-occurs with the weaker SH, eastern NC is still under the influence of cold-air intrusion from the polar region relevant to the negative AO, whereas western NC is impacted by the anomalous warm-air advection related to the weaker SH. The weakening of the SH may be caused by the El Niño teleconnection. The reproducibility of the observed variations and possible causalities of WECDs in NC by 10 coupled models participating in CMIP5 has been assessed. All the models can reproduce the observed dominant EOF modes. The relevant large-scale circulation anomalies and possible causalities can also be well simulated by the multimodel ensemble.

scholarly journals Observations and transport modeling of dust storm event over Northeast Asia using HYSPLIT: case study

2019 ◽  
Vol 99 ◽  
pp. 02002
Author(s):  
Gantuya Ganbat ◽  
Dulam Jugder
Keyword(s):  
Dust Storm ◽  
Northeast Asia ◽  
Thick Layer ◽  
Northern China ◽  
Storm Event ◽  
Hysplit Model ◽  
Lidar Measurements ◽  
Dust Storm Event ◽  
High Concentrations ◽  
Dust Events

This study analyzes a regional dust storm event that occurred in spring 2016 using data from observation sites, Lidar measurements, and satellite imageries. PM10 concentrations at surface observation stations are considered as a primary indicator of the dust events. The dust events occurred on 3-12 March with PM10 reaching a maximum beyond 1682, 1498, 706, and 165 μg m−3 at observation sites in Mongolia, China, Korea and Japan, respectively. The dust event in Northeast Asia is captured by time series of PM10 concentrations at observation sites. On 3-4 March, the dust storm event originated from Mongolia move toward China, Korea and Japan. Vertical distributions of dust observed by Lidar measurements from stations in AD-Net capture a thick layer of nearly 2.2 km of high concentrations above surface in the area of origin. The maximum PM10 concentration drops with downwind transport. Dust source identification and dust-loaded air parcel trajectories are calculated using the HYSPLIT model. According to the HYSPLIT model, the dust storm started on 3-4 March from Mongolia and reached northern Japan in about 4 days passing over northern China and Korea.

scholarly journals Transition between Suppressed and Active Phases of Intraseasonal Oscillations in the Indo-Pacific Warm Pool

2006 ◽  
Vol 19 (21) ◽  
pp. 5519-5530 ◽  
Author(s):  
P. A. Agudelo ◽  
J. A. Curry ◽  
C. D. Hoyos ◽  
P. J. Webster
Keyword(s):  
Large Scale ◽  
Transition Period ◽  
Numerical Models ◽  
Convective Available Potential Energy ◽  
Lower Troposphere ◽  
Diagnostic Study ◽  
Tropical Ocean ◽  
Toga Coare ◽  
Ocean Atmosphere ◽  
Intraseasonal Oscillations

Abstract Intraseasonal oscillations (ISOs) are important large-amplitude and large-scale elements of the tropical Indo-Pacific climate with time scales in the 20–60-day period range, during which time they modulate higher-frequency tropical weather. Despite their importance, the ISO is poorly simulated and predicted by numerical models. A joint diagnostic and modeling study of the ISO is conducted, concentrating on the period between the suppressed and active (referred to as the “transition”) period that is hypothesized to be the defining stage for the development of the intraseasonal mode and the component that is most poorly simulated. The diagnostic study uses data from the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE). It is found that during the transition period, the ocean and the atmosphere undergo gradual but large-scale and high-amplitude changes, especially the moistening of the lower troposphere caused jointly by the anomalously warm sea surface temperature arising from minimal cloud and low winds during the suppressed phase and the large-scale subsidence that inhibits the formation of locally deep convection. Using a cloud classification scheme based on microwave and infrared satellite data, it is observed that midtop (cloud with a top in the middle troposphere) nonprecipitating clouds are a direct response of the low-level moisture buildup. To investigate the sensitivity of ISO simulations to the transitional phase, the European Centre for Medium-Range Weather Forecasts (ECMWF) coupled ocean–atmosphere climate model is used. The ECMWF was run serially in predictive ensemble mode (five members) for 30-day periods starting from 1 December 1992 to 30 January 1993, encompassing the ISO occurring in late December. Predictability of the active convective period of the ISO is poor when initialized before the transitional phases of the ISO. However, when initialized with the correct lower-tropospheric moisture field, predictability increases substantially, although the model convective parameterization appears to trigger convection too quickly without allowing an adequate buildup of convective available potential energy during the transition period.

Influence of Cold Air Intrusions on the Wet Season Onset over Amazonia

2006 ◽  
Vol 19 (2) ◽  
pp. 257-275 ◽  
Author(s):  
Wenhong Li ◽  
Rong Fu
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Atmospheric Condition ◽  
Lower Troposphere ◽  
Southeastern Brazil ◽  
Wet Season ◽  
Austral Spring ◽  
Cold Air ◽  
Cold Fronts ◽  
Thermodynamic Conditions

Abstract Using 15-yr data from the European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-15), the authors found that rapid southeastward expansion of the rainy area from the western Amazon to southeastern Brazil is a result of midlatitude cold air intrusions. During austral spring, as the large-scale thermodynamic structure over Amazonia becomes destabilized, the incursions of extratropical cold air can trigger intense rainfall along the leading edge of northwest–southeast-oriented cold fronts east of the Andes. As these fronts penetrate into Amazonia, the northerly or northwesterly wind transports warm, moist air from the western Amazon to southeast Brazil. Moisture convergence consequently intensifies, resulting in northwest–southeast-elongated rainy areas. The latter contribute to the observed rapid, southeastward expansion of rainy areas shown in rainfall climatology during austral spring. The authors’ analysis suggests that cold air intrusions during austral spring collectively assist the transformation of large-scale thermodynamic and dynamic environments to those favorable for the wet season onsets. Each time the cold fronts pass by, they tend to increase the atmospheric humidity and the buoyancy of the lower troposphere, which destabilizes the atmosphere. In the upper troposphere, the cold air intrusions supply kinetic energy for the development of anticyclonic flow. Cold air intrusions in the transitional season are not different from those occurring immediately before the wet season onsets except that the latter occurs under a more humid and unstable atmospheric condition. Thus, cold air intrusions can trigger the wet season onsets only when atmospheric and land surface conditions are “ready” for the onset. Comparisons among early, normal, and late onsets on an interannual scale further suggest that more frequent and stronger cold air intrusions trigger the early onsets of wet seasons given suitable large-scale thermodynamic conditions. Likewise, less frequent and weaker cold air intrusions could delay the wet season onset even though the large-scale thermodynamic conditions appear to be favorable. Occasionally, strong unstable atmospheric thermodynamic conditions and northerly reversal of cross-equatorial flow can lead to wet season onsets without cold air intrusions. In such cases, enhanced precipitation is centered over central and eastern Amazon, and rainfall increases more gradually compared to the onset with cold air intrusions.

Modeling Water Vapor and Clouds as Passive Tracers in an Idealized GCM

2018 ◽  
Vol 31 (2) ◽  
pp. 775-786 ◽  
Author(s):  
Yi Ming ◽  
Isaac M. Held
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Large Scale ◽  
Probability Distributions ◽  
Water Vapor Pressure ◽  
Substantial Reduction ◽  
Lower Troposphere ◽  
Circulation Model ◽  
Cloud Microphysics ◽  
Cloud Fraction

This paper introduces an idealized general circulation model (GCM) in which water vapor and clouds are tracked as tracers, but are not allowed to affect circulation through either latent heat release or cloud radiative effects. The cloud scheme includes an explicit treatment of cloud microphysics and diagnoses cloud fraction from a prescribed subgrid distribution of total water. The model is capable of qualitatively capturing many large-scale features of water vapor and cloud distributions outside of the boundary layer and deep tropics. The subtropical dry zones, midlatitude storm tracks, and upper-tropospheric cirrus are simulated reasonably well. The inclusion of cloud microphysics (namely rain re-evaporation) has a modest but significant effect of moistening the lower troposphere in this model. When being subjected to a uniform fractional increase of saturated water vapor pressure, the model produces little change in cloud fraction. A more realistic perturbation, which considers the nonlinearity of the Clausius–Clapeyron relation and spatial structure of CO2-induced warming, results in a substantial reduction in the free-tropospheric cloud fraction. This is reconciled with an increase of relative humidity by analyzing the probability distributions of both quantities, and may help explain partly similar decreases in cloud fraction in full GCMs. The model provides a means to isolate individual processes or model components for studying their influences on cloud simulation in the extratropical free troposphere.

Sign in / Sign up

Export Citation Format

Share Document