• Title/Summary/Keyword: winter monsoon

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Interaction among the East Asian Summer and Winter Monsoons, the Tropical Western Pacific and ENSO Cycle

  • Huang, Rong-Hui;Lu, Ri-Yu;Chen, Wen;Chen, Ji-Rong
    • Atmosphere
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    • v.13 no.2
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    • pp.47-68
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    • 2003
  • Recent advances in the studies on the interaction between Asian monsoon and ENSO cycle are reviewed in this paper. Through the recent studies, the East Asian summer monsoon circulation system and the East Asian climate system have proposed. Moreover, different responses of the (winter and summer) monsoon circulation and summer rainfall anomalies in East Asia to ENSO cycle during its different stages have been understood further. Recently, the studies on the dynamical effect of East Asian monsoon on the thermal variability of the tropical western Pacific and ENSO cycle have been greatly advanced. These studies demonstrated further that ENSO cycle originates from the tropical western Pacific, and pointed out that the dynamical effect of East Asian winter and summer monsoons on ENSO cycle may be through the atmospheric circulation and zonal wind anomalies over the tropical western Pacific, which can excite the oceanic Kelvin wave and Rossby waves in the equatorial Pacific. Besides, the scientific problems in the interaction between Asian monsoon and ENSO cycle, which should be studied further in the near future, are also pointed out in this paper.

SEASONAL INCIDENCE OF IXODID TICKS GROWN IN PASTURE OF BANGLADESH

  • Gaisuddin, M.;Haq, M.M.;Sarker, N.R.;Rahman, M.L.
    • Asian-Australasian Journal of Animal Sciences
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    • v.7 no.2
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    • pp.197-200
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    • 1994
  • The study was conducted in the Bangladesh Agricultural University campus, Mymensingh, from July 1988 to June 1990. Five grazing fields consisting of five different vegetations were selected for this study. The specimen were collected from this study. The specimen were collected from the grazing fields by dragging method. The results revealed that two species of ticks namely Boophilus microplus and Haemaphysalis bispinosa were collected from five different vegetation. The highest incidence of both B. microplus and H. bispinosa were recorded during winter season and lowest in Monsoon for the year of 1988-89 and 1989-90. These two species were significantly occurred in Winter followed by Monsoon and Autumn.

Numerical Simulation of the Asian Monsoon for the Mid-Holocene Using a Numerical Model (수치모델을 이용한 홀로세 중기의 아시아 몬순순환 변화 연구)

  • Kim, Seong-Joong;Lee, Bang-Yong;Park, Yoo-Min;Suk, Bong-Chool
    • Ocean and Polar Research
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    • v.27 no.3
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    • pp.289-297
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    • 2005
  • The change in global climate and Asian monsoon patterns during the mid-Holocene, 6000 years before present (6 ka), is simulated by a climate model at spectral truncations of T170 with 18 vertical layers, corresponding to grid-cell sizes of roughly 75km. The present simulation is forced with the observed monthly data of sea surface temperatures, and the specified concentration of atmospheric carbon dioxide, while in the mid-Holocene experiment, orbital parameters such as obliquity, precession, and eccentricity are changed to the 6ka conditions. Under such conditions, the precipitation associated with the summer monsoon is enhanced over a wider zonal band from the Middle East to Southeast Asia, while no significant alteration takes Place in winter. The monsoonal wind also increases over the Arabian Sea, showing the enhanced southwesterly wind during summer and northeasterly wind during winter. Overall, the showing of the Asian monsoon is enhanced during the mid-Holocene, especially in summer, which is consistent with the proxy estimates and other previous model simulations.

Three Reanalysis Data Comparison and Monsoon Regional Analysis of Apparent Heat Source and Moisture Sink (겉보기 열원 및 습기 흡원의 세 재분석 자료 비교와 몬순 지역별 분석)

  • Ha, Kyung-Ja;Kim, Seogyeong;Oh, Hyoeun;Moon, Suyeon
    • Atmosphere
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    • v.28 no.4
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    • pp.415-425
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    • 2018
  • The roles of atmospheric heating formation and distribution on the global circulation are of utmost importance, and those are directly related to not only spatial but also temporal characteristics of monsoon system. In this study, before we clarify the characteristics of apparent heat source <$Q_1$> and moisture sink <$Q_2$>, comparisons of three reanalysis datasets (NCEP2, ERA-Interim, and JRA-55) in its global or regional patterns are performed to clearly evaluate differences among datasets. Considering inter-hemispheric difference of global monsoon regions, seasonal means of June-July-August and December-January-February, which is summer (winter) and winter (summer) in the Northern (Southern) Hemisphere are employed respectively. Here we show the characteristics of eight different regional monsoon regions and find contributions of <$Q_2$> to <$Q_1$> for the regional monsoon regions. Each term in apparent heat source and moisture sink is shown to come from the ERA-Interim dataset, since the ERA-Interim could be representative of three datasets. The NCEP2 data has a different characteristic in the ratio of <$Q_2$> and <$Q_1$> because it overestimates <$Q_1$> compared to the other two different datasets. The Australia monsoon has been performing better over time, while some regional monsoons (South America, North America, and North Africa) have been showing increasing data inconsistency. In addition, the three reanalysis datasets are getting different marching with time, in particular since the early 2000s over South America, North America, and North Africa monsoon regions. The recent inconsistency among the three datasets that may be associated with the global warming hiatus remains unexplored.

A Numerical Study on the Formation Mechanism of a Mesoscale Low during East-Asia Winter Monsoon

  • Koo, Hyun-Suk;Kim, Hae-Dong;Kang, Sung-Dae;Shin, Dong-Wook
    • Journal of the Korean earth science society
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    • v.28 no.5
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    • pp.613-619
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    • 2007
  • Mesoscale low is often observed over the downstream region of the East Sea (or, northwest coast off the Japan Islands) during East-Asia winter monsoon. The low system causes a heavy snowfall at the region. A series of numerical experiments were conducted with the aid of a regional model (MM5 ver. 3.5) to examine the formation mechanism of the mesoscale low. The following results were obtained: 1) A well-developed mesoscale low was simulated by the regional model under real topography, NCEP reanalysis, and OISST; 2) The mesoscale low was simulated under a zonally averaged SST without topography. This implies that the meridional gradient of SST is the main factor in the formation of a mesoscale low; 3) A thermal contrast ($>10^{\circ}C$) of land-sea and topography-induced disturbance served as the second important factor for the formation; 4) Paektu Mountain caused the surface wind to decelerate downstream, which created a more favorable environment for thermodynamic modification than that was found in a flat topography; and 5) The types of cumulus parameterizations did not affect the development of the mesoscale low.

Variation of the Relationship Between Arctic Oscillation and East Asian Winter Monsoon in CCSM3 Simulation

  • Wie, Jieun;Moon, Byung-Kwon;Lee, Hyomee
    • Journal of the Korean earth science society
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    • v.40 no.1
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    • pp.1-8
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    • 2019
  • Although recent reports suggest that the negative correlation between the Arctic Oscillation (AO) and the East Asian winter monsoon (EAWM) has been strengthened, it is not clear whether this intermittent relationship is an intrinsic oscillation in the climate system. We investigate the oscillating behavior of the AO-EAWM relationship at decadal time scales using the long-term (500-yr) climate model simulation. The results show that ice cover over the East Siberian Seas is responsible for the change in the coupling strength between AO and EAWM. We found that increased ice cover over these seas strengthens the AO-EAWM linkage, subsequently enhancing cold advection over the East Asia due to anomalous northerly flow via a weakened jet stream. Thus, this strengthened relationship favors more frequent occurrences of cold surges in the EAWM region. Results also indicate that the oscillating relationship between AO and EAWM is a natural variability without anthropogenic drivers, which may help us understand the AO-EAWM linkage under climate change.

The characteristics of folk house related to climate in Cheju island (기후 특성과 관련된 제주도의 민가 경관)

  • Kim, Ki-Deog;Lee, Seung-Ho
    • Journal of the Korean association of regional geographers
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    • v.7 no.3
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    • pp.29-43
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    • 2001
  • This paper examined characteristics of folk houses related to climate in Cheju island using climate data, documents and field survey data. Precipitation and humidity affect characteristics of folk houses in the southern parts of the island during summer while in winter, northern parts are mainly affected by wind. Chuck-gub has been shown through all over Cheju island due to the characteristics of precipitation. Jaechangmoon exists in southern parts of the island and these parts are experienced high humidity in summer The double-row room houses, the low eaves, gentle slop roof and stone wall are distributed through Cheju island and is related to wind. The double door is common in the northern parts because of strong winter monsoon, and Yimoonkan exists in the coastal area of the northern parts. Outer wall, Pung-Che and Gorangche are affected by winter monsoon and abundant precipitation. Gorangche has shown through both the northern parts and southeastern parts. Folk houses in the southern parts are more open than in northern parts. Folk houses in the northern parts are divided into the coastal type and the piedmont type. In the southern parts, they are subdivided the eastern type and the western type by the appearance of Gorangche.

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Analysis of Regional Occurrence of Hail over Korean Peninsular (국내의 지역별 우박 발생 빈도 분석)

  • Lee, Young-Kyu;Lee, Jae-Soo;Lee, Sung-Su;Kim, Hak-Sun
    • 한국방재학회:학술대회논문집
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    • 2007.02a
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    • pp.81-84
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    • 2007
  • Data for occurrence of hail over Korean Peninsula for the period 1961-2005 are obtained from the Korea Meteorological Administration (KMA). According to the average occurrences during each season in Korea Peninsular, hail days are almost distributed uniformly in the spring, fall and winter, except the summer and have averages of 5 days for each season. Analysis of regional occurrence of hail shows that inland of Korea Peninsular is vulnerable to hail in the spring and summer and the islands of Ullung, Baegryeong and Cheju and the coastal regions vulnerable in the fall and winter. It can be postulated that these seasonal patterns of hail is affected by the Monsoon effect.

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A Study on the Safe Operations of Ships under Heavy Weather Conditions in the North Pacific(II) (북태평양의 악기상조건과 선박의 안전운항에 관한 연구(II))

  • 민병언
    • Journal of the Korean Institute of Navigation
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    • v.14 no.2
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    • pp.33-59
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    • 1990
  • In cold season, the developed extratropical cyclones and associated cold fronts, and NW winter monsoon are encountered very frequently in the North Pacific, especially in the northwest part of it. The two sea areas, namely, the northwest part of North Pacific, especially the eastern area far off Japan east coast, and Burmuda Triangle in the North Atlantic are generally known as two of the most dangerous areas in the world because of high incidence of sea casualties. Even large ocean going vessels were sunk frequently due to strong winds and very high seas caused by NW monsoon or developed cyclones during the winter months. The purpose of this paper is to analyse the real state of heavy weather and high sea phenomena on the vesscls at sea, thus helping mariners operate in such conditions.

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A Study on the Safe Operations of Ships under Heavy Weather Conditions in the North Pacific(I) (북태평양의 악기상조건과 선박의 안전운항에 관한 연구(I))

  • 민병언
    • Journal of the Korean Institute of Navigation
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    • v.11 no.1
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    • pp.107-144
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    • 1987
  • In cold season, ice accretion on ship, drift ice, NW winter monsoon, developed extratropical cyclones and associated cold fronts, in warm season, tropical cyclones and dense sea fogs, are encountered very frequently in the North Pacific, especially in the northwest part of it. The two areas, namely, the northwest part of the North Pacific and Burmuda Triangle in the North Atlantic are generally known as most dangerous areas in the world because its high incidence of sea cascualities. In recent years, the small fisherboats operating in the northern seas were frequently sunk in a group as they encountered ice accretion or drift ice. And ocean going vessels were also sunk frequently due to strong winds and very high seas in winter monsoon or developed cyclones and cold fronts. The purpose of this paper is to analyze the real state of heavy weather conditions such as ice accretion on ship drift, ice, typhoons and sea fogs, and also to analyse the effect of these heavy weather phenomena on the vessels at sea, thus helping mariners operate in such heavy weather conditions.

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