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seasonal　Transition　of　Summer　rainy　season　over　Indochina　and　Adjacent　Monsoon　Region

Advances in Atmospheric Sciences 1997年第2期14卷 108-122页

作者： Jun MatsumotoDepartment of Geography, University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo 113, Japan

The mean onset and withdrawal of summer rainy season over the Indochina Peninsula were investigated using 5-day averaged rainfall data (1975-87). The mean seasonal transition process during onset and retreat phases in Indochina, India and the South China Sea is also examined using 5-day mean OLR (1975-87) and 850 hPa wind (1980-88) data. It was found that the onset of summer rainy season begins earlier in the inland region of Indochina (Thailand) in late April to early May than in the coastal region along the Bay of Bengal. This early onset of rainy season is due to pre-monsoon rain under the mid-latitude westerly wind regime. The full summer monsoon circulation begins to establish in mid-May, causing active convective activity both over the west coast of Indochina and the central South China Sea. In case of withdrawal, the earliest retreat of summer rainy season is found in the central northern part of Indochina in late September. The wind field, on the other hand, already changes to easterlies in the northern South China Sea in early September. This easterly wind system covers the eastern part of Indochina where post-monsoon rain is still active. In late October, the wind field turns to winter time situation, but post monsoon rain still continues in the southern part of the Indochina Peninsula until late November.

关键词： seasonal transition rainy season Summer monsoon onset

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Estimation of precipitation condensation latent heat in rainy season over Qinghai-Tibet Plateau

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Research in Cold and Arid Regions 2009年第2期1卷 99-106页

作者： DongLiang Li Hui Wang Miao Liu NIM Nanjing University of Information Science and TechnologyNanjingJiangsu 210044China. Cold and Arid Regions Environmental and Engineering Research Institute CASLanzhouGansu 730000China. Climate Center of Zhejiang Province HangzhouZhejiang 310017China.

The basic data for this research comprise the outgoing long-wave radiation(OLR) data observed by the United States National Oceanic and Atmospheric Administration(NOAA) series satellites from June 1974 through December 2005 over the area of 75°-105°E and 25°-40°N(totaling 91 grid zones when the horizontal resolution is 2.5° longitude by 2.5° latitude) and the monthly rainfall data recorded,from 1961 through 2005,by 93 conventional meteorological stations on the Qinghai-Tibet Plateau.Based on the research of the relation between rainfall and OLR and climate regionalization,a mathematic model was established for each region and grid zone,which is applied to estimate the monthly rainfall and then to estimate the monthly latent heat resulting from the condensation of precipitation year by year from 1961 through 2005.The results indicated that the multi-year average precipitation is 401.5 mm and the condensation latent heat is 18.55×1020 J in the eastern part of the Qinghai-Tibet Plateau;the increasing rate of condensation latent heat is 0.218×1020J/10a in the recent 45 years;that is to say,it will increase 1.2 percent in each decade.Furthermore,the total condensation latent heat and its variation rate in the Qinghai-Tibet Plateau are slightly larger than in the east to the plateau.

关键词： Qinghai-Tibet Plateau rainy season rainfall OLR condensation latent heat

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Agroclimatological Characteristics of rainy seasons in Southwestern Burkina Faso during the 1970-2013 Period

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Atmospheric and Climate Sciences 2022年第2期12卷 330-357页

作者： Boubacar Ibrahim Moussa Waongo Moussa Sidibe Safietou Sanfo Boubacar Barry Département de Géologie Faculté des Sciences et Techniques Université Abdou Moumouni de Niamey Niamey Niger Centre Régional AGRHYMET Niamey Niger Competence Center West African Science Service Center on Climate Change and Adapted Land Use (WASCAL) Ouagadou-gou Burkina Faso Laboratoire de Developpement Agricole et Transformation de l’Agriculture (DATA) Université Thomas Sankara Ouagadougou Burkina Faso

The different drought phases observed during the 1970-2010 period have underlined important weaknesses of West African agricultural systems. The droughts resulted in important decreases in crop production, triggering a significant deficit in food availability. Many studies have identified changes in rain events seasonal patterns as the key drivers of agricultural production failure during these drought phases. In this study, seven agriculturally-relevant intra-seasonal rainfall characteristics (i.e., annual rainfall amount, onset and cessation of the rainy season, dry spells, extreme rain events, hot spells, and strong winds) and associated constraints to crop growth are described for the main cereals (maize, millet, and sorghum) in southwestern Burkina Faso. These characteristics are calculated or determined using daily climate data from a local network of 16 weather stations spanning the 1970-2013 period. A computation of the intensity and the occurrence of these phenomena during the rainy seasons helped to draw the rainy seasons’ nomenclature. Findings suggest that the rainy seasons during the drought phases are characterized by low annual rainfall amount, late onset, early cessation and more frequent long dry spells (>7 days). Furthermore, the long dry spells mostly occurred during the most sensitive phases of crop development: germination at the beginning of the rainy season and flowering at the end of the rainy season. Also, the intensity and the probability of occurrence of the other extreme events (hot spells and strong winds) during rainy seasons are very high in the establishment phase. Thus, adaptation strategies to mitigate these unfavorable climate conditions include a selection of short-cycle crop varieties combined with supplementary irrigation systems during long dry spells.

关键词： Climate Variability rainy season Dry Spell Hot Spell Burkina Faso

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The Influence of Local rainy and Dry seasons on the Diurnal Temperature Range in Nigeria

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Atmospheric and Climate Sciences 2023年第2期13卷 314-332页

作者： Stanley I. Echebima Andrew A. Obafemi Institute of Natural Resources Environment and Sustainable Development University of Port Harcourt Port Harcourt Nigeria

This study analyzed the impact of the local dry and rainy seasons on diurnal temperature range (DTR), for each major climatic zone of Nigeria namely the tropical monsoon, tropical savannah and semi-arid, using meteorological data from thirteen observation stations for the period 1981 to 2021. DTR was computed from the difference of minimum temperature from maximum temperature and yearly and forty one years’ monthly averages of DTR and rainfall were computed and plotted in different graphs. The overall results from each climatic zone showed that DTR fluctuates with the seasons and there is an inverse relationship between DTR and rainfall whereby the value of DTR decreases as the rainy season approaches but increases as the rainy season departs ushering in the dry season or conversely DTR increases as the dry season approaches and decreases as the dry season departs ushering-in the rainy season. Secondly, the average yearly patterns of rainfall and DTR are roughly and oppositely shaped parabolas where the peak value of rainfall is diametrically opposite to the trough value of DTR and the least or nil volume of rainfall corresponds to the highest value of DTR. Thirdly, due to the yearly seasonal cycle of dry and rainy seasons in Nigeria coupled with the inverse relationship between DTR and Rainfall, the seasonal plot of DTR and rainfall is also cyclic in pattern with DTR cycle lagging 180 degrees with the rainfall cycle and the intersection of the two cycles represents the departure of one season and onset of another season while each half-cycle represents either the dry or rainy season. Fourthly, the dependence of DTR on any season at hand in Nigeria makes DTR season-forcing. This fourth result is underpinned by a result that showed that the 1981 and 2021 patterns of DTR and 1981 and 2021 patterns of rainfall when compared were similar, the differences were in the volume of rainfall which was due to climate change that has taken place over the four decades and which also impacted DTR since DTR varies inversely with

关键词： Dry season rainy season Harmattan Period Primary and Secondary Axes of a Graph

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seasonal transition and its boundary layer characteristics in Anduo area of Tibetan Plateau

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Progress in Natural Science:Materials International 2005年第3期 47-53页

作者： ZUO Hongchao ˇˇ ,HU Yinqiao,LI Dongliang,L Shihua and MA Yaoming (Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences,Lanzhou730000,China)

Using the data,especially the GPS rawinsode data,observed in Anduo area of the Tibetan Plateau during the intensive observation period of GAME/Tibet in1998,the transition from the dry to the rainy season along with their boundary layer characteristics is analyzed comprehensively.The result shows that the formation of the rainy season in Anduo area is related closely to the general atmo-spheric circulation.The westerly belt moving north and the southeast damp current are basic conditions for development of the rainy season in Anduo area.In the dry season,the air is drier,air temperature higher,and the atmospheric boundary layer is strongly developed to cause its maximum height to reach about3550m.Moreover the sensible heat flux is dominant,and the latent heat flux is small in the in-teraction of land-atmosphere energy exchange,and a reverse humidity phenomenon occurs frequently.In the rainy season,the air is damper,air temperature lower,and the ABL height,with maximum of only about2300m,is lower.And the sensible heat flux becomes much smaller,the latent heat flux much larger in the interaction of land-atmosphere energy exchange.The reverse humidity phenomenon disappears.

关键词： dry season rainy season seasonal transition general atmospheric circulation land-atmosphere energy exchange.

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Main Polysaccharides Isolated and Quantified of Aloe vera Gel in Different seasons of the Year

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Food and Nutrition Sciences 2016年第6期7卷 447-453页

作者： Berenice Aranda Cuevas Carlos Hernán Herrera Méndez Ignacio Islas Flores Sara Solís-Pereira Luis Cuevas-Glory Gerardo Rivera Muñoz María de Lourdes Vargas y Vargas Jorge Tamayo Cortez Research and Postgraduate Division Instituto Tecnológico de Mérida Mérida Mexico Agroindustrial Engineering Department Universidad de Guanajuato Campus Celaya-Salvatierra Salvatierra México Centro de Investigación Científica de Yucatán Mérida México

We developed and implemented a methodology that allowed extracting and evaluating high molecular weight polysaccharides present in the gel of Aloe barbadensis Miller. One of the fractions evaluated revealed the presence of high molecular weight carbohydrates (200 kDa) with a behavior similar to that of acemannan and another fraction with compounds of molecular weights between 17 and 47 kDa. We quantified the concentration of acemannan for two different growing periods. The concentration of acemannan in the high molecular weight fraction was 99.97 ppm in the rainy season and 106.03 ppm in the dry season. The concentration of acemannan in the fraction of low molecular weight was 9.364 ppm during the season of greatest rainfall and 26.939 ppm in the dry season.

关键词： Acemannan Aloe vera Gel Polysaccharides rainy season Dry season

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