Seasonal Transition of Summer Rainy Season over Indochina and Adjacent Monsoon Region

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.

Reconstruction of the starting time series of rainy season in Yunnan and the evolvement of summer monsoon during 1711-1982

According to the textual research into the historical documents dominated by archives yearly, as well as the verification with several other kinds of data, the later or earlier starting time of the rainy seasons in Yunnan during 1711-1982 has been reconstructed. The analysis indicates that there are obvious fluctuations in the starting date of the rainy seasons in Yunnan in a year or years, and long fluctuation on the decadal scale. The rainy season comes earlier in the early 18th century, later in the 19th century and earlier again in the 20th century. This reflects to a certain degree the gradual change of the summer monsoon in Yunnan. There exists an obvious quasi-3 years cycle, which is related to EI-Nino＇s quasi-3 years cycle, and a 11.3-year cycle which is notably related to the 11-year cycle of the solar activity of starting date of the rainy seasons in Yunnan. Meanwhile, the dissertation finds that the EI-Nino is very important to the starting date of the rainy seasons in Yunnan. The starting date of the rainy seasons in Yunnan often comes later or normally in the year of EI-Nino. However, there is an obvious imperfect period in such influence, which in turn may mean that there is a certain fluctuation in the effect of ENSO on Asian summer monsoon.

Structure and Propagation Characteristics of Climatological Mean Kinetic Energy of Disturbance of Intraseasonal Oscillation in Asian Summer Monsoon Zone

[Objective] The research aimed to study the structure and propagation characteristics of climatological mean kinetic energy of disturbance of intraseasonal oscillation in Asian summer monsoon zone. [Method] When South China Sea monsoon started to break out, the kinetic energy of intraseasonal oscillation disturbance in the monsoon zone was analyzed, especially the researches about the variation of South China Sea monsoon, the development of Indian monsoon and the advancement of East Asian monsoon. [Result] The developed process of Asian summer monsoon had the close relationship with the kinetic energy activity of 30-60 d low-frequency oscillation disturbance. The kinetic energy of disturbance explained the eruption, occurrence, development and termination of monsoon from the energy angle. It was found that the kinetic energy of disturbance in Arabian Sea zone, Bay of Bengal and South China Sea area was the strongest, especially in Arabian Sea zone. It illustrated that Arabian Sea zone (Somali jet) was the biggest energy source of Asian monsoon. The starting mark of monsoon eruption in the whole Asia was the abrupt eruption of South China Sea monsoon. The eruption of South China Sea monsoon in the middle dekad of May was the westward transmission result of kinetic energy of disturbance on the east sea surface of Philippines. The kinetic energy of disturbance in East Asian monsoon zone had the seasonal northward advancement in summer. The high kinetic energy center of disturbance in Indian monsoon zone changed from one to two. They were respectively in Arabian Sea and Bay of Bengal. [Conclusion] The research provided the theory basis for analyzing the atmospheric intraseasonal oscillation.

T_(BB) DATA-REVEALED FEATURES OF ASIAN-AUSTRALIAN MONSOON SEASONAL TRANSITION AND ASIAN SUMMER MONSOOM ESTABLISHMENT

Based on TBB data from Meteorological Institute Research of Japan, study is carried out of the features of seasonal transition of Asian-Australian monsoons and Asian summer monsoon establishment,indicating that the transition begins as early as in April, followed by abrupt change in May-June; the Asian summer monsoon situation is fully established in June. The winter convective center in Sumatra moved steadily northwestward across the "land bridge" of the maritime continent and the Indo-China Peninsula as time goes from winter to summer, thus giving rise to the change in large scale circulations that is responsible for the summer monsoon establishment over SE Asia and India; the South China Sea to the western Pacific summer monsoon onset bears a close relation to the active convection in the Indo China Peninsula and steady eastward retreat of the subtropical TBB high-value band,corresponding to the western Pacific subtropical high.

Analysis of Causes and Seasonal Prediction of the Severe Floods in Yangtze／Huaihe Basins during Summer 1991

The present paper shows that a seasonal prediction for the large scale flooding and waterlogging of the mid-lower Yangtze/ Huaihe River basins in the summer of 1991 made successfully in early April 1991.The seasonal forecasting method and some predictors are also introduced and analyzed herein. Because the extra extent of the abnormally early onset of the plum rain period in 1991 was unexpected,great efforts have been made to find out the causes of this abnormality. These causes are mainly associated with the large scale warming of SST surrounding the south and east part of Asia during the preceding winter,while the ENSO-like pattern of SSTA occurred in the North Pacific.In addition,the possible influence of strong solar proton events is analyzed.In order to improve the seasonal pre4iction the usage of the predicted SOl in following spring/summer is also introduced.The author believes thatthe regional climate anomaly can be correctly predicted for one season ahead only on the basis of physical understanding of the interactions of many preceding factors.

夏闲季不同耕作措施对旱地麦田土壤养分含量和酶活性的影响

为明确夏闲季不同耕作措施对旱地麦田土壤理化特性和酶活性的影响,基于2018年开始设置在黄土高原与黄淮海平原交汇处典型旱作区洛宁县小界乡的夏闲季定位耕作管理大区试验,2020—2022年研究了传统翻耕(CT)、一次深翻(DT)、免耕覆盖(NTM)、深松覆盖(STM)和深松垄沟覆盖(SRFM)5种夏闲季耕作措施对旱地麦田土壤三相比、养分含量和酶活性的影响。结果表明,优化夏闲季耕作措施可改善旱地麦田土壤三相比,提高土壤养分含量和酶活性,总体以SRFM效果最好。与CT相比,STM和SRFM的三相比R值显著降低4.7%~28.2%和10.9%~33.7%,DT、STM和SRFM在0~40 cm土层土壤全氮含量分别提高2.8%~11.2%、11.7%~21.4%和15.6%~30.6%,有效磷含量分别提高6.9%~39.5%、7.4%~68.8%和13.6%~80.3%,速效钾含量分别提高5.2%~19.7%、9.6%~25.8%和13.8%~35.0%;土壤蔗糖酶活性分别提高7.8%~21.5%、17.1%~75.9%和27.9%~99.1%,脲酶活性分别提高7.6%~97.0%、12.8%~165.5%和23.5%~194.9%,过氧化氢酶活性分别提高5.5%~15.2%、16.3%~26.7%和20.8%~50.3%,增幅多达到显著水平且表现为SRFM>STM>DT,NTM可显著提高0~10 cm土层但降低20~40 cm土层土壤养分含量和酶活性。综合来看,夏闲季深松垄沟并结合秸秆覆盖的措施可改善土壤三相比,提高土壤养分含量和酶活性,是利于提高旱地麦田土壤质量的耕作措施。

云南区域夏季风雨季爆发前后大气热源和云量特征

本研究应用2001~2020年欧洲中期天气预报中心第五代再分析资料(ERA5)的气象场及卫星反演的降水和云量资料,研究了云南区域夏季风雨季爆发前后大气热源和云量的气候特征。研究结果表明:(1)云南区域的大气热源和云量会受夏季风环流的强烈影响,有着明显的逐月变化。6月受来自孟加拉湾东部的西南气流水汽输送影响,云南季风雨季爆发,大气总热源(特别是降水凝结释放的潜热)和云量较4~5月明显增强,而地表感热和大气辐射冷却作用减小。(2)基于Wang and LinHo(2002)方法计算的2001~2020年期间云南夏季风雨季的平均爆发时间约为第31候,区域大气总热源(潜热)和云量均与降水呈现出高度的时间相关性,而且云南区域大气热源和云量随夏季风雨季的时间变化呈现出与相邻的南亚热带季风区相似的单峰年变化特征。(3)云南夏季风雨季爆发时间存在明显的年际变化,雨季爆发偏早(晚)年的合成结果表明:在偏早年雨季爆发时,来自孟加拉湾东南部的低层西南气流可直达云南区域,该区域上空为辐散气流,有利于区域上升运动,云南区域大气总热源(潜热)和云量明显强于偏晚年;偏晚年同时段的孟加拉湾南支槽偏弱,西太平洋副高位置明显偏西,不利于云南区域上升运动和降水。在雨季盛期,偏早和偏晚年的区域降水率接近,偏晚年的区域大气总热源(潜热)和高云量值略高于偏早年。

夏播短季栽培对棉花成铃时空分布特征及产量构成的影响

以10个不同基因型棉花品系为试验材料,采用株式图记载棉株各部位蕾铃发生、生长和脱落情况,以探明棉花在夏播短季栽培条件下的棉铃形成时空分布特征。结果表明:在时间分布上,现蕾高峰期为播种后第56天至第80天,开花高峰期为播种后第77天至第96天,成铃高峰期为播种后第85天至第101天,各品系生殖器官(蕾、花、铃)数量积累均有显著差异;在空间分布上,P56-3、07单12、07单6和07单7表现为中部成铃最多,其余品系则表现为下部成铃最多;P56-3、07单6和07单7成铃率分布表现“下部果枝内空形”;各品系产量结构有显著差异,品系2003-29单株铃数较其他品系高19.53%~119.55%,籽棉和皮棉产量较其余品系分别高21.82%~106.32%、22.46%~134.05%,在所有参试品系中表现突出,成铃分布均匀,脱落较少,单株成铃数和产量最高,适宜在夏播短季栽培模式下种植。棉花夏播短季栽培成铃主要集中在8月,不能用传统的“三桃”比例来衡量高产优质栽培的成铃结构。

东亚夏季风和中国雨季的趋势变化和关键区气温和海温的影响

中国降水主要受到西风和季风环流的共同影响,表现出显著的年循环特征。本文基于1961~2020年CN05.1逐日降水资料和JRA55、CRU、HadISST再分析资料,采用谐波分析、相关和回归统计方法,分析了过去60年的东亚夏季风(中国雨季)的建立(开始)、撤退(结束)和持续时间等年循环参数趋势的变化特征。结果显示,自1961年以来,东亚夏季风有建立时间提前,撤退时间推后,持续时间增长的趋势,每十年分别达到了3.54、1.64、5.18天。1999年前后22年我国雨季也存在趋势变化,且在空间上存在显著差异。最近22年(1999~2020年),我国雨季提前主要集中在东北东部、青藏高原东部、西北北部地区,提前时间达5天以上,部分地区超过了20天。雨季滞后主要集中在青藏高原东北,长江以北和西部地区,时间超过了10天。雨季持续时间增加主要集中在青藏高原东北部、我国长江以北、东北东南部地区,时间超过15天以上,部分地区超过25天。研究发现,4月份环贝加尔湖地表气温增加及其伴随的局地反气旋性环流异常,是东亚夏季风建立和我国雨季开始时间提前的关键,而10月份的西北太平洋海温增暖及其伴随的西北太平洋副热带反气旋的异常是导致东亚夏季风撤退和中国北方雨季变长的关键。

基于“脾应长夏”的胃肠激素季节变化与松果腺褪黑素的相关性研究

目的:观察大鼠血清褪黑素(MT)、胃泌素(GAS)及胃动素(MTL)五季中的含量变化,探讨胃肠动力的季节变化与松果腺褪黑素的相关性,揭示“脾应长夏”内涵。方法:在春、夏、长夏、秋及冬季分批饲养SD雄性大鼠,每一季节中的大鼠随机分为对照组(不做任何处理)和模型组(行松果腺摘除术)。饲养至节气点时间春分、夏至、立秋前1 d、秋分及冬至取材,酶联免疫吸附测定法(ELISA法)检测血清中MT、GAS和MTL含量。结果:春、夏、长夏、秋、冬五季中对照组血清MT、GAS及MTL分泌存在季节性变化节律,均在长夏季节含量最低。松果腺摘除后,模型组中五季血清MT、GAS及MTL分泌的季节性变化节律发生改变,但各指标含量仍在长夏季节最低。长夏季节GAS及MTL分泌与褪黑素具有一致性。结论:胃肠消化系统的功能与中医脾藏象理论密切相关,松果腺褪黑素调节下的胃肠动力的季节变化为中医“脾应长夏”理论生理机制的研究提供了依据。

Characteristics of Atmospheric Rivers over the East Asia in Middle Summers from 2001 to 2016

Atmospheric Rivers(ARs) are narrow and elongated water vapor belts in troposphere with meridional transport across the mid-latitudes towards high-latitudes. Compared with ARs occurred over the northeastern Pacific, the western coast of North America and Europe, the ARs over the East Asia have received less attention. In this paper, the characteristics of ARs which affected China in the area 20?–60?N, 95?–165?E in the middle summer season from 2001 to 2016 were investigated by using European Center for Medium-Range Weather Forecasts(ECMWF) ERA-Interim reanalysis data and Multi-functional Transport Satellites-1 R(MTSAT-1 R) infrared data. Totally, 134 ARs occurred during that period, and averagely 8.4 ARs occurred per year. Statistically, 101 ARs were in east-west orientation, and 33 ARs were in north-south orientation, which accounts for about 75% and 25%, respectively. Herein we report the occurrence number, duration time, intensity, length, width, ratio of length to width, and extension orientation of these ARs, which provide the basic information for those who have interest in ARs over the East Asia.

气象节律视角下探析“脾主长夏”的涵义

“脾主长夏”是《黄帝内经》中脾与岁时关系的一种概念,历年来各医家均对其中长夏季的起止时间说法不一,后人对此概念阐释甚少,不利后学。运气理论中的气象节律蕴含着丰富的季节特征,其中的土季与长夏季,气候特点十分接近,运用其发病规律对长夏季病邪特点及具体时间段进行分析,认为长夏季可由1个主体时间段和2个缓冲时间段组成。主体时间段由夏至开始,到处暑结束,整体上以湿邪为主,其中前一阶段为夏至到大暑时段,暑邪流行,后一阶段为大暑到处暑时段,风湿邪气流行;处于主体时间段前后的2个缓冲时间段(芒种到夏至、处暑到白露)均蕴含湿气,并对于长夏季主体起到承前启后的作用。

2021年5月江西降水异常偏多特征及成因分析

2021年5月江西省降水异常偏多,多项降水指数突破历史极值,异常的降水在累计降水量、降水强度、日降水量等方面表现出极端性。利用1961—2021年江西省83站逐日降水资料和NCEP/NCAR再分析资料,分析了2021年5月江西降水异常偏多的主要原因。结果表明:5月大气环流异常是造成江西降水偏多的直接原因,欧亚中高纬500 hPa层环流呈“两脊一槽”的分布特征,受北大西洋三极子正位相影响,中国东北及周围地区位势高度为负距平,东北冷涡异常活跃,中高纬环流经向度增加,冷空气不断南下为降水提供了环流条件。西太平洋副热带高压月内加强西伸,为降水提供充足的水汽条件。此外,南海夏季风爆发偏晚和5月在印度洋活跃的热带季节内振荡对5月江西降水偏多有一定的指示意义。

An Analysis of the Spring-to-Summer Transition in the West Central Plains for Application to Long Range Forecasting

The spring-to-summer transition is of special importance in long range forecasting, as the general circulation transitions to a less energetic regime. This affects the Midwestern United States in a profound way, since agriculture is very sensitive to the variability of weather and climate. Beginning at the local scale, surface temperature observations are used from a representative station in the West Central Missouri Plains region in order to identify the shift from late spring to early summer. Using upper-air re-analyses as a supplement, the 500-mb height observations are examined to find a spring-to-summer transition date by tracking the location of a representative contour. Each of these is used to identify spring-to-summer transition date and then statistical analysis is performed on this long-term data set. Finally, teleconnections, specifically the influence of El Ni?o Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO), and blocking are examined in order to quantify interannual variability. It was found that examining these criteria, developed in an earlier study that covered a much shorter time period, produced similar statistics to this 68-year study of spring-to-summer transitions. It was also found that the onset of La Ni?a was associated with hotter summers in the region, a result first found in the earlier study, but this association was much stronger here.

桃源县棉花夏播短季轻简化栽培模式推广研究

我国棉花需求不断增长,但受耕地面积减少和粮食安全压力的影响,棉花种植面积难以大幅提高,因此,提高棉花单产水平对满足国内棉花需求具有重要意义。常德地区作为湖南省棉花生产大市,传统的宽行稀植、大棵壮株、大水大肥精细化栽培模式虽然单产较高,但劳动力投入大,难以适应现代农业发展趋势。为探索提高棉花单产水平的新模式,在桃源县开展了调查和试验研究。对2023年桃源县棉花生产示范点进行调查,了解不同品种、栽培方式、种植密度等情况,并调查了2020—2022年棉农种植成本、产量、收入和机械化程度。在生产示范区开展了常规与短季轻简化模式的对比试验。结果表明:虽然短季模式下单株结铃数较少,但由于种植密度提高,单位面积产量高于常规模式。在8元/kg收购价时,短季模式单位面积净收益比常规高168元。综合来看,棉花夏播短季轻简化栽培模式有望提高常德地区棉花单产和棉农收益,适应了农村劳动力成本上升趋势,兼顾粮棉赛季安排,具有较好的推广前景,但在实际推广中需结合当地实际情况灵活调整。

大型水利枢纽工程夏季降水关键区季内演变规律建模分析

为了监测并预测区域水文情况,提前预防自然灾害,建模分析大型水利枢纽工程夏季降水关键区季内演变规律。从降雨极值GP模型和降雨时间序列演变模型2个角度分析夏季降水关键区季内演变规律。引入降雨极值变化指标分析降雨超定量变化特征,构建月降雨量序列模型,获得标度指数,描述降雨时间序列长期变化行为,分析降雨序列内在规律。结果表明,关键区气象站1~3受到季风及地理条件影响,近10年夏季降雨规律呈现先升高后降低的变化趋势,气象站4~12未受地理环境影响,保持先降低后升高的统一降雨趋势,研究区域的降雨规律具有复杂性。

太行山区连翘雨季直播造林技术研究

在太行山区开展了连翘雨季直播造林试验,通过出苗率、越冬越夏存活率、留苗率、生长量等指标的测定,探讨连翘在无灌溉条件下的种植方法,包括种子处理、保水剂应用、雨季播种时机选择、造林地选择、有无地面覆盖物等。结果表明,在7月4日、7月9日、7月13日、7月20日,将经包衣剂或保水剂处理的种子播种于半阴坡、半阳坡或阳坡上,其出苗率、留苗率和生长量显著高于对照(CK)和其他处理;6月下旬进行直播,由于降水量相对少、雨期间隔时间久,不利于种子萌发。7月下旬至8月降水量充足,此时播种持续降雨会使种子被冲失,同时高温易抑制种子萌发。9月初播种幼苗生长期短,越冬难度大,留存率逐渐下降;在土层厚度≥12.5 cm,有地面覆盖物的阴坡、半阴坡,连翘幼苗越夏越冬存活率均在80%左右,株高在90.81 cm以上。故认为连翘在无灌溉条件下雨季直播造林,最适宜时期为7月上中旬,且在土层厚度大于12.5 cm的半阴坡或有植被覆盖的阳坡直播造林较好。

Anomalous Western Pacific Subtropical High during El Nino Developing Summer in Comparison with Decaying Summer

The anomalous behavior of the western Pacific subtropical high （WPSH） in E1 Nifio developing summer is studied based on the composite results of eight major E1 Nifio events during 1979-2013. It is shown that the WPSH tends to retreat eastwards with weak intensity during the developing summer. The anomaly exhibits an intraseasonal variation with a weaker anomaly in June and July and a stronger anomaly in August, indicating that different underlying physical mechanisms may be responsible for the anomalous WPSH during early and late summer periods. In June and July, owing to the cold advection anomaly characterized as a weak northerly anomaly from high latitudes, geopotential height in East Asia is reduced and the WPSH tends to retreat eastwards slightly. By contrast, enhanced convection over the warm pool in August makes the atmosphere more sensitive to E1 Nifio forcing. Consequently, a cyclonic anomaly in the western Pacific is induced, which is consistent with the seasonal march of atmospheric circulation from July to August. Accordingly, geopotential height in the western Pacific is reduced significantly, and the WPSH tends to retreat eastwards remarkably in August. Different from the developing summer, geopotential height in the decaying summer over East Asia and the western Pacific tends to enhance and extend northwards from June to August consistently, reaching the maximum anomaly in August. Therefore, the seasonal march plays an important role in the WPSH anomaly for both the developing and decaying summer.

Seasonal Variation and Physical Properties of the Cloud System over Southeastern China Derived from Cloud Sat Products

Based on the National Centers for Environmental Prediction（NCEP） and Climate Prediction Center（CPC） Merged Analysis of Precipitation（CMAP） data and Cloud Sat products, the seasonal variations of the cloud properties, vertical occurrence frequency, and ice water content of clouds over southeastern China were investigated in this study. In the Cloud Sat data, a significant alternation in high or low cloud patterns was observed from winter to summer over southeastern China. It was found that the East Asian Summer Monsoon（EASM） circulation and its transport of moisture leads to a conditional instability, which benefits the local upward motion in summer, and thereby results in an increased amount of high cloud. The deep convective cloud centers were found to coincide well with the northward march of the EASM, while cirrus lagged slightly behind the convection center and coincided well with the outflow and meridional wind divergence of the EASM. Analysis of the radiative heating rates revealed that both the plentiful summer moisture and higher clouds are effective in destabilizing the atmosphere. Moreover, clouds heat the mid-troposphere and the cloud radiative heating is balanced by adiabatic cooling through upward motion, which causes meridional wind by the Sverdrup balance. The cloud heating–forced circulation was observed to coincide well with the EASM circulation, serving as a positive effect on EASM circulation.

A Correction Method Suitable for Dynamical Seasonal Prediction

Based on the hindcast results of summer rainfall anomalies over China for the period 1981-2000 by the Dynamical Climate Prediction System （IAP-DCP） developed by the Institute of Atmospheric Physics, a correction method that can account for the dependence of model＇s systematic biases on SST anomalies is proposed. It is shown that this correction method can improve the hindcast skill of the IAP-DCP for summer rainfall anomalies over China, especially in western China and southeast China, which may imply its potential application to real-time seasonal prediction.