Climate prediction of the seasonal sea-ice early melt onset in the Bering Sea

基于大尺度环流异常对海冰消融的影响过程,本文采用年际增量预测方法研制了白令海季节性海冰早期消融开始日期(EMO)的统计预测模型.预测模型选取了3个具有明确物理意义的预测因子:1月波弗特高压,前期11月东西伯利亚地区海平面气压,以及11月东欧平原积雪覆盖率。1月波弗特高压可以通过海气相互作用影响白令海地区海温异常,该海温异常能够从1月持续到3月,进而影响白令海EMO.11月东西伯利亚地区海平面气压与11月至次年2月北太平洋中纬度东部海温密切相关。伴随着北太平洋中纬度东部冷海温异常的出现,白令海地区会出现暖海温异常,进而导致白令海海冰范围减少,EMO较晚.1月北极偶极子异常是11月东欧平原积雪覆盖率影响次年白令海EMO的桥梁之一.1981-2022年的交叉检验结果表明:统计模型对白令海EMO具有较好的预测能力,预测与观测的EMO之间时间相关系数达到了0.45,超过了99%的置信水平.统计模型对白令海EMO正常年份和异常年份的预测准确率分别为60%和41%.

Seasonal variations in the onset of ulcerative colitis in Japan

AIM:To investigate seasonal variations in the onset and relapse of ulcerative colitis(UC)in Japanese patients.METHODS:Between 1994 and 2006,198 Japanese patients diagnosed with UC according to conventional criteria in an academic hospital were enrolled for onset evaluation.Among 265 Japanese patients with UC who were observed for more than 12 mo,165 patients relapsed(239 times)and were enrolled for relapse evaluation.The patients’symptoms were recorded each month for 12 consecutive years.RESULTS:There was monthly seasonality in symptom onset during October and March for UC.The onset of symptoms in UC patients frequently occurred during the winter.Variation in UC onset was observed according to both month(P=0.015)and season(P=0.048).Relapse commonly occurred in October,and variations in relapse were not significant either in month(P=0.52)or season(P=0.12).Upper respiratory inflammation was the main factor responsible for relapse.CONCLUSION:Our results suggest that environmental factors associated with winter and spring seasonality may be responsible for triggering the clinical onset of UC in Japan.

Seasonal Forecast of South China Sea Summer Monsoon Onset Disturbed by Cold Tongue La Niña in the Past Decade

It has been suggested that a warm(cold)ENSO event in winter is mostly followed by a late(early)onset of the South China Sea(SCS)summer monsoon(SCSSM)in spring.Our results show this positive relationship,which is mainly determined by their phase correlation,has been broken under recent rapid global warming since 2011,due to the disturbance of cold tongue(CT)La Niña events.Different from its canonical counterpart,a CT La Niña event is characterized by surface meridional wind divergences in the central-eastern equatorial Pacific,which can delay the SCSSM onset by enhanced convections in the warming Indian Ocean and the western subtropical Pacific.Owing to the increased Indian−western Pacific warming and the prevalent CT La Niña events,empirical seasonal forecasting of SCSSM onset based on ENSO may be challenged in the future.

CHARACTERISTICS OF MIDDLE EAST JET STREAM DURING SEASONAL TRANSITION AND ITS RELATION WITH INDIAN SUMMER MONSOON ONSET

By using the NCEP/NCAR pentad reanalysis data from 1968 to 2009, the variation characteristics of Middle East jet stream(MEJS) and its thermal mechanism during seasonal transition are studied. Results show that the intensity and south-north location of MEJS center exhibit obvious seasonal variation characteristics. When MEJS is strong, it is at 27.5°N from the 67 th pentad to the 24 th pentad the following year; when MEJS is weak, it is at 45°N from the 38 th pentad to the 44 th pentad. The first Empirical Orthogonal Function(EOF) mode of 200-hPa zonal wind field shows that MEJS is mainly over Egypt and Saudi Arabia in winter and over the eastern Black Sea and the eastern Aral Sea in summer. MEJS intensity markedly weakens in summer in comparison with that in winter. The 26th-31 st pentad is the spring-summer transition of MEJS, and the 54th-61 st pentad the autumn-winter transition. During the two seasonal transitions, the temporal variations of the 500-200 hPa south-north temperature difference(SNTD) well match with 200-hPa zonal wind velocity, indicating that the former leads to the latter following the principle of thermal wind. A case analysis shows that there is a close relation between the onset date of Indian summer monsoon and the transition date of MEJS seasonal transition. When the outbreak date of Indian summer monsoon is earlier than normal, MEJS moves northward earlier because the larger SNTD between 500-200 hPa moves northward earlier, with the westerly jet in the lower troposphere over 40°-90°E appearing earlier than normal, and vice versa.

SEASONAL AND INTER-ANNUAL VARIABILITY OF THE SOUTH CHINA SEA WARM POOL AND ITS RELATION TO THE SOUTH CHINA SEA MONSOON ONSET

The South China Sea warm pool interacts vigorously with the summer monsoon which is active in the region. However, there has not been a definition concerning the former warm pool which is as specific as that for the latter. The seasonal and inter-annual variability of the South China Sea warm pool and its relations to the South China Sea monsoon onset were analyzed using Levitus and NCEP/NCAR OISST data. The results show that, the seasonal variability of the South China Sea warm pool is obvious, which is weak in winter, develops rapidly in spring, becomes strong and extensive in summer and early autumn, and quickly decays from mid-autumn. The South China Sea warm pool is 55 m in thickness in the strongest period and its axis is oriented from southwest to northeast with the main section locating along the western offshore steep slope of northern Kalimantan-Palawan Island. For the warm pools in the South China Sea, west Pacific and Indian Ocean, the oscillation, which is within the same large scale air-sea coupling system, is periodic around 5 years. There are additional oscillations of about 2.5 years and simultaneous inter-annual variations for the latter two warm pools. The intensity of the South China Sea warm pool varies by a lag of about 5 months as compared to the west Pacific one. The result also indicates that the inter-annual variation of the intensity index is closely related with the onset time of the South China Sea monsoon. When the former is persistently warmer (colder) in preceding winter and spring, the monsoon in the South China Sea usually sets in on a later (earlier) date in early summer. The relation is associated with the activity of the high pressure over the sea in early summer. An oceanic background is given for the prediction of the South China Sea summer monsoon, though the mechanism through which the warm pool and eventually the monsoon are affected remains unclear.

Interannual Variation of the Onset of Yunnan’s Rainy Season and Its Relationships with the Arctic Oscillation of the Preceding Winter

Based on an analysis of the circulation in May associated with the interannual variation of the onset of Yunnan’s rainy season, this study examined the rela-tionship between Arctic Oscillation (AO) and the onset timing of the rainy sea-son by using the NCEP/NCAR reanalysis and observational precipitation data for 1961-2010. The results indicated that, on an interannual time scale, intense Asian summer monsoon and an active EU-pattern wave train circulation in its positive phase, associated with a cold cyclonic cell covering the western part of the East Asian subtropical westerly jet (EASWJ), jointly contributed to the onset of the rainy season in May. Otherwise, the onset might be suppressed. The cold cyclonic cell over East Asia likely led to the southward shift and enhancement of EASWJ as well as its secondary circulation around the jet entrance, which could provide a favorable dynamic and thermal condition for rainfalls in Yunnan as was revealed in previous studies on 10 - 30-day time scale. Further examination showed that the preceding wintertime AO played a significant role in the timing of the onset of the rainy season before the mid-1980s’ by mostly modulating the wave-train-like circulation over East Asia in May. During that time period, when the AO index of the previous winter was positive (negative), Yunnan’s rainy season tended to begin earlier (later) than normal. Correspond-ingly, the precipitation in May was also closely linked to wintertime AO.

Comparison of Rainy Season Onset, Cessation and Duration for Ghana from RegCM4 and GMet Datasets

The socio-economic sector of West African countries is rain-fed agriculture driven. Information regarding the onset, cessation and duration of the rainy season is thus, very essential. In this paper, a comparison of the onset, cessation and duration of the rainy season has been carried out using simulated rainfall data from the fourth generation Regional Climate Model (RegCM4) and rain gauge measurements from Ghana Meteorological Agency (GMet), covering a period of 1998 to 2012. Similar onset and cessation dates were seen in both the simulated and guage rainfall measurements for the various agro-ecological zones, resulting in similar duration of the rainy season. The average duration of the rainy season were less than 200 days for the savannah and coastal zones whereas the duration of the rainy season were beyond 200 days for the forest and transition zones. The bias of these comparisons was less than 30 days and the root mean square error (RMSE) values were less than 15 days for all stations, except Saltpond. The Pearson’s correlation (r) typically ranged between 0.4 and 0.8. However, negative correlations were observed for Tamale in the savannah zone, and the entire coastal zone. These findings are indications that RegCM4 has the potential to clearly simulate the movement of the rain belt, and thus, could fairly determine the onset, cessation and duration of the rainy season. The findings have significant contributions to effective water resource management and food security in Ghana, as the thriving of these sectors depend on the dynamics of the rainfall seasons.

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.

Atmospheric Circulation Characteristics Associated with the Onset of Asian Summer Monsoon

The onset of the Asian summer monsoon has been a focus in the monsoon study for many years. In this paper, we study the variability and predictability of the Asian summer monsoon onset and demonstrate that this onset is associated with specific atmospheric circulation characteristics. The outbreak of the Asian summer mol）~soon is found to occur first over the southwestern part of the South China Sea （SCS） and the Malay Peninsula region, and the monsoon onset is closely related to intra-seasonal oscillations in the lower atmosphere. These intra-seasonal oscillations consist of two low-frequency vortex pairs, one located to the east of the Philippines and the other over the tropical eastern Indian Ocean. Prior to the Asian summer monsoon onset, a strong low-frequency westerly emerges over the equatorial Indian Ocean and the low-frequency vortex pair develops symmetrically along the equator. The formation and evolution of these low-frequency vortices are important and serve as a good indicator for the Asian summer monsoon onset. The relationship between the northward jumps of the westerly jet over East Asia and the Asian summer monsoon onset over SCS is investigated. It is shown that the northward jump of the westerly jet occurs twice during the transition from winter to summer and these jumps are closely related to the summer monsoon development. The first northward jump （from 25°-28°N to around 30°N） occurs on 8 May on average, about 7 days ahead of the summer monsoon onset over the SCS. It is found that the reverse of meridional temperature gradient in the upper-middle troposphere （500-200 hPa） and the enhancement and northward movement of the subtropical jet in the Southern Hemispheric subtropics are responsible for the first northward jump of the westerly jet.

The Onset of the Monsoon over the Bay of Bengal:The Observed Common Features for 2008-2011

In situ buoy observation data spanning four years(2008-2011) were collected and used to perform a composite analysis of the monsoon onset process in the Bay of Bengal(BoB).The sea surface temperature(SST) in the central BoB increases dramatically during the monsoon transition period and reaches its annual maximum just before the onset of the monsoon.This process is illustrated by the northward-propagating deep convection phase of the intraseasonal oscillation and the establishment of a steady southwest wind.It is argued that the SST peak plays a potential role in triggering the onset of the monsoon in the BoB and its vicinity.The general picture of the BoB monsoon onset summarized here reveals the possibility of regional land-ocean-atmosphere interaction.This possibility deserves further examination.

THE RELATIONSHIP BETWEEN SOUTH CHINA SEA SOUTHWEST MONSOON ANOMALIES AND IMPORTANT WEATHER IN GUANGDONG PROVINCE DURING THE RAINING SEASONS

The activity of South China Sea southwest monsoon (SCSSM) has direct impacts on the anomalies of important weather in Guangdong province during the raining seasons. So it is necessary to explore thoroughly the activity pattern of SCSSM and its relationship with important weather anomalies in the province. In this paper, the methods of composite analysis and correlation statistics are used to study the relationship between the onset date and intensity of SCSSM and the important weather, such as precipitation trends in Guangdong province during the annually first and second raining seasons, the timing of the annually first and last typhoon and the number of typhoons landing in Guangdong province. The results show that the rainfall is less than normal during the first raining season, but more than normal during the second one and there are more tropical cyclones landing in Guangdong province in the years of early SCSSM onset. The rainfall is more than normal during the second raining season and there are more tropical cyclones landing in Guangdong province in the years of strong SCSSM. The relationship between the SST of April - June, July - September and previous winter (December - February) and 500 hPa geopotential height and the onset date and intensity of SCSSM is analyzed. Some mechanisms between the onset dates and intensity of SCSSM and the important weather anomalies in Guangdong province are preliminarily explored. The results can be used for reference in short-term climate forecast.

强直性脊柱炎发病与二十四节气相关性研究

目的:分析陕西地区近19年强直性脊柱炎发病与二十四节气间的相关性,从时间医学角度为因时制宜理论提供临床依据。方法:采用回顾性研究方法对西安市第五医院2002年2月4日至2020年2月3日收治的12645例强直性脊柱炎住院患者的病历资料进行分析,应用圆形统计分析确定其发病高峰节气及相对高峰期。结果:2002-2020年陕西地区强直性脊柱炎患者的在发病节气上具有集中趋势(Z=47.73,P<0.05),大暑(8月5日)是发病的高峰节气,相对高峰期为春分到大雪(3月21日至12月20日)。结论:强直性脊柱炎虽不是季节性流行病,但是其发病与气候、环境及二十四节气的变化有一定的影响,陕西地区强直性脊柱炎的发病节气具有一定的集中趋势,大暑前后是发病高峰期,提示应注意该节气期间疾病的预防和早期治疗。

发热儿童的高热惊厥发生现状及其高危因素分析

目的探讨发热儿童的高热惊厥发生现状及其高危因素。方法方便选取2021年1月—2023年2月就诊于广东省东莞市长安医院发热门诊的2995例发热患儿为研究对象,经查阅患儿电子病历档案或询问患儿家长收集资料,调查发热儿童的高热惊厥发生现状,并分析其发生的相关危险因素。结果2995例发热患儿中,发生高热惊厥120例(4.01%),未发生高热惊厥2875例(95.99%)。单因素分析显示,高热惊厥组年龄<3岁、性别男、初发温度≥39.1℃、7~9月发病比例较非高热惊厥组高,差异有统计学意义(P均<0.05)。两组癫痫家族史、高热惊厥家族史、原发性感染性疾病、出生方式、围产期缺氧史和平均红细胞血红蛋白、平均红细胞体积、血红蛋白对比,差异无统计学意义(P均>0.05);经Logistic回归分析显示,年龄(OR=20.080,95%CI:12.524~32.192)、性别(OR=1.796,95%CI:1.195~2.700)、初发温度(OR=6.976,95%CI:4.793~10.153)、发病季节(OR=2.046,95%CI:1.250~3.349)是发热儿童高热惊厥发生的高危因素,差异有统计学意义(P均<0.05)。结论发热儿童高热惊厥发生率较高,其发生与患儿年龄、性别、发病季节和初发温度密切相关,应结合上述危险因素制定预防措施,以降低高热惊厥发生率。

2023年华南开汛偏早与大气环流和海温的关系

采用合成、相关分析及相关物理量诊断等方法,分析了华南地区三重La Ni1a背景下2023年华南开汛偏早的大气环流和海温特征并与2022年作对比,结果表明:(1)2022和2023年3月广东降水偏多与前冬北太平洋暖海温相关,2022、2023年华南开汛偏早分别与前冬中印度洋海岭海域海温、前冬东太平洋海丘的以东海域海温增暖有关。(2)2022和2023年3月850 hPa风场华南沿海均呈现反气旋式分布,华南处于西南到偏南气流中有利水汽输送。两年开汛偏早与冷空气南下有关。(3)2022和2023年3月华南地区局地哈德莱环流在赤道附近北支上升气流加强,北支下沉支减弱且南退,在0°N—20°N范围内为负距平,有利于2022和2023年3月广东降水偏多。

1961—2023年福建前汛期开汛时间年际变化和成因

根据华南汛期监测业务规定,使用相关分析、小波分析、合成分析等统计方法分析了福建1961—2023年前汛期开汛时间的年际变化特征,同时研究了其与福建各地降水量的关系,分析了福建前汛期开汛异常与前冬海温和早春大气环流的关系。结果表明:福建前汛期开汛时间年际变化特征明显,存在25 a的主振荡周期。开汛最早出现在1973年和1979年的4月2日,最晚出现在1963年6月1日,平均开汛时间是4月27日。福建前汛期开汛时间与福建大部春季降水量、中部沿海地区的3月降水量以及福建4月降水量相关较好。福建前汛期开汛偏早年,前冬西北太平洋中部海温偏低,热带中东太平洋东部海温偏高,早春副热带西风急流偏强,副热带高压偏强偏西,南海到福建上空西南气流偏强;开汛偏迟年则完全相反。

东亚地区夏季风爆发过程

利用中国１９４站 １９６１～１９９５年日降水资料及 ＮＣＥＰ １９７９～１９９７年候格点降水资料，探讨了亚洲地区自春到夏的雨季开始分布。结果表明，东亚地区自春到夏存在副热带季风雨季开始和热带季风雨季开始。前者于４月初开始于华南北部和江南地区，随后向南和向西南扩展，于４月末扩展到华南沿海和中南半岛，这个雨带主要是冷空气和副热带高压西侧转向的ＳＷ风以及南亚地区冬春副热带南支西风槽中西风汇合而形成的，是副热带季风雨季开始。后者是南海热带季风爆发后使原来由江南移到华南沿岸的副热带季风雨带随副热带高压北进而北进，前汛期雨季进入盛期，江南出现第二次雨峰，形成梅雨期和江淮及华北雨季。同时，热带季风雨带也自东向西传播到达南亚地区而形成热带季风雨季。还讨论了 １９９８年东亚地区夏季风爆发过程，指出南海夏季风爆发期的季风由副高北侧形成的新生气旋进入南海造成南海中部西风和南海越赤道气流转向的ＳＷ季风加强汇合而形成，因而是东亚季风系统中环流系统季节变化造成的，和印度季风无关。在南海季风爆发期阿拉伯海仍由副热带反气旋控制．南亚仍是上述副热带反气旋北侧ＮＷ风南下后转向的偏西副热带气流所控制，索马里低空急流仍未爆发，赤道西风并未影响南海。

广东汛期开始日期的年际和年代际变化研究

用小波分析和相关统计等方法 ,对近 5 0多年来广东开汛的年际和年代际变化及与副高、PDO指数的关系进行了研究 ,同时也研究了它与后期天气、前期 5 0 0hPa环流场和海温场的关系。结果表明 ,近 5 0年来广东开汛呈偏早的趋势 ,具有明显的 2～ 7年左右的年际和 34年左右的年代际周期振荡 ;开汛的年代际振荡与副高、PDO指数是一致的 ,并与它们存在反向的关系 ,且突变的时间也均发生在 2 0世纪 70年代中后期 ;广东开汛与后期天气的相关分析表明 ,它与广东 4月降水的相关最好 ,与 5 ,6月的相关则差 ;与广东降水集中期初日只有在 1986年以后至今才具有显著的正相关 ,而与降水集中期次数却在 1977年之前就具有显著的负相关 ;广东开汛的早晚与前冬 5 0 0hPa高度场存在几个显著的相关中心 ,与前秋北太平洋西风漂流区的海温异常也有明显的相关。

青藏高原加热与亚洲环流季节变化和夏季风爆发

利用逐日NCEP/NCAR再分析资料分析了春夏过渡季节青藏高原非绝热加热和大气环流季节变化以及亚洲季风爆发的关系。结果表明,过渡季节的早期（5月中旬以前）青藏高原总非绝热加热与感热加热的时间演变曲线趋势一致,感热加热在过渡季节早期的环流演变中有很重要的作用。青藏高原非绝热加热的时间演变与北半球环流的季节变化和亚洲夏季风爆发有很好的相关。在过渡季节里,青藏高原非绝热加热的变化引起了海-陆热力差异对比的变化,给亚洲夏季风的爆发建立了有利的背景环境,对亚洲夏季风爆发有明显的影响。结果还表明,用各区域纬向风垂直差异的时空分布能更准确地表示季节变化的区域差异。

960例慢性浅表性胃炎患者中医证候分布与发病季节、幽门螺杆菌感染、黏膜糜烂的关系研究

目的探讨慢性浅表性胃炎中医证候分布与发病季节、幽门螺杆菌(HP)组染、胃黏膜糜烂的关系。方法采用流行病学的调查方法,设计统一表格进行研究。结果慢性浅表性胃炎在春夏秋冬不同季节,各个证候出现的频率各不相同(P<0.05);而证候分布在HP组染和无HP组染及伴有或不伴有胃黏膜糜烂之间无明显差异(P>0.05)。结论慢性浅表性胃炎中医证候分布与发病季节关系密切;但证候分布与是否HP组染及是否伴有胃黏膜糜烂无明显关系。

华南前汛期区域持续性暴雨的分布特征及分型

利用广东和广西两省共175个台站的日降水观测资料,采用计算机检索的方法,对1961-2005年间华南前汛期区域持续性暴雨进行了定义。对南海夏季风爆发前后区域持续性暴雨的气候分布特征的分析发现,季风爆发前持续性暴雨频数从60年代至今呈现出正态分布的年代际变化特征,而季风爆发后的区域持续性暴雨频数变化则几乎相反;广东省前汛期区域持续性暴雨降水明显比广西强。此外,通过EOF方法和相关分析得到了夏季风爆发前后出现频率较高的几种分布雨型,它们能较好地代表季风爆发前后华南降水分布的特点。