The Northward Shift of Climatic Belts in China During the Last 50 Years and the Corresponding Seasonal Responses

Along the meridian of 105°E, the Chinese region are divided into two parts, east and west. The results show that in the east part of China the temperate extratropical belt, the warm extratropical belt,and the northern subtropical belt shift northward significantly, whereas the middle subtropical belt and the southern subtropical belt have less or no change. As for the northern subtropical belt, the maximal northward shift can reach 3.7 degrees of latitude. As for the warm extratropical belt, along the meridian of 120°-125°E, the maximal northward shift can reach 3-4 degrees. In the west part of China, each climatic belt changes little. Only in the Xinjiang area are the significant northward shifts. Correspondingly, it is found that in the last 50 years the traditional seasons have changed. For Beijing, Hailar, and Lanzhou, in general, summer becomes longer and winter shorter over the last 50 years. Summer begins early and ends late with respect to early 1950s. Contrary to the summer, winter begins la

The two annual northward jumps of the West Pacific Subtropical High and their relationship with summer rainfall in Eastern China under global warming

The two northward jumps of summer West Pacific Subtropical High （WPSH） are defined based on the pentad-scale ridge data of the WPSH ridge in 1951 to 2012. The times of the northward jumps are found to have obvious inter-annual and decadal characteristics, i.e., the occurrence of the first northward jump of WPSH shows a ＂consistently early-consistently late＂ decadal pattern, with the transition around 1980; the occurrence of the second northward jump of WPSH shows a ＂consistently late-consistently early-consistently late＂ decadal pattern, with the transitions about 1955 and 1978, respec- tively, which is consistent with global warming. In the meantime, the times of the two northward jumps not only have a good correspondence to the beginning and ending dates of the rainy season, but also greatly influence the position of the main rain belt in Eastern China. When the first northward jump occurs early, the main rain belt is located from just north of 30~ N to the south of North China, while the opposite situation appears when the first jump occurs late. When the second jump occurs early, more rain falls over North China and South China, but less falls in the Yangtze River region, while the opposite situation appears when the second jump occurs late. In the four cases when abnormalities occur in the same year as early or late northward jumps, the position of the main rain belt can be considered as a superposition of isolated abnormal effects of the two northward jumps. Moreover, the prophase and synchronous forces of the sea surface temperature in the Pacific has great influence on the times of the northward jumps, and the driving forces of the two jumps differ.

Northward Shift in Landfall Locations of Tropical Cyclones over the Western North Pacific during the Last Four Decades

This study analyzes landfall locations of tropical cyclones(TCs)over the western North Pacific during 1979–2018.Results demonstrate that the landfall locations of TCs over this region have shifted northward during the last four decades,primarily due to the shift of landfalling TC tracks,with the decreasing/increasing proportion of westward/northward TC tracks.In particular,the northward shift of the landfalling TCs was not related to their formation locations,which have not markedly changed,whereas"no-landed"TCs have significantly shifted northward.TC movement was significantly and positively correlated to the zonal component of the steering flow,while the correlation between TC movement and the meridional component of the steering flow was relatively unobvious.The westward steering flow in the tropical central Pacific that occurred around the formation and early development of the westward TCs was significantly weakened,which was unfavorable for their westward movement,thereby,causing the higher proportions of northward moving tracks.This weakened westward flow was related to the northward shift of the subtropical high ridge,which was caused by significant weakening of the southern part of the subtropical high.The vertical wind shear,sea surface temperature,and convective available potential energy also showed that the northern region of the western North Pacific became more favorable for TC development,whereas the upper divergence,low-layer relative vorticity,and accumulated water vapor content were not obviously related to the northward shift of TCs.

Intensified Eastward and Northward Propagation of Tropical Intraseasonal Oscillation over the Equatorial Indian Ocean in a Global Warming Scenario

Northward propagation in summer and eastward propagation in winter are two distinguished features of tropical intraseasonal oscillation （TISO） over the equatorial Indian Ocean. According to numerical modeling results, under a global warming scenario, both propagations were intensified. The enhanced northward propagation in summer can be attributed to the enhanced atmosphere-ocean interaction and the strengthened mean southerly wind; and the intensified eastward propagation in winter is associated with the enhanced convection-wind coupling process and the strengthened equatorial Kevin wave. Future changes of TISO propagations need to be explored in more climate models.

Impacts of Two Types of Northward Jumps of the East Asian Upper-tropospheric Jet Stream in Midsummer on Rainfall in Eastern China

The East Asian upper-tropospheric jet stream （EAJS） typically jumps north of 45~N in midsummer. These annual northward jumps are mostly classified into two dominant types： the first type corresponds to the enhanced westerly to the north of the EAJS＇s axis （type A）, while the second type is related to the weakened westerly within the EAJS＇s axis （type B）. In this study, the impacts of these two types of northward jumps on rainfall in eastern China are investigated. Our results show that rainfall significantly increases in northern Northeast China and decreases in the Yellow River-Huaihe River valleys, as well as in North China, during the type A jump. As a result of the type B jump, rainfall is enhanced in North China and suppressed in the Yangtze River valley. The changes in rainfall in eastern China during these two types of northward jumps are mainly caused by the northward shifts of the ascending air flow that is directly related to the EAJS. Concurrent with the type A （B） jump, the EAJS-related ascending branch moves from the Yangtze-Huai River valley to northern Northeast （North） China when the EAJS＇s axis jumps from 40~N to 55~N （50~N）. Meanwhile, the type A jump also strengthens the Northeast Asian low in the lower troposphere, leading to more moisture transport to northern Northeast China. The type B jump, however, induces a northwestward extension of the lower-tropospheric western North Pacific subtropical high and more moisture transport to North China.

Upper layer waters and their northward extension from Prydz Bay in summer

In this paper, CTD observational data obtained during the 15th Chinese National Antarctic Research Expedition (CHINARE-15) in the Southern Ocean are used to analyse and study water mass distribution in the Prydz Bay and its adjacent seas. The area, depth, and the thermohaline characteristics are identified for the Prydz Bay summer coastal surface water, the Prydz Bay winter water, the Prydz Bay shelf water, and the circumpolar deep water. Based on the above discussion, the northward extention of the Prydz Bay shelf water are found. Then the thermodynamic and the dynamic characteristics are further discussed, dealing with the inversion layer depth of the water temperature, the locations of the minima of the vertical temperature distribution and the temperature vertical gradient in the water column, the baraclinicity, and the effect of Coriolis deflection force.

A DIAGNOSTIC RESEARCH OF THE SEASONAL NORTHWARD BEATING OF THE SUBTROPICAL HIGH

Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 ×2.5 at 500 hPa May through July in 1988 and 1991. It is concluded that it is globally observed that the subtropical high has northward beats that propagate westward; the source of beating mainly lies in the region of Arabian Sea and central Pacific and the sink in eastern Pacific; the seasonal beating is dominated by effects of the disturbance field; low frequency oscillation plays a key role in the beating and the westward propagation so that the difference in the latter in individual years is caused by the varying source of disturbance and the low frequency waves it excites.

Relationship between a function of the northward pressure gradient and the Pacific Equatorial Undercurrent

The Equatorial Undercurrent（EUC） plays an important role in ocean circulation and global climate change. Near the equator, as the Coriolis parameter goes to 0, equatorial currents cannot be described by geostrophy in which the pressure gradient force term is balanced by the Coriolis force term. Many previous studies focus on the relationships between the EUC and El Ni？o-Southern Oscillation（ENSO）, the thermocline, sea surface topography, the distribution of equatorial wind stress and other atmosphere-ocean factors. However, little attention has been paid to the northward pressure gradient（NGT）, which may also be important to the EUC. The pressure can be regarded as a complex nonlinear function of terms including temperature, salinity and density.This study attempts to reveal the connection between a function of the northward pressure gradient（FNP） and the EUC. The connection is derived from primitive equations, by simplifying the equations with using scaling analysis, and shows that the beta effect may be the main reason why the FNP is important to the EUC. The vertical structure of the EUC can be partially described by the FNP. The NGT has an obvious influence on the EUC while the eastward pressure gradient has a relatively smaller effect.

Early Cretaceous subduction initiation beneath southern Tibet caused the northward flight of India

Collision between the Indian and Eurasian plates formed the ~2500 km long Yarlung Zangbo Suture Zone and produced the Himalaya mountains and Tibetan plateau.Here we offer a new explanation for tectonic events leading to this collision:that the northward flight of India was caused by an Early Cretaceous episode of subduction initiation on the southern margin of Tibet.Compiled data for ophiolites along the Yarlung Zangbo Suture Zone show restricted ages between 120 Ma and 130 Ma,and their supra-subduction zone affinities are best explained by seafloor spreading in what became the forearc of a north-dipping subduction zone on the southern margin of Tibet.The subsequent evolution of this new subduction zone is revealed by integrating data for arcrelated igneous rocks of the Lhasa terrane and Xigaze forearc basin deposits.Strong slab pull from this new subduction zone triggered the rifting of India from East Gondwana in Early Cretaceous time and pulled it northward to collide with Tibet in Early Paleogene time.

Northward Heat Flux in Midwest Summers

Watching the winds in northwest Iowa during more than 30 summers has led me to two conclusions about the local atmosphere at ground level: there is a net northward transport of heat and water taking place throughout the summer;warm humid winds from the south continually alternate with cool dry winds from the north. The proposed northward heat transfer is consistent with the constraint, placed on the motions of the oceans and the atmosphere, of the earth’s heat balance due to the increased absorption of solar radiation at low latitudes compared to that at high latitudes. At mid-latitudes in the interior of continents, like North America, it is the job of the atmosphere alone to constantly help satisfy the global heat balance. Although qualitative in nature, the predicted northward heat flux is strongly based on frequent observations over lengthy time intervals.

Two Northward Jumps of the Summertime Western Pacific Subtropical High and Their Associations with the Tropical SST Anomalies

Based on the pentad mean ridgeline index of the western Pacific subtropical high (WPSH), the authors identified the two northward jumps of the WPSH from 1979 to 2008 and revealed their associations with the tropical SST anomalies. The authors show that the northward jumps, especially the second jump, exhibited remarkable interannual variability. In addition, the authors find that the two northward jumps were mutually independent and were influenced by the SST anomalies in the different regions of the tropical Pacific. The first jump was positively correlated with the SST anomalies in the tropical central Pacific from the preceding winter to June. In contrast, the second jump was positively related to ENSO in the preceding winter, but this correlation tended to weaken with the decay of ENSO and disappeared in July. Instead, a positive correlation was found in the Indian Ocean. We therefore suggest that ENSO plays an indirect role in the second jump through the capacitor effect of the Indian Ocean.

Northward expansion of the western Pacific Warm Pool in late 1990s and early 2000s

Based on 48-year (1958-2006) ocean reanalysis data of Simple Ocean Data Assimilation and 23-year (1984-2006) global ocean-surface heat flux products developed by the Objectively Analyzed Air-Sea Heat Flux Project, meridional variation of the western Pacific Warm Pool (WPWP) is addressed. The results show that there is a significant expansion of the northern edge of the WPWP in the late 1990s and early 2000s. This variation is mainly within 120°E-160°E by 8°N-20°N, we define this region (120°E-160°E by 8°N-20°N) as the core region. Furthermore, analyses on upper ocean heat budget show that the short wave radiation plays a key role in the northward expansion of the northern edge of the WPWP in the core region. It is proved that the northward expansion may be caused by the change of the mixed layer which became shallower in 1994-2006 compared with 1984-1993 in the study region. The short wave radiation flux distribution within the shallower mixed layer leads to a positive anomaly in seawater temperature, promoting the northward expansion of the WPWP.

高、低空急流耦合对山东“利奇马”台风暴雨增幅影响的诊断研究

受登陆北上台风“利奇马”等影响,2019年8月9~12日山东省出现连续暴雨,其中10日夜间出现降雨峰值。利用中国气象局上海台风研究所(Shanghai Typhoon Institute of China Meteorological Administration,简称CMA-STI)热带气旋最佳路径数据、山东省自动气象站逐时降雨量、常规观测资料、中国风云二号地球静止气象卫星(FY-2G)0.1°×0.1°逐小时云顶相当黑体亮温和美国环境预报中心(National Center of Environmental Prediction,简称NCEP)1°×1°逐6 h再分析等资料,主要运用纬向风局地变化方程与大气动能方程,诊断分析降雨明显增幅与高、低层风场变化的关系。结果表明:(1)暴雨主要影响系统有高低空急流、500 hPa西风槽、850 hPa台风倒槽及“利奇马”本体环流等。10日200 hPa中纬度大尺度西南风急流东南移影响鲁西北,当天08:00(北京时,下同)850 hPa因双台风活动而形成的大尺度东南风急流突然北伸越过山东省。台风倒槽对流云与本体环流对流云先、后北移经鲁中,累积效应造成该地区10日夜间雨量最大。(2)10日20:00850 hPa章丘站东北侧出现了过程最快东风增幅,纬向运动方程诊断结果表明,东风平流是东风增加最主要原因,地转偏向力项则不利于东风增加。(3)10日20:00章丘站200 hPa西南风风力明显加大形成急流,10日08:00至11日08:00青岛站850 hPa维持东南风低空急流。同时位于高空急流右后侧与低空急流左前方是鲁中附近10日夜间降雨增幅的重要原因。章丘200 hPa与青岛850 hPa都是在最大风力之前12 h动能增加最快。动能方程诊断表明,最有利于鲁西北高空急流形成的是位能平流项,最有利于鲁东南低空急流形成的是动能垂直通量散度项。(4)10日20:00至13日08:00“利奇马”本体环流一直在影响山东,暴雨期间山东中部地形的动力作用也一直存在,而降雨的峰值是出现在10日夜间,说明10日20:00前后高、低空急流的耦合可能是山东暴雨增幅的主要影响因子。其主要作用至少有加强山东中部的垂直运动、整层水汽输送与静力不稳定度等方面。

以确保“一泓清水永续北上” 引领南水北调中线水源区水土保持高质量发展

丹江口库区及上游是南水北调中线水源区(以下简称“水源区”),其水土保持高质量发展是保障“一泓清水永续北上”的重要支撑。文章针对水源区水土流失现状和特点,总结了丹江口库区及上游水土保持重点防治工程(以下简称“丹治”工程)实施以来的水土保持成效,分析了水土保持面临的新形势和新要求,梳理了水土保持存在的短板和不足,研究提出了引领丹江口库区及上游水土保持高质量发展的对策举措,为各级政府加强南水北调中线水源区水土保持治理管理提供参考。

江苏地方医派传承发展张仲景学说刍议

仲景学说自明清开始出现北学南移,此与江苏地方医派关系密切。除刊刻《仲景全书》,精研仲景学术思想外,江苏医家结合当地气候、饮食及患者体质等因素,灵活变通《伤寒杂病论》的证治思路,促进了温病学派的诞生。此外,江苏地方医派秉承寒温一体理论,临证融伤寒、温病之长,同时将此思想融入中医教育中;并且借鉴西方院校教育模式,发展中医学校教育,开辟当代中医教育之先河。文章对江苏中医流派的学术及教育学思想进行了简单阐述,并对后续的中医药数字化科普工作进行了思考及展望,为中医流派的守正创新研究提供思路。

北上台风时空变化特征及其与ENSO的关系

基于中国气象局热带气旋最佳路径数据集,对1949—2022年北上台风的时空变化特征进行统计分析,并探讨了厄尔尼诺-南方涛动(El Niño-Southern Oscillation,ENSO)对北上台风活动的影响。结果表明:1)74年间共有275个北上台风活动,频数的年际变化呈不显著上升趋势,但北上台风占西北太平洋生成台风总数的比例呈现显著的上升趋势;2)北上台风主要集中在7—9月生成,8月份进入定义区数量最多,生命期强度以超强台风、台风等高强度等级居多,且高强度等级北上台风出现的几率近些年有增加趋势;3)共有159个北上台风在中国登陆,未登陆转向路径台风大多在30°N、125°―130°E附近向东转向。北上台风生成位置大多集中在10°―20°N、130°―150°E,登陆类北上台风的生成位置更加偏西,消散类台风的生成位置纬度更高;4)Niño 3.4指数与北上台风频数和生命期强度分别呈显著的负相关和正相关关系,同时其对北上台风的生成位置也具有明显影响。与厄尔尼诺年相比,拉尼娜年生成的北上台风数量更多,生成位置更加偏西、偏北,但厄尔尼诺年发生的北上台风强度更高。

1949—2019年中心经过渤海的北上台风统计分析

利用中国气象局热带气旋最佳路径数据集、自动站资料和常规观测资料,统计1949—2019年中心经过渤海海域的北上台风,共计25次过程。台风强度统计结果表明44%的台风过程为热带低压,16%为热带风暴,28%为强热带风暴,12%为台风残涡。台风中心进入渤海后,48%的台风强度减弱,28%的强度不变,24%的强度增强。中心经过渤海的台风96%出现在7—8月,其中7月中下旬—8月上旬占总数的64%,8月上旬的台风数目最多,占总数的29%。北上台风中心最大风速在10~30 m/s,台风入海后平均风速减弱2 m/s。台风中心最小气压为970 hPa,中心最大气压为1 004 hPa,平均气压为992 hPa。西北路径台风中88%进入渤海后强度减弱,偏北路径台风中87.5%进入渤海后强度不变,东北路径台风中83.3%进入渤海后强度增强。

耕地布局北移对粮食产能的影响分析

耕地是粮食生产的命根子,是中华民族永续发展的根基。近年来,各地认真贯彻“藏粮于地、藏粮于技”战略,狠抓耕地要害,粮食单产水平稳步提高,种植结构不断优化,粮食总产量持续稳定在6500亿kg以上。但同时全国耕地面积总体呈下降趋势,特别是耕地布局持续北移,造成一定程度的粮食产能损失。本研究运用基尼系数和泰尔指数分析方法,选取2000—2020年31个省(自治区、直辖市)粮食产量指标,分析产区间差异变化,并对耕地数量、布局、占补平衡等影响因素对粮食产能的损失进行测算。与2009年相比,2019年受耕地数量、布局北移、占补平衡等影响,粮食产能合计损失约1500亿kg。其中,耕地数量减少造成损失约565亿kg;耕地布局北移造成损失约905亿kg,占补平衡造成损失约34亿kg。此外,水田减少影响粮食产能损失约225亿kg。确保国家粮食安全,必须坚决贯彻落实习近平总书记重要指示批示和有关重要论述精神,采取“长牙齿”的硬措施,守牢耕地红线,切实加强耕地质量保护与建设,谋划实施一揽子耕地质量建设工程,多措并举,提升耕地综合生产能力。

Interdecadal Change of the Northward Jump Time of the Western Pacific Subtropical High in Association with the Pacific Decadal Oscillation

In this paper, the northward jump time of the western Pacific subtropical high（WPSH） is defined and analyzed on the interdecadal timescale. The results show that under global warming, significant interdecadal changes have occurred in the time of the WPSH northward jumps. From 1951 to 2012, the time of the first northward jump of WPSH has changed from ＂continuously early＂ to ＂continuously late＂, with the transition occurring in 1980. The time of the second northward jump of WPSH shows a similar change, with the transition occurring in 1978. In this study, we offer a new perspective by using the time of the northward jump of WPSH to explain the eastern China summer rainfall pattern change from ＂north-abundant-southbelow-average＂ to ＂south-abundant-north-below-average＂ at the end of the 1970 s. The interdecadal change in the time of the northward jump of WPSH corresponds not only with the summer rainfall pattern, but also with the Pacific decadal oscillation（PDO）. The WPSH northward jump time corresponding to the cold（warm） phase of the PDO is early（late）. Although the PDO and the El Nino–Southern Oscillation（ENSO）both greatly influence the time of the two northward jumps of WPSH, the PDO＇s effect is noticed before the ENSO＇s by approximately 1–2 months. After excluding the ENSO influence, we derive composite vertical atmospheric circulation for different phases of the PDO. The results show that during the cold（warm）phase of the PDO, the atmospheric circulations at 200, 500, and 850 h Pa all contribute to an earlier（later）northward jump of the WPSH.

Impact of 10-60-Day Low-Frequency Steering Flows on Straight Northward-Moving Typhoon Tracks over the Western North Pacific

This study investigates the impact of low-frequency(intraseasonal and interannual) steering flows on straight northward-moving(defined as a meridional displacement two times greater than the zonal displacement) typhoons over the western North Pacific using observational data. The year-to-year change in the northward-moving tracks is affected by the interannual change in the location and intensity of the subtropical high. A strengthened northward steering flow east of 120°E and a weakened easterly steering flow south of the subtropical high favor more frequent straight northward tracks. Examining each of the individual northward-moving typhoons shows that they interact with three types of intraseasonal(10-60-day) background flows during their northward journey. The first type is the monsoon gyre pattern, in which the northward-moving typhoon is embedded in a closed cyclonic monsoon gyre circulation. The second type is the wave train pattern, where a cyclonic(anticyclonic) vorticity circulation is located to the west(east) of the northward-moving typhoon center. The third type is the mid-latitude trough pattern, in which the northward-moving typhoon center is located in the maximum vorticity region of the trough.