The characteristics of longitudinal movement of the subtropical high in the western Pacific in the pre-rainy season in South China

Using the NCEP/NCAR reanalysis data, the China rainfall data of the China Meteorological Administration, and the sea surface temperature (SST) data of NOAA from 1951-2000, the features of the anomalous longitudinal position of the subtropical high in the western Pacific (SHWP) in the pre-rainy season in South China and associated circulation and precipitation are studied. Furthermore, the relationship between SHWP and SST and the eastern Asian winter monsoon is also investigated. Associated with the anomalous longitudinal position of SHWP in the pre-rainy season in South China, the flow patterns in both the middle and lower latitudes are different. The circulation anomalies greatly influence the precipitation in the pre-rainy season in South China. When the SHWP is in a west position (WP), the South China quasi-stationary front is stronger with more abundant precipitation there. However, when the SHWP is in an east position (EP), a weaker front appears with a shortage of precipitation there. There exists a good relationship between the longitudinal position of SHWP and SST in the tropical region. A negative correlation can be found both in the central and eastern tropical Pacific and the Indian Ocean.This means that the higher (lower) SST there corresponds to a west (east) position of SHWP. This close relationship can be found even in the preceding autumn and winter. A positive correlation appears in the western and northern Pacific and large correlation coefficient values also occur in the preceding autumn and winter. A stronger eastern Asian winter monsoon will give rise to cooler SSTs in the Kuroshio and the South China Sea regions and it corresponds to negative SST anomaly (SSTA) in the central and eastern Pacific and positive SSTA in the western Pacific in winter and the following spring. The whole tropical SSTA pattern, that is, positive (negative) SSTA in the central and eastern Pacific and negative (positive) SSTA in the western Pacific, is favorable to the WP (EP) of SHWP.     

旱作水稻稻茬小麦增产栽培技术研究

水稻稻茬小麦因水稻收获晚、适耕期短、整地困难、播种质量差等因素的影响,很难适期播种,加之水稻稻茬土壤板化,理化性状差,导致稻茬小麦的单产长期低而不稳,在200kg上下徘徊。为改变这一现状,我们提出了以旱作水稻替代水稻,并进行试验研究。结果表明,旱作水稻比水稻早熟10天,并能调整土壤理化性状,旱作水稻稻茬小麦比水稻稻茬小麦增产100kg。     

气候变化对山东省潘庄灌区冬小麦生长的影响(英文)

Global climate change has significant impacts on agricultural production.Future climate change will bring important influences to the food security.The CERES-Wheat model was used to simulate the winter wheat growing process and production in Panzhuang Irrigation District(PID) during 2011-2040 under B2 climate scenario based on the Special Report on Emissions Scenarios(SRES) assumptions with the result of RCMs(Regional Climate Models) projections by PRECIS(Providing Regional Climates for Impacts Studies) system introduced to China from the Hadley Centre for Climate Prediction and Research.The CERES-Wheat model was calibrated and validated with independent field-measured growth data in 2002-2003 and 2007-2008 growing season under current climatic conditions at Yucheng Comprehensive Experimental Station(YCES),Chinese Academy of Sciences(CAS).The results show that a significant impact of climate change on crop growth and yield was noted in the PID study area.Average temperature at Yucheng Station rose by 0.86℃ for 1961-2008 in general.Under the B2 climate scenario,average temperature rose by 0.55℃ for 2011-2040 compared with the baseline period(1998-2008),which drastically shortened the growth period of winter-wheat.However,as the temperature keep increasing after 2030,the top-weight and yield of the winter wheat will turn to decrease.The simulated evapotranspiration shows an increasing trend,although it is not very significant,during 2011-2040.Water use efficiency will increase during 2011-2031,but decrease during 2031-2040.The results indicate that climate change enhances agricultural production in the short-term,whereas continuous increase in temperature limits crop production in the long-term.     

Relationship between Bering Sea Ice Cover and East Asian Winter Monsoon Year-to-Year Variations

In this study,the relationship between year-to-year variations in the Bering Sea ice cover(BSIC) and the East Asian winter monsoon(EAWM) for the period 1969-2001 was documented.The time series of total ice cover in the eastern Bering Sea correlated with the EAWM index at 0.49,indicating that they are two tightly related components.Our results show that the BSIC was closely associated with the simultaneous local and large-scale atmosphere over the Asian-northern Pacific region.Heavy BSIC corresponded to weaker EAWM circulations and light BSIC corresponded to stronger EAWM circulations.Thus,the BSIC should be considered as one of the possible factors affecting the EAWM variation.     

Three dimensional diagnostic study of the circulation in the South China Sea during winter 1998

On the basis of hydrographic data obtained from 28 November to 27 December, 1998, the three-dimensional structure of circulation in the South China Sea (SCS) is computed using a three-dimensional diagnostic model. The combination of sea surface height anomaly from altimeter data and numerical results provides a consistent circulation pattern for the SCS, and main circulation features can be summarized as follows: in the northern SCS there are a cold and cyclonic circulation C1 with two cores C1-1 and C1-2 northwest of Luzon and an anticyclonic eddy (W1) near Dongsha Islands. In the central SCS there is a stronger cyclonic circulation C2 with two cores C2-1 and C2-2 east of Vietnam and a weaker anticyclonic eddy W2 northwest of Palawan Island. A stronger coastal southward jet presents west of the eddy C2 and turns to the southeast in the region southwest of eddy C2-2, and it then turns to flow eastward in the region south of eddy C2-2. In the southern SCS there are a weak cyclonic eddy C3 northwest of Borneo and an anti-cyclonic circulation W3 in the subsurface layer. The net westward volume transport through section CD at 119.125°E from 18.975° to 21.725°N is about 10.3 × 10⁶ m³s⁻¹ in the layer above 400 m level. The most important dynamic mechanism generating the circulation in the SCS is a joint effect of the baroclinicity and relief (JEBAR), and the second dynamical mechanism is an interaction between the wind stress and relief (IBWSR). The strong upwelling occurs off northwest Luzon.     

南海湄公河水下三角洲上大沙丘的分布特征

根据2003和2004年冬季风之后的2次侧扫声呐调查结果,解释了湄公河水下三角洲上5个区85个水下大沙丘。沙丘尺度,高1.4~13.2 m,长72~672 m的属于Ashley (1990)分类的大和特大水下沙丘。沙丘普遍具有不对称的外形,陡坡指向W—SW。南海冬季季风引起的冬季环流汇同黑潮(分支)逆流是塑造沙丘的主要动力,据实测,金兰湾外冬季环流表层流速达1 ~1.4 m/s。水下沙丘形成于冰消期低海面时期,如今仍然顺南海冬季环流西侧自N向W—SW迁移,沙丘迁移速率约为2.78×10-5 m/s量级(按流速1.1 m/s计算)。     

EFFECTS OF VARIATION OF WINTER SEA-ICE AREA IN KARA AND BARENTS SEAS ON EAST ASIA WINTER MONSOON

By analyzing the observation data and performing the numerical simulation tests,it is shownthat the Kara and the Barents Sea area is a key region to influence climate variation over theNorthern Hemisphere.The variation of winter sea-ice area in the key region is closely associatedwith that of the EU teleconnection pattern at 500 hPa and East Asia winter monsoon(EAWM)intensity.When a heavy sea-ice prevails in the key region,the EU teleconnection pattern at 500hPa is excited easily(there are positive 500 hPa height anomalies over around Japan and WestEurope),and winter Siberia high is weakened,meanwhile,sea level pressure(SLP)has positiveanomalies over the Northern Pacific.Therefore,EAWM will be weakened,winter temperatureover East Asia is above normal and the frequency of cold-air activity in February in China will bedecreased.When the light sea-ice occurs in the key region,the results will be opposite.     

基于孔隙面积比的麦秸秆防腐分析及秸秆对粉土抗剪强度的影响

粉土性能不良,需改良后才能在高速公路路基中使用;麦秸秆环保可再生,掺入粉土会起到加筋作用,但自身易被水腐蚀,需防腐后才能使用。本文从孔隙面积比出发,分析聚乙烯醇对秸秆的防腐机理和防腐效果,通过抗拉强度试验分析防腐对秸秆抗拉强度的影响;通过直剪试验分析秸秆对粉土抗剪强度的影响。结果表明:聚乙烯醇通过自身防腐性能的发挥、填充麦秸秆孔隙减小吸水通路、在秸秆表面形成保护膜阻隔水分进入来实现防腐,孔隙面积比越小防腐效果越好;试验范围内,麦秸秆的防腐最佳浸泡时间为4 d,防腐剂最佳溶液浓度为10%,此时秸秆孔隙面积比最小,且防腐耗时最短,或经济最优。麦秸秆长度对孔隙面积比的影响主要在4 d内,与最终孔隙面积比关系不大。防腐麦秸秆抗拉强度提高。秸秆加筋土的黏聚力随秸秆掺量、麦秸秆长度的增加先增大后减小,最优掺量范围为0.4%～0.6%,最优秸秆长度为15 mm;内摩擦角随着秸秆掺量的增加略有增加,但增幅很小,不同长度下无明显规律。     

欧亚大陆冬季温度对北极海冰减少的敏感性及非线性响应研究

The recent decline in the Arctic sea ice has coincided with more cold winters in Eurasia.It has been hypothesized that the Arctic sea ice loss is causing more mid-latitude cold extremes and cold winters,yet there is lack of consensus in modeling studies on the impact of Arctic sea ice loss.Here we conducted modeling experiments with Community Atmosphere Model Version 5(CAM5) to investigate the sensitivity and linearity of Eurasian winter temperature response to the Atlantic sector and Pacific sector of the Arctic sea ice loss.Our experiments indicate that the Arctic sea ice reduction can significantly affect the atmospheric circulation by strengthening the Siberian High,exciting the stationary Rossby wave train,and weakening the polar jet stream,which in turn induce the cooling in Eurasia.The temperature decreases by more than 1°C in response to the ice loss in the Atlantic sector and the cooling is less and more shifts southward in response to the ice loss in the Pacific sector.More interestingly,sea ice loss in the Atlantic and Pacific sectors together barely induces cold temperatures in Eurasia,suggesting the nonlinearity of the atmospheric response to the Arctic sea ice loss.     

北太平洋涛动与淮河流域夏季降水异常的关系

研究了北太平洋涛动（NPO）与淮河流域夏季降水异常的关系。结果表明：冬季北太平洋涛动与次年夏季我国淮河流域降水异常呈明显的负相关：强（弱）涛动年,次年夏季淮河流域降水偏少（多）。进一步研究表明,1976年冬季NPO突变前,冬季北太平洋涛动指数（North Pacific Oscilla-tion index,INPO）与次年夏季淮河流域降水的负相关显著;突变后,负相关明显减弱;冬季INPO对淮河流域夏季降水预测的参考意义在突变前较好,在突变后减弱。