印度洋暖池热含量变化对低纬高原汛期降水的影响

 利用美国Scripps海洋研究所提供的1961—2003年的海洋热含量再分析资料、低纬高原148站降水资料和NCEP/NCAR环流再分资料,采用EOF分析、相关分析、合成分析等方法研究了印度洋暖池热含量变化,及其对低纬高原6—8月降水的影响及其可能原因.结果表明,印度洋暖池6—8月热含量变化E0F分析第1模态为全场一致型,解释方差为28%.印度洋暖池热含量与中国低纬高原6—8月降水的关系主要体现为与云南北部和东部等地区的显著正相关,这种相关关系源于前期2—4月,且随时间的推移其影响范围不断扩大,至同期时达到最好.在印度洋暖池热含量偏高年,暖池区持续的加热异常在东侧对流层低层激发出反气旋式环流异常,造成副高西伸,从而在副高外围形成一条自孟加拉湾向低纬高原区域的经向水汽输送带,为低纬高原区域输送大量的水汽,从而造成低纬高原区域降水增多.相反,在印度洋暖池热含量异常偏低时,西南风水汽输送带较弱,水汽输送无法穿越山脉输送到低纬高原区,造成低纬高原汛期降水偏少.
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青藏高原上中尺度对流系统东移的热力场特征

利用国家气象中心高分辨率有限区域分析预报系统产品(HLAFS)中的数值格点预报资料,运用空间数据挖掘中的聚类方法 (K 均值法和CLARANS法),对影响1998年夏季青藏高原上中尺度对流系统（MCSs）东移的热力场的空间分布特征进行了研究,得到了有利于MCSs移动和传播的热力学条件.结果表明,MCSs周边热力场中的温度场、湿度场以及水汽通量散度场空间分布特征的变化可以为MCSs发展和演变的预测提供重要线索,从而为探讨高原上MCSs的移动规律,揭示其发生和发展的机理提供了一种有效的新途径.     

Seasonal cycle of the zonal land-sea thermal contrast and East Asian subtropical monsoon circulation

Based on analysis of the climatic temperature latitudinal deviation on middle troposphere, its seasonal cycle suggests that due to the rapid warming from eastern China continent to the east of Tibetan Plateau and the heating of Tibetan Plateau in spring, seasonal transition of the thermal difference between East Asia continent and West Pacific first takes place in the subtropical region with greatest intensity. On the accompanying low troposphere, the prevailing wind turns from northerly in winter to southerly in summer with the convection precipitation occurring at the same time. This maybe indicates the onset of the East Asian subtropical summer monsoon. Consequently, we advice that the seasonal cycle formed by the zonal thermal contrast between Asian continent and West Pacific may be an independent driving force of East Asian subtropical monsoon.     

Estimation of wind erosion rates by using 137Cs tracing technique: A case study in Tariat-Xilin Gol transect, Mongolian Plateau

Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we established the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven sampling sites along the transect. We then estimated the soil wind erosion rates by using the 137Cs tracing technique and examined their spatial dynamics. Our results showed that the 137Cs inventories of sampling sites ranged from 265.63=44.91 to 1279.54=166.53 Bq. m-2, and the wind erosion rates varied from 64.58 to 419.63 t. km-2. a-~ accordingly. In the Mongolia section of the transect （from Tariat to Sainshand）, the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc., and the impact of human activities was negligible. While in the China section of the transect （Inner Mongolia）, the wind erosion rates of Xilin Hot and Zhengxiangbai Banner were thrice as much as those of Bayannur of Mongolia, although these three sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these two regions of Inner Mongolia.     

Relationship between the atmospheric heat source over Tibetan Plateau and the heat source and general circulation over East Asia

On the basis of NCEP/NCAR version I daily reanalysis data from 1971 to 2000 and by the methods of inverse calculation, correlation analysis and comparative analysis, the influences of atmospheric heat source （AHS） over the Tibetan Plateau on the large-scale AHS and the general circulation in summer are studied in this paper. The results show that AHS over the plateau in summer may trigger a heat source wavetrain propagating northeastward along the coast from the East Asian continent and West Pacific to Bering Strait-Arctic or even North America. In addition, if AHS over the eastern plateau is intense, South Asian High moves to southeast and West Pacific subtropical high moves to southwest; on the contrary, if AHS over the eastern plateau is weak, South Asian High moves to northwest and West Pacific subtropical high moves to northeast. Therefore, South Asian High and West Pacific subtropical high move in the horizontally-opposite directions in terms of interannual variation, for which AHS over the eastern plateau seems to be thermodynamically responsible.     

Identification of the deposited layers in landslides reservoir and investigation of the sediment yields during the later sixteenth century on the Hill Loess Plateau,China

There are many sediment trapping reservoirs in the Hill Loess Plateau. The Huangtuwa small catchment is selected as a research field where samples were collected in a sediment deposit profile with a vertical length of 12.73 m. By the variation of fine particle content and pollen concentration, 54 flood couples were identified. Taking the freeze-thawing disturbed texture as the sign of the latest flood couple in a year, it is ascertained that those 54 floods should happen in 31 years. Using pyramid volume calculation formula, the sediment yields of flood ranged between 716-30376 t· km^-2, The average sediment yield was 7106 t· km^-2, The annual sediment yields varied between 968-55579 t· （km^2· a）^-1, and the average value is 12629 t· （km^2· a）^-1. Compared with the modern annual sediment discharge of the Huaining River, the erosion rate in the Huangtuwa region 450 years ago was similar to the modern erosion rate. In the period from the 27th year to the 31st year, the average annual sediment yield increased sharply to 31309 t· （km^2· a）^-1. It implied that re-reclamation of the abandoned land in the catchment since the landslide disaster, where vegetation had rehabilitated already, caused very severe soil erosion in the catchment.     

Asian summer monsoon precipitation recorded by stalagmite oxygen isotopic composition in the western Loess Plateau during AD1875―2003 and its linkage with ocean-atmosphere system

Based on 5 high-precision 230Th dates and 103 stable oxygen isotope ratios (δ18O) obtained from the top 16 mm of a stalagmite collected from Wanxiang Cave,Wudu,Gansu,variation of monsoonal precipita-tion in the modern Asian Monsoon (AM) marginal zone over the past 100 years was reconstructed. Comparison of the speleothem δ18O record with instrumental precipitation data at Wudu in the past 50 years indicates a high parallelism between the two curves,suggesting that the speleothem δ18O is a good proxy for the AM strength and associated precipitation,controlled by "amount effect" of the pre-cipitation. Variation of the monsoonal precipitation during the past 100 years can be divided into three stages,increasing from AD 1875 to 1900,then decreasing from AD 1901 to 1946,and increasing again thereafter. This variation is quite similar to that of the Drought/Flooding index archived from Chinese historical documents. This speleothem-derived AM record shows a close association with the Pacific Decadal Oscillation (PDO) between AD 1875 and 1977,with higher monsoonal precipitation corre-sponding to cold PDO phase and vice versa at decadal timescale. The monsoonal precipitation varia-tion is out of phase with the PDO after AD 1977,probably resulting from the decadal climate jump in the north Pacific occurring at around AD 1976/77. These results demonstrate a strong linkage between the AM and associated precipitation and the Pacific Ocean via ocean/atmosphere interaction. This rela-tionship will aid to forecast future hydrological cycle for the AM monsoon region,and to improve forecasting potential of climatic model with observation data from cave.     

Using 137Cs tracing technique to estimate wind erosion rates in the typical steppe region,northern Mongolian Plateau

Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using ^137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km^-2.a^-1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm. a^-1, and wind erosion rates up to 6723.06 t· km^-2. a^-1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not induce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.     

简析黄土高原的生态环境建设

介绍了黄土高原生态环境现状,指出了环境恶化的危害,分析了形成生态环境脆弱的原因,提出了改善生态环境的几点建议。     

蒙中西医结合治疗慢性前列腺炎伴性功能障碍临床观察

目的：探讨蒙中西医结合治疗慢性前列腺炎伴性功能异常的疗效．方法：对50例慢性前列腺炎伴性功能异常患者的临床资料进行系统的分析、总结．结果：经过现代医学和传统医学方法诊断治疗的50例慢性前列腺炎伴性功能异常患者的临床症状明显好转或痊愈．结论：中蒙西医结合治疗慢性前列腺炎伴性功能障碍是目前行之有效的治疗手段之一．