THE CLIMATIC JUMP OF THE WESTERN PACIFIC WARM POOL AND ITS CLIMATIC EFFECTS

1INTRODUCTIONTropicalwesternPacificOceanisanareathathasthehighestoceantemperatureacrosstheglobe.Asmostofthewarmwaterconcentratesintheregion,itisknownasthe搘esternPacificwarmpool?Asshowninsomestudies[1-5],thegeneralcirculationandshort-termclimaticchangeswillbeseriouslyaffectedifthermodynamicconditionchangesinthewaters,whichthenhaveanimportantroletoplayintheonsetofanyENSOepisodes.Therehasnotbeenanyunifieddefinitionoftheindexforthewarmpool.FollowingthecriterionofWyrtki[4],however,theareae…     

应用GrADS绘图系统绘制小网格分析气候图

以广西 88站稳定通过 10℃起止日积温为例 ,采用回归分析方法 ,建立地理因素影响气候要素的气候方程 ,并结合 Gr ADS提供的数据处理及图形绘制功能 ,对余差项进行格点插值 ,最终求得小网格分析气候资料 ,并绘制气候分布图     

中国地质灾害与气候波动的耦合性探讨

搜集了元朝至民国期间历史资料所记载的地质灾害，以月为基本单位将各次地质灾害按时间顺序投影成时间谱图，并通过100个月的窗口进行1/2窗口的滑动平均统计得出相应的频数，对该频数的时间谱图和统计直方图的分析，揭示了中国地质灾害的发生具有274-290a的大周期和平均19.5a的小周期。在灾害发生的大周期中灾害随气候的连续递变而增强，灾害发生的大周期是气候变化周期的一半。灾害发生的小周期与地球章动（晃动）主周期、太阳-月亮-地球的公共会合周期、木星和土星的会合周期、沙罗周期等十分接近。     

孟加拉湾深海记录中的等深流活动特征及其环境意义初探

实地观测和对沉积记录的研究表明，孟加拉湾存在大的等深流活动。通过采自孟加拉深海东部和中部的3支活塞岩心的学积学研究表明，那些氧化色彩强烈，钼质生物壳体溶蚀严重，不存在粒序层理的粉砂质薄层实际上是等沉积作用的产物，源自两极的等深流是全球温盐循环系统的关键组分，它们的过去150ka的历史中曾经多次得到强化，不仅对研究区的环境变化产生重要影响，而且可能作为纽带，加强了低纬地区与极区在气候意义上的遥相关，等深流的强化与冰川旋顺之间似乎不存在密切关联，氧同位素第3，4，5期内均可发现明显的强化记录，关于强化的控制机制有待深入探讨。     

Changes in the Thermal Climate in Northwestern Europe during Marine Oxygen Isotope Stage 3, Estimated from Fossil Insect assemblages

More than 30 fossil coleopteran (beetle) assemblages have been recorded from oxygen isotope stage 3 in northern Europe, comprising several hundred identified species. Using the mutual climatic range method for quantifying palaeotemperatures, these assemblages show that the climates of the times can be divided into two distinct interstadial types. One, a short phase of temperate/oceanic climate occurred between 43,000 and 42,000 ¹⁴C yr B.P. when conditions were not much different from those of the present day. In spite of the temperate climate, trees did not colonize northwestern Europe at this time. Two, both before and after this temperate interlude there were phases of cold/continental climate during which summers were too cold for trees to grow and winters were of Siberian intensity. It is possible that periods of even colder conditions intervened from time to time between the interstadial but, because of the intensity of the cold, biological systems were so inhibited that no fossil evidence for them can be found in northern Europe. Evidence for them must be sought in the fossil records from the warmer parts of southern Europe or in the physical evidence in the Greenland ice cores.     

Recent environmental changes in Laguna Mar Chiquita (central Argentina): a sedimentary model for a highly variable saline lake

Abstract Laguna Mar Chiquita, a highly variable closed saline lake located in the Pampean plains of central Argentina, is presently the largest saline lake in South America (≈ 6000 km²). Recent variations in its hydrological budget have produced dry and wet intervals that resulted in distinctive lake level fluctuations. Results of a multiproxy study of a set of sedimentary cores indicate that the system has clearly recorded these hydrological variations from the end of the Little Ice Age (≈ ad 1770) to the present. Sedimentological and geochemical data combined with a robust chronology based on ²¹⁰Pb profiles and historical data provide the framework for a sedimentary model of a lacustrine basin with highly variable water depth and salinity. Lake level drops and concurrent increases in salinity promoted the development of gypsum–calcite–halite layers and a marked decrease in primary productivity. The deposits of these dry stages are evaporite‐bearing sediments with a low organic matter content. Conversely, highstands are recorded as diatomaceous organic matter‐rich muds. Average bulk sediment accumulation rose from 0·22 g cm^?2 year^?1 in lowstands to 0·32 g cm^?2 year^?1 during highstands. These results show that Laguna Mar Chiquita is a good sensor of high‐ and low‐frequency changes in the recent hydrological budget and, therefore, document climatic changes at middle latitudes in south‐eastern South America. Dry conditions were mostly dominant until the last quarter of the twentieth century, when a humid interval without precedent during the last 240 years of the lake's recorded history started. Thus, it is an ideal system to model sedimentary and geochemical response to environmental changes in a saline lacustrine basin.     

Estimation of tree transpiration and response of tree conductance to meteorological variables in desert-oasis system of Northwest China

Transpirations of three dominated tree species, namely Mongol Scotch Pine (Pinus sylvestris var. mongolica Litvin), White elm (Ulmus pumila) and Gansu Poplar (Populus gansuensis Wang et Yang) in oasis shelter forest (Linze site) and of two dominated tree species,namely Euphrates Poplar (Populus euphratica Oliv.) and Russia olive (Elaeagnus angustifolia Linn.) in lowland desert (Erjinaqi site) have been estimated using measured sapflow in summer,autumn and winter, 2002 and in spring, 2003. An ENVIS System was used for each site to measure microclimate variables, soil moisture and sapflow every half an hour, and the study time scale is one day. In the 104 days of observation during the growing season at the Linze site, the average daily sapflow of Gansu Poplar is 9.93L·d-1,and the average transpiration per unit leaf area is 1.99mm·d-1.For White elm tree,the daily average sapflow is 4.08L·d-1,while the daily average transpiration per unit leaf area is 0.49mm·d-1.The values for Mongol Scotch Pine are 3.91L·d-1 and 0.25mm·d-1,respectively.In the total 73 days of observation during the growing season at the Erjinaqi site, the daily average sapflows of Russia olive and Euphrates Poplar are 12.1 and 20.97L·d-1,respectively,and the average transpirations per unit leaf area are 0.22 amd 0.31mm·d-1,respectively.In the observation period of the growing season,tree conductances of Mongol Scotch Pine, White elm, Gansu Poplar or Russia olive show an exponential relationship with the daily average air temperature or vapour pressure deficit, but the relationship is not so obvious between tree conductance and global radiation. The transpiration process of each tree species is affected by all the observed four environmental variables. The response of tree conductance to different climatic factors changes with tree species. The effect of the same factor to the same tree species is also variable in different growing stages. The sapflow of every tree species is relatively large in later spring to early summer, and low in summer, and then reaches its largest value in later September. In the mid-November, the sapflow is relatively large, especially the deciduous tree species. This may be characteristic of the tree species in Arid Regions of Northwest China.     

SIMULATION ON CLIMATIC VARIATION OF ARCTIC SEA ICE THROUGH AN ICE-OCEAN COUPLED MODEL*

An ocean model developed by the Institute of Marine Research and the University of Bergen in Norway (BOM) and a state-of-the-art sea ice model developed by NCAR (CSIM4) are coupled, Considering influences of 9 major rivers,forced by the NCEP reanalysis atmospheric fields and the Levitus surface salinity,the Arctic sea ice climatic variation from January 1949 to December.1999 was simulated through the coupled model.The comparison of simulated results and observations shows that:(1)the long-term ice concentration variation tendencies are in consistent with the observations in the divisional ocean regions;(2)simulated ice thickness horizontal distribution is reasonable.Simulated ice thickness has a decreasing tendency in the central Arctic,which agrees with the submarine observations.Simulated annually maximum ice thickness is highly related to observed fast-ice thickness off the Russian coast;and (3)sea ice area/volume fluxes through the Fram Strait are in accord with the satellite-derived data.Generally,the coupled model successfully simulated the Arctic Ocean sea ice climatic variation.     

A study of the possible extended influence of the ENSO phenomenon

El Niño/Southern Oscillation (ENSO) is well known to have a worldwide impact, in particular on streamflows. As an illustration, we found a good correlation (～0.47, 5-month time delay) between the ENSO activity and the discharge of the main rivers in French Guiana. However, this calculation was made between climatic and hydrological processes at ‘isolated precise moments’. Using a new method of time series analysis, we considered the ENSO and Atlantic Ocean/river discharge correlation integrated over time. This method shows, with more than 99% confidence level, new possible delayed and combined influences between the phenomena (respectively ～20 and 40 months for ENSO and Atlantic Ocean influences). To cite this article: C. Gaucherel, C. R. Geoscience 336 (2004).     

不同气候区月蒸散发能力计算模式适用性分析

根据实测气象资料和蒸散发量资料，对几种蒸散发量计算模式进行了对比分析，提出不同气候区计算模式的适用性。以彭曼一蒙蒂斯公式计算的蒸散发量作为参考值，得出Φ20蒸发皿换算成蒸散发能力的折算系数。分析成果对我国水文水资源计算和进行气候变化影响评价具有指导意义。