测定卫星接收天线地理正南方的准确方法——时差日晷法

本文提出了时差日晷法,以伊春地面接收站为例,介绍地方真太阳时正午12点的时刻计算、地面接收站地理正南方的测定与检验的方法步骤。检验结果说明,时差日晷法是测定地理正南方的准确方法。

我国南方的旱灾

2004年9月以来，发生在我国南方的严重干旱已经造成经济损失40多亿元，720多万人出现了饮水困难。

Anomalous winter temperature and precipitation events in southern China

This paper analyzed the anomalous low-temperature events and the anomalous rain-abundant events in January since 1951 and winter since 1880 for southern China. The anomalous events are defined using ±1σ thresholds. Twelve cold Januaries are identified where temperature anomaly below -1σ, and ten wet Januaries are identified where precipitation anomaly above ＋1σ. Among these events there are three patterns of cold-wet Januaries, namely 1969, 1993 and 2008. The NCEP/NCAR reanalysis data are used to check the atmospheric circulation changes in association with the anomalous temperature and precipitation events. The results show that the strong Siberian High （SBH）, East Asian trough （EAT） and East Asian jet stream （EAJS） are favorable conditions for low-temperature in southern China. While the anomalous southerly flow at 850 hPa, the weak EAT at 500 hPa, the strong Middle East jet stream （MEJS） and the weaker EAJS are found to accompany a wetter southern China. The cold-wet winters in southern China, such as January of 2008, are mainly related to a stronger SBH, and the circulation in the middle to upper troposphere is precipitation-favorable. In wet winters, the water vapor below 500 hPa is mainly transported by the anomalous southwesterly flow and the anomalous southern flow over the Indo-China Peninsula and the South China Sea area. The correlation coefficients of MEJS, EAMVV （East Asian meridional wind） and EU （Eurasian pattern） to southern China precipitation in January are ＋0.65, -0.59 and -0.48 respectively, and the correlations for high-pass filtered data are ＋0.63 -0.55 and -0.44 respectively, the significant level is all at 99%. MEJS, EAMW and EU together can explain 49.4% variance in January precipitation. Explained variance for January and winter temperature by SBH, EU, WP （west Pacific pattern） and AO （Arctic Oscillation） are 47.2% and 51.5%, respectively. There is more precipitation in southern China during El Nitro winters, and less precipitation during La Nina winters. And there is no clear evidence that the occurrence of anomalous temperature events in winter over southern China is closely linked to ENSO events.

Effects of precipitation variation on severe acid rain in southern China

Acid rain has been recognized as a serious environmental problem in China since the 1980s, but little is known about the effects of the climatic change in regional precipitation on the temporal and spatial variability of severe acid rain. We present the effects of the regional precipitation trend change on the area and intensity of severe acid rain in southern China, and the spatio-temporal distribution characteristics of SO2 and NO2 concentrations are analyzed on the basis of SO2 and NO2 column concentration data. The results are as follows. （1） The emission levels of SO2 and NO2 have reached or passed the precipitation scavenging capacity in parts of southern China owing to the emission totals of SOz and NO2 increasing from 1993 to 2004. （2） Notable changes in the proportion of cities subject to severe acid rain occurred mainly in the south of the middle-lower reaches of the Yangtze River during 1993-2004. With an abrupt change in 1999, the severe acid rain regions were mainly located in central and western China during 1993-1999 and moved obviously eastward to the south of the lower-middle reaches of the Yangtze River with the proportion of cities subject to severe acid rain increasing significantly from 2000 to 2004. （3） The spatial distribution and variation in the seasonal precipitation change rate of more than 10 mm/10a are similar to those of severe acid rain in southern China. An abrupt change in 1999 is seen for winter and summer precipitation, the same as for the proportion of cities subject to severe acid rain in southern China. The significant increase in summer storm precipitation from 1991 to 1999 mitigated the annual precipitation acidity in the south of the Yangtze River and reduced the area of severe acid rainfall. On the other hand, the decrease in storm rainfall in summer expanded the area of severe acid rainfall in the south of the Yangtze River in 2000-2006. Therefore, the change in seasonal precipitation is an important factor in the severe acid rain regions moving eastward and expanding in southern China.

A GIS-BASED GLACIER INVENTORY FOR THE ANTARCTIC PENINSULA AND THE SOUTH SHETLAND ISLANDS——A FIRST CASE STUDY ON KING GEORGE ISLAND

The aim of the international project “Global Land Ice Measurements from Space (GLIMS)" headed by the US Geological Survey is to establish a world wide glacier inventory based on satellite imagery.This data set will form a first digital baseline study for future glacier monitoring.The presented GIS_based glacier inventory for King George Island is a case study for the area of the Antarctic Peninsula.In the database of the glacier inventory topographic information,specific glaciological parameters as well as metadata will be included.The topographic data consists of drainage basin limits,basin areas,altitudinal ranges,perimeters and mean lengths.Glaciological data sets should comprise information on glacier retreat in different periods,glacier velocities,ice thickness and bedrock topography as well as derived parameters.Modelled and measured mass balance parameters could be included as additional data layers.In particular,these metadata records must comprise background information on data accuracy and data sources and should be compatible with a future data model for the King George Island GIS (KGIS).Three examples illustrate that the GLIMS database will not only contain information valuable for glaciological applications,but also other environmental studies on the island will benefit from this standardised remote sensing data sets.Therefore,a very close link between the data models of KGIS and GLIMS has to be established to enable these synergisms.Finally,better access to historic aerial photography would enable a continuous record of glacier retreat from the beginning of the 1950’s onward.

Establishing the Basic Indicator for the Calculation of the Flood Vulnerability Index for River Basins in Vietnam

Along with the concept, the method of assessing the vulnerability is becoming more and more diversified in many directions and fields. In general, these methods can be classified into two groups： （i） direct-qualitative （survey methods, integrated map ...） and （ii） indirectly-quantitative （method index）. The set of indicator plays a very important role in the successful application to any method and brings reliable results. Each basin or area with different natural geography, economics and society and so on, requires a different set of indicator. However, assessing any river basin in Vietnam needs the basic indicator. This study will establish the basic indicator for the construction of flood vulnerability index in Vietnam.

Biostratigraphy and geography of the Ordovician-Silurian Lungmachi black shales in South China

Based on the new material of seven Ordovician-Silurian boundary sections investigated recently, together with previously published data, we analyze the temporal and spatial distributions of the Lungmachi black shales, a key petroleum source bed widely distributed in South China. The Lungmachi black shales range in age from the Normalograptus persculptus Biozone of the uppermost Ordovician to the Spirograptus guerichi Biozone of the lower Telychian, and ten graptolite biozones can be recognized within this unit. The basal and upper contacts of the Lungmachi black shales are diachronous. The basal contact ranges from the N. persculptus to the C. cyphus biozones, a span of five graptolite biozones over two stages. The upper contact ranges from the D. pectinatus-M. argenteus Biozone to the Spirograptus guerichi Biozone, which spans four graptolite biozones over two stages. The Yichang Uplift resulted in the formation of the Hunan-Hubei Submarine High in the border area of Hubei, Hunan, and Chongqing. This is supported by a break in sedimentation in this area spanning all or part of the Hirnantian, and in many areas extending into the underlying Katian and overlying Rhuddanian. Comparison of the distribution of the Katian to Rhuddanian strata in this area indicates a growth and subsequent reduction in area of the Hunan-Hubei Submarine High particularly in the Hirnantian to early Rhuddanian. This may partly represent the influence of the process of formation and melting of ice sheet in Ordovician South Pole and consequent sea level change.

First record of extinct fruit genus Chaneya in low-latitude tropic of South China

Fossil reproductive structure from the Eocene of the Changchang Basin (Hainan Island,South China) is recognized as Chaneya hainanensis sp.nov.This new species is characterized by persistent corolla of five obovate petals with three subparallel primary venation linked by arching secondary veins,circular central disk bearing two orbicular ovaries or fruit bodies.This discovery confirms the presence of the extinct fruit genus Chaneya in low-latitude tropical area,providing significant fossil evidence for investigating the origin,migration,and phytogeography of this genus and discussing the Tertiary floristic exchanges among North America,eastern Asia,and Europe.Considering the distribution of this genus and its extant relatives and the climate changes during the Cenozoic,we hypothesize that Chaneya was a widespread tropical or subtropical taxon,but,with climate cooling,became extinct in northern latitudes and evolved into Picrasma (Simaroubaceae) and Rutaceae mainly in modern tropics and subtropics.