安徽省含山县土地整理耕地质量评价及其变化研究

土地整理是改善土地利用条件,提高土地质量的有效措施,对土地整理后的耕地质量进行评价是土地整理重要工作之一。从耕地质量的内涵和土地整理项目的基本要求出发,选取耕地自然条件和耕地利用条件2个基本因素和12个影响因子,将特尔斐法与层次分析法相结合,确定各因子权重,构建基于土地整理的耕地质量评价指标体系。以安徽省含山县铜闸镇土地整理项目为例,采用传统的土壤调查与3S技术相结合的方法,分析土地整理复垦过程中耕地质量时空格局变化,得出整理前、后耕地质量的级别变化。研究结果表明,通过土地整理,研究区的耕地质量空间分布和级别发生了很大变化,整理后一级、二级、三级质量的土地比整理前分别增加了7.20%,11.95%和0.65%,四级、五级则分别减少了15.65%和4.16%,整理后的耕地质量总体水平是整理前的1.291倍。     

Geochemical constraints on the contribution of Louisville seamount materials to magmagenesis in the Lau back-arc basin,SW Pacific

Seamounts are an integral part of element recycling in global subduction zones. The published trace element and Pb-Sr-Nd isotope data for basaltic lavas from three key segments (Central Lau Spreading Ridge (CLSR), Eastern Lau Spreading Ridge (ELSR), and Valu Fa Ridge (VFR)) of the Lau back-arc basin were compiled to evaluate the contribution of Louisville seamount materials to their magma genesis. Two geochemical transitions, separating three provinces with distinct geochemical characteristics independent of ridge segmentation, were identified based on abrupt geochemical shifts. The origin of the geochemical transitions was determined to be the result of drastic compositional changes of subduction components added into the mantle source, rather than the transition from Indian to Pacific mid-ocean ridge basalt (MORB) mantle, or due to variable mantle fertilities. The most likely explanation for the drastic shifts in subduction input is the superimposition of Louisville materials on ‘normal’ subduction components consisting predominantly of aqueous fluids liberated from the down-going altered oceanic crust and minor pelagic sediment melts. Quantitative estimation reveals that Louisville materials contributed 0–74% and 21–83% of the Th budget, respectively, to CLSR and VFR lavas, but had no definite contribution to the lavas from the ELSR, which lies farthest away from the subducted Louisville seamount chain (LSC). The spatial association of the subducted LSC with the Louisville-affected segments suggests that the Louisville signature is regionally but not locally available in the Tonga subduction zone. Besides, the preferential melting of subducted old Cretaceous LSC crust instead of the old normal Pacific oceanic crust at similar depths implies that elevated temperature across the subduction interface or seamount erosion and rupture were required to trigger melting. A wider implication of this study, thus, is that seamount subduction may promote efficiency of element recycling in subduction zones.     

冬季降水相态的探空廓线分型研究

首先阐述了不同降水相态的形成机理及其与典型温度分布之间的联系,提出应用面积元方法计算出的探空廓线与0℃等温线相交形成的正、负区面积和两者的交点数,以及地面温度作为降水相态(雨,雨夹雪,雪,冻雨,冰粒)的预测因子。再利用我国120个测站2007—2013年冬季地面和高空观测资料,统计分析了探空廓线与降水相态的关系,指出可以根据交点数区分冻雨、冰粒与雨雪,地面温度区分冰针和米雪,而雨、雪和雨夹雪可以根据探空廓线与0℃线有1个交点和低层正面积区的大小进行相态区分。     

Dynamical downscaling simulation and projection for mean and extreme temperature and precipitation over central Asia

Climate Dynamics - As a typical arid and semi-arid area, central Asia (CA) has scarce water resources and fragile ecosystems that are particularly sensitive and vulnerable to climate change. In...     

基于MODIS-EVI数据的神农架林区植被指数变化特征研究

对植被覆盖动态变化监测可以提供生态系统状况有价值的信息,可以检测到人类或气候作用引起的变化.以2003-2012年MODIS的遥感数据为信息源,利用增强型植被指数(EVI),采用最大值合成法,对神农架林区植被覆盖动态变化进行监测,并与同期的气候因子进行相关性分析,结果表明:10 a来神农架林区植被覆盖整体呈增加趋势,且东部地区的EVI增幅大于西部增幅,特别是近5 a(2008-2012年),除2010年外,植被指数均为正距平.说明神农架林区近5 a来植被生长状况较好,生态环境得到了进一步改善.与气候因子进行相关性分析说明,气温是制约神农架植被生长的主要气候因子,而降水和日照是影响该地区植被生长的重要气候因子.     

Association of Indian Ocean ITCZ Variations with the Arctic Oscillation during Boreal Winter

In this study,the authors analyzed the associations between the Arctic Oscillation(AO)and the tropical Indian Ocean(TIO)intertropical convergence zone(ITCZ)in boreal winter for the period 1979–2009.A statistically significant AO-TIO ITCZ linkage was found.The ITCZ vertical air motion is significantly associated with the AO,with upward(downward)air motion corresponding to the positive(negative)AO phase.The Arabian Sea anticyclone plays a crucial role in linking the AO and the TIO ITCZ.The Arabian Sea vorticity is strongly linked to high-latitude disturbances in conjunction with jet stream waveguide effects of disturbance trapping and energy dispersion.During positive(negative)AO years,the Arabian Sea anticyclone tends to be stronger(weaker).The mean vorticity over the Arabian Sea,averaged from 850hPa to 200 hPa,has a significant negative correlation with AO(r=0.63).The anomalous anticyclone over the Arabian Sea brings stronger northeastern winds,which enhance the ITCZ after crossing the equator and result in greater-than-normal precipitation and minimum outgoing long-wave radiation.     

近34年河南首场暴雨时空分布特征及环流背景分析

利用1985-2018年河南省121个国家气象观测站每日20时至次日20时降水资料、常规高空地面观测资料、NCEP1°×1°再分析资料,通过统计和诊断分析方法分析了近34年河南首场暴雨的时空分布特征、影响系统、环流形势和物理量特征。研究结果表明:首场暴雨具有明显的年际变化和月变化特征,主要集中在4-5月,首场暴雨发生时间有提前的趋势;首场暴雨以全省性降水为主,黄淮之间沿黄及其以北和南部地区是暴雨的三个易发区;暴雨出现频次较多的站点和单日雨量最大的站点基本一致,首场暴雨出现的频次从河南省西北部到东南部逐渐增多。首场暴雨的地面影响系统主要是江淮气旋和江淮倒槽两类,高空影响系统500 hPa以低槽为主,700 hPa受低槽、切变线影响,850 hPa受低涡、切变线影响。江淮气旋类暴雨一般热力、动力条件较好,江淮倒槽类暴雨水汽条件较好。首场暴雨的水汽通量、辐合、辐散条件要优于夏季的,垂直速度略小于夏季的,比湿和不稳定度明显低于夏季的。     

江西省森林和植被碳汇价值研究

江西生态优势明显,森林覆盖率居全国前列,研究植被生态系统碳汇价值是应对气候变化和生态文明建设的具体体现。基于森林资源清查资料,研究了2001—2016年江西省森林碳汇价值;基于卫星遥感数据反演获取植被生态系统净初级生产力(NPP),评估了2000—2016年江西各设区市(县)植被碳汇分布特征。结果表明:1)2016年江西省森林碳储量价值为980.30亿元,植被和森林碳汇价值均呈上升趋势。2)江西省植被碳汇价值增加率为4.55亿元/a,2016年约为823.53亿元,每公顷所创造的碳汇经济价值为4930.67元,比2000年增加了11%。3)2016年各设区市植被碳汇价值排名前三位的分别是赣州、吉安和上饶,排名后三位的是新余、鹰潭和萍乡,单位面积固碳价值排名前三位的为赣州、吉安和抚州,排名后三位的是南昌、九江和鹰潭,其排名与森林面积和森林覆盖率有较大关系。