藏北高原D110点不同季节土壤温度的日变化特征

利用１９９８年ＧＡＭＥ－Ｔｉｂｅｔ加强观测期间取得的一个年周期的土壤温度资料,对藏北高原Ｄ１１０点土壤温度日变化特征的月际变化进行了分析。结果表明,在夏半年（５－９）月土壤温度存在明显的日变化,且基本上按正弦曲线变化,但相位随深度的增加而滞后;冬半年土壤温度尽管也存在日变化,但变幅较小。     

Multi-scale remote sensing to support insurance policies in agriculture: from mid-term to instantaneous deductions

ABSTRACT

Climate change is today one of the biggest issues for farmers. The increasing number of natural disasters and change of seasonal trends is making insurance companies more interested in new technologies that can somehow support them in quantifying and mapping risks. Remotely sensed data, with special focus on free ones, can certainly provide the most of information they need, making possible to better calibrate insurance fees in space and time. In this work, a prototype of service based on free remotely sensed data is proposed with the aim of supporting insurance companies’ strategies. The service is thought to calibrate annual insurance rates, longing for their reduction at such level that new customers could be attracted. The study moves from the entire Piemonte region (NW Italy), to specifically focus onto the Cuneo province (Southern Piemonte), which is mainly devoted to agriculture. MODIS MOD13Q1-v6 and Sentinel-2 L2A image time series were jointly used. NDVI maps from MODIS data were useful to describe the midterm phenological trends of main crops at regional level in the period 2000–2018; differently, Sentinel-2 data permitted to map local crop differences at field level in 2016 and 2017 years. With reference to MODIS data, the average phenological behavior of main crop classes in the area, obtained from the CORINE Land Cover map Level 3, was considered using a time series decomposition approach. Trend analyses showed that the most of the crop classes alternated three phases (about 7 years) suggesting that, presently, this is probably the time horizon to be considered to tune mid-term algorithms for risk estimates in the agricultural context. Crop classes trends were consequently split into three phases and each of them modeled by a first-order polynomial function used to update correspondent insurance risk rate. Sentinel-2 data were used to map phenological anomalies at field level for the 2016 and 2017 growing seasons; shifts from class average behavior were considered to locally and temporarily tune insurance premium around its average trend as described at the previous step. Synthesizing, one can say that this approach, integrating MODIS and Sentnel-2 data, makes possible to locally and temporarily calibrate premiums of indexed insurance policies by describing the average trends of crop performance (NDVI) at regional level by MODIS data and refining it at field and specific crop level by Sentinel-2 data.     

江淮梅雨与东亚副热带夏季风进程变异的关系

根据中国气象局《梅雨监测业务规定》中的入、出梅标准,结合1960—2016年全国661个常规气象站逐日气象资料,以及NCEP/NCAR月平均再分析资料,分析了江淮梅雨和东亚副热带夏季风进程变异的时空特征,提取季风关键区(32°~34°N,112°~120°E,包含17个站点),并分析了江淮梅雨和季风关键区的联系与成因。结果表明:1960—2016年平均梅雨期为6月8日—7月15日,平均梅雨量为303 mm。比东亚平均梅雨季的开始时间早9 d,比其结束时间晚7 d。梅雨量在近57 a中也呈波动式变化,但整体为上升趋势。入梅越早,出梅越晚,则梅雨期越长,梅雨量越多。副热带夏季风推进到关键区的平均时间为5月19日,其在1970s末和1990s末分别发生了由偏晚向偏早和由偏早向偏晚的突变。夏季风到达关键区偏早时,出梅日偏晚,梅雨量偏多,季风到达偏晚时,出梅日偏早,梅雨量偏少。副热带夏季风推进时间和江淮梅雨量呈全区一致的负相关,负相关区位于湖南、湖北及江西三省临近的两湖地区。东亚副热带夏季风到达关键区时间偏早(晚)年,500 hPa高度场上乌拉尔山—鄂霍茨克海为正(负)距平,阻塞高压增强(减弱);日本海附近为负(正)距平,东亚大槽加深(西退北缩),加强(削弱)了槽后冷空气向南输送且不(有)利于中低纬度副热带高压的北跳,西太平洋副热带高压中心强度增强(减弱),位置偏西(东),其西北侧的西南暖湿气流输送加强(减弱),江淮地区有水汽的辐合(辐散),有(不)利于梅雨量偏多。     

中国近代金矿开发概貌

总结了我国清末至民国初期(1840—1920年)长达80年的金矿开发概貌,按现行政区划,共涉及21个省。对各省的金矿,既扼要探讨历史沿革,又尽量地汇集具体产金地名及有关地质矿产信息,期望达到治史与古为今用相结合的双重目的。     

高原季风强弱对南亚高压活动的影响

分析了高原季风强弱对夏季南亚高压活动和三峡库区旱涝的影响,揭示了如高原夏季风偏强(弱),育藏高原上空及其以东地区100hPa南亚高压也偏强(弱),位置偏北偏东(偏南偏西)。高原季风强年,南亚高压脊线6月北跳比多年平均早1候,8月南撤晚1～2侯;高原季风弱年。脊线北跳晚1～2候,南撤早1候。同时显示了高原夏季风强年,5～6月三峡库区降水随着南亚高压脊线北移而增多,7～8月三峡库区降水减少;高原夏季风弱年,主汛期前期库区降水少,后期降水略有增多。     

Gamma Emitters on Micro-Becquerel Activity Level in Air at Kraków (Poland)

The Petryanov air filters combined into half-year sets were analyzed for the presence of ⁴⁰K, ¹³⁷Cs and ²²Na by means of low-background gamma rays spectrometry. Each sample contains aerosols from more than 1 Mm³ of air. Samples were collected in ground level air at Kraków (Southern Poland) from 1996 to 2002. Activity concentrations of ⁴⁰K are almost constant with the mean of 14.7± 4.5 Bq m^–3. Activity concentrations of ¹³⁷Cs, which are on the level of single Bq m^{– 3} show exponential decrease with effective half-life time of 7.07± 0.77 years. The cosmogenic ²²Na shows a strong seasonal variation with significant different mean values activity concentration between 0.333± 0.095 Bq m^–3 and 0.137± 0.045 Bq m^–3, for summer and winter, respectively. Moreover, the activity ratio for two cosmogenic radionuclides: ²²Na and measured previously ⁷Be show also changes with statistically significant seasonal differences. The lower values were found during winters. The mechanisms which might govern this ratio are discussed. The conclusion is that transport of ²²Na during summer seems to be so much effective, that results in kind of relative depletion of stratosphere of this nuclide.     

南海到西太平洋地区水汽输送和山东夏季降水量奇异值分解分析

利用奇异值分解(SVD)方法和山东省26个代表站1951～2000年6～8月降水量、NCEP／NCAR再分析1958～1998年1～12月925～300hPa5层月平均比湿和风场资料,分析了山东夏季降水与前期(冬季、春季)及同期(夏季)南海到西太平洋地区水汽输送之间相关场的分布型,从中找出了遥相关的“关键区”,并对找到的“关键区”的可靠性进行了验证。研究表明,山东夏季降水与前期(冬季、春季)和同期(夏季)南海到西太平洋地区水汽输送相关较好,春季的相关程度最高,冬季次之,夏季最小。     

0103号台风"榴莲"路径与致洪暴雨成因分析

通过对0103号台风"榴莲"的路径及特大暴雨天气的环流背景分析,认为造成这次致洪暴雨过程的最主要的天气原因是:深厚的副热带高压使台风偏向西行进入广西,与正在爆发的西南季风云系相遇,从而使降雨量大幅度增加,引发了广西南部特大洪水过程。     

昆仑山口西8.1级地震后青藏高原北部地区地震活动初步研究

利用相关震例分析了昆仑山口西8．1级地震后青藏高原北部地区未来1～3年地震活动特征．结果表明,沿东昆仑构造带及邻近地区发生Ms≥7．0地震后青藏高原北部地区中强地震活动有增强的趋势,祁连山地震带和东昆仑地震带的地震活动具有交替发生的特征,未来1～3年中强地震主体活动区为大型走滑活动断裂上应力转换部位和挤压会聚构造区,如东昆仑断裂带中东段和祁连山地震带中东段和西段。     

云南水汞在打破M≥5级地震平静后强震前的异常分析

通过普洱6．3、宁蒗6．2级和姚安6．5级3个在省内M≥5级地震平静了10余个月,打破5级平静后发生的M≥6级强震前水汞的异常分析,并着重短临异常研究,结果表明这3次地震前水汞均有中期和短、临异常,中、短、临异常台站数为两头少,中间多。中期异常表现为11％。22％的水汞观测台站震前出现2—10个月的中期异常;短期异常表现为震前2—3个月,平均44％的台站观测到短期异常,最大异常幅度与异常判定线比值在1．3—3．2倍之间：强震前都只有1个台站出现临震异常。短期异常有差异,宁蒗6．2级主震前,短期异常在2次前震前出现,普洱6．3、姚安6．5级地震前,水汞短期异常在打破5级平静的地震前出现,水汞短期异常有活跃、平静的现象。最早出现中期异常的台站相对靠近震中。