Spatial distribution and temporal trends of rainfall and erosivity in the Eastern Africa region

Soil erosion by water is one of the main environmental concerns in the drought‐prone Eastern Africa region. Understanding factors such as rainfall and erosivity is therefore of utmost importance for soil erosion risk assessment and soil and water conservation planning. In this study, we evaluated the spatial distribution and temporal trends of rainfall and erosivity for the Eastern Africa region during the period 1981–2016. The precipitation concentration index, seasonality index, and modified Fournier index have been analysed using 5 × 5‐km resolution multisource rainfall product (Climate Hazards Group InfraRed Precipitation with Stations). The mean annual rainfall of the region was 810 mm ranging from less than 300 mm in the lowland areas to over 1,200 mm in the highlands being influenced by orography of the Eastern Africa region. The precipitation concentration index and seasonality index revealed a spatial pattern of rainfall seasonality dependent on latitude, with a more pronounced seasonality as we go far from the equator. The modified Fournier index showed high spatial variability with about 55% of the region subject to high to very high rainfall erosivity. The mean annual R‐factor in the study region was calculated at 3,246 ± 1,895 MJ mm ha^?1 h^?1 yr^?1, implying a potentially high water erosion risk in the region. Moreover, both increasing and decreasing trends of annual rainfall and erosivity were observed but spatial variability of these trends was high. This study offers useful information for better soil erosion prediction as well as can support policy development to achieve sustainable regional environmental planning and management of soil and water resources.     

秦岭—大巴山高分辨率气温和降水格点数据集的建立及其对区域气候的指示

本文建立了秦岭—大巴山高分辨率(～29 m×29 m)的气候格点数据集,包括逐月气温和降水、年均温和年降水、春夏秋冬气温和降水。空间插值方法采用国际上较为先进的ANUSPLIN软件内置的薄盘光滑样条函数,以经度、纬度和海拔为独立变量。空间插值结果与流行的WorldClim 2.0气候格点数据集具有一致性,但是比后者更精确、分辨率更高、细节更突出。本文揭示和证实:秦岭南麓是最冷月气温的0℃分界线。秦岭—大巴山气温具有明显的垂直地带性。6月气温直减率最大,为0.61℃/100 m;12月气温直减率最小,为0.38℃/100 m;年均气温直减率为0.51℃/100 m。夏季和秋季降水从西南向东北递减,强降水中心出现在大巴山西南坡。冬季降水从东南向西北递减。大巴山是年降水1000 mm分界线,夏季降水500mm分界线;秦岭是年降水800 mm分界线,夏季降水400 mm分界线。与大尺度大气环流对比揭示:秦岭—大巴山气温和降水空间分布主要受到东亚季风和地形因子的控制。本文进一步明确了秦岭和大巴山的气候意义:大巴山主要阻挡夏季风北上,影响降水空间分布;秦岭主要阻挡冬季风南下,影响冬季气温空间分布。本文建立的高分辨率气候格点数据集,加深了对区域气候的认识,并将有多方面的用途。     

长序列北极海冰覆盖数据集对比分析

国家卫星气象中心使用2011年至今的风云三号卫星数据开发了一套基于Nasa Team2（NT2）算法的北极海冰密集度数据集,并可实时业务更新。将该数据集与其他国家不同机构业务运行并实时更新多种同类型数据集进行横向对比分析,其中包括:（1）美国冰雪中心基于Nasa Team（NT）算法以及SSM/I、SSMIS数据制作的1978年至今25 km分辨率全球极区海冰覆盖数据集;（2）美国冰雪中心基于Boot Strap（BS）算法以及SSM/I、SSMIS数据制作的1978年至今25 km分辨率全球极区海冰覆盖数据集;（3）美国NOAA基于多种卫星资料、地面观测数据以及海冰模型制作的2004年至今4 km分辨率北半球海冰覆盖数据集（IMS）。对比表明,上述数据集在北极地区不同的时空范围内存在一定的偏差。以分辨率较高的IMS数据集为基准,对其他3种长序列数据集进行初步评价,总体最大偏差超过100×104 km2,其中,NT2数据集过估较明显。经过与IMS数据集多年各月监测最大值的对比订正,NT2数据集过估情况得到改善。在此基础上的分析结果表明,NT、BS、NT2等3种数据集与IMS数据集相比,过估区域主要分布在海岸线附近,夏季过估比冬季更加明显,少估区域与算法、月份相关性明显,夏季少估面积也较冬季更大。NT、BS、NT2等3种数据集之中,NT2数据集与IMS数据集偏差最小,NT数据集次之,BS数据集与IMS数据集偏差最大。结果表明使用风云三号卫星数据的北极海冰覆盖数据集精度与国外3种同类型数据集相当。     

吉林省浑江市幅1∶50 000水系沉积物测量原始数据集

吉林省浑江市幅1∶50 000水系沉积物测量共采集1961件水系沉积物样品, 采样粒级为-10目~+80目, 平均采样密度为5.1个/km²。采用发射光谱法(AES)、泡沫塑料吸附石墨炉原子吸收分光光谱法(GFAAS)、原子荧光法(AFS)及等离子体质谱法(ICP-MS)分析了Au、Ag、Cu、Pb、Zn、As、Sb、Bi、Hg、W、Sn、Mo、Cd、Co、Cr、Ni 等16种元素, 形成吉林省1∶50 000浑江市幅水系沉积物测量原始数据集。数据集包含有1961件样品以及其16元素的原始数据表1个(Excel), MapGIS格式图集1套(含有1张矿产地质图、1张采样点位图、16张单元素地球化学图、16张单元素异常图)。通过本数据集新发现单元素地球化学异常403处, 综合异常24处, 结合地质、物探、化探、遥感及已有成矿线索圈定金矿找矿靶区3处、铜及多金属找矿靶区2处。本文数据集为该区域提供了一套基础性的数据资源, 为基础地质及其他领域应用提供基础地球化学依据。     

Argo光盘数据集的研制与应用

早期的Argo数据光盘主要基于文件系统的数据管理,都没有提供对查询结果的保存和打印功能,更没有引入数据库系统对浮标数据进行综合管理.文中针对Argo数据共享和分发过程中存在的不足,特别是Argo光盘数据集所存在的问题,提出了改进方法.并引进数据库技术对Argo光盘数据集进行了补充和完善:提出了使用Winrar压缩软件对光盘数据资料进行压缩,从而解决了日益增加的Argo数据与光盘容量有限的矛盾,可以更好的满足Argo数据分发和共享的需求.为了充分发挥Argo光盘数据集的功能,文中还针对Argo资料用户对图形文件的需求,利用VC++和Matlab混合编程的方法,开发了Argo视图软件.最后,基于数据库技术研制完成了一张包含了1997-2006年全球海洋上全部Argo剖面浮标观测的Argo光盘数据集,并系统介绍了该数据集的结构、功能和应用过程等.     

运用ArcGIS Desktop 9.0进行栅格数据的加载和地理参考变换

运用ArcGIS Desktop 9.0软件以海丰农场示意图为例,用DGPS进行控制点的测量,从建立坐标文件数据开始,把扫描的农场示意图(栅格图形数据)进行加载到地图中去并对其进行地理参考转换,使海丰农场示意图变成了一份具有地理坐标系统的数字化地图,从而为当前海丰农场精准农业研究提供了数字化的农场布局资料。     

CHOSEN: A synthesis of hydrometeorological data from intensively monitored catchments and comparative analysis of hydrologic extremes

Comparative hydrology has been hampered by limited availability of geographically extensive, intercompatible monitoring data on comprehensive water balance stores and fluxes. These limitations have, for example, restricted comprehensive assessment of multiple dimensions of wetting and drying related to climate change and hampered understanding of why widespread changes in precipitation extremes are uncorrelated with changes in streamflow extremes. Here, we address this knowledge gap and underlying data gap by developing a new data synthesis product and using that product to detect trends in the frequencies and magnitudes of a comprehensive set of hydroclimatic and hydrologic extremes. CHOSEN (Comprehensive Hydrologic Observatory Sensor Network) is a database of streamflow, soil moisture, and other hydroclimatic and hydrologic variables from 30 study areas across the United States. An accompanying data pipeline provides a reproducible, semi-automated approach for assimilating data from multiple sources, performing quality assurance and control, gap-filling and writing to a standard format. Based on the analysis of extreme events in the CHOSEN dataset, we detected hotspots, characterized by unusually large proportions of monitored variables exhibiting trends, in the Pacific Northwest, New England, Florida and Alaska. Extreme streamflow wetting and drying trends exhibited regional coherence. Drying trends in the Pacific Northwest and Southeast were often associated with trends in soil moisture and precipitation (Pacific Northwest) and evapotranspiration-related variables (Southeast). In contrast, wetting trends in the upper Midwest and the Rocky Mountains showed few univariate associations with other hydroclimatic extremes, but their latitudes and elevations suggested the importance of changing snowmelt characteristics. On the whole, observed trends are incompatible with a ‘drying-in-dry, wetting-in-wet’ paradigm for climate-induced hydrologic changes over land. Our analysis underscores the need for more extensive, longer-term observational data for soil moisture, snow and evapotranspiration.     

高原地区ERA40与NCEPI再分析资料对比分析

利用ERA40、NCEPI (NCEP/NCAR version Ⅰ)再分析资料以及高原地区的探空资料和1979年青藏高原地区第1次气象科学试验资料,详细的比较了高原地区位势高度的特征.结果表明,两套再分析资料在高原地区具有一定的相似性,但仍存在着明显的差别.相比较而言,高原北部地区ERA40再分析资料除1980-19...     

Study on the Structure of a Horizontal Shear Line over the Tibetan Plateau Based on CRA-Interim Datasets and Its Comparison with ERA-Interim Datasets

The CRA-Interim trial production of the global atmospheric reanalysis for 10 years from 2007 to 2016 is carried out by the China Meteorological Administration (CMA) in 2017. The structural characteristics of the horizontal shear line over the Tibetan Plateau (TPHSL) based on the CRA-Interim datasets are examined by objectively identifying the shear line, and compared with the analysis results of the European Centre for Medium-Range Weather Forecasts (ECMWF)the European Center (ECMWF) reanalysis data (ERA-Interim). The case occurred at 18UTC on July 5, 2016. The results show that both of the ERA-Interim and CRA-Interim datasets can well reveal the circulation background and the dynamic and thermal structure characteristics of TPHSL, and they have shown some similar features. The middle and high latitudes at 500 hPa are characterized by500hPa present the circulation situation of     

A global ocean reanalysis product in the China Ocean Reanalysis (CORA) project

The first version of a global ocean reanalysis over multiple decades (1979–2008) has been completed by the National Marine Data and Information Service within the China Ocean Reanalysis (CORA) project. The global ocean model employed is based upon the ocean general circulation model of the Massachusetts Institute of Technology. A sequential data assimilation scheme within the framework of 3D variational (3DVar) analysis, called multi-grid 3DVar, is implemented in 3D space for retrieving multiple-scale observational information. Assimilated oceanic observations include sea level anomalies (SLAs) from multi-altimeters, sea surface temperatures (SSTs) from remote sensing satellites, and in-situ temperature/salinity profiles. Evaluation showed that compared to the model simulation, the annual mean heat content of the global reanalysis is significantly approaching that of World Ocean Atlas 2009 (WOA09) data. The quality of the global temperature climatology was found to be comparable with the product of Simple Ocean Data Assimilation (SODA), and the major ENSO events were reconstructed. The global and Atlantic meridional overturning circulations showed some similarity as SODA, although significant differences were found to exist. The analysis of temperature and salinity in the current version has relatively larger errors at high latitudes and improvements are ongoing in an updated version. CORA was found to provide a simulation of the subsurface current in the equatorial Pacific with a correlation coefficient beyond about 0.6 compared with the Tropical Atmosphere Ocean (TAO) mooring data. The mean difference of SLAs between altimetry data and CORA was less than 0.1 m in most years.