Associations between the Autumn Arctic Sea Ice and North American Winter Precipitation

Associations between the autumn Arctic sea ice concentrations (SICs) and North American winter precipitation were examined using singular value decomposition. The results show that a reduced SIC in the majority of the Arctic is accompanied by dry conditions over the Great Plains, the southern United States, Mexico, eastern Alaska, and southeastern Greenland, and by wet conditions over the majority of Canada, the northeastern United States, and the majority of Greenland. Atmospheric circulation anomalies associated with the SIC variability show a wave train structure that is persistent from autumn to winter and is responsible for the covariability between the autumn Arctic SICs and North American winter precipitation. This relationship suggests a potential long-term outlook for the North American winter precipitation.     

中国雾水化学研究进展

1980年以来,中国雾水化学研究发展迅速.在城市、高山和海边广泛地开展了雾的观测试验和云雾水的取样分析,研究了各地云雾水的酸度和酸雾的来源,分析了不同地区雾水化学组分的基本特征.许多雾的综合观测试验,在对雾水连续取样的同时,还连续观测了与雾水化学相关的要素,研究了影响雾水化学组分浓度的主要因子.文中总结了近30年来中国...     

北京地区酸雨的天气影响因素及降水化学特征分析

对北京市2003-2009年的全市性酸雨过程进行研究,分析了影响北京地区酸雨的主要天气系统,并结合气流后向轨迹分析和上甸子站酸雨离子成分浓度分析,得到如下结论:影响北京地区酸雨的天气系统主要为低涡低槽型、西来槽型和副高边缘型天气系统.3种天气系统对应的降水平均pH值均小于4.5,达到强酸雨水平.降水前北京地区受持续的偏南风影响、上升运动的强度较强且维持时间较长,降水前出现逆温现象,都是导致北京地区出现强酸雨的重要因素.对北京大气污染有影响的气流轨迹在低涡低槽、西来槽和副高边缘型天气系统的比例分别为59％、74％和66％.西来槽型天气系统的电导率K值与水溶性离子浓度明显高于低涡低槽型和副高边缘型.     

Characteristics of daily and extreme temperature over Canada

利用重庆34个自动站1991-2015年逐小时降水资料,分别从降水比率、强降水占比、强降水频次、强降水事件、极大强降水及极端强降水阈值等方面分析了重庆时空分布特征。结果表明：（1）降水比率、强降水占比、强降水频次、强降水事件、极大强降水及极端强降水阈值在空间分布上具有一致性,高值区主要分布在东南部与西部,低值区主要位于东北部与中部。（2）降水比率、强降水占比、强降水频次及极大强降水在年变化上表现出波动起伏特征,且降水比率相对变化幅度较小,后三者表现出同相位的变化特点。在月变化上,降水比率呈双峰特征,后三者一致呈单峰特征。在日变化上,强降水高频次主要出现在03-05时,低频次主要是13-15时。（3）在强降水事件持续性上,强降水事件持续时间及其降水开始至最强降水时间的空间分布一致：高值区主要集中在东北部与东南部,而低值区主要分布在中部与西部。总体上看,持续时间越长,产生最强降水的时间越延后,且持续时间长的强降水事件主要产生在23时至次日04时。（4）第99、99.5、99.9百分位阈值与广义极值（GEV）分布函数5、10、20、50、100 a重现期阈值及极大强降水观测值在空间分布上与强降水具有一致性。

     

Potential Predictability of Sea Surface Temperature in a Coupled Ocean--Atmosphere GCM

Using the Flexible Global Ocean--Atmosphere--Land System model (FGOALS) version g1.11, a group of seasonal hindcasting experiments were carried out. In order to investigate the potential predictability of sea surface temperature (SST), singular value decomposition (SVD) analyses were applied to extract dominant coupled modes between observed and predicated SST from the hindcasting experiments in this study. The fields discussed are sea surface temperature anomalies over the tropical Pacific basin (20^oS--20^oN, 120^oE--80^oW), respectively starting in four seasons from 1982 to 2005. On the basis of SVD analysis, the simulated pattern was replaced with the corresponding observed pattern to reconstruct SST anomaly fields to improve the ability of the simulation. The predictive skill, anomaly correlation coefficients (ACC), after systematic error correction using the first five modes was regarded as potential predictability. Results showed that: 1) the statistical postprocessing approach was effective for systematic error correction; 2) model error sources mainly arose from mode 2 extracted from the SVD analysis---that is, during the transition phase of ENSO, the model encountered the spring predictability barrier; and 3) potential predictability (upper limits of predictability) could be high over most of the tropical Pacific basin, including the tropical western Pacific and an extra 10-degrees region of the mid and eastern Pacific.     

东北地区一次暴雨过程的落区分析

利用常规高空、地面观测资料和美国NCEP1°×1°的6 h再分析资料对2008年7月5日08时至6日08时发生在东北地区的暴雨过程进行诊断分析。结果表明：此次暴雨过程是蒙古高空槽和华北气旋共同作用下产生的,副热带高压西伸北抬后与东北高压脊叠加形成高压坝,水汽沿高压外围即渤海西岸向东北移动,华北气旋入渤海加强北上,是造成东北地区西部强降水的主要天气形势。风速大于等于16 m/s的低空西南急流的建立为暴雨的发生提供了动力和水汽条件。暴雨到大暴雨过程强降水中心的落区与比湿场的大值区、垂直速度场和涡度场的高值区有较好的对应关系。     

广义极值分布在重庆短历时极值降水中的应用

利用广义极值分布函数拟合1981—2016年重庆34个国家气象站短历时(1、3、6、12 h)极值降水序列,对拟合结果进行显著性水平检验,并给出不同重现期极值降水的空间分布。结果表明:广义极值分布函数能较好地拟合重庆地区的短历时极值降水。随着降水历时的延长,服从Weibull分布(Frechet分布)的站点数逐渐减少(增加)。各短历时不同重现期降水的空间分布具体表现为10 a以下及20 a以上基本相似,位于长江沿线以北的重庆西北部地区降水量明显大于重庆长江沿线以南地区,且渝东南降水的相对大值区位于彭水地区。随着重现期的增加,降水中心更加集中,渝东北的大值中心随着历时的延长向北移动。广义极值分布函数的形状参数的绝对值接近或超出0.5时,计算的高重现期(大于样本长度)极值降水存在较大偏差;当不同历时降水拟合的形状参数值具有明显差异时,高重现期降水可能出现与客观规律相悖的现象。     

Values of the Farmland Ecosystem Services of Qingdao City,China, and their Changes

The values of farmland ecosystem services are composed of several components: provisioning service value, regulating service value, supporting service value and cultural service value, so it is important to make a full assessment of the values of farmland ecosystem services for agriculture and farmland protection. Here, we assessed the values of farmland ecosystem services in Qingdao City in 1997, 2002, 2007, 2012 and 2017 by using various methods (market value method, carbon tax method, afforestation cost method, substitute cost method, equivalent factor method, etc.) based on establishing an assessment index system for the farmland ecosystem services value. The results show that the total yearly value of farmland ecosystem services increased from 499.74×10 ⁸ Yuan to 681.74×10 ⁸Yuan in the period of 1997-2017, and the yearly value of farmland ecosystem services per hectare increased from 6.57×10 ⁴ Yuan to 9.73×10 ⁴Yuan. The product provisioning service, carbon fixation service and oxygen release service, as well as the soil conservation service, are the main farmland ecosystem services, and the proportions of these four ecosystem service values to the total value of farmland ecosystem services in Qingdao City were large and kept increasing. Some countermeasures are put forward to adequately use the indirect service value of the farmland ecosystem and provide improved well-being for humans, such as protecting and wisely using farmland, developing agriculture that is rooted in local conditions, promoting agricultural production efficiency, speeding up construction of modern agriculture gardens, deepening the supply-side structural reform of agriculture, developing agricultural eco-tourism, etc.     

1975—2015年甘肃省白龙江流域自然保护区生态系统服务价值及其时空差异

利用1975-2015年7期遥感数据重建甘肃省白龙江流域8个野生动物自然保护区的生态系统时空变化特征,并在对该研究区各类生态系统服务价值当量修订的基础上,采用生态系统服务价值评估模型和敏感性指数,对不同时期的生态系统服务价值进行评估。结果表明:(1)白龙江流域自然保护区以森林生态系统为主,研究期内生态系统格局总体稳定,农田和裸地生态系统面积减少,而森林、草地、水域和人工表面生态系统呈增加趋势,且在2000年后变化最活跃。(2)研究区生态系统服务价值由1975年的239.68×10^8元上升到2015年的243.58×10^8元,净增加3.90×10^8元,农田和裸地生态系统服务价值持续减少,而森林、草地和水域生态系统服务价值则呈增加趋势。(3)整体上,研究区南部生态系统服务价值呈增长趋势,而中北部地区则处于阶段性变化状态,文县大鲵自然保护区单位面积生态系统服务价值密度最高,多儿自然保护区价值密度最低,且为唯一衰退型保护区。(4)在不同生态系统服务类型中,调节服务居主导地位,且以气候调节服务价值最高。白龙江流域自然保护区生态系统服务价值缺乏弹性,水域生态系统面积变化对研究区生态系统服务价值的变化具有放大作用。     

基于层次分析法和模糊评判法的西藏国家气象公园评价研究

本研究依据中国气象局发布的国家气象公园评价指标体系充分考虑高原文化特色,采用层次分析法(AHP)构建了适用于高原的气象公园评价体系。结果表明：在准则层中,天气景观>人文气象景观>环境保护>科学性,权重值分别为45.94%、32.48%、14.91%、6.67%,在因子层中,稀有度>人文价值>气候特征>科学性,权重值依次为25.80%、17.20%、9.70%、5.00%。在此基础上,对纳木措、羊卓雍措、玛旁雍措进行模糊综合评价分析表明,纳木措各因素综合评价为优,羊卓雍措各因素综合评价为良,玛旁雍措各因素综合评价为良。因此,在经济条件有限的基础上,认为纳木措建设成为国家气象公园是最优选择。本研究结果可为环境规划等相关部门和行业提供决策参考。