Assessment of the changes in extreme vulnerability over East Asia due to global warming

A number of indices have been employed to describe weather extremes on the basis of climate regimes and public concerns. In this study, we combined these traditional indices into four groups according to whether they relate to warm (T_warm), cold (T_cold), wet (P_wet), or dry (P_dry) extremes. Analysis of the combined indices calculated for the daily temperatures and precipitation at 750 meteorological stations in Korea, China, and Japan for 1960s?C2000s shows increasing trends in T_warm and P_dry events and decreasing trends in T_cold events in recent decades, particularly in the northern part of East Asia. A notable regional variation is an increase in the P_wet events in the Korean Peninsula. We applied the same analysis to a 200-year global climate model simulation for 1900?C2099 using the National Center for Atmospheric Research-Community Climate System Model 3. During the 20th century, the changes in T_warm and T_cold calculated from the model data are largely consistent with those calculated from the observations, especially in northern East Asia. The model projections for the 21st century indicate statistically significant increasing T_warm and decreasing T_cold trends in extreme events over the region. Results obtained from historical archives and model simulations using our combined weather extreme indices suggest that northern East Asia will be subject to increased warm and dry extremes and the Korea Peninsula will experience more wet extremes.     

Changing Trends of Daily Temperature Extremes with Different Intensities in China

By comparing two sets of quality-controlled daily temperature observation data with and without the inhomogeneity test and adjustment from 654 stations in China during 1956-2004 and 1956-2010, impacts of inhomogeneity on changing trends of four percentile temperature extreme indices, including occurrences of cold days, cold nights, warm days, and warm nights with varying intensities, were discussed. It is found that the inhomogeneity affected the long-term trends averaged over extensive regions limitedly. In order to minimize the inhomogeneity impact, the 83 stations identified with obvious inhomogeneity impacts were removed, and an updated analysis of changing trends of the four temperature extreme indices with varying intensities during 1956-2010 was conducted. The results show that annual occurrences of both cold nights and cold days decreased greatly while those of warm nights and warm days increased significantly during the recent 20 years. The more extreme the event is, the greater the magnitude of changing trends for the temperature extreme index is. An obvious increasing trend was observed in annual occurrences of cold days and cold nights in the recent four years. The magnitude of changing trends of warm extreme indices was greater than that of cold extreme indices, and it was greater in northern China than in southern China. Trends for summer occurrence of cold days were not significant. Decreasing trends of occurrences of both cold nights and cold days were the greatest in December, January, and February (DJF) but the least in June, July, and August (JJA), while increasing trends of warm nights were the greatest in JJA. Cold nights significantly decreased from 1956 to 1990, and then the decreasing trend considerably weakened. The decreasing trend also showed an obvious slowdown in recent years for occurrence of cold days. However, increasing trends of warm nights and warm days both have been accelerated continuously since the recent decades. Further analysis presents that the evolution of the trends for occurrences of the four temperature extreme indices was dominated by the changes in northern China.     

A Study of Surface Humidity Changes in China During the Recent 50 Years

This paper analyzes in detail the characteristics of surface humidity changes in China under the background of global warming in the recent 50 years by using the observation data compiled by the National Meteorological Information Center of China. The results reveal that (1) with the increase of temperature,surface saturation specific humidity (qs) shows basically an exponential growth, according to the Clausius-Clapeyron equation. The nationwide average moistening rate in winter is obviously less than the annual average rate and the summer rate. There are some regional differences in qstrends in different regions of China. For example, qsin central and eastern parts of China exhibits a reducing trend in summer, consistent with the weakening trend of temperature in these areas; (2) except parts of South China and Jianghuai Region in eastern China, unanimously increasing trends of annual and winter specific humidity (q) are found in most of China, especially in western China. In summer, except parts of Northeast China, Northwest China, and some areas over the Qinghai-Tibetan Plateau, the decreasing and drying trends are significant in most of China, which is not consistent with the global mean situation; (3) the surface relative humidity(RH) in most of China shows a reducing trend. One of the major reasons for the reduction of RH is that the increasing rates of q are smaller than those of qs. Nonetheless, upward trends of RH in central and eastern China mainly due to the cooling temperature and rising q in these regions are observed in summer, leading to more precipitation. From about 2003 or so, qshas remarkably increased while q has sharply decreased in most parts of China; therefore, RH has reduced to a great extent. This may be closely related to the persistent growth of drought areas in China in the recent 10 years.     

Effects of high-resolution land cover and topography on local circulations in two different coastal regions of Korea: a numerical modeling study

The effects of high-resolution land cover (LC) and topography (TP) on coastal wind circulations were evaluated in two different coastal regions of Korea (i.e. a southwestern coast (SWC), including a fairly complex coastline and a number of islands, and an eastern coast (EC), including a simple coastline with high mountains) during spring 2007. These analyses were performed based on a numerical modeling approach, using data sets with different resolutions, such as the LC and TP from the U.S. Geological Survey (USGS-LC and USGS-TP: a 900-m resolution), the LC from the Environmental Geographic Information System (EGIS-LC: a 90-m), and the TP from the Shuttle Radar Topography Mission (SRTM-TP: a 90-m). The combined effects of the LC and TP on the spatial distributions of the coastal winds in the SWC region during the day were somewhat higher than those of the EC region, mainly due to the daytime land surface warming or the extension of the coastal area resulting from changes in the LC. At night, the effects of the EC region were more apparent along the coastline and adjacent sea. From the correlation analyses, the effect of the LC on the vertical wind distributions on land during the day was higher in the SWC region than in the EC region and vice versa for the effect of the TP. In particular, large effects of the LC and TP occurred in the EC region at night and at sea due to the differences in the surface conditions and elevations resulting from the changes in the LC and TP, respectively. In addition, the circulation of coastal winds from the near surface to the upper levels occurred at a relatively high elevation in the EC region (about 1,500?m) relative to the SWC region (about 600?m).     

长治高温气候特征及分析预报

通过对长治市1977年-2004年6月-8月出现≥35℃的高温天气的地理分布特征、时间和强度等统计研究,给出了高温天气的气候背景。从500hPa高空形势分析,归纳出造成高温天气的四种主要环流形势（两槽一脊型、纬向环流型、大陆暖高型、副高控制型）;分析了风、云、降水等气象要素与高温天气的内在联系。通过850hPa高温预报指标站的选取及数值预报产品的统计分析,给出了高温天气的综合性预报模型。     

2009年天津地区首场降雪过程分析

基于NCEP再分析资料、多普勒天气雷达产品与风云卫星云参数反演产品,对天津地区2009年的首场降雪过程进行了分析,研究表明:①造成此次降雪的主要天气系统是东移高空槽和地面倒槽;②降雪回波具备典型层云稳定性降水回波的特点,最强回波不超过35 dBz,伴随着降雪结束,回波顶高有所下降;③降雪过程云粒子有效半径数值维持在20μm,云体过冷层厚度、云顶高度较大,云顶温度在-30℃左右.随着降雪结束,云粒子有效半径、云体过冷层厚度和云顶高度数值逐渐减小,云顶温度则有所升高;④地面降水量和云粒子有效半径、云顶高度、云体过冷层厚度呈现正相关,与云顶温度呈现负相关.     

C#哈希表在GPS网闭合环自动搜寻编程中的应用

哈希表作为一种通用而高效的面向查找的存储结构,被广泛地应用于计算机信息查询中。GPS网闭合环自动搜寻编程涉及大量的基线信息查询工作,将哈希表技术应用于GPS网闭合环自动搜寻,能够有效地提高程序运行的效率,减少计算过程的等待时间。     

地面几何标定的定向片自检校光束法区域网平差模型

针对航天线阵传感器,综合镜头光学畸变影响、像元尺寸与焦距的变化影响以及镜头的旋转作用,构建8标定参数的内方位自检校模型;利用定向片内插模型,描述影像的外方位元素变化;建立自检校光束法区域网平差模型,在对模型进行线性化的过程中,引入待标定的定向片外方位元素;利用SPOT5模拟数据对平差模型进行实验验证,结果表明,平差模型能够联合标定内方位自检校参数与外方位元素,标定结果准确。     

Soil CO2 efflux, carbon dynamics, and change in thermal conditions from contrasting clear-cut sites during natural restoration and uncut larch forests in northeastern China

With the implementation of the Chinese Natural Forest Conservation Program (NFCP) in 1998, over millions of hectares of forest in northeastern China have been protected through natural restoration (closure of hills). The impact of this program on the carbon budget of soil has not been evaluated until now. This paper presents results from a 6-year study of total CO₂ efflux from both soil and litter (R _total), CO₂ flux from soil (R _soil), soil organic matter (SOM), soil microbe density, and litter input and root biomass at an uncut larch (Larix gmelinii) forest and at a natural restoration site. The natural restoration area is a clear-cut site that was formerly part of a continuous portion of the uncut larch forest. Our objectives were to: (1) quantify the magnitude of CO₂ efflux from typical sites in northeastern China; (2) explore the changes in thermal conditions, SOM, and annual CO₂ flux during the 6-year natural restoration, and (3) evaluate the impact of NFCP on soil carbon processes. The annual R _soil at the clear-cut site (58.6–68.2 mol m^???2 year^???1) was 113.6–228.4% (mean 141.5%) higher than that at the uncut larch site (29.6–58.4 mol m^???2 year^???1). At the same time, annual CO₂ from litter at the clear-cut site (2.0–14.2 mol m^???2 year^???1) was only 23.5–84.5% (mean 52.5%) of that at the uncut larch site (5.4–16.8 mol m^???2 year^???1). SOM at the surface layer of the clear-cut site was 75% of that at the uncut larch site, but the soil microbial biomass (carbon) at the clear-cut site was much higher than that at the larch site (p?<?0.05). The percentage of bacteria, fungi and actinomycetes also were largely different between both sites. Natural restoration at the clear-cut site strongly affected thermal conditions. Although the soil temperature (T _soil) and effective accumulated $T_{\rm soil} > 0^{\circ}$ C at the clear-cut site was much higher, the temperature sensitivity (Q ₁₀) was much lower than that at the uncut larch site, and their differences decreased linearly from 2001 to 2006 (p?<?0.05). Moreover, Q ₁₀ at the clear-cut site significantly increased with the progress of natural restoration, which diminished the Q ₁₀ difference between the two sites (slope?=???0.2792, r ²?=?0.4744, p?<?0.05). These data imply that the NFCP natural restoration process has positively recovered the thermal condition of the clear-cut site to the level of uncut larch forest during the 6-year period. However, linear regression analysis showed that the 6-year natural restoration only slightly affected the annual soil CO₂ efflux and SOM at both sites, and also did not diminish the differences between the two sites (p?>?0.10), indicating that a much longer time is necessary to restore the soil carbon in the clear-cut site.     

070703天长超级单体龙卷的多普勒雷达典型特征

主要使用南京多普勒天气雷达资料,分析了2007年7月3日发生在安徽天长和江苏高邮的龙卷风天气,着重分析了中气旋和龙卷涡旋特征(TVS)等产品的典型特征.龙卷发生在飑线回波带的北端强烈发展的超级风暴单体中,回波带前沿存在强烈的水平风切变,使得回波带上不断有中气旋生成.对产生龙卷的超级风暴单体,龙卷发生30min前,雷达给出了中气旋(M)产品,该中气旋持续了7个体扫的时间(42min),在中气旋出现后第5个体扫,雷达给出龙卷涡旋特征(TVS)产品,龙卷涡旋特征持续了3个体扫,综合切变产品也给出了显著的提醒.实地调查结果,龙卷风和第2个TVS同时发生,龙卷风位置与TVS位置对应,但位于TVS的南侧,位于中气旋最大风速圈的南缘.虽然CINRAD/SA雷达的TVS产品有虚警的情况,但结合反射率因子、平均径向速度、中气旋、综合切变等产品的分析,对于龙卷监测和预警会很有帮助的.