Use of a land surface model to evaluate the observed soil moisture of grassland at the Tongyu reference site

A land surface model driven by the continuous three-year observed meteorological data with a time interval of 30 minutes at the Tongyu station, a reference site of the Coordinated Enhanced Observing Period （CEOP）, was used to evaluate the observation bias of soil moisture （SM） data and analyze the variation of SM at different time scales. The saline-alkaline soil of the grassland at the Tongyu site makes the measured SM too high, especially in boreal summer of 2003-05. The simulated annual mean SM has the lowest value in 2004 and its three-year variation corresponds to the change of precipitation, whereas the observation shows the increasing trend from 2003 to 2005. Compared to the variation range between -60% and 40% for the anomaly percentage of the simulated daily mean SM during May-October of 2004, the measured data show the higher values more than 40%. The magnitude of the variation trend of the observed daily mean SM in 2003 and 2005 is generally consistent with the simulation. The largest deficiency for the soil moisture observation of the grassland is the overestimated value in the drought year with less precipitation. The simulated monthly mean SM has the lowest value in March due to the large contribution of evaporation relative to precipitation and this phenomenon can not be reproduced in the observation.     

新一代格点大气环流模式与陆面生态模式AVIM的耦合研究

将陆面生态模式AVIM(Atmosphere-Vegetation Interaction Model)的物理模块(PHY-AVIM)耦合到中国科学院大气物理研究所新一代格点大气环流模式GAMIL(Grid-point Atmospheric Model)中,替换GAMIL中的陆面模式BATS.对两种方案GAMIL+BATS(旧版本)和GAMIL+(PHY-AVIM)(新版本),分别独立进行11年积分,取后10年的积分结果进行分析.结果发现:新版本明显改进冬、夏季陆地表面的感热、潜热场通量,尤其在夏季,非洲大陆的中北部、欧亚大陆、北美中部以及南美北部等地区,新版本的感热场模拟值均比旧版本低,更接近NCEP再分析资料的结果;同样,对于地表面温度场,新版本在夏季明显地减弱了旧版本在大陆上的的暖偏差,模拟的结果更合理;新版本对冬、夏季的海平面气压场、降水场也有一定的改进,但改进不是很明显.以上的所有改进主要是由于AVIM引入了更细致的陆面物理过程参数化方案,以及使用了分辨率(0.5°×0.5°)更高的陆地植被分类资料.     

新疆地区夏季多层土壤温度分布及其近45年的变化特征

利用覆盖新疆地区87个站点1961～2005年的资料,对新疆地区夏季的多层土壤温度进行了系统分析,并对降水量、日照时数和地面气温3个对地温扰动较大的气象因子进行相关分析。结果表明：（1）新疆地区夏季地温的空间分布特征表现为南疆高于北疆,平原高于山区。浅层土壤大部分地区有较高的地温,最高值达到38℃以上。深层土壤温度分布较低,其中北部的地温只有15℃左右。新疆南部和北疆的准格尔盆地地区有较大的深层-浅层地温较差分布,而天山附近和北疆的山地地区地温较差分布均较小;（2）地面温度45年来经历了20世纪60年代到70年代中期的下降,20世纪70年代中期到80年代初的较快增温,以及20世纪80年代以后的缓慢下降的3个阶段。地面温度（0 cm）在1978年左右有突变现象,其他层次的土壤温度年际变化没有明显的突变特征;（3）40 cm以上新疆地区夏季土壤温度梯度经历了20世纪60年代到70年代中期的下降,20世纪70年代中期到80年代初的较快增长以及20世纪80年代以后的缓慢下降过程,其中20世纪80年代较快增长时期的增长率达到0.0176℃cm–1 a–1。而且MK方法检验表明,1978年以后,新疆地区夏季土壤温度梯度增大趋势显著;（4）多层土壤温度的年际变化与降水量成负相关关系,与日照时数和地面气温主要成正相关关系。3个气象因子与多层地温的相关关系从高到底的排列为：地面气温、降水量、日照时数,而且浅层地温高于深层地温。     

SPATIOTEMPORAL VARIATION OF NO2 AND SUB-REGIONAL TRANSPORT DURING WINTER POLLUTION EVENTS IN HAIKOU, CHINA

An ensemble of satellite measurements, statistic data from government and meteorological diagnosis in regional background site (Haikou, China) has revealed the spatial and temporal characteristics of NO2 and associated synoptic transport patterns over southern China from January 2013 to February 2014. The result shows that: (1) Ozone Monitoring Instrument (OMI) satellite products had a good correlation with observation NO2 in Haikou. The correlation coefficients between Observation NO2 and tropospheric column NO2 and ratio of TroNO2/ TotNO2(tropospheric column NO2/ total column NO2) had all passed the confidence level of 99.9% test. (2) TroNO2 over southern China has an obvious seasonal variation, which is closely coupled with regional meteorology in each season. (3) NO2 concentration in Haikou revealed three pollution periods during December 2013 and January 2014. The variation of NO2 concentration in Haikou is related to the meteorological elements closely. (4) Compared to the monthly mean meteorological fields of the pollution periods, the results indicate that NO2 pollution event in Haikou is directly related to the exogenous transportation from PRD region. An ensemble analysis of meteorological dynamic factors, wind vectors and backward trajectories during the pollution periods further verified this conclusion.     

重污染下华南地区小雨和低云量的时空变化趋势特征

利用华南地区51个站点的逐日小雨降水和低云量等气象资料,采用气候趋势系数、一元回归和相关分析等方法,分析了小雨降水和低云量的年际、季节的长期趋势特征,同时结合华南地区气溶胶光学厚度(AOD)、气溶胶指数和国民生产总值(GDP)等资料进行原因探讨。(1) 华南地区小雨日和低云量呈相反的变化趋势(小雨日下降,低云量上升),而且表现为东部高于西部,沿海高于内陆的分布特征。(2) 小雨日和低云量的回归系数分别为-4.88 d/(10 a)和1.17%/(10 a)。(3) 春季和夏季小雨日变化相对较小,但是对年小雨日贡献较大,而低云量四季均呈现相反的上升趋势。(4) 华南地区的两个AOD大值区分别位于广西中部到南部沿海和广东珠三角地区,其中珠三角地区AOD高达0.7以上,气溶胶指数也表现为沿海地区高于内陆地区的分布特征。近27年华南地区的气溶胶指数呈现波动的上升趋势,与同期的小雨日呈负相关关系,而低云量呈正相关关系,近28年华南地区GDP一直处于明显上升趋势,其中以广东省增加最明显。      

气候与植被覆盖变化对中国西南亚高山区流域碳水循环的影响模拟

正确认识气候变化对流域森林植被和水文的影响对于林业经营管理与流域生态修复具有重要意义。为了揭示气候与植被覆盖变化对西南亚高山区流域碳水循环过程的影响,用生物物理/动态植被模型SSiB4/TRIFFID（Simplified Simple Biosphere model version 4, coupled with the Top-down Representation of Interactive Foliage and Flora Including Dynamics model）与流域地形指数水文模型TOPMODEL（Topographic Index Model）的耦合模型（以下记为SSiB4T/TRIFFID）模拟了不同气候情景下西南亚高山区的梭磨河流域植被演替和碳水循环过程。结果表明,所有试验流域植被经历了从C3到苔原灌木最后到森林的变化;控制试验流域蒸散在流域植被主要为苔原灌木时达到最大而径流深最小;增温5 ℃并且增雨40%试验[记为T+5, (1+40%) P试验]流域蒸散在流域为森林覆盖时达到最大而径流深最小。随着温度增加,森林蒸腾、冠层截留蒸发和蒸散的增加幅度明显大于草和苔原灌木,导致森林从控制试验的增加径流量变为减小径流量。从控制试验到T+5, (1+40%) P试验,温度增加使森林净初级生产力有所增加,但对草和苔原灌木的净初级生产力影响很小;植被水分利用效率随温度增加明显减小。西南山区随着海拔高度降低（温度升高）,森林从增加径流量转变为减少径流量,植被水分利用效率也相应明显减小。西南山区气候的垂直地带性对森林—径流关系和水分利用效率的空间变化有着重要的影响。     

一个海洋-大气-动态植被耦合模式评估——海洋环流模拟

利用中国科学院大气物理研究所（IAP）大气科学与地球流体力学数值模拟国家重点实验室(LASG)的全球耦合模式(GOALS〖CD*2〗AVIM),进行了100年积分。利用后40年的结果对模式耦合植被动态过程（AVIM）前后输出的海洋物理场对比分析。结果表明：耦合AVIM后的模式可以合理地模拟全球海洋温盐环流的气候态、季节变化,可以改进模式的模拟效果,在一定程度上克服了耦合AVIM前模式的缺点,使模拟结果更接近实测。由于植被〖CD*2〗大气的双向作用,在季节变化的模拟中,9月的改进效果大于3月的,北半球大于南半球;对于年平均气候态,耦合AVIM后的模式结果在热带海区海表面温度（SST）的模拟效果得到了明显改善,尤其是赤道太平洋海区的海温偏低现象得到了改善;在年际变化的模拟中,改善了耦合AVIM前模式模拟的年际变化分布,加大了赤道太平洋的标准差的模拟,使得耦合AVIM后模拟的年际变化大于耦合前;增强了耦合模式对赤道太平洋ENSO的模拟能力,较耦合AVIM前的模式模拟出了更多的ENSO基本特征,也改善了耦合AVIM前ENSO变化周期偏弱、偏短的现象;同样改善了对气候系统中存在的相互作用的模拟,对于热带印度洋SST变化与赤道太平洋SST的相互关联的模拟中,更加真实地模拟出了气候系统中存在的相互关联关系,体现出了AVIM动态植被过程对气候耦合模式的改善。     

Long-Term Trends in the Probability of Different Grades of Haze Days in China from 1960 to 2013

The number of haze days and daily visibility data for 543 stations in China were used to define the probabilities of four grades of haze days: slight haze(SLH) days; light haze(LIH) days; moderate haze(MOH) days; and severe haze(SEH) days. The change trends of the four grades of haze were investigated and the following results were obtained. The highest probability was obtained for SLH days(95.138%), which showed a decreasing trend over the last54 years with the fastest rate of decrease of-0.903% ·(10 years)-1 and a trend coefficient of-0.699, passing the 99.9%confidence level. The probabilities of LIH and MOH days increased steadily, whereas the probability of SEH days showed a slight downward trend during that period. The increasing probability of SLH days was mainly distributed to the east of 105°E and the south of 42°N and the highest value of the trend coefficient was located in the Pearl River Delta and Yangtze River Delta regions. The increasing probability of LIH days was mainly distributed in eastern China and the southeastern coastal region. The probabilities of MOH and SEH days was similar to the probability of LIH days. An analysis of the four grades of haze days in cities with different sizes suggested that the probability of SLH days in large cities and medium cities clearly decreased during the last 54 years. However, the probabilities of LIH days was 10% and increased steadily. The probability of MOH days showed a clear interdecadal fluctuation and the probability of SEH days showed a weak upward trend. The probability of SLH days in small cities within 0.8° of large or medium cities decreased steadily, but the probability of LIH and MOH days clearly increased, which might be attributed to the impact of large and medium cities. The probability of SLH days in small cities 1.5° from a large or medium city showed an increasing trend and reached 100% after 1990; the probability of the other three grades was small and decreased significantly.     

基于一个不同网格相互嵌套的陆气耦合模式的气候模拟研究

将一个大气植被相互作用模式(AVIM)与大气所LASG的R15九层大气环流模式GOALS相耦合．用来模拟多年平均的全球气候状况。AVIM是一个陆地表面陆面和生理过程相互反馈的模型。作为陆气耦合的第一步,暂不考虑AVIM中的生理过程,而首光将其物理过程[相当于通常的SVAT(土壤—植被—大气—传输方案)模型]与大气所LASG的九层大气环流模式耦合起来．其中海洋模式部分不参与积分,海面温度是多年平均的气候伯。考虑到GCM的分辨率较低(7．5°×4．5°)而植被分布必须有较高的分辨率(1.5°×1.5°),采取广大气与地表面粗细网格的嵌套耦合。模式积分15年,取最后10年的平均值作分析。将模拟的气候要素场与观测值和NCEP再分析资料作了比较,气候模拟结果反映了全球环流与温湿场的主要特征,特别是降水和地面气温的模拟效果较好。这为今后气候模式与生物圈的耦合奠定广一个良好的基础。     

西太平洋副热带高压与中国植被的关系（英文）

There is a lack of simple ways to predict the vegetation responses to the East Asian Monsoon(EAM) variability in China due to the complexity of the monsoon system. In this study, we found the variation of the Western Pacific Subtropical High(WPSH), which is one of the major components of the EAM, has a profound influence on the vegetation growth in China. When the WPSH is located more to the west of its climate average, the eastern and northwestern parts experience increased yearly-averaged normalized difference vegetation index(NDVI) and gross primary productivity(GPP) by 0.3%–2.2%, and 0.2%–2.2%, respectively. In contrast, when the WPSH is located more to the east of its climate average, the above areas experience decreased yearly-averaged NDVI and GPP by 0.4% to 1.6%, and 1.3% to 4.5%, respectively. The WPSH serves as a major circulation index to predict the response of vegetation to monsoon.