简单生物圈模式 (SiB2) 中湍流能量通量对近地层两类阻抗系数的敏感性研究

陆—气之间的能量交换是通过近地层湍流热量和水汽通量来实现的.以往的研究表明近地层阻抗对湍流能量通量有着不同程度的影响,但是关于陆面模式中阻抗系数的取值范围却始终没有统一的标准.为了深入了解简单生物圈模式 (SiB₂) 中近地层阻抗系数取值变化对湍流能量通量的影响,我们以那曲站为例,分别采用传统的逐个因子分析法和考虑参数间相互作用的部分因子分析法定量地研究了夏季该观测站近地层湍流能量通量分别对冠层阻抗系数C₁和地表阻抗系数C₂的敏感性响应.结果表明,感热通量对地表阻抗系数C₂更为敏感,而潜热通量则对冠层阻抗系数C₁较为敏感;感热通量随C₁增加而增大,随C₂增加而减小,而潜热通量则随C₁或C₂的增加而减小;不管是感热通量还是潜热通量,它们对阻抗系数的敏感度随阻抗系数的增大而减小,而对阻抗系数的相对敏感度则随阻抗系数的增大而增大.最后,结合那曲站夏季下垫面稀疏短草的分布特点分析了造成感热通量和潜热通量敏感变化各异的原因.     

气象参数对人体舒适度的影响研究

为研究气象参数对人体舒适度的影响,用慕尼黑人体热量平衡模型(MEMI)分析了南京舒适感的概率分布、年际、月际变化以及气象参数和生理等效温度(PET)的相互关系。结果表明:各舒适感觉出现的频率差别较大,在年际分布上有波动,月际分布上很不均匀。PET随温度线性增加,在多云天气1m/s风速时增幅最大;PET和平均辐射温度之间也是线性增加关系,温度较高时增幅大;PET随着风速的增加呈现先快后慢的非线性减小关系,低温时降幅明显,高温阴天时降幅最小;相对湿度在高温时可使PET显著增加。     

中国及邻近地区污染排放对对流层臭氧变化与辐射影响的研究

利用双向耦合的区域气候模式和大气化学模式系统, 研究了中国与邻近地区人为污染排放引起对流层臭氧变化和产生的辐射强迫.结果表明, 污染排放对对流层臭氧含量的影响有明显的季节变化, 对北方的影响不如南方显著, 西部的季节变化稳定且小于东部, 内陆污染地区各季节臭氧柱含量的变化量均较高.对整个模拟区域而言, 臭氧变化量的年平均值为30.928 DU, 春季最大为32.168 DU, 而空间分布变化在12～38 DU之间.臭氧变化量对北方地区辐射的影响较小, 而对低纬和华东地区影响较大, 臭氧变化量引起的晴空地气系统短波辐射强迫、长波辐射强迫的平均值分别是0.185 W·m-2和0.464 W·m-2, 标准化短波辐射强迫与净辐射强迫值为0.006 W·m-2·DU-1和0.021 W·m-2·DU-1.气候反馈过程对对流层臭氧含量的影响范围在-0.470～0.752 DU之间, 包含气候反馈过程的区域年平均臭氧变化量是30.942 DU.在气候反馈条件下, 臭氧变化量的短波和长波辐射强迫分别是0.249 W·m-2及 0.482 W·m-2, 标准化的短波与净辐射强迫值为0.008 W·m-2·DU-1和0.024 W·m-2·DU-1.臭氧变化量导致地表温度的变化范围在±0.80 K之间.     

辐射方案对GRAPES全球模式的影响

辐射过程是中期数值天气预报模式和气候模式中一个重要的物理过程。本文针对GRAPES (Global/Regional Assimilation and PrEdiction System) 全球模式非静力半隐式半拉格朗日的特点, 进行了不同辐射方案的敏感性比较试验, 以期找到一个适合于GRAPES全球模式的辐射方案。用到的方案包括WRF模式中的RRTM长波辐射方案、 NASA的Goddard短波辐射方案以及ECMWF的长短波辐射方案。试验结果表明, ECMWF的辐射方案更适合于GRAPES模式, 30天平均的北半球500 hPa高度场距平相关系数较WRF的辐射方案提高了近2%。另外, 针对实际运行中存在的辐射计算不稳定问题, 对辐射方案进行了气压订正和温度订正, 并对2005年7月影响我国的海棠台风进行了模拟试验, 气压订正后的120小时模式预报在对副热带高压和台风的描述上更接近于分析, 可用预报时效也有了明显提高。     

气候模式中云的次网格结构对全球辐射影响的研究

利用一种用于大尺度天气、气候模式的随机云产生器(SCG)和独立气柱近似(ICA)辐射算法,研究了次网格云的水平结构以及垂直重叠结构对全球辐射场的影响.比较了水平非均匀云(IHCLD)和水平均匀云(HCLD)的辐射场差异以及云的最大.随机重叠(MRO)和一般重叠(GenO)的辐射场差异.结果显示,与HCLD相比,IHCLD一方面可增加地面净短波辐射通量,纬向平均最大值(约1W/m~2)和次大值(约0.6 W/m~2)分别位于高纬度低云密集地区和对流旺盛的热带地区;另一方面可增加大气顶的净长波辐射通量,纬向平均最大值(0.3 W/m~2)出现在热带地区.不同的重叠结构对短波和长波辐射收支也有很大的影响.MRO和GenO的短波辐射通量差异在热带辐合带最大.达到30-40W/m~2,在高纬度低云带的纬向平均也可达到5W/m~2左右;长波辐射通量差异具有相似的地区分布,但量值相对较小.不同重叠结构可以造成大气上下层的辐射加热率差异,影响大气热力层结.云的水平和垂直结构对有云区域辐射收支的影响将改变大气热力、动力状况以及水汽条件,从而影响模拟的气候系统的演变.文中采用单向云-辐射计算,排除了与气候系统其他过程复杂的相互作用,从而使其结果具有一定的普适性,可为不同大尺度模式进行次网格云辐射参数化提供参考.     

中国地球系统模式对全球地表入射短波辐射和大气逆辐射的模拟效果评估

以云和地球辐射能量系统(CERES)数据集为准,量化了中国地球系统模式对地表入射短波辐射和大气逆辐射时空变化的模拟性能,明确了多模式间模拟结果存在不确定性的区域。结果表明：中国模式均能模拟出北半球地表入射短波辐射和大气逆辐射“夏高冬低”的季节变化特征。陆地上,中国模式对两个辐射分量月均值的模拟结果与CERES相当,在海洋上低于CERES结果。中国模式能模拟出地表入射短波辐射下降、大气逆辐射上升的年际变化趋势。对于2001—2014年均值,中国模式模拟的地表入射短波辐射在海洋和陆地上较CERES分别偏低3.3和3.0 W·m^-2,模拟的大气逆辐射在海洋上与CERES结果相当,在陆地上较CERES低1.3 W·m^-2。除南北纬30°附近之外,中国模式在其他纬度均低估地表入射短波辐射,以热带和北极最为明显。模式对大气逆辐射的模拟偏差呈纬向波动特征,模拟误差大值出现在高大山脉处。中国模式模拟地表入射短波辐射不确定性极大的区域分布在热带雨林和南极洲沿海,模拟大气逆辐射不确定性极大的区域分布在格林兰岛、青藏高原、安第斯山脉和南极洲沿海。     

气象条件对玉米生长发育影响的试验与评估模式研究

根据田间试验资料 ,采用模拟模式及统计分析方法 ,分析了玉米生长期的农业气象条件及其对生长发育、干物质积累、灌浆速率及产量的影响。建立了相应的评估模式     

秸秆燃烧对北京秋季气溶胶浓度和短波辐射影响的模拟研究

利用地面细颗粒物（PM2.5）浓度和气象常规观测资料、地基 AERONET观测资料、GFED生物质燃烧排放清单和大气化学—天气耦合模式WRF-Chem,模拟研究了华北地区2014年10月气象要素和大气污染物的时空演变,重点关注北京10月7～11日的一次重霾事件及其天气形势、边界层气象特征、输送路径、PM2.5及其化学成分浓度变化等特征,以及秸秆燃烧对华北和北京地区细颗粒物浓度和地面短波辐射的影响。与观测资料的对比结果显示,模式可以很好地模拟北京地区地面气象要素和PM2.5质量浓度,考虑秸秆燃烧排放源可以明显改进北京PM2.5浓度模拟的准确性,但在重度污染情况下,模式总体上低估气溶胶光学厚度和高估地面短波辐射。10月7～11日北京地区重霾事件主要是不利气象条件下人为污染物累积和区域输送造成,也受到华北地区南部秸秆燃烧的影响。河南北部、河北南部和山东西部大面积秸秆燃烧释放的气态污染物和颗粒物在南风的作用下输送至北京,秸秆燃烧对北京地区地面PM2.5、有机碳（OC）、硝酸盐、铵盐、硫酸盐和黑碳（BC）的平均贡献率分别为24.6%、36.8%、23.2%、22.6%、7.1%和19.8%,秸秆燃烧产生的气溶胶可以导致北京地面平均短波辐射最大减小超过20 W m－2,约占总气溶胶导致地表短波辐射变化的24%。     

NUIST地球系统模式模拟ENSO对西北太平洋热带气旋活动的影响

地球系统模式已经逐步成为研究热带气旋（TC）活动气候变化的重要工具之一,之前的研究发现南京信息工程大学地球系统模式（NESM）高分辨率版本可以较好地模拟全球海温分布及TC活动的气候特征。本研究进一步分析了NESM地球系统模式模拟西北太平洋TC活动的年际变化,并与1967～2016年观测的TC活动进行对比。NESM模式高分辨率版本能够较好地模拟西北太平洋平均海温及与ENSO事件联系的海温异常变化特点,对El Ni?o事件发生时西北太平洋TC的生成频数和路径分布的模拟较好,也能模拟El Ni?o年TC生成位置比La Ni?a年偏东的特征,但是未能模拟出TC平均生命周期和Ni?o3.4地区海温的相关性。并且模式模拟的La Ni?a年TC的生成位置偏东,主要原因是模拟La Ni?a年季风槽平均位置偏东。研究结果有助于进一步改进NESM模式和利用NESM模式研究TC活动。     

GRAPES与日本模式对东莞单站预报效果的对比

利用统计检验方法,对2011年前汛期(4～6月)GRAPES区域中尺度模式与日本GSM全球谱模式东莞单站的逐日降水和气温预报进行定量检验和对比。结果表明:降水预报GRAPES区域中尺度模式略优于日本模式;对于前汛期由锋面低槽和季风槽引起的明显降水过程,GRAPES区域中尺度模式预报好于日本模式,且两个模式都对锋面低槽降水预报优于各自对季风槽降水预报;对日最高气温的预报,日本模式比GRAPES区域中尺度模式表现的更加稳定,对日最低气温的预报,日本模式具有较好的参考性。     

Impacts of uncertainty in AVOC emissions on the summer ROx budget and ozone production rate in the three most rapidly-developing economic growth regions of China

High levels of uncertainty in non-methane volatile organic compound （NMVOC） emissions in China could lead to significant variation in the budget of the sum of hydroxyl （OH） and peroxy （HO2,RO2） radicals （ROx =OH ＋ HO2 ＋ RO2） and the ozone production rate [P（O3）],but few studies have investigated this possibility,particularly with three-dimensional air quality models.We added diagnostic variables into the WRF-Chem model to assess the impact of the uncertainty in anthropogenic NMVOC （AVOC） emissions on the ROx budget and P（O3） in the Beijing-Tianjin-Hebei region,Yangtze River Delta,and Pearl River Delta of China.The WRF-Chem simulations were compared with satellite and ground observations,and previous observation-based model studies.Results indicated that 68％ increases （decreases） in AVOC emissions produced 4％-280％ increases （2％-80％ decreases） in the concentrations of OH,HO2,and RO2 in the three regions,and resulted in 35％-48％ enhancements （26％-39％ reductions） in the primary ROx production and ～ 65％ decreases （68％-73％ increases） of the P（O3） in Beijing,Shanghai,and Guangzhou.For the three cities,the two largest contributors to the ROx production rate were the reaction of O1D ＋ H2O and photolysis of HCHO,ALD2,and others; the reaction of OH ＋ NO2 （71％-85％） was the major ROx sink; and the major contributor to P（O3） was the reaction of HO2 ＋ NO （～ 65％）.Our results showed that AVOC emissions in 2006 from Zhang et al.（2009） have been underestimated by ～ 68％ in suburban areas and by ＞ 68％ in urban areas,implying that daily and hourly concentrations of secondary organic aerosols and inorganic aerosols could be substantially underestimated,and cloud condensation nuclei could be underestimated,whereas local and regional radiation was overestimated.     

餐饮源挥发性有机物(VOCs)排放特征及对臭氧生成的影响

餐饮排放是城市地区挥发性有机物（VOCs）重要的无组织来源,由于其排放特征复杂,是大气环境研究和管理的薄弱环节.本研究采用了现场和实验模拟两种采样方式,利用2,4-二硝基苯肼（DNPH）采样柱和不锈钢罐分别采集羰基化合物和全空气样品,然后利用高效液相色谱（HPLC）和气相色谱-质谱联用仪（GC-MS/FID）对116种组分进行定性定量分析.在此基础上,分析了餐饮源VOCs的排放特征及其影响因素.总体来看,含氧有机物（OVOCs）和烷烃是VOCs浓度的主要贡献者,但不同餐饮源的源谱特征差异较大.另外,通过比较发现食用油的种类、油的使用次数、加热方式、烹饪方式和调味料等因素会对餐饮源VOCs排放特征造成显著影响.进一步分析了不同菜系所排放VOCs的臭氧生成潜势（OFP）,关键组分主要是甲醛、乙醛、丁烯醛、乙烯和丙烯等.本研究成果能够补充我国餐饮源VOCs控制所需的基础数据.     

A Methodological Study on Using Weather Research and Forecasting(WRF) Model Outputs to Drive a One-Dimensional Cloud Model简

A new method for driving a One-Dimensional Stratiform Cold （1DSC） cloud model with Weather Research and Fore casting （WRF） model outputs was developed by conducting numerical experiments for a typical large-scale stratiform rainfall event that took place on 4-5 July 2004 in Changchun, China. Sensitivity test results suggested that, with hydrometeor pro files extracted from the WRF outputs as the initial input, and with continuous updating of soundings and vertical velocities （including downdraft） derived from the WRF model, the new WRF-driven 1DSC modeling system （WRF-1DSC） was able to successfully reproduce both the generation and dissipation processes of the precipitation event. The simulated rainfall intensity showed a time-lag behind that observed, which could have been caused by simulation errors of soundings, vertical velocities and hydrometeor profiles in the WRF output. Taking into consideration the simulated and observed movement path of the precipitation system, a nearby grid point was found to possess more accurate environmental fields in terms of their similarity to those observed in Changchun Station. Using profiles from this nearby grid point, WRF-1DSC was able to repro duce a realistic precipitation pattern. This study demonstrates that 1D cloud-seeding models do indeed have the potential to predict realistic precipitation patterns when properly driven by accurate atmospheric profiles derived from a regional short range forecasting system, This opens a novel and important approach to developing an ensemble-based rain enhancement prediction and operation system under a probabilistic framework concept.     

A modelling study of aerosol processing by stratocumulus clouds and its impact on general circulation model parameterisations of cloud and aerosol

A model of the aqueous phase processing of an aerosol population undergoing multiple cycling through a stratocumulus (Sc) cloud layer is presented. Results indicate that a significant modification of the aerosol properties is achieved following the first cycle through cloud. In a polluted atmosphere, further modification in subsequent cycles is seen to be hydrogen peroxide limited unless there is a flux of ammonia entering the system through cloud base (CB). The modification of the aerosol population is seen to have little effect on the microphysics (specifically the cloud droplet concentration and effective radius) of the processing cloud. However, it enables processed aerosols to subsequently act as efficient cloud condensation nuclei (CCN) in less vigorous clouds (as a result of reducing the critical supersaturation required to activate them). The effects of variations in the internal mixture of soluble components of aerosols on the microphysics of clouds forming on them are also investigated using the cloud model. A (K2) parameterisation of the effects of variations in internally mixed nitrate loadings on the cloud droplet number concentration is presented. The effects of applying this K2 correction to the droplet number (derived from a parameterisation based on sulphate) for the presence of nitrate in aerosol have been investigated using the HadAM3 version of the Hadley Centre General Circulation Model (GCM). The effect on global annual mean simulations of the indirect forcing and effective radius is small, but more pronounced regionally. Suggestions (based on model results and observations) for parameterising the size distribution and in-cloud growth of aerosols for use in GCMs are presented.     

The impact of nonlinear stability and instability on the validity of the tangent linear model

l.Intr0ducti0nTheequationsgoverningthemotionsoftheatmosphereandoceanaren0nlinear0nes.Itisdiffcultandcomplicatedtodealwiththenonlinearproblem.Sothetangentlinearmodel(TLM),whichisobtainedbylinearizingthenonlinearmodelinthevicinityofthebasicflow.iswidelyutilizedinthetheoreticalresearchandpracticalimplementationintheatmosphericandoceanicsciences.First-TLMcanbeusedtoestimatetheev0luti0nofsmallPerturbati0nsinaf0recastmodel.Second,itisadoptedinextendedKalmanfilterinthedataassimilation(Evensen,l99…     

Evaluation of CMIP5 Earth System Models in Reproducing Leaf Area Index and Vegetation Cover over the Tibetan Plateau

The abilities of 12 earth system models (ESMs) from the Coupled Model Intercomparison Project Phase5 (CMIP5) to reproduce satellite-derived vegetation biological variables over the Tibetan Plateau (TP) were examined. The results show that most of the models tend to overestimate the observed leaf area index (LAI) and vegetation carbon above the ground, with the possible reasons being overestimation of photosynthesis and precipitation. The model simulations show a consistent increasing trend with observed LAI over most of the TP during the reference period of 1986-2005, while they fail to reproduce the downward trend around the headstream of the Yellow River shown in the observation due to their coarse resolutions. Three of the models: CCSM4, CESM1-BGC, and NorESM1-ME, which share the same vegetation model, show some common strengths and weaknesses in their simulations according to our analysis. The model ensemble indicates a reasonable spatial distribution but overestimated land coverage, with a significant decreasing trend (-1.48% per decade) for tree coverage and a slight increasing trend (0.58% per decade) for bare ground during the period 1950-2005. No significant sign of variation is found for grass. To quantify the relative performance of the models in representing the observed mean state, seasonal cycle, and interannual variability, a model ranking method was performed with respect to simulated LAI. INMCM4, bcc-csm-1.1m, MPI-ESM-LR, IPSL CM5A-LR, HadGEM2-ES, and CCSM4 were ranked as the best six models in reproducing vegetation dynamics among the 12 models.     

东亚强对流云的季节变化及其与对流层顶关系初探

利用GMS 5/VISSR长波红外（10.5～11.5 μm）和水汽通道（6.5～7.0 μm）探测原理的差异, 结合红外阈值法和区域平滑滤波技术提取 “高、 厚、 密” 强对流云, 分析了东亚强对流云活动的空间分布及其季节变化规律。GMS 5卫星视场内各个子地区强对流云云顶温度与发生频率的季节变化基本为单峰单谷型, 前者夏低冬高, 但不同地区引起的原因不同。强对流云发生频率36°N以北夏低冬高, 以南夏高冬低。东亚对流层顶由冬春至夏秋升高, 对流层顶气压随之降低, 而对流层顶温度的季节变化以45°N为界, 北部夏高冬低, 南部夏低冬高。作者所研究的东亚几个子地区强对流云与对流层顶季节变化位相基本保持同步, 2000年强对流云云顶温度与对流层顶温度的月均值相关系数达0.757, 强对流云云顶温度与对流层顶气压的月均值相关系数达0.901, 对流层顶温度比强对流云云顶温度平均低9.42℃。强对流云的发展受对流层顶制约作用显著。     

江南丘陵和云贵高原地形对一次西南涡暴雨影响的数值试验

运用MM5数值模式对1998年7月22~23日一次由西南涡引发形成湖南大暴雨的个例进行了数值试验。模式中设计了全地形、去掉江南丘陵地形、去掉江南丘陵和云贵高原地形三种方案。对比试验表明:在去掉江南丘陵和云贵高原后,由于地形的狭管作用消失,南北热力差异减弱,低空急流随之减弱;由于低空急流对西南涡和切变线的正涡度平流输送减弱,以及500 hPa高空槽引导切变线向南移与西南涡结合,造成西南涡增强,切变线减弱、消失。同时,本文还对三种模拟试验中地形作阶梯化处理,进一步验证江南丘陵、云贵高原对偏南风存在狭管作用,对低空急流的形成有促进作用。     

汕头市PM2.5的气象要素影响分析及预报研究

利用2014—2017年汕头市PM_2.5的日浓度资料、以及汕头市国家基准气象观测站的同期地面气象资料,重点分析了汕头市PM_2.5浓度的变化特征以及风、混合层厚度、降水等气象条件对PM_2.5浓度的影响,同时探讨了污染物浓度变化的成因。在此基础上,根据汕头市的气候特点,采用BP （Back-Propagation）人工神经网络方法针对汛期和非汛期分别建立了PM_2.5质量浓度预报模型。结果表明：与多数内陆城市不同,汕头市PM_2.5浓度日变化为单峰型,这与汕头地处沿海受海陆风影响有关;PM_2.5浓度日峰值出现在08时左右,除早高峰污染物排放增加的因素外,与早晨时段的低风速环境有关;PM_2.5日均浓度随着风速的增大呈现减小趋势,PM_2.5日均浓度与08时混合层厚度显著相关（相关系数为-0.143）;汕头市非汛期PM_2.5浓度比汛期高,这与汕头市的亚热带季风气候特征有关,汛期各量级降水（暴雨以上除外）对PM_2.5的清除效果无明显差别,而非汛期降水对PM_2.5浓度有明显清除作用;BP人工神经网络模型的预报效果表明,汛期和非汛期的PM_2.5级别命中率TS分别为100%和90.3%,准确指数分别为87.7%和89.9%,总体预报效果良好。不同时期预报模型出现正误差的数量和程度均大于负误差,汛期预报模型在有强降水发生时误差较大,而非汛期预报模型在有冷空气入侵时误差较大。     

Impacts of Weather Conditions Modified by Urban Expansion on Surface Ozone： Comparison between the Pearl River Delta and Yangtze River Delta Regions

In this paper, the online weather research and forecasting and chemistry (WRF-Chem) model is used to explore the impacts of urban expansion on regional weather conditions and its implication on surface ozone concentrations over the Pearl River Delta(PRD) and Yangtze River Delta(YRD) regions. Two scenarios of urban maps are used in the WRF-Chem to represent the early 1990s (pre-urbanization) and the current urban distribution in the PRD and the YRD. Month-long simulation results using the above land-use scenarios for March 2001 show that urbanization increases both the day- and night-time 2-m temperatures by about 0.6^oC and 1.4^oC, respectively. Daytime reduction in the wind speed by about 3.0 m s^-1 is larger than that for the nighttime (0.5 to 2 m s^-1). The daytime increase in the PBL height (> 200 m) is also larger than the nighttime (50--100 m). The meteorological conditions modified by urbanization lead to detectable ozone-concentration changes in the PRD and the YRD. Urbanization increases the nighttime surface-ozone concentrations by about 4.7%--8.5% and by about 2.9%--4.2% for the daytime. In addition to modifying individual meteorological variables, urbanization also enhances the convergence zones, especially in the PRD. More importantly, urbanization has different effects on the surface ozone for the PRD and the YRD, presumably due to their urbanization characteristics and geographical locations. Even though the PRD has a smaller increase in the surface temperature than the YRD, it has (a) weaker surface wind speed, (b) smaller increase in PBL heights, and (c) stronger convergence zones. The latter three factors outweighed the temperature increase and resulted in a larger ozone enhancement in the PRD than the YRD.