Adjoint Sensitivity Analyses on the Anomalous Circulation Features in East Asian Summer Monsoon

ＡｄｊｏｉｎｔＳｅｎｓｉｔｉｖｉｔｙＡｎａｌｙｓｅｓｏｎｔｈｅＡｎｏｍａｌｏｕｓＣｉｒｃｕｌａｔｉｏｎＦｅａｔｕｒｅｓｉｎＥａｓｔＡｓｉａｎＳｕｍｍｅｒＭｏｎｓｏｏｎ①ＹａｎｇＹａｎ（杨燕），ＬｉＺｈｉｊｉｎ（李志锦）ａｎｄＪｉＬｉｒｅｎ（纪立人）Ｉ...     

1991年夏季持续性异常环流的共轭敏感性分析

在共轭敏感性分析的基础上发展了最敏感扰动的概念。用共轭模式对江淮流域大水1991年东亚夏季环流的持续异常特征,包括乌拉尔阻塞高压、鄂霍次克海偶极子型阻塞以及副热带高压的变动过程进行了分析,分别得到了对这些过程影响最大的初始扰动。结果从新的角度揭示了这些系统最重要的影响因子,也显示了共轭敏感性分析方法在大气环流物理过程诊断中的有效性和应用前景。     

From shared socio-economic pathways (SSPs) to oceanic system pathways (OSPs): Building policy-relevant scenarios for global oceanic ecosystems and fisheries

There is an urgent need for developing policy-relevant future scenarios of biodiversity and ecosystem services. This paper is a milestone toward this aim focusing on open ocean fisheries. We develop five contrasting Oceanic System Pathways (OSPs), based on the existing five archetypal worlds of Shared Socioeconomic Pathways (SSPs) developed for climate change research (e.g., Nakicenovic et al., 2014 and Riahi et al., 2016). First, we specify the boundaries of the oceanic social-ecological system under focus. Second, the two major driving forces of oceanic social-ecological systems are identified in each of three domains, viz., economy, management and governance. For each OSP (OSP1 “sustainability first”, OSP2 “conventional trends”, OSP3 “dislocation”, OSP4 “global elite and inequality”, OSP5 “high tech and market”), a storyline is outlined describing the evolution of the driving forces with the corresponding SSP. Finally, we compare the different pathways of oceanic social-ecological systems by projecting them in the two-dimensional spaces defined by the driving forces, in each of the economy, management and governance domains. We expect that the OSPs will serve as a common basis for future model-based scenario studies in the context of the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES).     

最敏感扰动的演变与夏季乌拉尔地区的持续性异常环流

通过数值实验对初始扰动不稳定发展建立异常环流型的过程进行了分析。选择了东亚夏季风异常的１９９１年和１９８５年两个典型年份的平均环流作为基流,以共轭敏感性分析得到的最敏感扰动作为初始扰动,分析其在不同的环流背景下的发展情况。结果说明,１９９１年欧亚地区的基流不稳定性较强,且初始扰动结构有利扰动发展,因而通过能量频散在乌拉尔地区激发扰动并强烈发展,建立起阻塞形势。而１９８５年的扰动在乌拉尔地区形成正涡度距平,不利于阻高的建立。从而导致１９９１年和１９８５年夏季乌拉尔地区几乎相反的异常环流。一系列对比实验说明,异常环流型的建立,不仅依靠能量的频散,更依靠扰动通过正压不稳定过程从基流吸收能量而发展。它既有赖于基流自身的不稳定,又取决于初始扰动的结构以及相对于基流的位置。基流选择了具有特定结构的初始扰动型,只要在有利位置上给予扰动,就能够激发出扰动波列,建立强的持续异常环流型。不论初始波列的位相在一定范围内如何改变,扰动总是倾向于在基流的特定不稳定区域发展。     

集合敏感性在预报误差及可预报性研究中的应用进展综述

研究大气的可预报性和预报误差产生的原因,对于改进数值预报,提升业务预报技巧具有重要意义。集合敏感性基于具有流依赖特性的集合预报,通过建立预报与初始场或前期预报大气状态之间的统计关系,为揭示与预报对象可预报性相关的动力学特征及理解预报误差来源和传播机制提供了一种新方法。同时,介绍了集合敏感性的定义和度量,并综述了其针对典型天气系统和高影响天气事件研究的进展,并讨论了该方法的优势和局限性。     

江西中西部地区一次暴雨过程的地形敏感性试验

利用常规观测、加密自动站资料和NCEP再分析资料,分析2005年5月江西萍乡地区春季一次暴雨过程发现,该过程仅萍乡南部地区出现暴雨,而中北部地区为小到中雨。考虑到萍乡中南部特殊地形,通过WRF中尺度模式模拟再现这次暴雨过程,并设计降低、增高和移除地形三组敏感性试验探究地形对降水的影响。结果表明：（1）萍乡地形的屏障作用在南部地区造成的风场辐合是南部产生暴雨的重要原因;（2）地形通过影响切变线附近风场辐合以及水汽汇集的位置和强度来改变暴雨的落区与强度;（3）较高的地形造成气流在山前堆积,造成明显的水平气压梯度,使局地气流与背景气流在山前辐合,有利于山前降水增强。     

Multi-year Simulations and Experimental Seasonal Predictions for Rainy Seasons in China by Using a Nested Regional Climate Model （RegCM_NCC）. Part Ⅰ： Sensitivity Study

A modified version of the NCAR/RegCM2 has been developed at the National Climate Center （NCC）, China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcasts, with a special emphasis on the adequate choice of physical parameterization schemes suitable for the East Asian monsoon climate. This regional climate model is nested with the NCC/IAP （Institute of Atmospheric Physics） T63 coupled GCM to make an experimental seasonal prediction for China and East Asia. The four-year （2001 to 2004） prediction results are encouraging. This paper is the first part of a two-part paper, and it mainly describes the sensitivity study of the physical process paraxneterization represented in the model. The systematic errors produced by the different physical parameterization schemes such as the land surface processes, convective precipitation, cloud-radiation transfer process, boundary layer process and large-scale terrain features have been identified based on multi-year and extreme flooding event simulations. A number of comparative experiments has shown that the mass flux scheme （MFS） and Betts-Miller scheme （BM） for convective precipitation, the LPMI （land surface process model I） and LPMII （land surface process model Ⅱ） for the land surface process, the CCM3 radiation transfer scheme for cloud-radiation transfer processes, the TKE （turbulent kinetic energy） scheme for the boundary layer processes and the topography treatment schemes for the Tibetan Plateau are suitable for simulations and prediction of the East Asia monsoon climate in rainy seasons. Based on the above sensitivity study, a modified version of the RegCM2 （RegCM_NCC） has been set up for climate simulations and seasonal predictions.     

Multi-year Simulations and Experimental Seasonal Predictions for Rainy Seasons in China by Using a Nested Regional Climate Model (RegCM_NCC). Part Ⅰ: Sensitivity Study

A modified version of the NCAR/RegCM2 has been developed at the National Climate Center (NCC), China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcasts, with a special emphasis on the adequate choice of physical parameterization schemes suitable for the East Asian monsoon climate. This regional climate model is nested with the NCC/IAP (Institute of Atmospheric Physics) T63 coupled GCM to make an experimental seasonal prediction for China and East Asia. The four-year (2001 to 2004) prediction results are encouraging. This paper is the first part of a two-part paper, and it mainly describes the sensitivity study of the physical process parameterization represented in the model. The systematic errors produced by the different physical parameterization schemes such as the land surface processes, convective precipitation, cloud-radiation transfer process, boundary layer process and large-scale terrain features have been identified based on multi-year and extreme flooding event simulations. A number of comparative experiments has shown that the mass flux scheme (MFS) and Betts-Miller scheme (BM) for convective precipitation, the LPMI (land surface process model I) and LPMII (land surface process model Ⅱ) for the land surface process, the CCM3 radiation transfer scheme for cloud-radiation transfer processes, the TKE (turbulent kinetic energy) scheme for the boundary layer processes and the topography treatment schemes for the Tibetan Plateau are suitable for simulations and prediction of the East Asia monsoon climate in rainy seasons. Based on the above sensitivity study, a modified version of the RegCM2 (RegCM_NCC) has been set up for climate simulations and seasonal predictions.     

太行山对北京“7.21”特大暴雨的影响及水汽敏感性分析的数值研究

运用GRAPES_Meso模式对2012年7月21—22日发生在北京地区附近的特大暴雨过程进行数值模拟和地形、水汽的敏感性试验。地形敏感性试验发现,在这次特大暴雨过程中,由于太行山北端的阻挡作用,使得气流和水汽辐合、抬升,加强了对流过程;对流层低层山前东南风和西南风、北风的辐合带增大了气旋性涡度,使东移到北京的低涡稳定维持5 h左右,对降水有明显的增幅作用;而且地形起伏和地形海拔高度对降水都有明显增幅作用,地形起伏的增幅作用较地形高度的大。水汽敏感性试验发现在这次特大暴雨过程中,水汽条件较小的变化,会导致水汽输送的明显差异,从而导致降水量显著地改变。     

Sensitivity of the Indian Monsoon to Human Activities

In this paper the authors perform an extensive sensitivity analysis of the Indian summer monsoon rainfall to changes in parameters and boundary conditions which are influenced by human activities. For this study the authors use a box model of the Indian monsoon which reproduces key features of the observed monsoon dynamics such as the annual course of precipitation and the transitions between winter and summer regimes. Because of its transparency and computational efficiency, this model is highly suitable for exploring the effects of anthropogenic perturbations such as emissions of greenhouse gases and sulfur dioxide, and land cover changes, on the Indian monsoon. Results of a systematic sensitivity analysis indicate that changes in those parameters which are related to emissions of greenhouse gases lead to an increase in Indian summer rainfall. In contrast, all parameters related to higher atmospheric aerosol concentrations lead to a decrease in Indian rainfall. Similarly, changes in parameters which can be related to forest conversion or desertifieation, act to decrease the summer precipitation. The results indicate that the sign of precipitation changes over India will be dependent on the direction and relative magnitude of different human perturbations.     

New evidences on the climatic causes of the formation of the spring persistent rains over southeastern China

The spring persistent rains (SPR) over southeastern China (SEC) are a unique synoptic and climatic phenomenon in East Asia. A former study has found that the southwesterly flow which lies on the southeastern flank of the Tibetan Plateau (TP) is one of the deflected westerly flows of the TP, and it is suggested to be the direct climatic cause of SPR. This study found that the southwesterly flow is also highly correlated with the sensible heating of the southeastern TP in interannual variability, in addition to having a high correlation in seasonal variability. These facts suggest that the thermal forcing of the TP is another important climatic cause of SPR. Numerical sensitivity experiments further prove that the mechanical and thermal forcings of the TP are the climatic causes of the formation of the SPR. On the other hand, the Nanling Mountains and Wuyi Mountains (NWM) over southeastern China not only increase the SPR precipitation amount evidently, but also make the SPR rain belt move to the south by blocking the strong southwesterly flow.     

作物模型参数敏感性分析现状与展望

作物模型作为作物产量预测等方面应用广泛、作用巨大的重要工具,其参数的校正和优化等工作是模型模拟的前提。普通的试错法缺乏客观性且效率低下,对作物模型的输入参数进行敏感性分析,识别模拟过程中参数的敏感程度,能够有效识别关键参数并减少率定的参数量,为后续模型参数优化和校正工作奠定基础。本文主要分析了作物模型的局部敏感性分析方法和全局敏感性方法的利弊及其适应条件,涵盖傅立叶幅度灵敏度检验法(FAST)、Morris法、LH-OAT法、普适似然不确定性估计法(GLUE)、Sobol法以及扩展傅立叶幅度灵敏度检验法(EFAST)等,回顾各方法在作物模型中的研究现状,并对作物模型参数敏感性分析方法提出了展望。     

正、斜压流场演变及相互转换所伴随的偶极型阻塞生命史

将阻塞过程中的大气运动流场分解为正,斜压流场,研究了它们在乌拉尔山偶极型阻塞个例中的演变特征。揭示了正、斜压流场的演变及相互转换所源发的阻塞生命史的全过程。     

长江流域一次大暴雨过程的低空急流形成和影响机制分析

利用WRF模式对2016年6月30日—7月6日长江流域的一次大暴雨天气过程中的低空急流进行数值模拟,在成功模拟低空急流基础上,分析此次急流过程中可能的影响机制;同时对地形高度进行敏感性试验,分析地形因素对此次低空急流可能的影响。(1)此次低空急流发生时,东侧为西太平洋副热带高压,西侧则为西南涡。这种“东高西低”的高低压配置为低空急流的形成与发展提供了有利的背景场。(2)高空急流和低空急流的耦合作用是低空急流发展的一个重要背景条件。(3)垂直方向高空动量不断下传为低空系统的发展提供了动力支持,是低空急流发生的一个重要条件。(4)逆温和垂直风切变之间的正反馈机制是低空急流形成与加强的因素之一。(5)山体在急流生成及发展过程中对气流有摩擦和阻挡作用,这种阻挡作用随着山体地形高度的增加而有所加强,同时山脉的走向会改变原始的风向,使得急流前端超前或滞后。青藏高原有强背风波效应,它的绕流和挤压作用会使得低空气流表现为狭长的带状,使动量更加聚集从而风速增加形成低空急流。      

Southern Hemisphere blocking: A comparison between two indices

Summary Two different blocking indices are computed for the Southern Hemisphere for the period 1979–1985, one is based on sea level pressure and the other on upper tropospheric zonal wind. The Southern Hemisphere blocking climatology based on these two indices separately presents very similar results, mainly in identifying the region of maximum occurrence over eastern Australia and the western Pacific. The sea level presure index shows strong orographic influences, while the 250hPa zonal wind index is not affected by orography but does exaggerate seasonal variations. It is apparent that blocking occurrence in the eastern Australia and neighbouring areas has a link with climatological atmospheric features.With 8 Figures     

North Atlantic winter eddy-driven jet and atmospheric blocking variability in the Community Earth System Model version 1 Large Ensemble simulations

Climate Dynamics - The atmospheric jet and blocking distributions, especially in the North Atlantic sector, have been challenging features for a climate model to realistically reproduce. This study...     

阻塞过程的正、斜压涡度拟能场诊断研究

应用正、斜压涡度拟能方程，对1998年6月3～11日发生在鄂霍次克海的一次阻塞环流进行诊断。结果表明:阻塞区内总涡度拟能和正压涡度拟能具有显著的变化，它清楚地揭示了阻塞过程中酝酿、维持和崩溃阶段中的不同特征，而正、斜压动能所显示的阻塞过程的变化特征则不明显。正、斜压涡度拟能场相互转换及阻塞区内外正、斜压涡度拟能场的净通量机制是鄂霍次克海阻塞环流建立和维持的两项主要因子。其过程是:首先通过斜压涡度拟能净通量机制，使斜压涡度拟能增长；又通过正斜压涡度拟能场的转换机制将增长的斜压涡度拟能转为正压涡度拟能；与此同时，通过正压涡度拟能净通量机制使正压涡度拟能增长。这两种不同的机制相互结合，从而使正压涡度拟能增长和维持，形成阻塞环流。而斜压涡度拟能增长甚微。     

北太平洋阻塞的年际年代际变化及其与SST、遥相关及风暴路径的关系

利用NCEP／NCAR再分析资料，对1948／1949－1999／2000共52个冬季的北太平洋上空中纬度阻塞异常的气修特征进行了统计分析，小波分析和功率谱分析结果表明该区域阻塞发生的频数具有很明显的3－7年的年际振荡和年代际变化特征。同时2－7年带通平均的小波方差谱分析结果表明阻塞的这种年际变化的振幅存在着缓慢下降的趋势，且气候突变在20世纪70年代，这进一步证明了北太平洋上空的阻塞活动具有年代际变化特征。对强阻塞异常的冬季和弱阻塞异常的冬季分别进行合成分析，结果表明，对于阻塞异常强的冬季，北太平洋西向东北方向加强并分裂成两个中心，而SST异常在中纬度太平洋则对应着典型的PDO型，在赤道地区则为类La Nina型的海温分布。而对于阻塞异常弱的冬季则对应截然不同甚至相反的分布特征，即500hPa高度异常场表现为符号相反的PNA型，风暴路径中心在日界线附近呈纬向型分布。同时SST异常在赤道地区则为典型的El Nino型的海温分布。以上结果揭示出北太平洋阻塞活动的年际变化可能主要与热带海温的遥响应相联系，而年代际变化则主要与中纬度局地的PDO型海温及其通过斜压瞬变波的海－气相互作用有关。     

Sensitivity Studies for Monitoring Tropospheric Ozone from Space Using the Ultraviolet,Visible,and Polarization Bands

The authors analyzed the retrieval sensitivity of tropospheric ozone using simulated the Global Ozone Monitoring Experiment-2 （GOME-2） measurements. The retrieval sensitivity was evaluated by the degree of free- dom for signal （DFS）. The combination of the ultraviolet （UV）, UV polarization （UVPOL）, and visible （VIS） bands enhances DFS of tropospheric ozone and improves the vertical resolution of the retrieved ozone profile. UVPOL reduces the dependence on solar zenith angle, mainly in- creases the sensitivity in upper troposphere. Polarization increased the DFS by 20% on the eastern side of the GOME-2 orbit, with little improvement on the western side because the increase in DFS due to polarization is depend- ent on the relative azimuth angle. The inclusion of the visi- ble band reduces significantly the dependence on viewing geometry, and mainly increases the DFS in the lower tro- posphere （0-6 kin） by a factor of two. It was possible to retrieve several independent pieces of tropospheric ozone information from GOME-2 UV/UVPOL/VIS measure- ments, especially in the lower troposphere.