利用珠海CORS监测大气可降水量

依托珠海城市连续运行参考站（continuously operating reference stations,CORS）系统,采用地基全球导航卫星系统（global navigation satellite system,GNSS）反演大气可降水量（precipitable water vapor,PWV）,展开大气可降水量监测系统的应用研究。系统采用精密单点定位（Precise Point Positioning,PPP）技术与IGS(International GNSS Service)轨道、钟差产品实时或事后估计CORS站点上的大气可降水量,可实时更新发布水汽监测数据。通过对监测系统的内符合精度与外符合精度的测试,表明本大气可降水量监测系统对PWV的估计精度优于2 mm,能实现对珠海北斗CORS(ZHBDCORS)网中站点间小区域的水汽监测,区分各站之间的水汽变化,能满足实时对流层水汽监测及其他气象应用需求,有效地拓展ZHBDCORS系统的服务领域。     

The flexible global ocean-atmosphere-land system model, Grid-point Version 2: FGOALS-g2

This study mainly introduces the development of the Flexible Global Ocean-Atmosphere-Land System Model: Grid-point Version 2 (FGOALS-g2) and the preliminary evaluations of its performances based on results from the pre-industrial control run and four members of historical runs according to the fifth phase of the Coupled Model Intercomparison Project (CMIP5) experiment design. The results suggest that many obvious improvements have been achieved by the FGOALS-g2 compared with the previous version,FGOALS-g1, including its climatological mean states, climate variability, and 20th century surface temperature evolution. For example,FGOALS-g2 better simulates the frequency of tropical land precipitation, East Asian Monsoon precipitation and its seasonal cycle, MJO and ENSO, which are closely related to the updated cumulus parameterization scheme, as well as the alleviation of uncertainties in some key parameters in shallow and deep convection schemes, cloud fraction, cloud macro/microphysical processes and the boundary layer scheme in its atmospheric model. The annual cycle of sea surface temperature along the equator in the Pacific is significantly improved in the new version. The sea ice salinity simulation is one of the unique characteristics of FGOALS-g2, although it is somehow inconsistent with empirical observations in the Antarctic.     

ENSO phase-locking in an ocean-atmosphere coupled model FGCM-1.0

The mean climatology and the basic characteristics of the ENSO cycle simulated by a coupled model FGCM-1.0 are investigated in this study. Although with some common model biases as in other directly coupled models, FGCM-1.0 is capable of producing the interannual variability of the tropical Pacific, such as the ENSO phenomenon. The mechanism of the ENSO events in the coupled model can be explained by “delayed oscillator” and “recharge-discharge” hypotheses. Compared to the observations, the simulated ENSO events show larger amplitude with two distinctive types of phase-locking： one with its peak phase-locked to boreal winter and the other to boreal summer. These two types of events have a similar frequency of occurrence, but since the second type of event is seldom observed, it may be related to the biases of the coupled model. Analysis show that the heat content anomalies originate from the central south Pacific in the type of events peaking in boreal summer, which can be attributed to a different background climatology from the normal events. The mechanisms of their evolutions are also discussed.     

新一代天气雷达（CINRAD／CC）发射系统典型故障分析与处理

根据雷达发射系统工作原理、故障现象和故障原因,对甘肃省新一代多普勒天气雷达运行多年来发生的20余次发射系统故障维修工作进行归纳总结。甘肃省新一代多普勒天气雷达发射系统故障可归纳为6类典型故障,对应找出具体维修措施,并给出了关键测试点的波形、调试指标,供技术人员参考;发射系统组成部件复杂,高压器件较多,维修难度大,维修人员需掌握系统组成和工作原理,然后进行故障分级判断和故障定位;发射系统维修常用检查仪器主要是示波器和三用表,因此要求技术保障人员熟练使用。随着雷达使用年限的增加,雷达设备故障率也在增加,而故障维修工作纷繁复杂,这就需要把雷达故障进行总结、分类,同一种类型的故障对应相应故障处理方法,这样就能大大提高雷达维修的时效性。     

冬季北太平洋海表热通量异常和海气相互作用——基于一个全球海气耦合模式长期积分的诊断分析

利用一个全球海气耦合模式长期积分所给出的资料,分析了冬季北太平洋海表湍流热通量（潜热和感热）异常及其对海表温度（SST）异常的影响,并比较了海表热通量诸分量和海洋内部的动力学过程对SST变化的相对重要性。结果表明,冬季热带外海洋上的湍流热通量是影响SST的主要因子,但在北太平洋中部海水的平流作用也不可忽视。冬季热带外海洋向大气释放的潜热和感热通量与SST倾向（而不是SST本身）之间存在着显著的相关,这同Cayan和Reynolds等利用COADS资料和NCEP资料同化模式分析的结果是一致的。模式诊断的结果支持这样一种看法：和热带海洋不同,冬季热带外海洋上的海气相互作用主要地表现为大气对海洋的强迫作用,而不是相反。模式给出的SST倾向的第一个EOF分量及其与海平面气压场的相关特征同Wallace等从观测资料分析所得到的结果是一致的;进一步的分析表明：在冬季北太平洋的大部分区域（特别是西太平洋）,大尺度大气环流异常在很大程度上决定着SST的异常,而这种决定作用正是通过它对湍流热通量的强烈影响来实现的。     

海洋环流对全球增暖趋势的调制：基于FGOALS-s2的数值模拟研究

在工业革命以来全球长期增暖趋势背景下,全球平均表面气温还同时表现出年代际变化特征,二者叠加在一起使得全球平均气温在某些年份增暖相对停滞(如1999～2008年)或者增暖相对较快(如1980～1998年).利用中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG)发展的耦合气候模式FGOALS-s2历史气候和典型路径浓度(RCPs)模拟试验结果研究了可能造成全球增暖的年代际停滞及加速现象的原因,特别是海洋环流对全球变暖趋势的调制作用.该模式模拟的全球平均气温与观测类似,即在长期增暖趋势之上,还叠加了显著的年代际变化.对全球平均能量收支分析表明,模拟的气温年代际变化与大气顶净辐射通量无关,意味着年代际表面气温变化可能与能量在气候系统内部的重新分配有关.通过对全球增暖加速和停滞时期大气和海洋环流变化的合成分析及回归分析,发现全球表面气温与大部分海区海表温度(SST)均表现出几乎一致的变化特征.在增暖停滞时期,SST降低,更多热量进入海洋次表层和深层,使其温度增加;而在增暖加速时期,更多热量停留在表层,使得大部分海区SST显著增加,次表层海水和深海相对冷却.进一步分析表明,热带太平洋表层和次表层海温年代际变化主要是由于副热带—热带经圈环流(STC)的年代际变化所致,然后热带太平洋海温异常可以通过风应力和热通量强迫作用引起印度洋、大西洋海温的年代际变化.在此过程中,海洋环流变化起到了重要作用,例如印度尼西亚贯穿流(ITF)年代际异常对南印度洋次表层海温变化起到关键作用,而大西洋经圈翻转环流(AMOC)则能直接影响到北大西洋深层海温变化.     

基于虚拟路由冗余协议和双向转发检测的基层气象通信网络设计和实现

目前陕西省气象宽带通信网省、市、县3级连接中,区县局出口是以单台路由器连接双运营商线路接入市局,这一架构造成明显的路由器单点故障风险,同时也不能有效解决台站各业务之间带宽竞争的问题。据此改造市-县级网络拓扑,在区县局出口部署双路由器,分别对接电信、广电运营商线路。启用VRRP(虚拟路由冗余协议),并配置VRRP的负载分担模式,对台站业务根据带宽消耗和时效性高低进行分流传输,在链路冗余的基础上实现了双机热备和负载均衡。同时配置BFD(双向转发检测协议)和VRRP联动,通过BFD监控VRRP路由器的上行链路状态,实现主备路由器的快速切换。经过在西安市多个区县局的广域网建设实践和一年多的业务运行,收到了预期的效果,方案可为同级气象部门提供参考。     

植被对干旱趋势的影响

历史干旱事件的观测和数值研究表明,植被可通过地—气水分、能量和其他通量交换影响和反馈干旱.本研究旨在了解气候变化情形下植被对干旱趋势的影响和机制.应用美国大陆七个动力气候降尺度区域气候变化情景,计算和分析了现在和未来的干旱指数、空间分布和季节变化.通过比较同一气候区两种植被类型区域干旱强度和频率理解植被的影响.集成分析结果表明,未来美国干旱很可能增加,其中大平原中部所有季节都很显著,而东南和西南地区夏秋更为显著.植被对干旱趋势的影响和气候区有关.在温暖和潮湿/干燥气候区,林地(草地)未来干旱强度和频率的增幅大于对应的农田(荒漠)区域,因此植被可以放大未来干旱的风险.相反,在寒冷和潮湿气候区,林地(草地)区域未来干旱强度和频率增幅较小,表明植被放大未来干旱的作用可能只在某些气候情形下出现.这种植被对未来干旱影响的复杂性和对气候区的依赖性对气候模式提供可靠的干旱模拟和预测及森林管理部门制定适应和减缓气候变化的策略提出了新的挑战.     

用 IAP／LASG GOALS模式模拟CO2增加引起的东亚地区气候变化

Two simulations, one for the control run and another for the perturbation run, with a global coupled ocean-atmosphere-land system model (IAP / LASG GOALS version 4) have been carried out to study the global warming, with much detailed emphasis on East Asia. Results indicate that there is no climate drift in the control run and at the time of CO2 doubling the global temperature increases about 1.65℃. The GOALS model is able to simulate the observed spatial distribution and annual cycles of temperature and precipitation for East Asia quite well. But, in general, the model underestimates temperature and overestimates rainfall amount for regional annual average. For the climate change in East Asia, the temperature and precipitation in East Asia increase 2. l℃ and 5% respectively, and the maximum warming occurs at middle-latitude continent and the maximum precipitation increase occurs around 25°N with reduced precipitation in the tropical western Pacific.     

A Study on the Dynamic Mechanism of the Formation of Mesoscale Vortex in Col Field

The mesoscale vortex associated with a mesoscale low-level jet(mLLJ) usually causes heavy rainfall in the col field.The col field is defined as a region between two highs and two lows,with the isobaric surface similar to a col.Using a two-dimensional shallow water model,the meso-β scale vortex couplets(MβVCs) induced by eight types of mesoscale wind perturbations in an ideal col field were numerically simulated.With the sizes of ～100 km,the MβVCs induced by northerly perturbation(NP) and southerly perturbation(SP) moved toward the col point.The sizes of MβVCs induced by southwesterly perturbation(SWP),southeasterly perturbation(SEP),northwesterly perturbation(NWP),and northeasterly perturbation(NEP) were relatively small for the perturbations moving toward dilatation axis.The MβVC induced by easterly perturbation(EP) and westerly perturbation(WP) could not develop because they quickly moved away from the col point,before the circulation could form.The size of the circulation was determined by the distance between the vortex and the col point.The closer to the col point the vortex was,the larger the size of vortex.The comparisons of maximum vorticity and vorticity root mean square error(RMSE) of the NP,the SWP,and the WP show that the maximum vorticity and the vorticity RMSE of the NP decreased slower than other perturbations.Therefore,the weak environment of the col field favors the maintenance of vorticity and the formation of vortex.When a mesoscale vortex forms near the col point or moves toward the col point,it may maintain a quasi-stationary state in the stable col field.