基于风廓线雷达资料的暴雨天气过程分析

2008年6月1～2日大理市暴雨过程的风廓线雷达资料和每小时的雨量资料分析发现：暴雨过程具有明显的中小尺度系统影响特征,雷达水平风廓线资料可以很直观地显示随时间变化风场的垂直结构;高空气流的向下脉动与降水强度的增强有着紧密的联系;风廓线雷达产品（垂直速度、折射率结构常数和信号噪声比）清楚地反映降水的开始、结束以及降水的强度。     

隧道塌方的尖点灾变模型及应用

针对隧道塌方失稳问题，运用灾变理论建立隧道塌方失稳的尖点灾变模型。基于平衡曲面方程，可求得隧道围岩体内承载区介质刚度与对应的松驰区弱化介质本构曲线拐点处理刚度之比值K，并给出了塌方与否的判据，当K≤1时，隧道将发生塌方失稳；当K＞1时，隧道将不会发生塌方失稳。根据此模型，笔者解释了隧道中几种常见的灾变破坏机理，并提出了相应的治理方案。     

Paleoclimate Modelling at the Institute of Atmospheric Physics, Chinese Academy of Sciences

Paleoclimate modelling is one of the core topics in the Past Global Changes project under the International Geosphere-Biosphere Programme and has received much attention worldwide in recent decades. Here we summarize the research on the Paleoclimate modeling, including the Holocene, Last Glacial Maximum, and pre-Quaternary climate intervals or events performed at the Institute of Atmospheric Physics under the Chinese Academy of Sciences (IAP/CAS) for over one decade. As an attempt to review these academic activities, we emphasize that vegetation and ocean feedbacks can amplify East Asian climate response to the Earth’s orbital parameters and atmospheric CO2 concentration at the mid-Holocene. At the Last Glacial Maximum, additional cooling in interior China is caused by the feedback effects of East Asian vegetation and the ice sheet over the Tibetan Plateau, and the regional climate model RegCM2 generally reduces data-model discrepancies in East Asia. The simulated mid-Pliocene climate is characterized by warmer and drier conditions as well as significantly weakened summer and winter monsoon systems in interior China. On a tectonic timescale, both the Tibetan Plateau uplift and the Paratethys Sea retreat play important roles in the formation of East Asian monsoon-dominant environmental pattern during the Cenozoic.     

94/220 GHz星载雷达双波长比对非球形冰晶云参数敏感性分析

利用不同形状冰晶的散射特性,获得了非球形冰晶云的94/220 GHz测云雷达双波长比,探讨了非球形冰晶云的双波长比与云内微物理参数的关系,分析了衰减前后的星载雷达反射率因子及双波长比的垂直廓线。结果表明:（1）双波长比可以反映小到0.1 mm中值尺度的冰粒子,对粒子总数、谱的形状参数不敏感,对粒子大小、形状、云衰减较敏感。（2）雷达灵敏度一定时,星载雷达可测云厚与雷达波长、冰含水量（IWC）的垂直分布、云厚及衰减有关;没有进行衰减订正时,双波长比和衰减有关,冰含水量越大,波长越短,衰减越大,双波长比最大值与可探测云厚有关。两部雷达可探测冰含水量为0.001—0.1 g/m3、厚2 km的冰云;当云厚5 km、冰含水量垂直分布在0.001—0.2 g/m3时,云厚的94%基本可以被220 GHz云雷达探测到。（3）如果两部雷达气象方程中用水的介电因子,测量回波强度应进行介电因子的订正后再计算双波长比。      

车贝雪夫多项式的约简算法

解释了文献「１」中关于化整后的车贝雪夫多项式约简处理的技术原理,给出了一种可快速实现多项式约简处理的求算方法。     

Simulations of seasonal variations of sulfur compounds in the remote marine atmosphere

A photochemical box model is used to simulate seasonal variations in concentrations of sulfur compounds at latitude 40° S. It is assumed that the hydroxyl radical (OH) addition reaction to sulfur in the dimethyl sulfide (DMS) molecule is the predominant pathway for methanesulfonic acid (MSA) production, and that the rate constant increases as the air temperature decreases. Concentration of the nitrate radical (NO₃) is a function of the DMS flux, because the reaction of DMS with NO₃ is the most important loss mechanism of NO₃. While the diurnally averaged concentration of OH in winter is a factor of about 8 smaller than in summer, due to the weak photolysis process, the diurnally averaged concentration of NO₃ in winter is a factor of about 4–5 larger than in summer, due to the decrease of DMS flux. Therefore, at middle and high latitudes in winter, atmospheric DMS is mainly oxidized by the reaction with NO₃. The calculated ratio of the MSA to SO₂ production rates is smaller in winter than in summer, and the MSA to non-sea-salt sulfate (nssSO₄ ^2-) molar ratio varies seasonally. This result agrees with data on the seasonal variation of the MSA/nssSO₄ ^2- molar ratio obtained at middle and high latitudes. The calculations indicate that during winter the reaction of DMS with NO₃ is likely to be a more important sink of NO_x (NO+NO₂) than the reaction of NO₂ with OH, and to serve as a significant pathway of the HNO₃ production. If dimethyl sulfoxide (DMSO) is produced through the OH addition reaction and is heterogeneously oxidized in aqueous solutions, half of the nssSO₄ ^2- produced in summer may be through the oxidation process of DMSO. It is necessary to further investigate the oxidation products by the reaction of DMS with OH, and the possibility of the reaction of DMS with NO₃ during winter.     

全球增暖1.5/2℃下中国区域极端降水的风险变化及其影响因子

利用24个CMIP6全球气候模式的逐日降水模拟资料,基于广义极值分布(GEV)模型,研究了全球增暖1.5/2℃下我国20、50和100 a重现期极端降水的未来风险变化。可以发现,相对于历史时期(1995—2014年),全球升温1.5和2℃下极端降水发生概率风险空间分布相近,总体上呈现增加趋势,但额外增暖0.5℃将导致更高的风险。如50 a重现期极端降水,在增暖1.5/2℃下其重现期将分别变为17/14 a,极端降水将变得更加频繁。不同区域对气候变暖的响应存在区域差异,其中中国西部长江黄河中上游和青藏高原地区、中国东部长江黄河中下游及其以南地区,极端降水发生概率比达到3以上,局部更是达到5以上,为我国极端降水气候变化响应高敏感区域。进一步,基于概率分布函数从理论角度探讨了位置和尺度参数对发生概率风险的影响与贡献度量,并用于探讨极端降水气候平均态和变率变化对极端降水发生风险的影响,结果显示：位置和尺度参数的增量变化、风险变化率存在着显著的东西部差异,从而导致极端降水发生风险的影响因素存在差异。如中国西部尽管极端降水气候平均态和变率变化幅度不大,但因风险变化率较高,从而导致该区域的发生风险大...     

青藏高原东边缘山区极值风速推算方法的研究

利用1971—2001年青藏高原东边缘地区12个气象台站风资料,分析了影响极值风速的主要因子,通过对地形的参数化处理,建立了极值风速随海拔高度和地形参数变化的拟合模型,可推算该地山区的极值风速,并利用山区临时观测资料对拟合模型进行了检验。结果表明,利用引入地形参数所建立的极值风速拟合模型来推算山区极值风速具有一定的可行性。     

粗粒料动三轴试验颗粒流模拟对称性研究

以粗粒料动三轴数值模拟为例,分析了不同对称模型(1/2,1/4,1/8,1/12)条件下,粗粒料动剪切模量和阻尼比的变化规律。计算结果表明,不同对称模型的计算结果存在一定的差异,但其变化规律基本一致,随着模型对称比例的增大动剪切模量逐渐增大,阻尼比逐渐减小,计算时间成倍减少。分析了颗粒生成过程中不均匀性对试验结果的影响。计算结果表明:1/8模型动剪切模量和阻尼比影响较小;1/12模型动剪切模量影响较大,阻尼比影响较小。建议在动力分析过程中采用1/8模型即可。     

钢板混凝土联肢剪力墙抗震性能试验研究

以轴压比和钢连梁弯剪比为主要参数,设计并制作了3个1/4缩尺的钢板混凝土联肢剪力墙子结构,对试件施加恒定轴压力和水平往复加载.观察了各试件破坏特征,对比了顶层水平荷载-侧移曲线和骨架曲线以及延性系数和等效黏滞阻尼系数等抗震性能指标.结果表明:高轴压比会使整个试件的延性变差;弯剪比越大试件耗能能力越好,弯剪比越小试件刚度...