扰动变量在强对流天气分析和模式评估中的应用——以苏北里下河地区引发龙卷的扰动系统为例

2016年6月23日14:00—15:00时,江苏省盐城市阜宁县发生了EF-4级有记录以来的强龙卷风过程,造成了当地30 km长,1.7 km宽的严重气象灾害。受局地环境影响,邻近地区在近50年中发生了大于10人次死亡事件的龙卷风11次,其中6次发生于1979年以后。文章首先是:(1)把6次事件日的再分析变量场分解成瞬时气候和扰动两个部分,发现6次事件都与近地面层出现的负高度扰动轴线和扰动冷暖气团的对峙有关,龙卷发生在暖气团一侧;(2)用模式初始场分解的扰动变量和扰动物理量评估欧美模式对产生阜宁龙卷扰动系统的预报能力。后者的结果也发现,当日14时925 hPa高度扰动槽和850 hPa扰动风辐合线作为环境扰动系统,以及湿涡度扰动和湿散度扰动等环境扰动指标量能够突出地表达有利于龙卷风发生的环境条件。欧洲全球模式能够提前42 h稳定预报出后来扰动槽和环境扰动指标量的位置,美国全球模式也可以提前18 h预报出这样的扰动特征。这些扰动变量和扰动指标量能够快速地帮助预报员判断有可能发生强对流天气的大致时空区域和特征。     

An Evaluation of Tropical Cyclone Genesis Forecast over the Western North Pacificand the South China Sea from the CMA-TRAMS

Tropical cyclone (TC) genesis forecasting is essential for daily operational practices during the typhoon season.The updated version of the Tropical Regional Atmosphere Model for the South China Sea (CMA-TRAMS) offersforecasters reliable numerical weather prediction (NWP) products with improved configurations and fine resolution. Whiletraditional evaluation of typhoon forecasts has focused on track and intensity, the increasing accuracy of TC genesisforecasts calls for more comprehensive evaluation methods to assess the reliability of these predictions. This study aims toevaluate the effectiveness of the CMA-TRAMS for cyclogenesis forecasts over the western North Pacific and South ChinaSea. Based on previous research and typhoon observation data over five years, a set of localized, objective criteria has beenproposed. The analysis results indicate that the CMA-TRAMS demonstrated superiority in cyclogenesis forecasts, pre dicting 6 out of 22 TCs with a forecast lead time of up to 144 h. Additionally, over 80% of the total could be predicted 72 hin advance. The model also showed an average TC genesis position error of 218.3 km, comparable to the track errors ofoperational models according to the annual evaluation. The study also briefly investigated the forecast of Noul (2011). Theforecast field of the CMA-TRAMS depicted thermal and dynamical conditions that could trigger typhoon genesis, con sistent with the analysis field. The 96-hour forecast field of the CMA-TRAMS displayed a relatively organized three dimensional structure of the typhoon. These results can enhance understanding of the mechanism behind typhoon genesis,fine-tune model configurations and dynamical frameworks, and provide reliable forecasts for forecasters.     

Spatial relationships of salt distribution and related physical changes of underlying rocks on naturally weathered sandstone exposures (Bohemian Switzerland National Park,Czech Republic)

Efflorescence, case hardening, and granular disintegration represent common weathering features of Upper Cretaceous quartz sandstones exposed in the Bohemian Switzerland National Park (NW Bohemia, Czech Republic). Salt species (sulphates: gypsum (CaSO₄·2H₂O), potassium alum (KAl(SO₄)₂·12H₂O), tschermigite (NH₄Al(SO₄)₂·12H₂O), alunite (K(Al₃(SO₄)₂(OH)₆), and alunogen (Al₂(SO₄)₃·17H₂O), minor nitrates: nitrammite (NH₄NO₃)) determined by X-ray diffraction exhibit vertical and geographic zoning. More soluble salts (chlorides, nitrates, tschermigite) crystallize preferentially on the cliffs exposed to the south, whereas the north face is characterized by the presence of less soluble phases: gypsum and K(Al₃(SO₄)₂(OH)₆. Vertical zoning of salt distribution on natural outcrops differs from the salt distribution in masonry. Salt distribution near the base of the cliff (profile to about 2–2.5 m above the ground) is affected by capillary rise from the ground level (first maximum of water-soluble salts at the level of 1–1.5 m above the ground) and by percolation of precipitation through the overhanging rock sequence (second maximum of 2–2.5 m above the ground). Percolation of salt solution from higher parts is affected by the asperity of the rock surface. The concentration of salts (determined by ion exchange chromatography) correlates to the changes of physical properties: bulk porosity, microporosity and water absorption. The porosity, microporosity, moisture content and absorption generally increase with the increasing volume of sulphates and nitrates.     

南极旅游发展与管理的国际协议

南极旅游管理的国际组织机构主要包括南极条约协商会议（ATCM）、环境保护委员会（CEP）和国际南极旅游组织协会（IAATO）。南极条约体系（ATS）是南极一切活动必须遵循的国际协议,南极旅游活动须充分维护ATS的基本价值与原则,维护和平、科学研究和环境保护是ATS的三大原则。1998年协商国签字生效的《环境保护议定书》...     

支撑向量机及其遥感影像空间特征提取和分类的应用研究

提出了基于支撑向量机（SVM）的遥感影像空间特征提取的新方法，并以SPOT全色波段影像上城市特征信息的提取为应用实例，并与人工神经网络（ANN）等特征提取方法进行综合比较，认为SVM方法不但能够获得比较高的分类精度，而且在学习速度、自适应能力、特征空间高维不限制、可表达性等方面具有优势。     

香港能见度、大气悬浮粒子浓度与气象条件的关系

利用2005年赤鱲角能见度及东涌悬浮粒子 (PM2.5) 浓度的每小时数据,发现PM2.5 浓度与能见度 (撇除雨雾及相对湿度≥95%的个例) 呈倒数关系,相关系数约为0.8。此外,出现低能见度 (能见度低于8 km,而雨雾及相对湿度≥95%的个例不计) 的每月总时数与月平均PM2.5浓度都呈现相类似的季节趋势,即冬季较高,夏季较低。利用HYSPLIT作反轨迹图分析显示这现象跟影响香港的空气来源有关。来自内陆的轨迹中,出现低能见度的日平均时数及日平均PM2.5的浓度,分别远高于来自海洋的轨迹。文中还分析了一个有热带气旋接近本港的个例,论证气象条件对能见度及PM2.5浓度的重要性。     

Narrowing gaps between research and policy development in climate change adaptation work in the water resources and agriculture sectors of Cambodia

Narrowing research and policy, while challenging, is especially important in climate change adaptation work (CCA) due to the high uncertainties involved in planning for climate change. This article aims to seek stakeholders’ opinions regarding how research and policy development can be bridged within the Cambodian water resources and agriculture sectors. The study used institutional ethnography methods with informants from government organizations, local academia, and development partners (DPs). This article identifies a number of challenges, and barriers for narrowing research–policy development gaps, including: limited effectiveness of governmental policies and planning; lack of relevant information required to promote evidence-based planning and policy development; and communication barriers. Evidence-based planning is valued by government officials most when there is actual and effective implementation of policies and plans. In practice, this often implies that governmental policies and plans need be scoped and scaled down to meet the available budget, and thus be achievable. In the long term, it also means building the capacity for policy-relevant research on climate change adaptation within Cambodia. Engaging policy stakeholders in research process for co-producing adaptation knowledge, and introducing knowledge intermediaries are suggested by informants as means to narrowing gaps between research and policy development. The presence of the Cambodia's Prime Minister in research–policy dialogues is recommended as important for attracting the attention of high-level policy makers.

Policy relevance

As a least developed and highly climate-vulnerable country, Cambodia has received climate change funding to implement a number of climate adaptation initiatives. Cambodia is likely to receive more climate change finance in the future. This article aims to assist evidence-based planning, in particular, through policy-relevant research on CCA, so that resources for adaptation in Cambodia are used effectively and efficiently. This research also directly benefits the sustainable development of the country.     

Dissimilarity among Ocean Reanalyses in Equatorial Pacific Upper-Ocean Heat Content and Its Relationship with ENSO

This study focuses on the temporal variation of dissimilarity in heat content(HC)anomalies in the upper 300 m of ocean(HC300A)in the equatorial Pacific(±10°N)and its response to the El Ni?o-Southern Oscillation(ENSO).The HC300A anomalies are derived from four ocean reanalyses that are commonly used in ENSO studies and are compared using a simple differencing method.The dissimilarity in HC300A is found to vary closely with the magnitude of ENSO(regardless of phase),meaning that it tends to be greater during strong ENSO events.However,the dissimilarity among ocean reanalyses persists after the event decays.This effect is more pronounced after strong events.The persistence of the dissimilarity after ENSO events is a result of a late maturation of the ENSO signal,its persistence,and the interruption of the signal decay due to follow-up ENSO events.The combined effect of these three factors slows down the decay of HC300A in the region and hence results in the slow decay of dissimilarity.It is also found that areas with a significant spread in vertical temperature profiles collocate with the ENSO signal during warm ENSO phases.Thus,differences in subsurface process reconstruction are a significant factor in the dissimilarity among ocean reanalyses during warm ENSO events.     

澳门路凼湿地的水质调查与评价

从2003年11月至2004年的9月对澳门路凼填海区湿地中的咸水湖和十字门水道的水质状况进行了6次调查。依照《海水水质标准》,除非离子氨和化学需氧量(COD)含量两水体都属IV类水质外,咸水湖的无机氮,磷酸盐均属于Ⅰ类水质,而十字门水道的无机氮属于IV类水质,磷酸盐属于Ⅲ类水质。以富营养化指数来评价,咸水湖与十字门水道两水体都处于富营养化范围,但十字门水道水体富营养化指数显著高于咸水湖。