MRI模式对华南春雨气候态及年际变率的模拟：不同模式分辨率的比较

本文利用日本气象研究所（MRI）参加第五次国际耦合模式比较计划（CMIP5）的大气环流模式在高、中、低三种分辨率下的AMIP试验结果,评估了其对华南春雨气候态和年际变率的模拟能力,比较了不同分辨率的模拟结果。结果表明,三种不同水平分辨率（120 km、60 km和20 km）的模式均能再现北半球春季位于中国东南部的降水中心。相较于120 km模式,20 km模式能够更为合理地模拟出华南春雨位于南岭—武夷山脉的降水中心。水汽收支分析表明,60 km、20 km模式高估了水汽辐合,使得华南春雨的降水强度被高估。在年际变率方面,在三种分辨率下,模式均能较好地再现观测中El Ni?o衰减年春季的西北太平洋反气旋以及华南春雨降水正异常。较之120 km模式,60 km、20 km模式模拟的降水正异常的空间分布和强度更接近观测,原因是后者模拟的El Ni?o衰减年春季华南地区的水平水汽平流异常更接近观测。本研究表明,发展高分辨率气候模式是提高华南春雨的气候态和年际变率模拟水平的有效途径之一。     

A new prediction model for grain yield in Northeast China based on spring North Atlantic Oscillation and late-winter Bering Sea ice cover

Accurate estimations of grain output in the agriculturally important region of Northeast China are of great strategic significance for guaranteeing food security. New prediction models for maize and rice yields are built in this paper based on the spring North Atlantic Oscillation index and the Bering Sea ice cover index. The year-to-year increment is first forecasted and then the original yield value is obtained by adding the historical yield of the previous year. The multivariate linear prediction model of maize shows good predictive ability, with a low normalized root-mean-square error (NRMSE) of 13.9%, and the simulated yield accounts for 81% of the total variance of the observation. To improve the performance of the multivariate linear model, a combined forecasting model of rice is built by considering the weight of the predictors. The NRMSE of the model is 12.9% and the predicted rice yield explains 71% of the total variance. The corresponding cross-validation test and independent samples test further demonstrate the efficiency of the models. It is inferred that the statistical models established here by applying year-to-year increment approach could make rational prediction for the maize and rice yield in Northeast China before harvest. The present study may shed new light on yield prediction in advance by use of antecedent large-scale climate signals adequately.     

An examination of the Galileo NeQuick model: comparison with GPS and JASON TEC

GPS Solutions - We evaluate the performance of Galileo broadcast NeQuick model by comparing it with GPS broadcast Klobuchar and the original NeQuick2 models. The broadcast coefficients of Galileo...     

江西省早稻雨洗花灾害指标构建与灾损评估

构建早稻雨洗花灾害指标及适于早稻产量估算的灾损评估模型,对开展早稻雨洗花灾害监测、损失评估、灾害保险等具有重要意义。该文以江西省早稻为研究对象,利用1981-2015年14个水稻气象观测站逐日气象资料和农业气象观测资料,筛选出基于早稻抽穗扬花期间过程降水量、最大降水量、降水日数及实际产量的雨洗花灾害样本78个,在此基础上,利用相关分析、正态分布以及主成分回归法,建立了雨洗花灾害指标和灾损评估模型,并对其进行验证。结果表明:抽穗扬花期降水对雨洗花灾害形成有显著影响,其主要影响时段为抽穗扬花普遍期前后5 d内,关键时段为抽穗扬花普遍期前后3 d内。日降水量40 mm可作为早稻抽穗扬花期雨洗花灾害临界指标。以该指标为基础,统计日降水量不低于40 mm的降水日数及其对应的累积降水量,当累积降水量为40~170 mm时,为轻度雨洗花灾害,早稻一般减产小于15%,平均减产10%;当累积降水量不小于170 mm时,为重度雨洗花灾害,早稻一般减产不低于15%,平均减产22%。指标验证结果与历史实际灾害发生情况有较好的一致性。雨洗花灾损评估模型检验结果表明:雨洗花年模拟产量与实际产量吻合度较高,平均相对模拟误差为4.3%,78.0%的资料相对误差在5%以内,可利用该模型对雨洗花年的早稻减产率进行模拟和预测。     

湖南省油菜春季涝渍过程灾变判别指标

以湖南省油菜为研究对象,综合洪涝与连阴雨的致灾因子,利用历史灾情数据反演涝渍过程样本,构建临灾、受灾状态样本,采用均值t检验方法,定量分析不同降水累积衰减系数w情况下,降水因子差异的显著性,构建有效累积降水量P_E。基于Fisher判别准则,计算涝渍灾害临灾与受灾的临界线,构建逐日动态的油菜春季涝渍过程灾变判别指标y,并进行涝渍过程样本反演及独立样本验证。分析春季涝渍受灾频率与相对气象产量的关系,构建灾害影响评价模型。结果表明:当w=0.899时,受灾与临灾样本P_E的差异最显著。灾变判别指标y可逐日动态监测涝渍灾变过程及灾害后续影响,为动态监测区域油菜涝渍过程提供了数据支撑;指标指示的灾变范围与实际受灾情况基本一致,为区域防灾减灾提供了科学参考。开花期及结荚期湖南油菜涝渍受灾频率较高,成熟期较低。湖南省油菜春季涝渍灾害影响指数呈东南高西北低,长沙东部、株洲中部及北部、湘潭、永州及郴州中部油菜产量受涝渍灾害影响最重。     

1981—2013年四川省视程障碍类天气现象分析

利用四川省1981—2013年雾、轻雾、吹雪、雪暴、烟幕、霾、沙尘暴、扬沙和浮尘9种视程障碍天气现象资料,对其发生日数、发生概率和分布特征进行统计。结果表明:(1)各天气现象发生日数排序为:轻雾>雾>浮尘>霾>烟幕>扬沙>沙尘暴>吹雪>雪暴。(2)轻雾和雾年发生日数为分别为176d/a和29d/a,日发生概率分别为48%和8%,远高出其他天气现象。(3)季节变化方面,雾和轻雾主要出现在秋季和冬季;霾、吹雪和雪暴集中出现在冬季;浮尘发生春季;扬沙多发生在冬季和春季;而沙尘暴、烟幕主要发生在春季和秋季。(4)变化趋势上轻雾基本保持平稳;烟幕呈增加趋势;而雾、霾、沙尘暴、扬沙和浮尘呈下降趋势。(5)大气层结稳定、水汽充足、风速较小、人口集中和排放量较大,易于盆地雾、轻雾、霾和烟幕的形成;不合理利用水和土地资源,北方地区沙尘天气随冷空气南下,是沙尘天气发生的重要原因;而吹雪和雪暴均发生在冬季降雪量大且风速较大的川西高原。     

地面气象资料一体化统计加工系统设计与实现

地面气象资料一体化统计加工系统是基于国省统一的CIMISS数据环境,准实时生成日、候、旬、月、年值等统计产品的业务系统,能够满足用户对准实时质控后地面气象资料统计值的业务需求。本文主要介绍地面气象资料实时历史一体化统计加工系统的开发,从软件的需求分析、统计方法、功能实现、关键技术等方面阐述了如何在技术上实现地面气象资料一体化统计加工系统。通过运行策略配置,实现了系统定时自动运行,进一步丰富了CIMISS系统地面气象资料的产品库。     

两广地区夏季降水异常与澳大利亚东侧海温异常的联系及可能机制

广东省和广西壮族自治区(两广地区)夏季降水时空分布很不均匀,存在显著的年际变化。利用站点观测降水资料、海洋及大气再分析资料,研究了近40 a两广地区夏季降水年际异常与澳大利亚东侧海温异常的联系及机理。在年际时间尺度上,两广夏季降水异常与澳大利亚东侧的海温异常存在显著的负相关关系。当澳大利亚东侧海温异常偏高时,一方面,部分水汽由热带中太平洋向澳大利亚东侧海区辐合,部分沿西太平洋副热带高压边缘向东亚地区输送,两广地区为水汽辐散区域,另一方面,澳大利亚东侧海区的对流活动增强,该地区上空的上升运动异常增强,通过"大气桥"遥相关使得海洋性大陆地区的异常上升运动增强,从而加强了东亚地区的局地Hadley环流,使得两广地区下沉运动增强,二者共同作用致使两广地区夏季干旱少雨;反之亦然。     

Observed particle sizes and fluxes of Aeolian sediment in the near surface layer during sand-dust storms in the Taklamakan Desert

Monitoring, modeling and predicting the formation and movement of dust storms across the global deserts has drawn great attention in recent decades. Nevertheless, the scarcity of real-time observations of the wind-driven emission, transport and deposition of dusts has severely impeded progress in this area. In this study, we report an observational analysis of sand-dust storm samples collected at seven vertical levels from an 80-m-high flux tower located in the hinterland of the great Taklamakan Desert for ten sand-dust storm events that occurred during 2008–2010. We analyzed the vertical distribution of sandstorm particle grain sizes and horizontal sand-dust sediment fluxes from the near surface up to 80 m high in this extremely harsh but highly representative environment. The results showed that the average sandstorm grain size was in the range of 70 to 85 μm. With the natural presence of sand dunes and valleys, the horizontal dust flux appeared to increase with height within the lower surface layer, but was almost invariant above 32 m. The average flux values varied within the range of 8 to 14 kg m^?2 and the vertical distribution was dominated by the wind speed in the boundary layer. The dominant dust particle size was PM₁₀₀ and below, which on average accounted for 60–80 % of the samples collected, with 0.9–2.5 % for PM_0–2.5, 3.5–7.0 % for PM_0–10, 5.0–14.0 % for PM_0–20 and 20.0–40.0 % for PM_0–50. The observations suggested that on average the sand-dust vertical flux potential is about 0.29 kg m^?2 from the top of the 80 m tower to the upper planetary boundary layer and free atmosphere through the transport of particles smaller than PM₂₀. Some of our results differed from previous measurements from other desert surfaces and laboratory wind-dust experiments, and therefore provide valuable observations to support further improvement of modeling of sandstorms across different natural environmental conditions.     

江汉和江南西部春玉米涝渍指标及风险评估

以江汉和江南西部地区春玉米为研究对象,利用研究区域内57个气象站1961-2012年的逐日降水量资料、春玉米生育期资料和春玉米涝渍灾情资料,筛选春玉米不同生育时期的涝渍灾害样本。采用多元线性回归分析方法,定量分析当前过程降水量和前期降水量对春玉米涝渍灾害的影响,并据此构建当量降水量。基于正态分布的Lilliefors检验和t-分布区间估计方法,计算不同生育时期、不同等级涝渍灾害的当量降水量指标阈值,由此构建该区域春玉米不同生育时期的涝渍灾害等级指标并进行独立样本验证。在此基础上,利用信息扩散理论风险评估方法,计算各站点的春玉米涝渍致灾风险指数。结果表明:当前过程降水量和前2旬降水量对该区域春玉米涝渍灾害有显著性影响;构建的区域春玉米涝渍等级指标能够较好地反映实际受灾情况,指标验证结果与历史记录有较高一致性;出苗-拔节期和拔节-抽雄期发生春玉米涝渍灾害的风险相对较低,抽雄-成熟期为春玉米涝渍灾害的高风险时期,高风险区域主要位于湖北省恩施市、宜昌市西南部、荆州市西南部以及湖南省张家界市北部。