Effects of Non-orographic Gravity Wave Drag on Seasonal and Medium-range Predictions in a Global Forecast Model

This study implements the parameterizations of convective and frontal gravity wave drag (GWD) with wide phase speed spectra into a global forecast model with a model top near 0.3 hPa. The new convective GWD scheme replaces the existing one that considers only a stationary convective GW, and the frontal GWD scheme is newly introduced. When the new GWD schemes are used, the Rayleigh friction, applied above 2 hPa to mimic the effects of missing GWD, is removed. The convective (frontal) GWs are generated mainly in the Intertropical Convergence Zone and winter extratropical storm track regions (extratropics where strong baroclinicity exists). The convective and frontal GWD derived from the new schemes are significant near the model top, with maxima of ~2-4 and ~26-58 m s^?1 day^?1, respectively. The differences in convective GWD between the stationary and non-stationary schemes appear mainly in the tropics and summer hemisphere, where stationary GWs cannot propagate upward. The new schemes improve the seasonal representation of stratospheric wind, through changes in both the GWD and the resolved wave forcing, which is modulated by the changed large-scale wind due to the GWD. The downward influence, in response to the changed GWD, is also positive in the tropospheric fields, such as subtropical jet and planetary-scale disturbances. For the medium-range forecasts, improved skill scores on wind speed are achieved globally with the new schemes. The improvements mostly appear only in the stratosphere during the early forecast period (~3 days) but expand to the troposphere as forecast time increases.     

Investigation of Primary Factors Affecting the Variation of Modeled Oak Pollen Concentrations: A Case Study for Southeast Texas in 2010

Oak pollen concentrations over the Houston-Galveston-Brazoria (HGB) area in southeastern Texas were modeled and evaluated against in-situ data. We modified the Community Multi-scale Air Quality (CMAQ) model to include oak pollen emission, dispersion, and deposition. The Oak Pollen Emission Model (OPEM) calculated gridded oak pollen emissions, which are based on a parameterized equation considering a plant-specific factor (C _e ), surface characteristics, and meteorology. The simulation period was chosen to be February 21 to April 30 in the spring of 2010, when the observed monthly mean oak pollen concentrations were the highest in six years (2009-2014). The results indicated C _e and meteorology played an important role in the calculation of oak pollen emissions. While C _e was critical in determining the magnitude of oak pollen emissions, meteorology determined their variability. In particular, the contribution of the meteorology to the variation in oak pollen emissions increased with the oak pollen emission rate. The evaluation results using in-situ surface data revealed that the model underestimated pollen concentrations and was unable to accurately reproduce the peak pollen episodes. The model error was likely due to uncertainty in climatology-based C _e used for the estimation of oak pollen emissions and inaccuracy in the wind fields from the Weather Research and Forecast (WRF) model.     

净举力及常规可控气象要素对探空高度的影响研究

为提高探空气球的施放高度,利用克拉玛依国家基本气象站2011年以来的观测数据作为研究对象,选取净举力、天气现象、风向、风速、温度、气压、湿度、降水量8个影响因子,突破以往定性的研究模式,首次从定量的角度通过大量实验数据借助SPSS软件构建了多元线性回归模型,比较深入地研究了探空高度与净举力及常规可控气象要素之间的关系,对该模型进行了检验优化,确定了最优的回归模型,并对模型进行了预测验证。研究结果表明,该模型预测效果良好,能有效地应用到克拉玛依探空气象的实际观测工作中。根据上述研究结果,总结出了不同天气下净举力的选取范围,从而为克拉玛依探空提供具有实际可操作性的作业指导。     

称重雨量数据处理卡尔曼滤波应用

降雨量的测量,目前业务上应用较为广泛的是翻斗式雨量计,它只能测降雨,对于冰雹、降雪等固态降水的测量采用人工观测为主,称重式雨量计与翻斗式雨量计相比,其优势在于能实现所有类型降水的全天候自动化观测。本研究随机选择了一天无降水数据确定了滤波参数Q和R(过程噪声方差和观测噪声方差),根据确定的滤波参数,随机选择了无降水(2016年4月3日)和有降水(2015年7月21日、2015年8月7日)日采用卡尔曼滤波,并结合翻斗雨量传感器数据进行验证,结果表明,本研究确定的滤波参数采用卡尔曼滤波后能够有效去除称重雨量中的噪声,使滤波后的曲线变得平稳光滑,减小了数据的抖动频率和误差。     

一种基于射频识别的气象探测装备动态信息管理平台设计

为不断提高气象探测装备保障业务的科技含量与信息化水平,亟待建立高效及时的相关管理平台。本文结合北京市气象装备管理的实际情况和业务需求,设计了一种基于射频识别(Radio Frequency Identification,RFID)的气象探测装备动态信息管理平台,对平台结构设计进行相关阐述,重点分析了平台基于RFID技术的信息传输以及详细功能,并针对平台建设提出一些思考与展望。     

关于唐代气候冷暖问题的讨论

本文就历史文献记载的资料详细讨论了唐代气候冷暖两方面的证据。从现有支持气候温暖的证据来分析,它们难于确定相应的气候限制因子,并且类似的证据存在于不同的气候条件下。从有关的寒冷资料分析,唐代气候至少可分为两大阶段,8世纪50年代以前大体与现代相差不大,但8世纪60年代以后气候变冷,某些时段寒冷的特征可与明清小冰期相似。     

Factors Affecting the Wintering Habitat of Major Fishery Resources in Southwestern Korean Waters

We investigated the temperature and salinity effects on the major fish species in the wintering grounds based on trawl surveys and oceanographic observations in the southwestern waters of Korea during March-early April in 2002-2003. The influence area of warm Kuroshio water was limited to the southwestern area of Korea in 2003 with a range of 7.7-16.3°C, 32.54-34.70 of salinity, wider than that of 2002. The number of fish species and density of major fish species in 2003 were higher than in 2002. Geographical estimation showed high proportions of species number and catches in the areas around Jeju Islands, southwestern waters and the southeastern coast of Korea. Five species; silver pomfret (Pampus echinogaster), hairtail (Trichiurus lepturus), anchovy (Engraulis japonicus), small yellow croaker (Larimichthys polyactis) and yellow goosefish (Lophius litulon) were most abundant, composing above 60% of the total catch in 2002 and 2003. More than 50% of catch in the major fish species were mostly distributed in the range of 9.5-11.0°C of temperature and 33.1-33.9 of salinity. Non-parametric estimation for the major species showed the 1st mode around 10°C and the 2nd mode at 8-9°C in 2002 and 11-14°C in 2003. A m o n g major fish species, hairtail was principally composed of juveniles, and larger individuals were caught in southeastern waters. These results are considered to be helpful for the areabased fishery management strategy for the wintering grounds of the Yellow Sea and coastal waters of Korea.     

Surge hindcast in the East China sea

Two typhoon surges generated during July–August 1978 are investigated numerically with the use of a vertically-integrated finite-difference model of the Yellow Sea and the East China Sea. The hindcast scheme involves processing pressure data from weather charts to provide the necessary meteorological forcing to a sea model that computes the response in terms of water levels and currents. Computed residuals are compared with hourly records from selected tide gauges (Inchon, Kunsan, Mokpo, Jeju and Yeosu) along the coast of Korea. Some of the preliminary results are presented and discussed.     

Molecular phylogenetic analyses of threeSynechococcus strains isolated from seawater near the ieodo ocean research station

ThreeSynechococcus strains were isolated from seawater near the Ieodo Ocean Research Station (IORS), and their 16S rDNA genes and the internal transcribed spacer (ITS) between the 16S and 23S rRNA genes were sequenced to investigate their phylogenetic relationships. Phylogenetic trees based on the 16S rDNA and ITS sequences showed that they clustered in the main MC-ASynechococcus group (subcluster 5.1), but formed branches differentiating them from the described clades. As the IORS is located in an area affected by diverse water masses, highSynechococcus diversity is expected in the area. Therefore, the IORS might be a good site to study the diversity, physiology, and distribution of theSynechococcus group. Key words —Synechococcus, Phylogeney, 16S rRNA, ITS gene, Ieodo     

Recent sediment accumulation and origin of shelf mud deposits in the Yellow and East China Seas

Modern (last 100 yr) accumulation rates of shelf mud deposits in the Yellow and East China Seas were investigated using the distribution of excess ²¹⁰Pb (²¹⁰Pb_ex) in sediment core samples. Compilation and merger of new and previously published data helped clarify sediment accumulation in these seas. The estimated accumulation rates, together with data of suspended sediment concentrations, provided findings on the sediment budget, origin, and transport pathway of the mud deposits. The overall accumulation distribution in the Yellow and East China Sea shelf revealed a general, cross-shelf decreasing trend along the sediment dispersal system away from the rivers, except for the South Sea (SSM) and southeastern Yellow Sea (SEYSM) mud patches found along the Korean coast. Notably, ²¹⁰Pb_ex activity profiles within the SSM and the SEYSM yielded a relatively high accumulation rate of 2-5 mm/yr, implying a sedimentation rate of 4-15 × 10⁷ tons per year in this coastal zone. Such an annual accumulation rate is about one order of magnitude greater than the total sediment discharge (6-20 × 10⁶ tons/yr) from Korean rivers, suggesting an additional offshore source. The distribution pattern of the well-defined suspended plume clearly showed the possible transport and exchange of fine-grained sediments between the ECS shelf and the coastal area of Korea, especially during winter. Such a high accumulation in Korean coastal areas is attributable to the sediments supplied from the mud deposit of the ECS (i.e., SWCIM), with origins in Chinese rivers. Therefore, the Korean coastal area may be an important sink for some of Chinese river sediments being transported from the south by the Yellow Sea Warm Current.