温盐深测量仪(CTD)资料质量对比分析

温盐深测量仪(CTD)是目前国际上应用最为广泛的物理海洋调查仪器设备之一。2014年中国科学院海洋研究所在黄海布放的潜标上搭载了三种不同型号的CTD(37Coastal、CTD48和304Plus),本文对这三种CTD所获取的数据资料分别进行了对比分析。三者数据两两对比结果显示,37Coastal与CTD48压力以及温度数据最为接近,盐度数据则为37Coastal与304Plus相差最小。三种设备的压力、温度以及电导率数据稳定性对比结果如下, 37Coastal压力数据稳定性表现最好;其温度数据稳定性三者表现一致;而盐度数据稳定性则是37Coastal和CTD48一致。     

舱体式防渔拖海床基的研制和应用

介绍了一种新型舱体式防渔拖海床基,可布放在200m以浅海域进行长期、定点、连续、综合观测。该型海床基由坐底平台、浮体仪器舱和释放器等配件组成,可以搭载多种观测传感器进行多学科综合观测。同时,针对该型海床基设计了安全有效的布放回收方法。通过实际海上应用,结果表明舱体式防渔拖海床基具有长时间自动观测、隐蔽性好及有效防渔拖等优点,可实现对海洋环境的长期综合观测。     

Temporal variation in biodeposit organic content and sinking velocity in long-line shellfish culture

We measured the organic content and sinking velocities of biodeposits from two scallop species (Chlamys farreri, Patinopecten yessoensis) and abalone (Haliotis discus hannai) that were cultured on suspended long-lines. Measurements were conducted every two months from April 2010 to February 2011. The shellfish were divided into three size groups (small, middle, and big sizes). At each sample point, we assessed biodeposit organic content, average sinking velocity, the frequency distribution of sinking velocities, and the correlation between organic content and sinking velocity. The organic content of biodeposits varied significantly among months (P<0.05) and the pattern of change varied among species. Sinking velocities varied significantly, ranging from <0.5 cm/s to >1.9 cm/s. The sinking velocities of biodeposits from C. farreri and P. yessoensis were 0.5–1.5 cm/s and from H. discus hannai were <0.7 cm/s. The organic content was significantly negatively correlated to the sinking velocity of biodeposits in C. farreri (P<0.001) and P. yessoensis (P<0.05).     

Swelling model study of expansive soil at K-0 and triaxial stress stateEI北大核心CSCD

A series of swelling tests is performed on a typical Nanyang expansive soil with medium swelling capacity compacted at various initial densities and water contents. The swelling tests are separately conducted using the conventional oedometer to confine the lateral swelling of the soil specimens, and using the GDS triaxial apparatus to allow the free volumetric swelling. The multiple nonlinear mathematical method is adopted to obtain the lateral swelling model (i.e. K-0 model), which fully considers the coupled effect of initial degree of compaction, moisture content and overburden pressure on the swelling strain. Also, an empirical model for the relationship between spherical stress and volumetric strain is proposed by triaxial swelling test. Based on the K-0 swelling model, a formula is proposed to quantitatively evaluate the swell potential, and also a theoretical calculation method is derived to determine the processing layer thickness of expansive soil slope. Based on the assumption that volumetric swelling strain only changes with spherical stress and is not affected by the deviatoric stress, the correlations between the K-0 model and triaxial model are analyzed, and a method to calculate the volumetric swelling strain by only employing the K-0 model is given. Experimental results show that the proposed K-0 model with multifactor coupling is reasonable to predict the swelling potential of compacted expansive soil. It is found that the key factor to link the K-0 model and triaxial swelling model is assuming an average static lateral pressure coefficient. The average static lateral pressure coefficient tends to decreases with increasing overburden pressure by inversion method. This tendency of average static lateral pressure coefficient is believed to rely on the fact that lateral swelling pressure decreases with the increase of overburden pressure.     

The strong El Niño of 2015/16 and its dominant impacts on global and China's climate

The oceanic and atmospheric conditions and the related climate impacts of the 2015/16 ENSO cycle were analyzed, based on the latest global climate observational data, especially that of China. The results show that this strong El Niño event fully established in spring 2015 and has been rapidly developing into one of the three strongest El Niño episodes in recorded history. Meanwhile, it is also expected to be the longest event recorded, attributable to the stable maintenance of the abnormally warm conditions in the equatorial Pacific Ocean since spring 2014. Owing to the impacts of this strong event, along with climate warming background, the global surface temperature and the surface air temperature over Chinese mainland reached record highs in 2015. Disastrous weather in various places worldwide have occurred in association with this severe El Niño episode, and summer precipitation has reduced significantly in North China, especially over the bend of the Yellow River, central Inner Mongolia, and the coastal areas surrounding Bohai Bay. Serious drought has occurred in some of the above areas. The El Niño episode reached its peak strength during November-December 2015, when a lower-troposphere anomalous anticyclonic circulation prevailed over the Philippines, bringing about abnormal southerlies and substantially increased precipitation in southeastern China. At the same time, a negative phase of the Eurasia-Pacific teleconnection pattern dominated over the mid-high latitudes, which suppressed northerly winds in North China. These two factors together resulted in high concentrations of fine particulate matter (PM_2.5) and frequent haze weather in this region. Currently, this strong El Niño is weakening very rapidly, but its impact on climate will continue in the coming months in some regions, especially in China.     

国家气候中心MJO监测预测业务产品研发及应用

热带大气低频振荡 (MJO) 和北半球夏季季节内振荡 (BSISO) 对全球范围天气气候事件有重要影响,是次季节-季节 (S2S) 预报最主要的可预报性来源之一。国家气候中心 (BCC) 基于我国完全自主的T639全球分析场数据、风云三号气象卫星射出长波辐射 (OLR) 资料以及BCC第2代大气环流模式系统的实时预报,发展了MJO实时监测预测一体化业务技术,建立了ISV/MJO监测预测业务系统 (IMPRESS1.0),已投入实时业务运行,在全国气象业务系统得到应用。该文着重介绍该系统提供的MJO和BSISO指数监测预测数据和图形产品,并描述了这些业务产品在2015年对MJO典型个例的实时监测预测应用情况。监测分析和预报检验表明,基于我国自主资料的监测结果能够较为准确地表征MJO和BSISO指数的振荡和演变过程,该系统对MJO和BSISO事件分别至少具备16 d和10 d左右的预报技巧。因此,基于IMPRESS1.0的MJO/BSISO监测预测一体化业务产品可为制作延伸期预报提供重要的参考依据。     

Calculation and accuracy evaluation of TGD from IFB for BDS

With the development of new global navigation satellite system applications, the demand of high accurate positioning navigation timing (PNT) service becomes urgent. For precise PNT, the timing group delay (TGD) is regarded as an important parameter in the satellite navigation message. Instead of using the absolute receiver hardware delay, a method based on receiver inter-frequency bias (IFB, i.e., differential receiver hardware delay between different frequencies) calibration is presented to deal with the rank deficiency of a calculation matrix and to reduce jumps in TGD solutions in BDS. The double-differenced pseudorange obtained from a pair of zero baseline receivers is used to evaluate the IFB calibration accuracy. The estimated precision of TGD is evaluated and compared with GPS TGD provided by IGS. In order to ensure the quality of assessment, a method based on the difference of dual-frequency ionospheric delay is proposed to compare the accuracy of the estimated TGD and broadcast TGD. Finally, the effect of TGD on the user equivalent range error is analyzed. The analysis result shows that for BDS IGSO satellites, the precision of TGD1, which is the differential hardware delay between B1 (1561.098 MHz) and B3 (1268.52 MHz) frequencies, is better than 0.5 ns, and for GEO and MEO satellites the TGD1 is better than 1 and 2 ns, respectively. The precision of TGD2 of all satellites, which is the differential hardware delay between B2 (1207.14 MHz) and B3 frequencies, is better than 0.5 ns. The accuracy analysis result reveals that the proposed TGD estimation method can provide better results when compared with the broadcast data.     

A Spatial Conditioned Latin Hypercube Sampling Method for Mapping Using Ancillary Data

For obtaining maps of good precision by the spatial inference method, the distribution of sampling sites in geographical and feature space is very important. For a regional variable with trends, the predicting error comes from trend estimation, variogram estimation and spatial interpolation. Based on the cLHS (conditioned Latin hypercube Sampling) method, a sampling method called scLHS (spatial cLHS) considering all these three aspects with the help of ancillary data is proposed in this article. Its advantage lies in simultaneously improving trend estimation, variogram estimation and spatial interpolation. MODIS data and simulated data were used as sampling fields to draw sample sets using scLHS, cLHS, cLHS with x and y coordinates as covariates, simple random and spatial even sampling methods, and the distribution and prediction errors of sample sets from different methods were evaluated. The results showed that scLHS performed well in balancing spreading in geographic and feature space, and can generate points pairs with small distances, and the sample sets drawn by scLHS produced smaller mapping error, especially when there were trends in the target variable.