Role of sea surface temperature and rainfall in determining the stock and fishery of the common octopus (Octopus vulgaris,Mollusca, Cephalopoda) in Tunisia

Octopus (Octopus vulgaris, Mollusca, Cephalopoda) is an important and valuable fishery resource on the eastern and southern coasts of Tunisia, but its landings are highly variable. This paper explores the effect of environment on octopus catch per unit effort (CPUE) during a 12‐year period, through correlation analyses and the incorporation into surplus production models of sea surface temperature (SST) and rainfall data collected during cold (January–May) and hot (August–October) seasons. CLIMPROD software was used to select the appropriate model and fit it to the fishery and environment data. In both seasons, SST significantly contributed to CPUE variability; fishery production was influenced positively by cold season SST but negatively by hot season SST. Due to a poor fit with cold season data, the impact of rainfall was analysed only for the hot season, during which it has a positive effect on production. Results are discussed in view of the life‐cycle of octopus and the dynamics of the Tunisian fishery. This first study of octopus variability in Tunisia highlights the necessity to incorporate environmental influence into stock assessment and management advice.     

基于二分图的温度网络拓扑性质研究

利用中国地区435个台站1961—2002年逐日平均温度序列,将温度变化发生在9天时间尺度上的特征编码在网络中,通过研究二分图温度网络(BGT网络)中节点与项目的关系,揭示出9天时间尺度上温度变化的特征及其在空间上的拓扑统计性质.网络中各节点RRRD, RrDD, eeed, DRRD, DDRR等所代表的温度波动模态在网络中异常频发,对9天尺度温度变化的预报有一定的指导意义.统计网络的节点度分布,集群系数等拓扑结构特征量,发现BGT网络服从正态分布特征.BGT网络项目内节点度的多样性大体上     

Study on the negative bias temperature instability effect under dynamic stress

This paper studies negative bias temperature instability (NBTI) under alternant and alternating current (AC) stress. Under alternant stress, the degradation smaller than that of single negative stress is obtained. The smaller degradation is resulted from the recovery of positive stress. There are two reasons for the recovery. One is the passivation of H dangling bonds, and another is the detrapping of charges trapped in the oxide. Under different frequencies of AC stress, the parameters all show regular degradation, and also smaller than that of the direct current stress. The higher the frequency is, the smaller the degradation becomes. As the negative stress time is too small under higher frequency, the deeper defects are hard to be filled in. Therefore, the detrapping of oxide charges is easy to occur under positive bias and the degradation is smaller with higher frequency.     

pT-effects of Pleistocene glacial periods on permafrost,gas hydrate stability zones and reservoir of the Mittelplate oil field,northern Germany

During the past two million years low surface temperatures as well as episodically advancing ice sheets from Scandinavia acted on the subsurface pT-regime of northern Germany. Their likely effects on the petroleum system of Schleswig-Holstein were investigated. For the entire Quaternary mean annual ground temperature (MAGT) was reconstructed at a resolution of 1000 years by calibrating oxygen isotope records from ODP-site 659 to the climate of northern Germany of the past 120 kyr. The resulting MAGT trend served as input to an ice sheet model and a permafrost model along a 2D section crossing the petroleum bearing south-western part of Schleswig-Holstein. Here advances and retreats of the Scandinavian ice sheet during Saalian and Elsterian glaciation Stages were reconstructed. Maximum ice thicknesses of up to 1700 m and up to 20 periods of regional permafrost in northern Germany were reconstructed for the past 1.25 million years. Based on a basal heat flow of 50 mW/m² permafrost thicknesses exceeded 100 m during most of these periods, temporarily extending down to depths of more than 300 m. Favourable surface temperatures and long durations of cold periods provided favourable conditions for onshore gas hydrate stability zones at Mittelplate. Implementing these glacial dynamics into 2D basin modelling (PetroMod, IES, Aachen, Germany) of the Mittelplate oil field reveals five phases of gas hydrate stability at depths down to 750 m. The latest of these events occurred during the Weichselian about 20 kyr ago. The effect of the ice sheets on pore pressure in the subsurface strongly depends on the hydraulic boundary conditions at the ice base (e.g. frozen vs. temperate ice sheet base). Excess pore pressure in the reservoir of more than 10 MPa during ice overriding is possible and probable. The calculated temperature effect of the Pleistocene cooling on the Mittelplate reservoir is in the range of 3–7 °C. Even today temperature in the reservoir is still lowered by about 4 °C in comparison to pre-Pleistocene times. Despite the fact that a significant influence of glacial effects on petroleum generation can be ruled out at Mittelplate, we state that pT-effects in reservoirs related to glacial processes in formerly glaciated areas have been underestimated in the past.     

Dynamics of the Mackenzie River plume on the inner Beaufort shelf during an open water period in summer

The oceanographic conditions of the Mackenzie River plume in the Arctic Ocean were examined during a 12-day period in August 2007. Field observations in the river channel and the delta region (2–6 m depth), ship-based observations on the shelf and satellite observations of sea surface temperatures indicate that movements of plume density fronts cause changes in water temperatures of over 10  C over a few days. We used a 1D model to compare the strength of stratification versus surface wind stress, and a 3D numerical model to simulate the plume motions under forcing from the river flows, local wind and water level variations from tides and wind-driven surge. The results indicate that the coastal region is stratified with a ∼2 m thick surface plume even in water depths of 3–4 m, resulting in strong vertical variation of horizontal currents. Moderate easterly winds of 5–10 m/s are sufficient to induce offshore transport of the surface plume and onshore transport of the deeper shelf water, leading to large fluctuations in temperature and salinity in the coastal region. This study examined a period of offshore transport and mean water level set-down, and indicates the rapid response of the plume to wind over the shallow delta.     

山东半岛南部水温统计分析

利用1997—1998年的水温实测资料对麦岛、石岛海洋站和海阳水温观测站的水温进行了相关性分析,分析表明3个站位的水温相关性较好,但8月较差。利用得到的相关关系和等间距分布法,在推算出海阳15 a的水温后,对3个站位1991—2005年的水温进行了统计分析。结果表明:夏半年海阳的水温最高,石岛的水温最低,而在冬半年海阳的水温最低,对其形成原因进行了初步分析。     

近20年京津唐主体城区地表热场空间特征变化分析

基于Landsat遥感影像获取京津唐主体城区1995~2015年地表温度(Land Surface Temperature, LST)和不透水地表盖度(Impervious Surface Percentage, ISP)数据。采用热点聚集和阈值分割法,依据地表的温度和不透水盖度属性将京津唐主体城区划分成9种地表热场类型,分析并探讨地表热场的发展规律、年际变化状况和区域贡献作用。研究发现,京津唐主体城区地表温度与不透水地表盖度间存在显著的正向相关关系,两者分别呈现“阶梯降”和“两端高、中间低”的变化特征。京津唐主体城区地表热场的发展主轴保持在西北-东南方向,且随时间推移沿主轴呈聚集态势。 京津唐主体城区地表热场的影响范围在空间上持续扩张,对于不同的主体城区,其在整体区域的热场贡献中有差异化表现。     

阿勒泰地区植被覆盖度及ET对气温变化的响应

研究气温对植被覆盖度和ET (Evapotranspiration,ET)的影响,对干旱区应对气候变化、维系生态系统稳定具有重要意义。基于阿勒泰地区及周边7个气象站,CRU数据集中的气温数据及MODIS ET数据,采用Mann-Kendall非参数检验、植被盖度反演等方法,对阿勒泰地区气温变化对植被覆盖度及ET的影响进行了研究。结果表明：（1）在1901—2016年过去的116 a间,阿勒泰地区年平均气温以0.18 ℃·(10 a)^-1速率增加,在1982年由突变前的2.2 ℃增加到突变后的3.5 ℃。（2）2000—2017年阿勒泰地区植被覆盖度变化的空间差异明显,植被覆盖度增加的面积与降低的面积总体相当;全区66.71%的区域植被覆盖度变化与气温呈负相关,而呈正相关的比例仅占18.55%,且全区气温变暖而盖度降低区域的占比达31.71%。（3）2000—2016年阿勒泰地区ET总体呈降低趋势,整个区域61.65%的面积温度降低、ET降低,而19.92%的区域表现为温度增加而植被ET降低。     

荒漠绿洲湿地土壤水热盐动态过程及其影响机制

以甘肃临泽荒漠绿洲湿地为研究对象,通过对土壤温度、含水量、电导率及蒸散量的野外观测,在植物生长期和冻融期分别深入分析水热盐耦合运移过程及其影响因素,探讨水热梯度对盐分运移及其分布格局的控制作用。结果表明：土壤温度整体呈现出春夏季逐渐升高、秋冬季降低趋势。在冻结期,土壤表现为脱盐状态,表层电导率由2.8 mS·cm^-1降到1.2 mS·cm^-1;而在消融期为积盐状态,表层电导率由1.2 mS·cm^-1升到3.7 mS·cm^-1。在生长期,土壤含水量和电导率波动较为剧烈,表层含水量27%~43%,表层电导率3~5.5 mS·cm^-1,土壤脱盐、积盐反复出现。全年蒸散量总体呈单峰变化趋势,年蒸散量507 mm;土壤电导率与蒸散量呈正比关系,与地下水位呈负相关关系;蒸散发作用是土壤表层积盐的主要驱动力,而地下水波动影响着湿地脱盐、洗盐过程。因此,荒漠绿洲湿地土壤盐分累积过程是水分运移和热量传输过程发生变化的结果。     

乌兰布和沙漠东北缘地温变化特征及其影响因子

基于内蒙古磴口荒漠生态系统国家定位观测研究站监测数据,分析2014年1—12月不同土层的地温数据及同期气象数据,进而阐明乌兰布和沙漠东北缘地温变化特征。结果表明：（1）乌兰布和沙漠地温及气温具有显著的日变化特征,气温最高值与最低值出现时刻相对巴丹吉林沙漠提前2 h,相对东部地区滞后1 h;地温与气温季节变化特征一致,各季节地温最值出现时刻相对气温滞后1 h;（2）地温变化速率随着土壤深度的增加而减小,在土壤深度达到70 cm以后,地温全年在0℃以上;低于0℃的5 cm地温持续时间约为4个月;（3）地温与空气温度、太阳辐射变化趋势一致,地温相对太阳辐射及气温明显滞后。相关分析与逐步回归表明,对地温变化起决定作用的环境因子为空气温度、蒸发量、太阳总辐射、风速、空气相对湿度、降水。