2004年苏门答腊地震前后海面高趋势的变化

利用苏门答腊附近海域T/P、Jason-1测高卫星近20年的海面高连续观测资料,分别计算了该区域(80°E~105°E,5°S~20°N)在2004年苏门答腊大地震前后的海面高变化趋势,并与该区域对应时间段GRACE重力卫星反演的地表质量迁移结果进行比较。研究结果表明,由卫星测高观测资料估算的震区地震前后海平面趋势的变化与卫星重力反演结果基本一致。由于卫星测高沿轨观测具有高精度、高时空分辨率的特性,卫星测高资料估算的海平面趋势变化可以更为准确地反映震区海平面变化的局部特征。还对该区域震后形变特征进行了初步分析。     

淤泥质潮滩沉积物含水量遥感反演模型研究

潮滩沉积物含水量是表征潮滩地物信息的一个重要特征量,它影响着遥感提取潮滩地物信息的准确性。利用含水量-反射率指数衰减模式建立单波段模型,同时参考4种植被指数的形式构建含水量指数,建立适用于潮滩环境的含水量反演波段组合模型,实现了沉积物含水量的遥感反演。研究结果显示:对反射率数据利用干土反射率进行归一化处理后构建的NEWCI(Normalized Enhanced Water Content Index)归一化增强型含水量指数模型的含水量反演效果最佳。在含水量结果中,除了砂类别反演的确定性系数R2为0.675以外,粉砂、砂质粉砂、粉砂质砂、粘土质粉砂等4种沉积物类型反演的确定性系数均在0.83以上;当不考虑沉积物类型时,NEWCI指数模型的反演精度也达到0.8,RMSE为0.059,表明NEWCI指数模型对沉积物类型不敏感,且能够保持较高的含水量模拟精度,因而适合潮滩沉积物含水量的大范围预测。其反演结果可在潮滩地物信息遥感反演时有效削弱水分的影响,进而提高地物信息提取的效率。     

一种基于相对梯度法的海水温度分层模型

提出了一种以海表面温度为输入参数的海水温度分层模型。以2005—2012年的Argo气候态数据集与Argo浮标数据为基础,采用相对梯度法对海水温度垂向结构进行了分层,并据此获取了各层拟合方程所需的参数,包括:混合层深度、混合层梯度、温跃层上界深度、温跃层下界深度、深层大洋起始深度以及方程拟合系数。本文通过世界大洋数据库09版的CTD、XBT实测剖面数据对模型进行了检验。检验结果表明,该模型可以有效地对海水温度结构进行模拟,特别是400m以上的中上层大洋。模拟结果的总体均方根差(RMSE)为0.778℃,而在水深400m以上的中上层区域误差为0.494℃。     

Distributions of Picophytoplankton and Phytoplankton Pigments Along a Salinity Gradient in the Changjiang River Estuary,China

We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary.The average numbers of Synechococcus spp.（Syn） and picoeukaryotes （Euk） were （2.7 ±5.1）×l03 and （1.1±1.4）×l03 cells mL-1,respectively.Prochlorococcus spp.（Pro） was only found in the high-salinity brackish water with the concentration of 3.0× 10^3 cells mL-1.Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk.The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean.The response of different picophytoplankton groups to environmental variables was different.Water temperature was more important in its control over Euk than over Syn,while nutrients were more important in their influence over Syn than over Euk.Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient （i.e.,freshwater zone with 0-5 range,fresh and saline water mixing zone with 5-20 range,and high-salinity brackish water zone with 20-32 range）,where three different phytoplankton communities were discovered,suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.     

流转设“线” 规模有“度”——对推进农地规模化经营的思考

正针对日前国家下发的《关于引导农村土地经营权有序流转发展农业适度规模经营的意见》,有关专家认为,过分追求土地规模化,将颠覆传统土地利用模式,危害水土资源安全,并对部分农户产生挤出效应,必须把握土地流转"有序"和规模经营"适度"。中央确定了推进农村土地规模化经营的政策方     

山石成精·山岭之巅风光无限——广西浦北五皇山国家地质公园

山不在高,有仙则名。 听闻广西浦北五皇山山顶风光无限,怪石成精。还传闻五皇山的树,会＂抓＂石,还会＂咬＂人。于是我们慕名前来,观赏广西浦北五皇山国家地质公园。对于这些传闻的真假,只有到实地察看才见分晓。     

海水酸化会削弱鲨鱼的感官功能

<正>一般说来,海洋肉食动物鲨鱼在很大程度上靠嗅觉寻找分散于广阔环境中的猎物。然而,研究人员不久前在Global Change Bilolgy杂志在线版上报道说:根据预测,随着全球海洋的变化,鲨鱼这种久经历练的捕猎能力可能会受到损害。由于人类活动释放到大气中的二氧化碳被海水吸收,海水的酸度变得越来越大。以前的研究表明,富含二氧化碳的酸性海水可能会削弱珊瑚礁鱼类嗅     

The Soil Moisture and Net Primary Production Affected by CO_2 and Climate Change Using a Coupled Model

In this paper, a coupled model was used to estimate the responses of soil moisture and net primary production of vegetation （NPP） to increasing atmospheric CO2 concentration and climate change. The analysis uses three experiments simulated by the second-generation Earth System Model （CanESM2） of the Canadian Centre for Climate Modelling and Analysis （CCCma）, which are part of the phase 5 of the Coupled Model Intercomparison Project （CMIP5）. The authors focus on the magnitude and evolution of responses in soil moisture and NPP using simulations modeled by CanESM, in which the individual effects of increasing CO2 concentration and climate change and their combined effect are separately accounted for. When considering only the single effect of climate change, the soil moisture and NPP have a linear trend of 0.03 kg m^-2 yr^-1 and-0.14 gC m^- 2 yr^-2, respec- tively. However, such a reduction in the global NPP results from the decrease of NPP at lower latitudes and in the Southern Hemisphere, although increased NPP has been shown in high northern latitudes. The largest negative trend is located in the Amazon basin at -1.79 gC m^-2 yr^-2. For the individual effect of increasing CO2 concentration, both soil moisture and NPP show increases, with an elevated linear trend of 0.02 kg m^-2 yr^-1 and 0.84 gC m^-2 yr^-2, respectively. Most regions show an increasing NPP, except Alaska. For the combined effect of increasing atmospheric CO2 and climate change, the increased soil moisture and NPP exhibit a linear trend of 0.04 kg m^2 yr^-1 and 0.83 gC m^2 yr^-2 at a global scale. In the Amazon basin, the higher reduction in soil moisture is illustrated by the model, with a linear trend of-0.39 kg m^-2 yr^-1, for the combined effect. Such a change in soil moisture is caused by a weakened Walker circulation simulated by this coupled model, compared with the single effect of increasing CO2 concentration （experiment M2）, and a consequence of the reduction in NPP is also shown in this area, with a linear trend of-     

The Role of the Aerosol Indirect Effect in the Northern Indian Ocean Warming Simulated by CMIP5 Models

The northern Indian Ocean （NIO） experienced a decadal-scale persistent warming from 1950 to 2000, which has influenced both regional and global climate. Because the NIO is a region susceptible to aerosols emis- sion changes, and there are still large uncertainties in the representation of the aerosol indirect effect （ALE） in CMIP5 （Coupled Model Intercomparison Project Phase 5） models, it is necessary to investigate the role of the AIE in the NIO warming simulated by these models. In this study, the authors select seven CMIP5 models with both the aerosol direct and indirect effects to investigate their performance in simulating the basin-wide decadal-scale NIO warming. The results show that the decreasing trend of the downwelling shortwave flux （FSDS） at the surface has the major damping effect on the SST increasing trend, which counteracts the warming effect of greenhouse gases （GHGs）. The FSDS decreasing trend is mostly contrib- uted by the decreasing trend of cloudy-sky surface downwelling shortwave flux （FSDSCL）, a metric used to measure the strength of the AIE, and partly by the clear-sky surface downwelling shortwave flux （FSDSC）. Models with a relatively weaker AIE can simulate well the SST increasing trend, as compared to observation. In contrast, models with a relatively stronger AIE produce a much smaller magnitude of the increasing trend, indicat- ing that the strength of the AIE in these models may be overestimated in the NIO.     

无震脊或海山链俯冲对超俯冲带处的地质效应

全球海底分布着众多的无震脊或海山链,且在太平洋、印度洋及大西洋均存在靠近俯冲带的海岭。除小安德列斯弧外的巴拉克达脊和蒂勃朗脊起源自转换断层外,一般认为它们由与板块构造动力学迥异的地幔柱动力学所形成的。在板块汇聚边缘处,与扩张脊处所形成的正常洋壳一起,无震脊或海山链俯冲于陆缘弧或洋内弧之下,其对弧及弧后地区的地质效应(构造、地貌、地震以及岩浆作用等)有别于正常洋壳俯冲。无震脊或海山链的俯冲通常造成俯冲带地区的上驮板块的局部异常抬升、俯冲剥蚀作用效应的加强、海沟的向陆迁移以及地震强度的增加。同时,无震脊或海山链俯冲时,其携带的具富集地球化学特征的物质不仅影响着地幔地球化学,也对弧及弧后火山熔岩化学产生明显影响,并对超俯冲地区的热液矿床的形成产生重要影响。最后,本文指出了我国有关无震脊或海山链俯冲的可能的研究方向包括黄岩海山链俯冲对吕宋岛弧的可能影响、印度洋无震脊俯冲对青藏高原局部地区的影响,有我国学者参与的IODP344航次的研究对象——科科斯脊俯冲对哥斯达黎加地震成因的效应以及位于西太平洋地区靠近俯冲带的一些无震脊等。