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41.
《Limnologica》2015
We studied the changes in the submerged aquatic vegetation (SAV) and phytoplankton community in a hard water lake during different meteorological conditions. We hypothesized that variations in climatic conditions (precipitation and temperature) can influence the physicochemical parameters of water and, in turn, affect SAV and phytoplankton development. The investigations were performed in Lake Rogóźno (the West Polesie region, Eastern Poland) over 10 years from 2003 to 2013. The physicochemical parameters, the structure of macrophytes and the phytoplankton community in the dry (2003–2006, DP) and wet periods (2007–2013, WP) were analyzed. Between the dry and wet periods, the water color and the concentration of dissolved organic carbon (DOC) increased considerably, whereas water conductivity decreased. Other parameters (concentration of nutrients, water reaction and transparency) were comparable during both periods. When the precipitation and water level were low (DP), charophytes dominated the SAV and cyanobacteria dominated the phytoplankton community. After the precipitation and water level increased (WP), the charophyte population declined and the vascular plants and bryophytes dominated. Furthermore, flagellated algae belonging to the dinophytes and cryptophytes were the most numerous in the phytoplankton community. These changes in the SAV and phytoplankton were linked with the variations of physicochemical parameters determined by the total precipitation and mean air temperature in March. 相似文献
42.
近140年中国、北半球和全球气温的标度律 总被引:2,自引:0,他引:2
运用非趋势波动分析方法,有效地消除数据中噪声和非平稳性质的影响,研究全球、北半球和中国近140年气温变化的长程幂律相关性。结果表明:全球气温、北半球气温和中国气温都有由交叉点划分的两个标度不变区域,可能对应两个不同的物理机制。其一,都可以表现出正长程相关的性质,而且全球气温的持续性最强,北半球次之,中国气温最弱;其二,全球气温和北半球气温还可以有几乎是1/f噪声性质的变化,中国气温则可表现出介于1/f和布朗噪声之间的行为。 相似文献
43.
中国东部土壤温度、湿度变化的长期趋势及其与气候背景的联系 总被引:2,自引:0,他引:2
利用1971—2000年中国722站逐月的土壤温度资料和1981—1998年178站逐旬的土壤湿度观测资料,分析了中国东部土壤温度、湿度变化的长期趋势及其与气温、降水变化的关系。结果表明:①我国东部土壤温度的变化在年际—年代际时间尺度上存在明显的区域性差异,其中东北地区表现为持续上升型,而西北东部—华北、江淮和西南—华南地区均为先降后升型;②1970—2000年代,土壤温度的变化在东北以及西北东部—华北地区有显著的上升趋势,而在江淮和西南—华南地区,总体而言变化趋势不显著。此外,1980—1990年代,各区域土壤湿度的变化趋势均不显著;③在年际—年代际尺度上,各区域土壤温度和气温的变化具有显著的正相关关系,而土壤湿度与土壤温度的变化普遍呈负相关关系,其中尤以西北东部—华北地区最为显著。而在较长的时间尺度上,土壤湿度与降水的变化仍然存在较好的正相关关系。 相似文献
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46.
Catarina Frazão Santos Zara Gonçalves Teixeira João Janeiro Renata Sousa Gonçalves Rhema Bjorkland Michael Orbach 《Marine Policy》2012
The EU Marine Strategy Framework Directive (MSFD) is considered to be the environmental pillar of the EU Integrated Maritime Policy, establishing a framework within which member states must take the necessary measures to achieve, or maintain, good environmental status in their marine waters. This study presents Portugal's contributions to the Directive development, describes the Portuguese institutional framework within the MSFD and, finally, highlights the opportunities and threats to the success of the MSFD implementation in Portugal. The latter entails an analysis of the Directive's long term adequacy in its link to (1) marine spatial planning, (2) climate change and (3) the economic/financial crisis. With one of Europe's largest exclusive economic zones. Portugal's interest in the MSFD is paramount. Efforts towards the approval of the final document were assured during the Portuguese presidency of the European Council of Ministers, in 2007, while chairing a thorough discussion between the Council and the European Parliament. In the Portuguese context, the Directive implementation will rely on the Water Institute as the authoritative entity, which will be responsible for coordinating all necessary efforts at the national level. The success of such process depends on a close cooperation among the institutions involved as well as on how approved measures account for long term issues. In addition, the MSFD implementation must be built on lessons learned within the Water Framework Directive, in order to be successful. Although it poses a methodological challenge to Portugal, the MSFD implementation is expected to contribute significantly to the improvement of coastal/marine conservation and management at the national level. 相似文献
47.
刘勰倾注其毕生的追求与思索而创作的体大思精的《文心雕龙》正是其美学生命与心理体验的显现。刘勰将其在独特的人生旅途中获得的心理体验贯穿于《文心雕龙》的文道论、创作论、鉴赏批评论和文体论之中,其中,"割情析采"中的鉴赏批评论蕴含了刘勰的"觇文见心"的同情体验、"贵古贱今"的孤独体验以及这两种体验的实践与超越,这些共同构成了其丰富深刻又灵动精妙的心理体验与美学生命。 相似文献
48.
系统分析了1970~2007年间新疆境内70个5级以上地震序列的余震持续时间和余震区长轴与主震震级的统计关系,以及主震破裂方式对余震时空特征参数的影响。研究结果表明,新疆及分区地震带余震持续时间和余震区长轴分别与主震震级弱相关,主震震级较低时两者关系离散,震级较高时则呈线性增强。不同的地震带这种线性关系存在差异,对于相同的主震震级,天山地震带余震持续时间一般大于西昆仑地震带,而余震区长轴前者小于后者。新疆地区主震破裂方式对余震的持续时间影响不大,但对余震区长轴影响较大,走滑型主震余震区长轴一般大于逆断型地震。 相似文献
49.
利用浙江省义乌市2015—2019年逐小时气象观测数据(相对湿度、风速、地气温差、能见度)和空气质量指数(Air Quality Index, AQI)数据, 分析了义乌地区低能见度天气(观测能见度lt; 10 km)的分布特征和气象要素条件。利用长短期记忆神经网络(Long Short Term Memory Neural Network, LSTM)模型对逐小时能见度进行模拟, 分别对比了观测能见度作为输入变量与否的模拟效果; 根据义乌地区低能见度天气条件的特征, 将模拟时段分为三个时期(11月至翌年2月, 3—6月, 7—10月), 对比了分时期模拟的效果; 以及评估了模型的预报步长。结果表明: 高湿、高污染、气温高于地温和低风速是义乌地区低能见度天气的主要特征。LSTM模型对单站能见度有较好的模拟效果, 当输入参数中加入历史观测能见度时, 能大幅提高模拟准确度, 日均能见度模拟结果均方根误差RMSE=0.63 km, 平均绝对误差MAE=0.51 km, 拟合优度R2=0.99;分时期进行模拟能得到更精准的模拟结果。本研究中选用的输入要素在冬季(11月至翌年2月)模拟效果最好, RMSE=2.35 km, MAE=1.46 km, 低能见度均方根误差RMSE_10 km=1.81 km, 低能见度平均绝对误差MAE_10 km=1.13 km, R2=0.83; 3—6月的模拟中, 输入变量中不加AQI模拟效果更好, 这意味着3—6月义乌地区的低能见度天气以雾天气为主导, 加入过多变量并不一定能提高模型准确度; 随着预报步长增大, 模型预报效果变差, 预测步长等于3 h, R2=0.71, 预测结果已不具备实际应用意义。 相似文献
50.
A rich foraminiferal assemblage, consisting of abundant Aulotortus sinuosus and A. tumidus in association with Lamelliconus multispirus, Endoteba ex gr. controversa, E. ex gr. badouxi, Endotebanella kocaeliensis, Endotriada tyrrhenica, Endotriadella wirzi, Malayspirina fontainei, Ammobaculites rhaeticus, Diplotremina astrofimbriata, Agathammina austroalpina, and others, was found in the Doi Long Formation of the Triassic Lampang Group, Northern Thailand. These foraminifers suggest that the formation is referable to the Carnian (early Late Triassic), which is consistent with the age estimated by ammonoids. In microfacies, peloidal grainstone, bioclastic grainstone, sponge-microbial boundstone, and oolitic grainstone were recognized in the Doi Long Formation. Based on microfacies, three depositional facies, the lagoon facies, reef facies, and shoal facies, are recognized in this formation. These lines of evidence are suggestive that the Doi Long Formation was deposited in a reef or bank setting rather than a ramp setting. 相似文献