1960-2014年湖南省极端气温事件变化特征分析

利用1960-2014年湖南省88个地面气象站日最高和最低气温的均一化资料,运用百分位阈值法统计暖日、暖夜、冷日和冷夜数,采用线性回归、M-K突变检验、Morlet小波分析等方法,研究湖南省55a以来极端气温事件的时空变化特征。结果表明：(1)湖南省暖日和暖夜数呈上升趋势,其年际变化倾向率分别为0.68d.(10a)-1、2.73 d.(10a)-1,冷日和冷夜数呈下降趋势,其年际变化倾向率分别为-0.45d.(10a)-1、-2.46d.(10a)-1,夜间增暖幅度大于白天增暖幅度;(2)湖南省大部分地区的暖日、暖夜数呈上升趋势,冷日数、冷夜数呈下降趋势,其中湘北、湘南部分地区变化趋势明显;(3)暖日、暖夜、冷夜数有明显的阶段性变化,其突变检验特征较明显,暖日、暖夜分别在2008、2003年突变增加,冷夜在1986年突变减少;(4)湖南省极端气温日数在不同的时间段存在着长短不同的振荡周期。     

强度尺度分解方法在气候温度场检验中的应用

本文首次将Casati等提出的强度尺度分解方法应用到气候地表温度场的检验中,探讨此方法用于评估气候模拟场误差的详细空间信息的适用性。以新一代气候系统模式模拟的月平均地表温度为例,传统的统计分析方法（较为常用的是空间相关系数和均方根误差、EOF分析等）不能完全反映模拟场误差的空间信息;强度尺度分解方法可计算不同阈值和空间尺度上的均方误差和模拟技巧,评估对应的模拟能力,定量给出模拟场主要误差的空间信息（误差范围即温度阈值及对应的空间尺度）,例如,亚洲东部地区1月单年及多年平均的模拟场在230 K阈值1600 km模拟技巧非常低。本研究表明强度尺度分解方法适用于气候温度场的检验评估,能定量给出误差的空间信息。     

多普勒雷达观测在北京7.21暴雨数值模拟中的三维变分同化研究

基于背景误差的特征长度理论,研究调整背景误差水平分辨率对多普勒雷达资料三维变分同化的影响。首先利用NMC方法针对暴雨落区统计不同水平分辨率的背景误差协方差,分析两种不同分辨率的背景误差的结构特征,研究水平分辨率对背景误差特征长度的影响。将其应用于雷达资料同化中,研究背景误差水平分辨率变化对雷达资料同化的影响。结果表明:背景误差水平分辨率由27 km提高到3 km时,在大气低层体现出更细致的动力场信息,其动力场水平特征长度按水平分辨率的二次根递减,而温度场与水汽场水平特征长度变化不明显。在将不同分辨率的背景误差用于三维变分同化时,更高分辨率的背景误差可以在分析场增量中体现更细致的中小尺度信息,能够明显改善雷达径向速度资料同化效果,并在随后的暴雨数值模拟中雨量及其分布形态更接近实况。     

多尺度细节增强的遥感影像超分辨率重建

鉴于现有超分辨率重建方法难以突显重建影像细节信息的问题,提出多尺度细节增强的遥感影像超分辨率重建模型框架。首先,通过最小二乘滤波方法将序列影像分解成包含大尺度边缘的平滑信息和包含中小型尺度的细节信息;其次,利用插值方法得到相应的高分辨率细节信息和平滑信息,构造纹理细节增强函数,提升中小型细节的增强幅度;最终,融合细节信息和平滑信息,得到初始的超分辨率重建结果,并利用局部优化模型进一步改善重建影像质量。选取同时相和多时相遥感影像作为试验数据。试验结果表明,本文重建结果与插值方法、TV方法和MAP方法相比,在客观评价指标上均有显著提高,明显改善了重建影像的纹理细节。论文提出的多尺度细节增强的超分辨率重建方法,可以使重建影像提供更多高频细节信息,具有较好鲁棒性和普适性。     

遥感影像超分辨率处理方法与研究进展

随着人们对影像高分辨率需求的不断增加,图像超分辨率技术已成为相关研究领域的热点之一。针对在遥感领域并非所有的超分辨率方法都可用的现状,该文按照遥感影像超分辨率处理的流程,将超分辨率问题分为退化模型、配准、重建和精度评定4大模块。对于其中每一模块的理论、常用方法与研究进展进行了较全面的综述及比较分析。最后对这一领域的未来发展进行思考和展望。     

Study on the Global Carbon Assimilation System Based on Multisource Remote Sensing Data

The Paris agreement signed in April, 2016 aims to balance global anthropogenic carbon emissions and terrestrial carbon sinks by the middle of the 21^st century. To fulfill this goal, it is necessary to calculate carbon fluxes of different regions reliably. The global carbon assimilation system is an effective technique for achieving this goal. The Ministry of Science and Technology of China supports the project entitled as study on the global carbon assimilation system based on multisource remote sensing data through the national key research and development programs for global change and adaptation during the thirteen-five period. This project will develop synergic inversion techniques for retrieving key parameters of biological and atmospheric cycles and for assimilating multisource remote sensing and ground based data. Then, the high resolution global carbon assimilation system coupled with an ecological model will be constructed. This system is able to assimilate jointly multisource observation data and to optimize key model parameters, photosynthesis and respiration carbon fluxes of global terrestrial ecosystems, and anthropogenic carbon emission fluxes of key regions. This system will be used to study quantitatively the spatial and temporal patterns of carbon fluxes of global terrestrial ecosystems and anthropogenic carbon emission fluxes of key regions and to identify the mechanisms driving the global terrestrial carbon sinks and sources. The outputs of this study will be helpful for the fulfillment of the key research and development programs for global change and adaptation and provide valuable data and technical support for the decision-making in China.     

Review on Montane Forest Eco-hydrology in Arid Area

Since the forest eco-hydrology of arid area shows a well sensitivity of the global climate change, the relationship between forest and water and the hydrological function has attracted the attention of academic communites and management departments. This paper expounds the research progress in arid mountain forest eco-hydrology, and analyses the formation and stable mechanism of forest patch pattern, the relationship between forest and water yield and the response of forest eco-hydrology to climate change from three aspects: Forest spatial pattern, hydrological process and its response to climate change. In addition, combined with the current research progress, the research emphases in the future are put forward: Strengthening the research on the coupling of vegetation pattern and hydrological process; solving the scale problem by using remote sensing technique and model; enhancing the understanding towards the hydrological function of forest; determining the suitable forest scale which can balance the relationship of ecology and hydrological effect.     

Assessing potential spatial and temporal conflicts in Washington's marine waters

This paper uses spatial, temporal, and use-intensity data for 27 major marine uses in Washington waters to feature a method for assessing potential use conflicts in a variety of scenarios. The study represents a first step towards quantifying potential conflicts within Washington’s Marine Spatial Planning (MSP) study area by using a cumulative analysis to highlight high- and low-use intensity areas and the novel Marine Potential Conflict Index (MPCI), which incorporates space, time, and intensity of use, to quantify pairwise potential conflicts between uses. About 10% of pairs of uses do not overlap spatially and are likely compatible with one another. Temporally, the number of uses peaks in July and August and falls during January and February. Additionally, the MPCI identified three important use types with a substantial degree of potential conflict: commercial fishing, tribal fishing, and shipping. External data were used in three cases to ground-truth the analysis, as a limited test of its utility in managing any potential conflict. This article assesses the extent of Washington’s existing marine uses along spatial, temporal, and intensity axes, and more broadly provides a straightforward way to examine potential conflicts between marine uses.     

Interaction between scale and scheduling choices in simulations of spatial agents

Spatial simulations are a valuable tool in understanding dynamic spatial processes. In developing these simulations, it is often required to make decisions about how to represent features in the environment and how events unfold in time. These spatial and temporal choices have been shown to significantly alter model outcomes, yet their interaction is less well understood. In this paper, we make use of a simple group foraging model and systematically vary how features are represented (cell size of the landscape) as well as how events unfold in time (order in which foragers take action) to better understand their interaction. Our results show similar nonlinear responses to changes in spatial representation found in the literature, and an effect of the order in which agents were processed. There was also a clear interaction between how features are represented and how events unfold in time, where, under certain environmental representations results were found to be more sensitive to the order in which individuals were processed. Furthermore, the effects of feature representation, scheduling of agents, and their interaction were all found to be influenced by the heterogeneity of the spatial surface (food), suggesting that the statistical properties of the underlying spatial variable will additionally play a role. We suggest that navigating these interactions can be facilitated through a better understanding of how these choices affect the decision landscape(s) on which agents operate. Specifically, how changes to representation affect aggregation and resolution of the decision surface, and thereby the degree to which agents interact directly or indirectly. We suggest that the challenges of dealing with spatial representation, scheduling, and their interaction, while building models could also present an opportunity. As explicitly including alternate representations and scheduling choices during model selection can aid in identifying optimal agent–environment representations. Potentially leading to improved insights into the relationships between spatial processes and the environments in which they occur.