东亚土地覆盖对ENSO事件的响应特征

对1982—1993年气候年际变化的强信号———ENSO进行了确认及再分类。以美国地质调查局EROS中心提供的AVHRR8kmNDVI为数据源,应用地理信息系统技术,计算了1982—1993年每年夏季(5—9月)NDVI平均影像。在此基础上用数据断面分析法对ENSO年东亚地区土地覆盖的空间分布进行了分析,再用主成分分析法对同一时间序列NDVI平均影像进行了运算,发现其第7主成分影像所反映的土地覆盖分布与数据断面分析法所反映的结果是一致的。对此,进一步分析了第7主成分的特征向量与代表ENSO变化特征的南方涛动指数(SOI)之间的关系,进而,对ENSO驱动下的东亚地区土地覆盖年际变化的空间分布特征进行了总结。

Uncertainties in estimates of cropland area in China: a comparison between an AVHRR-derived dataset and a Landsat TM-derived dataset

The large uncertainties in estimates of cropland area in China may have significant implications for major cross-cutting themes of global environmental change-food production and trade, water resources, and the carbon and nitrogen cycles. Many earlier studies have indicated significant under-reporting of cropland area in China from official agricultural census statistics datasets. Space-borne remote sensing analyses provide an alternative and independent approach for estimating cropland area in China. In this study, we report estimates of cropland area from the National Land Cover Dataset (NLCD-96) at the 1:100,000 scale, which was generated by a multi-year National Land Cover Project in China through visual interpretation and digitization of Landsat TM images acquired mostly in 1995 and 1996. We compared the NLCD-96 dataset to another land cover dataset at I-km spatial resolution (the IGBP DIScover dataset version 2.0), which was generated from monthly Advanced Very High Resolution Radiometer (AVHRR)-derived Normalized Difference Vegetation Index (NDVI) from April, 1992 to March, 1993. The data comparison highlighted the limitation and uncertainty of cropland area estimates from the DIScover dataset. (C) 2003 Elsevier Science B.V. All rights reserved.

Radiation-use efficiency and the harvest index of winter wheat at different nitrogen levels and their relationships to canopy spectral reflectance

Radiation-use efficiency (RUE, g/MJ) and the harvest index (HI, unitless) are two helpful characteristics in interpreting crop response to environmental and climatic changes. They are also increasingly important for accurate crop yield simulation, but they are affected by various environmental factors. In this study, the RUE and HI of winter wheat and their relationships to canopy spectral reflectance were investigated based on the massive field measurements of five nitrogen (N) treatments. Crop production can be separated into light interception and RUE. The results indicated that during a long period of slow growth from emergence to regreening, the effect of N on crop production mainly showed up in an increased light interception by the canopy. During the period of rapid growth from regreening to maturity, it was present in both light interception and RUE. The temporal variations of RUEAPAR (aboveground biomass produced per unit of photosynthetically active radiation absorbed by the canopy) during the period from regreening to maturity had different patterns corresponding to the N deficiency, N adequacy and N-excess conditions. Moreover, significant relationships were found between the RUEAPAR and the accumulative normalised difference vegetation index (NDVI) in the integrated season (R-2 = 0.68), between the HI and the accumulative NDVI after anthesis (R-2 = 0.89), and between the RUEgrain (ratio of grain yield to the total amount of photosynthetically active radiation absorbed by the canopy) and the accumulative NDVI of the whole season (R-2 = 0.89) and that after anthesis (R-2 = 0.94). It suggested that canopy spectral reflectance has the potential to reveal the spatial information of the RUEAPAR, HI and RUEgrain. It is hoped that this information will be useful in improving the accuracy of crop yield simulation in large areas.

东海赤潮高发区水色遥感算法及赤潮遥感监测研究

本文针对东海赤潮高发区，主要进行水色遥感算法研究，以及赤潮遥感监测方法研究的探讨，希望对生物光学-遥感原理与新方法研究及赤潮的预测预报研究有所贡献。 在多年出海实测资料基础上，分析了水体组分固有光学量及浓度之间的关系，了解海区水体光谱特性，并发展了以水体组分浓度作为输入的水体离水遥感反射率光谱模型及参数优化形式。与实测光谱的比较结果，在光谱形状上较为接近，但在绝对量值上比实测值来得偏小，绝对值平均相对偏差较大，最大的551nm波段达到66.7%；对模型参数进行优化，优化后整体性能得到很大提升，均方根误差及绝对值平均相对偏差都得到大幅度降低，相关系数也得到较大提高，模拟的光谱形状与实测光谱进一步接近，在量值上也更为接近。 在光谱模拟的基础上提出了基于神经网络技术的二类水体大气修正算法，基于模拟数据的性能评估试验表明，网络模型反演的总体效果不错，对添加随机噪声不太敏感。将建立的神经网络大气修正算法应用于MODIS数据的处理，利用与卫星图像对应的现场实测光谱进行检验分析，结果表明，算法反演结果在光谱形状上与实测光谱相当接近，绝对量值上有所差别，总体偏大。 建立了叶绿素a浓度半分析反演算法，与实测数据比较，绝对值平均相对误差为38.34%。 建立了水体组分浓度神经网络反演算法，与半分析叶绿素a浓度反演算法相比，神经网络能得到更好的反演效果，绝对值平均相对误差为28.9%。 探讨了从MODIS卫星资料直接反演水体组分浓度的人工神经网络算法，基于模拟数据的性能评估试验表明，网络模型反演的总体效果不错，对添加随机噪声不太敏感。 发展了一种多波段MODIS资料赤潮监测方法，并在东海赤潮高发区进行了初步应用研究，结果表明采用此方法可有效地排除悬浮泥沙等水体干扰影响，确定可能发生赤潮的海区位置及提取海区大范围赤潮的信息。

青藏公路与铁路沿途1981年～2001年植被覆盖变化

在青藏公路与铁路沿途区域,利用1981年至2001年的8km分辨率PathfinderNOAA/NDVI数据,基于每个象元变化的年植被峰值计算进行了像元水平的线性趋势分析,并运用地理信息系统(GIS)软件研究了区域植被覆盖的空间分布和动态变化特征.主要结论:①在研究区内,反映植被覆盖的NDVI值在空间上呈现出两端高中间低的态势,依次是农作区和森林区＞高寒草甸＞高寒草原＞荒漠草原;②20年间,研究区植被覆盖程度变化总体趋于稳定,覆盖程度呈减少趋势的区域明显高于增加的区域,植被覆盖程度增减因区域而异;植被覆盖程度增加和显著减少地区主要分布在农作区和高寒草甸区,轻微减少地区主要分布在高寒草原和荒漠草原区;③植被覆盖变化程度在拉萨河谷地、湟水谷地和黄河流域等人类活动比较频繁的区域增减趋势比较明显;而在可可西里地区等人类活动比较少的区域变化轻微.

Monitoring and simulation of water, heat,and CO2 fluxes in terrestrial ecosystems based on the APEIS-FLUX system

The Integrated Environmental Monitoring (IEM) project, part of the Asia-Pacific Environmental Innovation Strategy (APEIS) project, developed an integrated environmental monitoring system that can be used to detect, monitor, and assess environmental disasters, degradation, and their impacts in the Asia-Pacific region. The system primarily employs data from the moderate resolution imaging spectrometer (MODIS) sensor on the Earth Observation System- (EOS-) Terra/Aqua satellite,as well as those from ground observations at five sites in different ecological systems in China. From the preliminary data analysis on both annual and daily variations of water, heat and CO2 fluxes, we can confirm that this system basically has been working well. The results show that both latent flux and CO2 flux are much greater in the crop field than those in the grassland and the saline desert, whereas the sensible heat flux shows the opposite trend. Different data products from MODIS have very different correspondence, e.g. MODIS-derived land surface temperature has a close correlation with measured ones, but LAI and NPP are quite different from ground measurements, which suggests that the algorithms used to process MODIS data need to be revised by using the local dataset. We are now using the APEIS-FLUX data to develop an integrated model, which can simulate the regional water,heat, and carbon fluxes. Finally, we are expected to use this model to develop more precise high-order MODIS products in Asia-Pacific region.

不同类型生态系统水热碳通量的监测与研究

亚太地区环境革新战略项目(APEIS)在中国5种主要生态系统类型区(草地:海北、耕地:禹城、稻田:桃源、林地:千烟洲、荒漠:阜康)建立了一个以连续观测能量、水分和碳素通量为中心,包括气象、水文、土壤、植被等各项生态要素的监测网络系统,被称之为APEIS-FLUX系统.作者首先对APEIS-FLUX系统的观测数据进行了初步分析,表明该系统稳定可靠,它可以实时地提供高质量、高精度、长期而连续的通量及生态要素的观测数据.对数据的比较清楚地反映出了不同生态系统类型区的水热碳通量的差异性.其次,利用APEIS-FLUX数据对美国航空航天局(NASA)的MODIS数据产品进行比较验证后发现,除部分产品如地表面温度(MOD11)等与观测数据较吻合以外,大部分数据产品如土地覆盖(MOD12),叶面积指数(MOD15)和光合速率与净第一性生产力(MOD17)等都与观测数据相差深远,有必要对其处理程序和模式进行修正.为此,我们利用APEIS-FLUX的数据作为MOD15和MOD17的生成模型(BIOME-BGC)的输入数据,并对该模型的有关参数进行了修订.结果表明,该模式在通过修正后,可以很好地模拟植被的生长过程及其相应的水热碳循环过程.

亚太地区环境综合监测的研究方法--APEIS项目研究综述

为了对亚太地区的环境灾害、环境破坏和环境退化及其影响进行监测和评估,由日本环境省发起的亚太地区环境革新战略项目(APEIS)环境综合监测子项目(IEM)自2001年开始,建立了一个以MODIS卫星数据和地面观测资料为基础的综合环境监视网络系统.该网络系统起初是由日本国立环境研究所(NIES)和中国科学院地理科学与资源研究所(IGSNRR)共同合作建成的.之后,新加坡国立大学和澳大利亚联邦科学产业研究组织(CSIRO)地球观测中心也正式宣布加入,该系统覆盖整个亚太地区.美国宇航局(NASA)提供了一套MODIS的高级数据产品,然而,这些产品没能在亚洲地区利用当地的实测资料进行充分地比较和验证.APEIS项目旨在提供利用该地区精确地面观测数据进行了比较验证的高质量数据集.利用该数据集可以推导出水分亏缺指数、沙尘暴指数、地表面温度、土地覆盖变化,以及净第一性生产量等一系列生态环境指标,从而对环境破坏、环境退化和生态脆弱区进行长期有效的监测.为了评价水资源、食物生产等生态系所提供的产品与服务的现状和变化特征,本研究还开发了一个可利用MODIS数据的流域环境综合管理模型.该模型已经被用于对流域规模的水、热、碳循环、泥沙转移以及农业生产等生态要素的模拟和评估,并利用高精度的观测资料对其进行了验证.利用该模式可以对流域生态系统所提供的产品与服务的有效利用,以及流域的可持续发展提供一系列战略性的政策选项.

巴丹吉林沙漠沙丘、植被和湖泊演化

The formation and evolution of magedunes and lakes in Badain Jaran desert is focused by scholars for a long time. In this paper, detailed investigation was made with the Remote Sensing, Geographic Information Systems, climatological data of research region to study the evolution of magedunes, vegetation and lakes. The main conclusions are presented as follows: (1) The magedunes are mainly located in south and northeast of the desert. The density of magedunes decreases from south to north, east to west, and greatest in southeast of the desert. Most of magedunes strike NE30°~60°, and which are NE-SW and NNE-SSW directions. The distribution of magedunes’ strikes indicates that the paleowind of the desert is northwest and west wind. (2) The vegetation cover is low in the Badain Jaran Desert, but there are some well-vegetated areas in the desert, and the value of NDVI is 0.6107. In southeast of the desert, the vegetation degradated seriously from 1987 to 2000. (3) At about 2000, the total area of permanent lakes was 2231.64 hm2 (±5.9%) in southeast of Badain Jaran Desert. From 1960 to about 2000, the lakes changed as followings: in the early 30 years, the area of lakes increased, but after 1990 it decreased. When lakes were large, the toral area of lakes is 20648 hm2 in Badain Jaran Desert, much larger than that of present lakes. (4) From 1961 to 2001, the mean annual evaporation of lakes was 1039.8mm (±10%) in Badain Jaran Desert, and the difference between years was large. The monthly evaporation of lakes was mainly affected by rainfall, temperature. And it was largest in June, 140.9mm(±10%). (5) Based on water balance calculation of present lakes and old lakes in southeast of Badain Jaran Desert, the total precipitation is more than the total evaporation in this area. So it is probable that the precipitation in the lake area supplies water to the lakes, and also to groundwater in west and north part of the desert.

基于遥感和GIS的巢湖流域生态系统健康评价

该文以巢湖流域为研究对象,以生态系统健康理论为基础,将流域生态系统的结构和功能结合起来,通过遥感和地理信息系统(GIS)技术获取生态环境变化信息,监测和评价小流域单元的健康状况,分析人类活动对生态系统结构和功能变化的影响,为巢湖流域的生态管理和政策制定提供指导.论文的主要内容包括:1、从生态系统研究的发展入手,对生态系统健康研究的发展、评价指标、度量、研究尺度、评价单元选择进行了概括,提出生态系统健康评价应以结构和功能评价为基础、把人类作为生态系统的一部分,对生态系统进行动态监测.2、以压力-状态-反映指标为概念框架,设计了巢湖流域生态系统健康评价指标体系;3、利用RS和GIS技术获取巢湖流域内各个小流域的生态系统数据,解决了小流域人口和社会经济数据获取难的问题;4、基于GIS技术,对流域生态系统健康评价状况进行定量评价,在此基础上,采用典型相关分析方法,分析了人类社会经济活动变化与生态系统健康状况变化的关系;分析了小流域NDVI多年月变化与生态系统健康状况的关系.