The temporal and spatial relationship between NDVI and climatological parameters in Colorado

This paper describes the spatial and temporal relationship between AVHRR/NDVI (Normalized Difference Vegetation Index) and climatological parameters (temperature and precipitation), which, in some sense, is influenced by topographical factors and land-cover types in Colorado. The correlation coefficients and partial correlation coefficients have been computed pixel by pixel over Colorado in order to analyze the relationship. The temporal variation and correlation of AVHRR/NDVI, temperature and precipitation were analyzed with a sampling method. The study reveals that there exists a close correspondence between monthly NDVI and temperature, which has strong impact from temperature on the changes of NDVI in Colorado. The spatial changes of NDVI are not influenced obviously by the precipitation since these two variables are different from each other in time series in Colorado. The study clearly revealed the spatial variation and its distribution patterns of relationship between NDVI and climatic parameters (temperature and precipitation) in Colorado.     

应用卫星多角度遥感识别被老鼠和昆虫破坏的草地(英文)

该文研究用ＡＶＨＲＲ数据监测Ｒｕｏｒｇａｉ县大草原被老鼠、昆虫破坏的情况。鼠虫危害区的光谱特征是：ＡＶＨＲＲ数据的可见光波段（０．５８－０．６８μｍ）地面反射率（ＣＨ１）较高，近红外波段（０．７２５－１．１μｍ）的地面反射率（ＣＨ２）较低，红外辐射波段（３．５５－３．９３μｍ）的亮度温度（ＣＨ３）较高；鼠虫危害区的遥感信息特征在雨季７月最为明显；可用比值植被指数ＲＶＩ（ＣＨ２／ＣＨ１）确定鼠虫危害程度；用多角度获得的ＲＶＩ可反映鼠虫危害。结果显示在这方面上，多角度遥感比多波段光谱法能更好地识别老鼠、昆虫破坏的地区。     

青海省积雪的遥感监测方法

介绍了利用气象卫星ＡＶＨＲＲ资料对青海省冬春季积雪进行监测的原理和方法，并通过积雪遥感监测系统的建立，确定积雪范围，计算积雪面积和深度，提供积雪分布图和雪情分析报告，为防为抗灾部门提供科学依据。     

在GIS支持下用NOAA/AVHRR数据进行旱情监测

旱灾是影响农作物生产的一种重大自然灾害,它对中国北方春小麦生产的影响极大。本文介绍了一个应用遥感、ＧＩＳ技术对黄淮海平原春小麦的旱情进行监测的系统及其方法。它综合使用的ＮＯＡＡ／ＡＶＨＲＲ数据、地面气象资料和地图,选用作物缺水指数（ＣＷＳＩ）模型和热惯理模型对旱情进行监测。监测结果分别用分县的旱情等级分布图和相应不同等级的旱情面积、面积比例数统计表来表示。该系统自１９９４年起投入运行３年,监测结果     

渤海、黄海、东海AVHRR海表温度场的季节变化特征

海表温度场表征了海洋热力、动力过程和海洋与大气相互作用的综合结果.它不仅是研究海面水汽和热量交换的一个重要物理参数,也为海洋环流、水团、海洋锋、上升流和海水混合等海洋学课题的研究提供一种直观的指示量.20世纪60年代以来,我国海洋工作者在历次海上观测和台站资料的基础上,对渤海、黄海、东海表层温度的空间分布和变化进行了较为详细的分析研究[1～4],并绘制了系列的水温气候图集.这些研究成果对认识黄海、东海海域的平均海表温度场的分布、变化以及相关物理海洋现象的研究起到了重要的作用.     

Hawaii Cyclonic Eddies and Blue Marlin Catches: The Case Study of the 1995 Hawaiian International Billfish Tournament

The combination of prevailing northeasterly tradewinds and island topography results in the formation of vigorous, westward propagating cyclonic eddies in the lee of the Hawaiian Islands on time scales of 50–70 days. These mesoscale (∼10² km) features are nowhere more conspicuous or spin up more frequently than in the Alenuihaha Channel between the Island of Maui and the Big Island of Hawaii. Cyclonic eddies in subtropical waters such as those around Hawaii vertically displace the underlying nutricline into the overlying, nutrient-depleted euphotic zone creating localized biologically enhanced patches. Insight into how these eddies may directly influence pelagic fish distribution is provided by examination of recreational fish catch data coinciding with the presence of eddies on the fishing grounds. We highlight the 1995 Hawaii International Billfish Tournament in which a cyclonic eddy dominated the ocean conditions during the weeklong event and the fish catch distribution differed significantly from the average historical tournament catch patterns. On the tournament fishing grounds, well-mixed surface layers and strong current flows induced by the eddy's presence characterized the inshore waters where the highest catches of the prized Pacific blue marlin (Makaira mazara) occurred, suggesting possible direct (e.g., physiological limitations) or indirect (e.g., prey availability) biological responses of blue marlin to the prevailing environment. This revised version was published online in August 2006 with corrections to the Cover Date.     

Empirical regression models using NDVI, rainfall and temperature data for the early prediction of wheat grain yields in Morocco

In Morocco, no operational system actually exists for the early prediction of the grain yields of wheat (Triticum aestivum L.). This study proposes empirical ordinary least squares regression models to forecast the yields at provincial and national levels. The predictions were based on dekadal (10-daily) NDVI/AVHRR, dekadal rainfall sums and average monthly air temperatures. The Global Land Cover raster map (GLC2000) was used to select only the NDVI pixels that are related to agricultural land. Provincial wheat yields were assessed with errors varying from 80 to 762 kg ha⁻¹, depending on the province. At national level, wheat yield was predicted at the third dekad of April with 73 kg ha⁻¹ error, using NDVI and rainfall. However, earlier forecasts are possible, starting from the second dekad of March with 84 kg ha⁻¹ error, at least 1 month before harvest. At the provincial and national levels, most of the yield variation was accounted for by NDVI. The proposed models can be used in an operational context to early forecast wheat yields in Morocco.     

Evaluating the Impact of Drought Using Remote Sensing in a Mediterranean,Semi-arid Region

This paper analyses monthly differences in drought impact on vegetation activity in a semi-arid region in the north-east of the Iberian Peninsula between 1987 and 2000. The study determines spatial differences in the effects of drought on the natural vegetation and agricultural crops by means of the joint use of vegetation indexes derived from AVHRR images, a drought index (standardized precipitation index), and Geographic Information Systems. The results show that the effect of drought on vegetation varies noticeably between areas, a pattern that is determined mainly by the location of land-cover types. The influence also varies each month and, in general, is higher during the spring and summer. Aridity and vegetation characteristics similarly account, in part, for spatial differences in the impact of drought on vegetation. In general, the most arid areas, where vegetation cover and activity are low, are those in which the interannual variability of vegetation activity is more determined by the drought occurrence. In assessing drought impact, this analysis takes into account the effects of drought on the vegetation and also considers spatial and seasonal differences. The results should be useful for the management of natural vegetation and crops and for the development of better drought mitigation strategies.     

Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data

The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw.     

推算NOAA AVHRR 1、2通道衰减率的一种方法

给出了一种确定NOAA AVHRR可见光（通道1）和近红外（通道2）辐射仪传感器衰减率的方法。首先在中国西部沙漠地区选择38个沙漠目标区（尺度为20 km×20 km），用同一卫星相隔多年的两个不同时期的晴天过境观测资料，建立各自的观测反射率与卫星天顶角的函数关系。通过两个不同时期的函数关系的比较，用逐步回归法确定出传感器的衰减率。用1985年10月与1988年9月NOAA-9 AVHRR资料推算其通道1与通道2的衰减率分别为5.8%/年和4.6%/年。该方法也适用于不同NOAA卫星间的定标归一化。