基于NOAA/AVHRR的中亚地区荒漠化动态变化监测   总被引：1，自引：0，他引：1  

韩旭  孙一权  冯仲科  程彦培  曹忠 《测绘科学》2012,37(5):69-71

本文通过对影像特征的荒漠化解译,监测荒漠化土地面积和荒漠化程度,分析探讨1989年至2009年中亚地区荒漠化的变化趋势。结果表明本文所采用的监测方法,具有一定可靠性和实用性,能够对中亚地区进行快速地荒漠化的宏观实时监测。  相似文献   

利用NOAA/AVHRR数据获取地表特征参数的方法研究   总被引：5，自引：1，他引：4  

王黎明  周云轩  万力 《地球物理学进展》2004,19(3):672-677

地表特征参数的正确与否直接影响到区域陆面蒸散量估算精度,因此在区域非均匀陆面蒸散研究中,地表特征参数的获取方法是一个值得探讨的问题．与传统的方法相比,卫星遥感技术在求取地表特征参数时有其独特的优势．NOAA气象卫星AVHRR资料以其时间分辨率高、覆盖面广、价格低廉等优点广泛应用于非均匀陆面蒸散研究和应用中．本文建立了NOAA／AVHRR计算地表特征参数的参数化模型,选取中国东北松嫩平原西部地区2000年7月8日的AVHRR资料,试算了研究区地表温度、地表发射率、地表反照率、NDVI等主要地表特征参数,并且参照2000年研究区土地利用数据对各参数的空间分布特征及合理性进行了分析。  相似文献   

一种卫星云图局部标准差图像的快速算法     

权维俊  高燕虎  刘勇洪  栾庆祖 《气象科技》2013,41(2):217-223

局部标准差图像(Local Standard Deviation image,LSD)在卫星图像的空间一致性检测中有着重要的作用,然而利用传统的滑动窗技术计算局部标准差图像时,由于大量的循环过程使运算速度较慢,特别是当卫星图像较大而滑动窗较小时,这种运算更为耗时.采用了矩阵运算的思路,提出了根据滑动窗大小将卫星图像数组按一定方向和偏移量进行整体平移,然后对经过平移后的图像数组进行数学运算来获取标准差图像的快速算法.通过计算2005年1月1日的NOAA-16/AVHRR通道4亮温局部标准差图像实例表明,采用快速算法的计算效率相对于传统滑动窗算法计算效率提高明显.  相似文献   

Retrieval of Atmospheric Horizontal Visibility by Statistical Regression from NOAA/AVHRR Satellite Data     

HUANG Fei WANG Hong QIAN Junping WANG Guofu 《中国海洋大学学报(英文版)》2006,5(3):207-212

Based on the atmospheric horizontal visibility data from forty-seven observational stations along the eastern coast of China near the Taiwan Strait and simultaneous NOAA/AVHRR multichannel satellite data during January 2001 to December 2002, the spectral characters associated with visibility were investigated. Successful retrieval of visibility from multichannel NOAA/AVHRR data was performed using the principal component regression （PCR） method. A sample of retrieved visibility distribution was discussed with a sea fog process. The correlation coefficient between the observed and retrieved visibility was about 0.82, which is far higher than the 99.9% confidence level by statistical test. The rate of successful retrieval is 94.98% of the 458 cases during 2001 2002. The error distribution showed that high visibilities were usually under-estimated and low visibilities were over-estimated and the relative error between the observed and retrieved visibilities was about 21.4%.  相似文献   

Suspended sediment in the Ganges and Brahmaputra Rivers in Bangladesh: observation from TM and AVHRR data     

Mohammad Rezwanul Islam  Yasushi Yamaguchi  Katsuro Ogawa 《水文研究》2001,15(3):493-509

Remote sensing was used to understand the seasonal and spatial variation of suspended sediment in the Ganges and Brahmaputra Rivers in Bangladesh for two different discharge periods. Suspended sediment concentration (SSC) in these rivers was estimated from the reflectance of Landsat TM band 3. During the high discharge period, SSC in the Ganges is higher than that in the Brahmaputra. But in the low discharge period, this is reversed. Both erosional and depositional processes are active on their flood plains. Significant fluctuations in SSC and in suspended sediment load were observed along their courses because of river bank erosion and deposition and/or scouring and aggradation of river beds. Owing to scouring and turbulence, SSC increases markedly at the confluence of these rivers. Reflectance of AVHRR band 1 data was also analysed to study the distribution of suspended sediment along other reaches of these rivers. Like SSC, reflectance at the confluence zone increases compared with that in the Brahmaputra. However, this increase is not marked compared with the Ganges. The influence of their tributaries on the suspended sediment load could be inferred from the pattern of reflectance. Remote sensing data used in this study was corrected for atmospheric effects. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Historical extension of operational NDVI products for livestock insurance in Kenya     

《International Journal of Applied Earth Observation and Geoinformation》2014

Droughts induce livestock losses that severely affect Kenyan pastoralists. Recent index insurance schemes have the potential of being a viable tool for insuring pastoralists against drought-related risk. Such schemes require as input a forage scarcity (or drought) index that can be reliably updated in near real-time, and that strongly relates to livestock mortality. Generally, a long record (>25 years) of the index is needed to correctly estimate mortality risk and calculate the related insurance premium. Data from current operational satellites used for large-scale vegetation monitoring span over a maximum of 15 years, a time period that is considered insufficient for accurate premium computation. This study examines how operational NDVI datasets compare to, and could be combined with the non-operational recently constructed 30-year GIMMS AVHRR record (1981–2011) to provide a near-real time drought index with a long term archive for the arid lands of Kenya. We compared six freely available, near-real time NDVI products: five from MODIS and one from SPOT-VEGETATION. Prior to comparison, all datasets were averaged in time for the two vegetative seasons in Kenya, and aggregated spatially at the administrative division level at which the insurance is offered. The feasibility of extending the resulting aggregated drought indices back in time was assessed using jackknifed R² statistics (leave-one-year-out) for the overlapping period 2002–2011. We found that division-specific models were more effective than a global model for linking the division-level temporal variability of the index between NDVI products. Based on our results, good scope exists for historically extending the aggregated drought index, thus providing a longer operational record for insurance purposes. We showed that this extension may have large effects on the calculated insurance premium. Finally, we discuss several possible improvements to the drought index.  相似文献   

基于NOAA/AVHRR卫星资料的北京地区霾识别研究   总被引：1，自引：1，他引：0  

刘勇洪 《气象》2014,40(5):619-627

利用2008—2013年NOAA/AVHRRlB卫星资料和气象观测资料,应用米氏散射理论、图像色彩处理技术、频数分布图和可见光通道表观反射率阈值技术,开展了北京地区霾的遥感识别研究,并在京津冀地区进行了应用。研究结果表明:易于识别的霾在NOAA/AVHRR遥感图像上一般以1、2、1波段或4、2、1波段进行红、绿、蓝三通道假彩色合成.图像颜色以灰色、紫色和蓝色三大系列为主;一般仅靠遥感图像难以识别霾与轻雾,但借助先验知识、周围环境和图像色彩.可在一定程度上区分霾与轻雾;NOAA/AVHRR图像的第一波段表观反射率作为光谱指标可以对霾进行较好识别,反射率识别指标值分别为:冬季0.15～0.32,春季0.15～0.30,夏季0.14～0.30,秋季0.14～0.32;指标对霾的有效识别准确率为82%。利用上述建立的颜色指标和光谱指标可以较好地对2013年1—3月发生在京津冀地区的雾霾进行有效监测。  相似文献   

NOAA/AVHRR sea surface temperature accuracy in the East/Japan Sea     

《International Journal of Digital Earth》2013,6(10):784-804

Sea surface temperature (SST) retrieved from Advanced Very High Resolution Radiometer (AVHRR) onboard National Oceanic and Atmospheric Administration (NOAA) polar orbiting environmental satellites were validated in the East/Japan Sea (EJS) using surface drifter measurements as ground truths from 2005 to 2010. Overall, the root-mean-square (rms) errors of multichannel SSTs (MCSSTs) and non-linear SSTs (NLSSTs) using global SST coefficients were approximately 0.85°C and 0.80°C, respectively. An analysis of the SST errors (satellite – drifter) revealed a dependence on the amount of atmospheric moisture. In addition, satellite-derived SSTs tended to be related to wind speeds, particularly during the night. The SST errors also demonstrated diurnal variations with relatively higher rms from 0.80°C to 1.00°C during the night than the day, with a small rms of about 0.50°C. Bias also exhibited reasonable diurnal differences, showing small biases during the daytime. Although a satellite zenith angle has been considered in the global SST coefficients, its effect on the SST errors still remained in case of the EJS. Given the diverse use of SST data, the continuous validation and understanding of the characteristic errors of satellite SSTs should be conducted based on extensive in-situ temperature measurements in the global ocean as well as local seas.  相似文献   

Estimation of Surface Temperature and Rainfall in Ghana     

V. C.K. Kakane  H. Søgaard 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):76-85

Geografisk Tidsskrift, Danish Journal of Geography 97: 76–85, 1997.

Daily Meteosat images for 1989 have been analysed for the purpose of mapping surface temperature and rainfall in Ghana. The images in the time-series are georeferenced and the maximum value composite (MVC) technique is applied to the temperature calibrated IR-channel images after a cloud screening of the images. The cloud covered areas are outlined and traced using the Meteosat visible channels. Stratiform clouds are detected using surface albedo while cumuliform clouds are detected based on a technique calculating the spatial variability within a 5 pixel by 5 pixel window around each point in the image. The cloud covered parts of the scene are then delimitated by comparing the normal albedo values and the spatial variance in albedo.

The paper then discusses how the outlined procedure can be applied in an environmental monitoring context. For each of the months June to November 1989 the mean monthly rainfall amounts at 35 meteorological stations are plotted against the mean surface temperature. It is found that apart from the month of June statistical significant linear relationships are obtained and that the scattering around the line is decreasing for increasing sampling length.  相似文献   

Mesoscale Satellite Bioclimatology     

《The Professional geographer》2013,65(2):331-344

This paper examines the strength of relationships between the Normalized Difference Vegetation Index (NDVI) and climatic data, when examined at the mesoscale. Mean monthly AVHRR NDVI data for 1988-1996 for the months of April through October for State of Kansas, its nine climatic divisions (CDs), and dominant land cover types within each CD were used. Corresponding climatic and water budget data were obtained or derived from National Climatic Data Center data. Temperature, precipitation, and NDVI deviations from normal were determined. Statistical analysis revealed significant relationships between NDVI and climatic variables, although strengths of the associations were modest. The highest correlation coefficient (r) for the state as a whole was 0.53, between NDVI and estimated actual evapotranspiration. When examined by climatic division or major land cover type, relationships between NDVI and a drought index were statistically significant in most cases and ranged from 0.30 to 0.56.  相似文献