نتایج جستجو برای: ndwi
تعداد نتایج: 418 فیلتر نتایج به سال:
The Weishan Irrigation Zone along the lower reaches of the Yellow River consists of a total irrigated area of 3600 ha. The region has an average annual rainfall of 500–600 mm, with 60–70% of local rainfall occurring during the summer, and with less than 15% in spring. The water deficit during the spring affects the winter wheat growth from March to early June, which is a major growth period sig...
Cloud contamination is one of the severest problems for the time-series analysis of optical remote sensing data such as vegetation phenology detection. Sub-pixel clouds are especially difficult to identify and remove. It is important for accuracy improvement in various terrestrial remote sensing applications to clarify the influence of these residual clouds on spectral vegetation indices. This ...
Variation of MODIS reflectance and vegetation indices with viewing geometry and soybean development.
Directional effects introduce a variability in reflectance and vegetation index determination, especially when large field-of-view sensors are used (e.g., Moderate Resolution Imaging Spectroradiometer - MODIS). In this study, we evaluated directional effects on MODIS reflectance and four vegetation indices (Normalized Difference Vegetation Index - NDVI; Enhanced Vegetation Index - EVI; Normaliz...
With more than 80% of Brazilians living in cities, urbanization has had an important impact on climatic variations. São José dos Campos is located in a region experiencing rapid urbanization, which has produced a remarkable Urban Heat Island (UHI) effect. This effect influences the climate, environment and socio-economic development on a regional scale. In this study, the brightness temperature...
Whether or not reservoirs contain water throughout the dry season is critical to avoiding late season crop failure in seasonally-arid agricultural landscapes. Locations, volumes, and temporal dynamics, particularly of small (<1 Mm3) reservoirs are poorly documented globally, thus making it difficult to identify geographic and intra-annual gaps in reservoir water availability. Yet, small reservo...
امروزه یکی از مهمترین معضلات زیستمحیطی در کلانشهرها افزایش دمای سطح و در نتیجه افزایش شدت جزیرة حرارتی شهری است. هدف از این پژوهش بررسی تأثیر پارامترهای محیطی و جمعیتی در توزیع مکانی دمای سطح کلانشهر تهران است. بدین منظور، از ده تصویر ماهوارهای لندست مربوط به سالهای 2010 و 2011 برای استخراج نقشههای پارامترهای محیطی، کاربری پوشش سطح زمین، و دمای سطح زمین استفاده شد. برای طبقهبندی کاربری ...
پایش و پهنهبندی سیلاب کارکرد زیادی در کاهش خسارتهای ناشی از آن دارد. هدف از مقالۀ حاضر، بررسی خطر سیل فروردین 1398 خوزستان با استفاده از دادههای لندست-8 است. ابتدا پیشپردازش تصاویر در نرمافزار ENVI 5.3 انجام شد. سپس، برای پایش سیل فروردین 1398 از شاخصهای MNDWI و NDWI استفاده شد. پس از آن، نقشۀ پهنۀ خطر سیل در نرمافزار ArcGIS10.4 تهیه شد. نتایج نشان میدهد بخشهای جنوب و جنوب غربی از وض...
In Mongolia, drought is a major natural disaster that can influence and devastate large regions, reduce livestock production, cause economic damage, and accelerate desertification in association with destructive human activities. The objective of this article is to determine the optimal satellite-derived drought indices for accurate and real-time expression of grassland drought in Mongolia. Fir...
Monitoring open water bodies accurately is an important and basic application in remote sensing. Various water body mapping approaches have been developed to extract water bodies from multispectral images. The method based on the spectral water index, especially the Modified Normalized Difference Water Index (MDNWI) calculated from the green and Shortwave-Infrared (SWIR) bands, is one of the mo...
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