TY - JOUR T1 - Estimation of Air Temperature Using Temperature-Vegetation Index (TVX) Method TT - تخمین دمای هوا با استفاده از روش شاخص پوشش گیاهی- دما (TVX) JF - JSTNAR JO - JSTNAR VL - 15 IS - 56 UR - http://jstnar.iut.ac.ir/article-1-1704-en.html Y1 - 2011 SP - 21 EP - 34 KW - Air temperature KW - Land surface temperature KW - Vegetation index (NDVI) KW - TVX method KW - Sefidrod River basin. N2 - The determination of air temperature is important in the energy balance calculation, hydrology and meteorological studies. In this regard, the limited number of meteorological stations is one of the serious problems for air temperature determination on a large spatial scale. The remote sensing technique by covering large areas and using updated satellite images might be appropriate for estimation of this parameter. In this research, the negative correlation between land surface temperature and vegetation index (NDVI) has been used for air temperature estimation through TVX method in which the inference of air temperature is based on the hypothesis that the temperature of the dense vegetation canopy is close to air temperature. For investigation the performance of TVX method, images of MODIS sensor have been applied for the Sefidrod River basin in the years 1381- 1382-1384. The spilt window technique which was developed by Price has been used for land surface temperature calculation. The mean difference between observed and estimated land surface temperature using Price algorithm was about 6.2Co. This error can affect the air temperature values. Because of using NDVI index in TVX method, this method has the sensitivity to the vegetation density, though in the parts with sparse vegetation, the value of error increases. 4 percent variation of air temperature against the 0.05 increasing of maximum NDVI indicates the high performance of TVX method for air temperature estimation in large areas. M3 ER -