Abstract
Both land surface/skin temperature and vegetation indices data provided routinely and globally by NASA MODIS sensors at 1-km grid resolution represent an important piece of information assimilated into various environmental applications/models. Previous studies based on these and similar remotely data sets and on two-component pixel representation (accounting for pixel-aggregated vegetation and bare soil temperatures only) have shown a rather strong linear relationship between the pixel's skin temperature and the vegetation index/fraction. Deviations (Δ0) from this relationship are frequently used for soil moisture content estimates at a pixel scale. As the two-component pixel model does not account for subpixel heterogeneity (associated, for example, with bare soil temperature variability within the pixel), its role in controlling a magnitude of Δ0 has been examined. A simple tri-component pixel model describing vegetation and wet and dry bare soil temperatures was suggested to analyse an impact of this heterogeneity on Δ0 estimates. This model was considered to provide a 'true' estimate of Δ0 as compared with Δ0 evaluated from the two-component pixel model. A comparison between the models shows that a substantial underestimation of Δ0 was likely to occur at a level of individual pixels when the two-component approach was applied for interpretation of the observed relationship between the skin temperature and the vegetation index. Depending on the fraction of pixel occupied by the dry soil, this underestimation might be as much as 100%.
Original language | English |
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Pages (from-to) | 2819-2831 |
Number of pages | 13 |
Journal | International Journal of Remote Sensing |
Volume | 29 |
Issue number | 10 |
DOIs | |
State | Published - May 2008 |
Externally published | Yes |
Funding
This research was sponsored by the National Aeronautical and Space Administration through NAS1303032 via the Mississippi Research Consortium. Encouragement, and support by Dr David Shaw is highly appreciated. The authors acknowledge thorough comments provided by anonymous reviewers.
Funders | Funder number |
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Mississippi Research Consortium | |
National Aeronautics and Space Administration | NAS1303032 |