Shade estimation over streams using distributed temperature sensing

The characterization of temporal and spatial distribution of sunlight is essential for understanding energy transport in natural ecosystems. Fiber-optic distributed temperature sensing (DTS) allows meter resolution measurements of temperature at subminute resolution. The difference in temperature due to absorption and reflection of a pair of helically twisted black and white fiber-optic cables was measured with a DTS to document areas exposed to sunlight over the Walla Walla River. A high correlation (R-2 = 0.99) was found between DTS-based results and manual field observations of effective shade. These preliminary results provide proof of the concept that this method can be used for estimating the effective shade at fine spatial resolutions. Potential shortcomings and the need for a more quantitative physical model are suggested for further research.