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Ruth Branch

Engineer IV

Email

rbranch@apl.washington.edu

Phone

206-221-7623

Education

B.S. Physics, University of Washington, 1998

M.S. Physics, University of Washington, 1999

M.S. Civil Engineering, University of Washington, 2003

Publications

2000-present and while at APL-UW

Remote measurements of tides and river slope using an airborne Lidar instrument

Hudson, A.S., S.A. Talke, R. Branch, C. Chickadel, G. Farquharson, and A. Jessup, "Remote measurements of tides and river slope using an airborne Lidar instrument," J. Atmos.Ocean.Technol., 34, 897–904, doi:10.1175/JTECH-D-16-0197.1, 2017.

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24 Apr 2017

Tides and river slope are fundamental characteristics of estuaries, but they are usually undersampled due to deficiencies in the spatial coverage of water level measurements. This study aims to address this issue by investigating the use of airborne lidar measurements to study tidal statistics and river slope in the Columbia River estuary. Eight plane transects over a 12-h period yield at least eight independent measurements of water level at 2.5-km increments over a 65-km stretch of the estuary. These data are fit to a sinusoidal curve and the results are compared to seven in situ gauges. In situ– and lidar-based tide curves agree to within a root-mean-square error of 0.21 m, and the lidar-based river slope estimate of 1.8 × 10−5 agrees well with the in situ–based estimate of 1.4 × 10−5 (4 mm km−1 difference). Lidar-based amplitude and phase estimates are within 10% and 8°, respectively, of their in situ counterparts throughout most of the estuary. Error analysis suggests that increased measurement accuracy and more transects are required to reduce the errors in estimates of tidal amplitude and phase. However, the results validate the use of airborne remote sensing to measure tides and suggest this approach can be used to systematically study water levels at a spatial density not possible with in situ gauges.

Infrared emissivity of seawater and foam at large incidence angles in the 3–14 μm wavelength range

Branch, R., C.C. Chickadel, and A.T. Jessup, "Infrared emissivity of seawater and foam at large incidence angles in the 3–14 μm wavelength range," Remote Sens. Environ., 184, 15-24, doi:10.1016/j.rse.2016.06.009, 2016.

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1 Oct 2016

Highlights

We measured infrared emissivity of seawater and sea foam in a laboratory experiment.

We developed a method to estimate emissivity for incidence angles up to 85°.

Foam emissivity is higher than water for all wavelengths and angles > 65°.

The difference between foam and water emissivity increases with incidence angle.

Thermal infrared multipath reflection from breaking waves observed at large incidence angles

Branch, R., C.C. Chickadel, and A.T. Jessup, "Thermal infrared multipath reflection from breaking waves observed at large incidence angles," IEEE Trans. Geosci. Remote Sens., 52, 249-256, doi:10.1109/TGRS.2013.2238241, 2014.

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1 Jan 2014

The infrared signature of breaking waves at large incidence angles was investigated using laboratory experiments and a radiometric model. Infrared imagery of the water surface at incidence angles greater than 70° shows multipath reflections for both spilling and plunging waves generated using a programmable wave maker. For the spilling breakers, the multipath signature was initially distinct from the breaking wave front roller signature but then merged to create a single large bright distributed target. For the plunging breakers, the roller and multipath signatures overlapped from the inception of breaking. The radiance of the multipath reflection was higher than the surrounding water for simulated cold sky conditions and lower for a simulated warm sky. A specular double-reflection model successfully predicted the presence of multipath reflection but the magnitude was sensitive to small uncertainties in geometry, wave slope, and input temperatures. The results show that multipath reflection from breaking waves is characteristic of large incidence angle infrared measurements and increases the area and magnitude of the infrared signature of breaking waves compared to the background.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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