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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.

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Upwelling intensity and wave exposure determine recruitment of intertidal mussels and barnacles in the southern Benguela upwelling region

Pfaff, M.C., G.M. Branch, E.A. Wieters, R.A. Branch, and B.R. Broitman, "Upwelling intensity and wave exposure determine recruitment of intertidal mussels and barnacles in the southern Benguela upwelling region," Mar. Ecol. Prog. Ser., 435, 141-152, doi:10.3354/meps09003, 2011.

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14 Mar 2011

Marine larval dispersal and recruitment dynamics are fundamentally linked with nearshore circulation. In coastal upwelling systems, shoreline topography induces predictable circulation patterns, spanning a range of spatial and temporal scales. Based on a 5 yr time series of monthly recruitment of intertidal mussels and barnacles at 8 sites along 400 km of the southern Benguela upwelling region, which extends around the Cape of Good Hope, South Africa, we addressed the hypothesis that recruitment will exhibit spatial and temporal patterns reflecting the influence of topography and season on upwelling.

Both taxa showed strongly seasonal recruitment peaks: mussels during the summer upwelling season and barnacles during spring. Spatially, mussels and barnacles differed in their regional-scale recruitment trends: recruitment of mussels increased northwards while that of barnacles peaked in the south. However, their mesoscale recruitment patterns were alike, with lower recruitment rates at headland upwelling centers than in adjacent bays. On a smaller scale of hundreds of meters, wave exposure had a positive effect on the recruitment of mussels and (to a lesser extent) barnacles. Spatial patterns were remarkably persistent over time and, for barnacles, strongly negatively correlated with upwelling, as quantified by a site-specific coastal upwelling index.

The effect of temporal upwelling dynamics on recruitment was site dependent: mussel recruitment was strongly and positively correlated with upwelling at all sites, while barnacle recruitment showed a weak and spatially inconsistent link to upwelling fluctuations. The persistence of the spatial structure of recruitment and its coherence between unrelated taxa emphasizes the role of shoreline topography, thereby increasing our capacity to include regional-scale processes in the management and conservation of coastal ecosystems.

Remotely sensed river surface features compared with modeling and in situ measurements

Plant, W.J., R. Branch, G. Chatham, C.C. Chickadel, K. Hayes, B. Hayworth, A. Horner-Devine, A. Jessup, D.A. Fong, O.B. Fringer, S.N. Giddings, S. Monismith, and B. Wang, "Remotely sensed river surface features compared with modeling and in situ measurements," J. Geophys. Res., 114, doi:10.1029/2009JC005440, 2009.

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3 Nov 2009

Images of river surface features that reflect the bathymetry and flow in the river have been obtained using remote sensing at microwave, visible, and infrared frequencies. The experiments were conducted at Jetty Island near the mouth of the Snohomish River at Everett, Washington, where complex tidal flow occurs over a varied bathymetry, which was measured as part of these experiments. An X band (9.36 GHz) Doppler radar was operated from the river bank and produced images of normalized radar cross sections and radial surface velocities every 20 min over many tidal cycles. The visible and infrared instruments were flown in an airplane. All of these techniques showed surface evidence of frontal features, flow over a sill, and flow conditioned by a deep hole. These features were modeled numerically, and the model results correspond well to the remote observations. In situ measurements made near the hole showed that changes in measured velocities correlate well with the occurrence of the features in the images. In addition to tidal phase, the occurrence of these features in the imagery depends on tidal range. The surface roughness observed in the imagery appears to be generated by the bathymetry and flow themselves rather than by the modulation of wind waves.

Relating microwave modulation to microbreaking observed in infrared imagery

Branch, R., W.J. Plant, M. Gade, A.T. Jessup, "Relating microwave modulation to microbreaking observed in infrared imagery," IEEE Geosci. Remote Sens. Lett., 5, 364-367, 10.1109/LGRS.2008.916198, 2008.

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16 Jul 2008

Microwave modulation by swell waves and its relation to microbreaking waves were investigated in an ocean experiment. Simultaneous collocated microwave and infrared (IR) measurements of wind waves and swell on the ocean were made. The normalized radar cross section sigma0 and the skin temperature Tskin were both modulated by the swell, but with differing phases. In general, sigma0 maxima occurred on the front face, whereas Tskin maxima occurred on the rear face of the swell. Infrared imagery has shown that swell-induced microbreaking occurred at or near the swell crest and that the resulting warm wakes occurred on the rear face of the wave. When tilt and range modulations are taken into account, the location of microbreaking also accounts for the maximum of sigma0 occurring on the front face of the swell. Thus, microbreaking waves generated near the crest of low-amplitude swell can produce microwave and IR signatures with the observed phase. The relationship between microwave and IR signals was further emphasized by comparing microwave Doppler spectra with simultaneous IR and visible images of the sea surface from the same location. When small and microscale breaking waves were present, Doppler spectra exhibited characteristics that are similar to those from whitecaps, having peaks with large Doppler offsets and polarization ratios near unity. When no microbreakers were present, Doppler offsets and polarization ratios were much smaller in accordance with a composite surface scattering theory.

Comparisons of shipboard infrared sea surface skin temperature measurements from the CIRIMS and the M-AERI

Branch, R., A.T. Jessup, P.J. Minnett, and E.L. Key, "Comparisons of shipboard infrared sea surface skin temperature measurements from the CIRIMS and the M-AERI," J. Atmos. Ocean. Technol., 25, 598-606, 2008.

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1 Apr 2008

Extensive comparisons are made of the infrared sea surface skin temperature Tskin measured by the Calibrated Infrared In situ Measurement System (CIRIMS) and the Marine-Atmospheric Emitted Radiance Interferometer (M-AERI). Data were collected from four separate deployments on the NOAA research vessel (R/V) Ronald H. Brown and the U.S. Coast Guard (USCG) Polar Sea over a wide range of latitudes and environmental conditions. The deployment time totaled roughly 6 months over a 4-yr period and resulted in over 7000 comparison values.

The mean offset between the two instruments showed that CIRIMS consistently measured a lower temperature than the M-AERI, but by less than 0.10°C. This mean offset was found to be dependent upon sky condition, wind speed, and ship roll, which implies the offset is likely due to uncertainty in the emissivity. The CIRIMS Tskin was recomputed using two alterative emissivity values, one based on emissivity measured by the M-AERI and the other based on a wind-speed-dependent model. In both cases, the recomputation of the CIRIMS Tskin significantly reduced the mean offset. The overall standard deviation between the M-AERI and CIRIMS Tskin was 0.16°C, did not significantly depend on environmental conditions, and was within the expected values of instrument and comparison uncertainties. These comparisons demonstrate the success of CIRIMS in achieving good agreement with the M-AERI over a wide range of conditions. The results also highlight the importance of the sea surface emissivity when measuring the ocean surface skin temperature.

Integrated ocean skin and bulk temperature measurements using the Calibrated Infrared in Situ Measurement System (CIRIMS) and through-hull ports

Jessup, A.T., and R. Branch, "Integrated ocean skin and bulk temperature measurements using the Calibrated Infrared in Situ Measurement System (CIRIMS) and through-hull ports," J. Atmos. Ocean. Technol., 25, 579-597, 2008.

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1 Apr 2008

The design and performance of a shipboard-integrated system for underway skin and bulk temperature is presented. The system consists of the Calibrated Infrared In situ Measurement System (CIRIMS) and through-hull temperature sensors. The CIRIMS is an autonomous shipboard radiometer system that measures the sea surface skin temperature Tskin for validation of satellite-derived sea surface temperature products. General design considerations for shipboard radiometer systems are discussed and the philosophy behind the CIRIMS design is presented. Unique features of the design include a constant temperature housing to stabilize instrument drift, a two-point dynamic calibration procedure, separate sky- and sea-viewing radiometers for simultaneous measurements, and the ability to use an infrared transparent window for environmental protection. Laboratory testing and field deployments are used to establish an estimated error budget, which includes instrumentation and environmental uncertainties.

The combination of this testing and field comparison to the Marine-Atmosphere Emitted Radiance Interferometer (M-AERI) and Infrared SST Autonomous Radiometer (ISAR) instruments indicates that the CIRIMS meets the design goal of ±0.10°C accuracy. Temperature and pressure sensors were installed in custom-designed through-hull ports on the NOAA research vessel (R/V) Ronald H. Brown and the University of Washington R/V Thomas G. Thompson to complement the CIRIMS measurements. The ports allow sensors to be installed while the ship is in water and can accommodate a variety of sensors. The combined system provides the ability to measure near-surface temperature profiles from the skin to a depth of 5 m while underway.

Infrared signatures of microbreaking wave modulation

Branch, R., and A.T. Jessup, "Infrared signatures of microbreaking wave modulation," IEEE Geosci. Remote Sens. Lett., 4, 372-376, doi:10.1109/LGRS.2007.895688, 2007.

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16 Jul 2007

Infrared (IR) imagery of microbreaking waves in the ocean and laboratory showed modulation of breaking by swell and paddle-generated waves, respectively. Skin temperature also was modulated by the long waves, with the maxima occurring on the rear face of the long waves in both the laboratory and the field. The IR imagery from the ocean and laboratory showed that long-wave-induced microbreaking occurred at or near the long wave crest, and the resulting warm wakes occurred on the rear face. Thus, microbreaking waves generated near the crest of low-amplitude long waves can produce modulation with the maxima on the rear face. This mechanism was shown to be responsible for modulation of the measured in the laboratory and also likely contributed to the modulation observed in the field.

Ship-based measurements for infrared sensor validation during Aerosol and Ocean Science Expedition 2004

Nalli, N.R., P. Clemente-Colon, P.J. Minnett, M. Szczodrak, V. Morris, E. Joseph, M.D. Goldberg, C.D. Barnet, W.W. Wolf, A. Jessup, R. Branch, R.O. Knuteson, and W.F. Feltz, "Ship-based measurements for infrared sensor validation during Aerosol and Ocean Science Expedition 2004," J. Geophys. Res., 111, 10.1029/2005JD006385, 2006.

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7 Apr 2006

This paper describes a unique validation data set acquired from a marine intensive observing period (IOP) conducted on board the NOAA Ship Ronald H. Brown (RHB) during the 2004 Aerosol and Ocean Science Expedition (AEROSE) in the tropical North Atlantic Ocean from 29 February to 26 March 2004. The radiometric and in situ data complement includes marine observations of the Saharan air layer (SAL), including two significant Saharan dust outbreaks over the Atlantic Ocean. Because the impact of tropospheric dust aerosols on satellite infrared (IR) radiometric observations has not yet been fully characterized, the AEROSE data are particularly valuable for IR sensor validation. Shipboard radiometric data germane to satellite validation include observations from a Marine Atmospheric Emitted Radiance Interferometer (M-AERI), a Calibrated Infrared In situ Measurement System (CIRIMS), and Microtops handheld sunphotometers. Among other things, these data provide, for the first time, coincident IR spectra of the dry, dusty SAL from both the uplooking M-AERI and the downlooking Atmospheric Infrared Sounder (AIRS) on board the Aqua satellite. In situ data collected throughout the cruise include Vaisala RS80/90 radiosondes, launched 3-hourly to include Aqua overpass times. The Aqua matchup profiles provide data for validation of AIRS in the presence of high dust loading, along with temperature and water vapor profile retrievals of the SAL. The frequency of sonde launches also enables validation of coincident uplooking M-AERI boundary layer profile retrievals. Preliminary analyses of the AEROSE data are presented here. Focused AEROSE validation studies are the subjects of separate papers.

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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