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Andy Jessup

Senior Principal Oceanographer

Professor, Civil and Environmental Engineering and Affiliate Associate Professor, Mechanical Engineering





Research Interests

Air-Sea Interaction, Remote Sensing


Dr. Jessup joined APL-UW as a research scientist in 1990 after receiving his Ph.D. in Oceanography and Ocean Engineering from the MIT/WHOI Joint Program. He began a program in air-sea interaction using infrared techniques that has led to a wide variety of field and laboratory investigations.

His recent interests include remote sensing of river inlets and the infrared signature of breaking waves relevant to wake detection. He is Chair of the Air-Sea Interaction and Remote Sensing Department and a Professor in Civil and Environmental Engineering.


B.S.E. Engineering Science, University of Michigan, 1980

M.S.E. Civil Engineering, Massachusetts Institute of Technology, 1988

Ph.D. Oceanography & Ocean Engineering, MIT and WHOI Joint Program, 1990


Salinity Processes in the Upper Ocean Regional Study — SPURS

The NASA SPURS research effort is actively addressing the essential role of the ocean in the global water cycle by measuring salinity and accumulating other data to improve our basic understanding of the ocean's water cycle and its ties to climate.

15 Apr 2015

Skin and Bulk Sea Surface Temperature Validation Program

There is a growing consensus that sea surface temperature (SST) products derived from satellite-based infrared (IR) sensors should include ocean skin temperature. To validate satellite-based measurements of skin temperature, widespread, in situ data are required.


Fluxes, Air-Sea Interaction, and Remote Sensing (FAIRS) Experiment

The transfer of momentum, heat, and gas across the air-sea boundary is characterized and quantified by measuring the underlying physical mechanisms with remote sensing instruments.


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IRISS — InfraRed In situ Skin and Subskin — Experiments

Infrared radiometers are used to take the temperature of the very surface of the ocean. In this project 'gold standard' radiometers used to measure the ocean skin temperature are compared alongside simplified and miniaturized infrared systems. The goal is to deploy these small, lightweight, and comparatively inexpensive sensing systems on uncrewed surface vehicles to increase data coverage of the global ocean.

12 Oct 2021

NASA Expedition Measures the Salty Seas

Chief Scientist Andy Jessup and a multi-institutional team of researchers embarked on an expedition to the tropical Pacific Ocean in early August 2016.

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19 Aug 2016

The team is measuring near-surface ocean salinity and the atmospheric and oceanic dynamics that control it. For their part, researchers from APL-UW’s Air-Sea Interactions and Remote Sensing Department are using several platforms on the R/V Revelle to measure the ocean’s response to freshwater input during and immediately after intense bursts of rainfall that are typical of the eastern tropical Pacific Ocean

DARLA: Data Assimilation and Remote Sensing for Littoral Applications

Investigators completed a series of experiments in April 2013 at the mouth of the Columbia River, where they collected data using drifting and airborne platforms. DARLA's remote sensing data will be used to drive representations of the wave, circulation, and bathymetry fields in complex near-shore environments.

5 Dec 2013

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2000-present and while at APL-UW

Laboratory heat flux estimates of seawater foam for low wind speeds

Chickadel, C.C., R. Branch, W.E. Asher, and A.T. Jessup, "Laboratory heat flux estimates of seawater foam for low wind speeds," Remote Sens., 14, doi:10.3390/rs14081925, 2022.

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15 Apr 2022

Laboratory experiments were conducted to measure the heat flux from seafoam continuously generated in natural seawater. Using a control volume technique, heat flux was calculated from foam and foam-free surfaces as a function of ambient humidity (ranged from 40% to 78%), air–water temperature difference (ranged from –9°C to 0°C), and wind speed (variable up to 3 m s-1). Water-surface skin temperature was imaged with a calibrated thermal infrared camera, and near-surface temperature profiles in the air, water, and foam were recorded. Net heat flux from foam surfaces increased with increasing wind speed and was shown to be up to four times greater than a foam-free surface. The fraction of the total heat flux due to the latent heat flux was observed for foam to be 0.75, with this value being relatively constant with wind speed. In contrast, for a foam-free surface the fraction of the total heat flux due to the latent heat flux decreased at higher wind speeds. Temperature profiles through foam are linear and have larger gradients, which increased with wind speed, while foam free surfaces show the expected logarithmic profile and show no variation with temperature. The radiometric surface temperatures show that foam is cooler and more variable than a foam-free surface, and bubble-resolving thermal images show that radiometrically transparent bubble caps and burst bubbles reveal warm foam below the cool surface layer, contributing to the enhanced variability.

Surface turbulence reveals riverbed drag coefficient

Branch, R.A., A.R. Horner-Devine, C.C. Chickadel, S.A. Talke, D. Clark, and A.T. Jessup, "Surface turbulence reveals riverbed drag coefficient," Geophys. Res. Lett., 48, doi:10.1029/2020GL092326, 2021.

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28 May 2021

Flow in rivers and the coastal ocean is controlled by the frictional force exerted on the water by riverbed or seabed roughness. The frictional force is typically characterized by a drag coefficient Cd, which is estimated from bulk measurements and often assumed constant. Here, we demonstrate a relationship between bed roughness and water surface turbulence that can be used to make remote estimates of CdCd, and validate this relationship by comparing remotely sensed estimates of Cd to those from in situ measurements. Thus, our results provide an approach for estimating bottom roughness and Cd based entirely on remotely sensed data, including their spatial variability, which can improve modeling of river discharge and morphodynamics in data-poor regions.

Surf zone waves at the onset of breaking: 1. LIDAR and IR data fusion methods

Carini, R.J., C.C. Chickadel, and A.T. Jessup, "Surf zone waves at the onset of breaking: 1. LIDAR and IR data fusion methods," J. Geophys. Res., 126, doi:10.1029/2020JC016934, 2021.

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1 Apr 2021

This is the first of a 2‐part series concerning remote observation and wave‐by‐wave analysis of the onset of breaking in the surf zone. In the surf zone, breaking waves drive nearshore circulation, suspend sediment, and promote air–sea gas exchange. Nearshore wave model predictions often diverge from in situ measurements near the break point location because common parameterizations do not account for the rapid changes that occur near the onset of breaking. This work presents extensive methodology to combine data from a line‐scanning LIDAR and thermal infrared cameras to detect breaking, classify breaker type, and measure geometric wave parameters on a wave‐by‐wave basis, which can be used to improve breaker parameterizations. Over 2,600 non‐breaking and 1,600 breaking waves are analyzed from data collected at the USACE Field Research Facility in Duck, NC, including 413 spilling and 111 plunging waves for which the onset of breaking was observed. Wave height is estimated using a spatio‐temporal method for wave tracking that preserves the sea surface elevation maximum and overcomes field of view limitations. Methods for estimating instantaneous wave speed are refined by fitting a skewed Gaussian function to each wave profile before tracking the peaks. Wave slope is estimated from a linear fit to the upper 80% of the wave face, which provides a robust metric and strong correlation with geometric wave slope defined relative to mean sea level. Finally, breaking wave face foam coverage is analyzed to assess common model assumptions about roller length for wave energy dissipation parameterizations.

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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