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Andy Jessup

Chair, AIRS Department & 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.


More Projects


2000-present and while at APL-UW

Estimating rain-generated turbulence at the ocean surface using the active controlled flux technique

Asher, W.E., K. Drushka, A.T. Jessup, E.J. Thompson, and D. Clark, "Estimating rain-generated turbulence at the ocean surface using the active controlled flux technique," Oceanography, 32, 108-115, doi:10.5670/oceanog.2019.218, 2019.

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14 Jun 2019

Rain-generated lenses of fresher water at the ocean surface affect satellite remote sensing of salinity, mixed-layer dynamics, and air-sea exchange of heat, momentum, and gases. Understanding how rain and wind generate turbulence at the ocean surface is important in modeling the generation and evolution of these fresh lenses. This paper discusses the use of the active controlled flux technique (ACFT) to determine relative levels of turbulence in the top centimeter of the ocean surface in the presence of rain. ACFT measurements were made during the 2016 second Salinity Processes in the Upper-ocean Regional Study (SPURS-2) in the eastern equatorial Pacific Ocean. The data show that at wind speeds below 4 m s-1, the turbulence dissipation rate at the ocean surface (as parameterized by the water-side surface renewal time constant) is correlated with the instantaneous rain rate. However, at higher wind speeds, the wind stress dominates turbulence production and rain is not a significant source of turbulence. There is also evidence that internal waves can be a significant source of turbulence at the ocean surface under non-raining conditions when a diurnal warm layer is present.

High-resolution rain maps from an X-band marine radar and their use in understanding ocean freshening

Thompson, E.J., W.E. Asher, A.T. Jessup, and K. Drushka, "High-resolution rain maps from an X-band marine radar and their use in understanding ocean freshening," Oceanography, 32, 58-65, doi:10.5670/oceanog.2019.213, 2019.

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14 Jun 2019

Ship-based X-band radar observations of rain were collected with high spatial resolution during the 2016 and 2017 Salinity Processes in the Upper-ocean Regional Study 2 (SPURS-2) field experiments in the eastern tropical Pacific Ocean. These observations were collected with a repurposed marine radar that is not typically used for weather monitoring. The radar images captured during SPURS-2 show the spatial extent and variable intensity of rain at a horizontal resolution of 180 m within 30 km of the ship. When analyzed alongside collocated measurements of oceanic and atmospheric properties collected during SPURS-2, the radar-derived rain maps enable a clearer understanding of the impact of spatially and temporally varying freshwater fluxes on ocean salinity. Ocean surface freshening, measured by ship gauges, is found to be affected by local rain accumulation, and also by prior rain accumulation in surrounding locations that was measured by radar. In one example, the X-band marine radar measured rain directly ahead of the ship’s path. The ship then sampled a near-surface freshening signature within the time period expected based on the ship speed, ship heading, and rain area measured by the radar. ­

Capturing fresh layers with the surface salinity profiler

Drushka, K., A.E. Asher, A.T. Jessup, E.J. Thompson, S. Iyer, and D. Clark, "Capturing fresh layers with the surface salinity profiler," Oceanography, 32, 76-85, doi:10.5670/oceanog.2019.215, 2019.

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11 Jun 2019

During the second Salinity Processes in the Upper-ocean Regional Study (SPURS-2) field experiments in 2016 and 2017 in the eastern tropical Pacific Ocean, the surface salinity profiler (SSP) measured temperature and salinity profiles in the upper 1.1 m of the ocean. The SSP captured the response of the ocean surface to 35 rain events, providing insight into the generation and evolution of rain-formed fresh layers. This paper describes the measurements made with the SSP during SPURS-2 and quantifies the fresh layers in terms of their vertical salinity gradients between 0.05 m and 1.1 m, ΔS1.1 - 0.05 m. For the 35 rain events sampled with the SSP in 2016 and 2017, the maximum value of ΔS1.1 - 0.05 m is well correlated with the accumulated rainfall. The maximum value of ΔS1.1 - 0.05 m is shown to be linearly proportional to the maximum rain rate and inversely proportional to the wind speed. This wind speed-dependent relationship shows a high degree of scatter, reflecting that the vertical salinity gradient formed during any individual rain event depends on the complex interaction between the local ocean dynamics and the highly variable forcing from rain and wind.

More Publications


Lighter-than-Air Visible and Infrared Imaging SYstem for Persistent Surveillance

Record of Invention Number: 8283D

Andy Jessup, Dan Clark


4 Feb 2009

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