APL Home
APL-UW Home

Jobs
About
Campus Map
Contact
Privacy
Intranet

Matthew Alford

Affiliate Principal Oceanographer

Affiliate Professor, Oceanography

Email

malford@apl.washington.edu

Research Interests

Ocean dynamics (including internal waves, the mixed layer, abyssal overflows and turbulence) and their impact on the global circulation and coastal ecosystems

Biosketch

Dr. Alford is a seagoing physical oceanographer. Whether purchased off the shelf or built by him and/or others at the Laboratory, he employs specialized instruments to better describe and understand processes that occur on scales, say, < 10 km; however, he is also interested in how these affect both coastal processes and the larger-scale circulation. His research focuses on 1) process studies of these phenomena themselves, 2) instrument development, 3) observational techniques to better study them, and 4) the specific ways in which they affect global-scale phenomena as well as biological/chemical processes such as anoxia. In 2002 Alford received the Office of Naval Research's prestigious Young Investigator Program (YIP) Award, and in 2009 received the University of Washington College of Fishery and Ocean Sciences' Distinguished Research Award. He has over 70 refereed publications in top-tier journals including Nature and Journal of Physical Oceanography, and has led several ambitious experiments funded by the Office of Naval Research and the National Science Foundation.

Department Affiliation

Ocean Physics

Education

B.A. Astrophysics, Swarthmore College, 1993

Ph.D. Oceanography, Scripps Institution of Oceanography, 1998

Projects

Tasmania Internal Tide Experiment

The Tasmanian continental slope will be instrumented with a range of tools including moored profiler, chi-pods, CTDs, and gliders to understand the process, strength, and distribution of ocean mixing from breaking internal waves.

27 Nov 2011

Samoan Passage Abyssal Mixing

The Samoan Passage, 5500 m beneath the sea surface, is one of the "choke points" in the abyssal circulation. A veritable river of Antarctic Bottom water flows through it on its way into the North Pacific. As it enters the constriction, substantial turbulence, hydraulic processes and internal waves must occur, which modify the water. The overall goal is to understand these deep processes and the way they impact the flow, and to develop a strategy for eventually monitoring the flow through the Passage.

27 Sep 2011

Washington Real-time Coastal Moorings (NEMO)

The Northwest Enhanced Moored Observatory (NEMO), which consists of a heavily-instrumented real-time surface mooring (Cha Ba), a real-time subsurface profiling mooring (NEMO-Subsurface) and a Seaglider to collect spatial information, aims to improve our understanding of complex physical, chemical and biological processes on the largely unsampled Washington shelf.

27 Sep 2011

More Projects

Videos

Ocean Acidification

Scientists from APL-UW and NOAA are studying the changing pH of Washington's coastal waters. Puget Sound may be hit hard and fast by the threat of ocean acidification.

3 Oct 2013

NEMO Deployment and Shelf Science Cruise

The primary purpose of the cruise is to deploy the NEMO (Northwest Enhanced Moored Observatory) moorings off the Washington coast in water about 100 m deep. While at sea, the team will also conduct science experiments to detect and track non-linear internal waves (NLIWs) traveling across the continental shelf break. Surveys with an echo sounder and the towed body SWIMS will be run from the shelf break toward the mooring location as well as in the Juan de Fuca Canyon.

16 Apr 2013

Wave Chasers: Deep Flows Through the Samoan Passage

The 'Wave Chasers' research team cruised the South Pacific Ocean to study the Samoan Passage — a 5500-m deep choke point that Antarctic bottom water must flow through on its way to the North Pacific. Three movies chronicle the expedition's motivations & methods, the fun of crushing objects under the pressures of the abyssal ocean, and the cultural exchanges with Samoans on Upolu Island.

More Info

22 Feb 2012

"Instruments & Measurements," movie #1, explains the motivation and experimental design to study Antarctic bottom water as it flows through the constriction of the Samoan Passage. The flow is modified by substantial turbulence, hydraulic processes, and internal waves.

Movie #2, "Crush Cam," documents how Oceanographers Matthew Alford and John Mickett are always looking for better ways to share scientific research with the public. They came up with this "Crush Cam." It's a video camera mounted to the instrument package that is lower from the ship and the sea surface to varying depths in the Samoan Passage — it's a way to video objects under extreme pressure.

The third movie, "Cultural Exchanges," follows the Wave Chasers as they visit the village of LufiLufi on the north coast of Upolu Island.

More Videos

Publications

2000-present and while at APL-UW

Global observations of open-ocean mode-1 M2 internal tides

Zhao, Z., M.H. Alford, J.B. Girton, L. Rainville, and H.L. Simmons, "Global observations of open-ocean mode-1 M2 internal tides," J. Phys. Oceanogr., 46, 1657-1684, doi:10.1175/JPO-D-15-0105.1, 2016.

More Info

1 Jun 2016

A global map of open-ocean mode-1 M2 internal tides is constructed using sea-surface height (SSH) measurements from multiple satellite altimeters during 1992–2012, representing a 20-year coherent internal tide field. A two-dimensional plane wave fit method is employed to (1) suppress mesoscale contamination by extracting internal tides with both spatial and temporal coherence, and (2) separately resolve multiple internal tidal waves. Global maps of amplitude, phase, energy and flux of mode-1 M2 internal tides are presented. M2 internal tides are mainly generated over topographic features including continental slopes, mid-ocean ridges and seamounts. Internal tidal beams of 100–300 km width are observed to propagate hundreds to thousands of km. Multi-wave interference of some degree is widespread, due to the M2 internal tide's numerous generation sites and long-range propagation. The M2 internal tide propagates across the critical latitudes for parametric subharmonic instability (28.8°S/N) with little energy loss, consistent with field measurements by MacKinnon et al. (2013). In the eastern Pacific Ocean, the M2 internal tide loses significant energy in propagating across the Equator; in contrast, little energy loss is observed in the equatorial zones of the Atlantic, Indian, and western Pacific oceans. Global integration of the satellite observations yields a total energy of 36 PJ (1 PJ = 1015 J) for the coherent mode-1 M2 internal tide. The satellite observed M2 internal tides compare favorably with field mooring measurements and a global eddy-resolving numerical model.

An inductive charging and real-time communications system for profiling moorings

Alford, M.H., T. McGinnis, and B.M. Howe, "An inductive charging and real-time communications system for profiling moorings," J. Atmos. Ocean. Technol., 32, 2243-2252, doi:10.1175/JTECH-D-15-0103.1, 2015.

More Info

1 Dec 2015

We describe a system for providing power and communications to moored profiling vehicles. A McLane Moored Profiler (MP) was equipped with a rechargeable battery pack and an inductive charging system to allow it to move periodically to a charging dock at the top of the subsurface mooring. Power was provided from a large bank of alkaline batteries housed in two 0.95-m steel spheres. Data were transferred inductively from the profiler to a mooring controller, and from there back to shore via radio and Iridium satellite modems housed in a small surface communications float on an "L" tether. An acoustic modem provided backup communications to a nearby ship in the event of loss or damage to the surface float. The system was tested in a 180-m-deep fjord (Puget Sound, WA) and at station ALOHA, a 4748-m deep open-ocean location north of Hawaii. Basic functionality of the system was demonstrated, with the Profiler repeatedly recharging at about 300W (with an overall efficiency of about 70%). Data were relayed back to shore via Iridium, and to a nearby ship via the radio and acoustic modems. The system profiled flawlessly for the entire 6-week test in Puget Sound, but charging at the deep site stopped after only 9 days in the deep-ocean deployment owing to damage to the charging station, possibly by surface wave action.

Instabilities in nonlinear internal waves on the Washington continental shelf

Zhang, S., and M.H. Alford, "Instabilities in nonlinear internal waves on the Washington continental shelf," J. Geophys. Res., 120, 5272-5283, doi:10.1002/2014JC010638, 2015.

More Info

31 Jul 2015

Previous studies have identified two primary mechanisms (shear instability and convective instability) by which nonlinear internal waves (NLIWs) induce mixing on continental shelves. To determine the relative importance of these and their dependence on background flow conditions, we examine a much longer (6 month) data set from a moored ADCP/thermistor chain with 2 m vertical spacing in which over 600 NLIWs are detected. Turbulent properties of the 318 waves with detectable overturning instabilities are documented using Thorpe scales. The 130 waves detected while an ADCP was functioning are classified based on a Froude number criterion (Fr). Of these, 108 waves are identified as shear-instability (Type I; Fr <1) waves and 22 as convective instability (Type II; Fr 1). Composites are constructed by averaging in a wave coordinate frame over all waves in each category, showing the mean spatial structure of dissipation and other wave quantities. Turbulence is highest at the sheared interface for Type I waves and throughout the wave core for Type II waves. No relationship between wave instability mechanisms and wave/background parameters such as wave steepness, stratification, or mean flow is found, except that unstable waves tend to be more energetic, demonstrating a need to better understand wave propagation and breaking in complex and variable coastal oceanographic background flows.

More Publications

In The News

Voyage traces stirred-up Arctic heat

BBC, Jonathan Webb

Using a gadget developed by UW's Applied Physics Laboratory, oceanographers have gathered evidence that turbulence in the Arctic Ocean is stirring up heat from the depths.

28 Sep 2015

Underwater waves are the Earth's 'lumbering giants'

USA Today, Traci Watson

A 70-foot wave is a terrifying wall of water that only the best surfers can ride. But it's a midget compared with the colossal and mysterious waves that lurk under the ocean's surface.

These underwater waves, though seldom noticed, can rival skyscrapers in height and measure more than 100 miles wide. They can imperil submarines and disrupt operations on offshore oil platforms. They've been photographed by astronauts in orbit,and they've been cursed by bewildered sailors. Scientists are gaining fresh insights into these massive waves, including their potentially important role in climate change.

22 May 2014

First siting of deep lee waves: Kaena RIdge, Hawaii

EOS, Trans. Am. Geophys. Union, JoAnna Wendel

Previous studies with remote observations and numerical models have predicted the existence of breaking deep internal lee waves driven by the tide, but until now, none have been observed directly.

22 Apr 2014

More News Items

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
Close

 

Close