Ole Aarup Mikkelsen, President & CEO
My initial life plan was to become a theoretical physicist, Stephen Hawking was an early idol. But in high school I had a phenomenal geography teacher, so that’s what I ended up studying in college instead. My Ph.D. thesis (2001) dealt with suspended particle dynamics in Danish coastal waters, and had lots of LISST results in it. One of Sequoia’s very first customers was my supervisor, Professor Morten Pejrup at University of Copenhagen, and to a large extent my life and career has been intertwined with Sequoia since he bought LISST-100 s/n 1019 from Sequoia in 1997. (That unit, btw, is still going strong today (2019), and despite decades of use it has only been back for service once in 22 years).
A series of early visits to Sequoia during my Ph.D. (1998-2001) and subsequent postdocs in Canada and the UK (2002-2007) led me to being hired by Sequoia and relocating to Seattle in November 2007. During my Ph.D. I used a LISST to study the dynamics sedimentology of suspended particles in Danish coastal waters, leading to some of the first papers on in-situ estimates of flocculation time scales, the influence of flocculation on remote sensing estimates of particle concentration, and a new settling velocity model. During my 2001 visit to Sequoia I started working on the randomly shape particle studies, which culminated in 2008 with the JGR publication of the randomly shaped particle matrices. Sequoia is still the only company in the world to have done this. During my post doc in Canada I developed the INSSECT sampling platform for studying dynamic sedimentology in coastal areas, deployed in a number of locations in Canada and the Adriatic Sea 2002-2005. My work on Schlieren, which can potentially affect all optical instruments, also was initiated during my Canadian postdoc, and finalized during my postdoc in the UK (2005-2007). Upon relocating to Seattle work continued on the randomly shaped particle topic, leading to a couple of papers in Applied Optics with published phase functions for randomly shaped particles.
I left Sequoia in 2013 but was brought back as President 1/1/2019 as Yogi retired.
Chuck Pottsmith, VP, Operations
All of my life I have been fascinated by what makes things work. My whole career as a mechanical engineer has just been an extension of the curiosity I had as a kid. I think I have the best job in the world…I get paid to invent, build, and make work a wide variety of interesting things.
I started my career as a fluid dynamics laboratory technician at Flow Research while going to school at the University of Washington. I learned many things about experimental science and fluid mechanics. In addition to learning the science I also learned the art of machining. My hours spent working with and talking to the “elders” of the machine shop taught me how to be a much better mechanical engineer.
In 1988 I met Dr. Yogi Agrawal. After graduating I started working with Yogi full time and I have been working with him ever since. We have built many unique instruments for our oceanographic research. Most, if not all, included some kind of optics and electronics. Some examples are Laser Doppler Velocimeters, Laser particle size analyzers, and underwater cameras. All of which were in-situ instruments that required close coupling of electronics, optics and mechanical components.
Yogi and I started Sequoia in early 1995 on the idea that we could build a better science and technology company. We wanted to work at a place that could do both high caliber contract science and manufacture state of the art research equipment. We feel that we have achieved that goal.
RETIRED / FORMER STAFF
Yogesh C. Agrawal, President (Emeritus)
Yogi Agrawal arrived at University of California, Berkeley in 1969, after a B. Tech. degree with Distinction (like Cum Laude) from the Indian Institute of Technology in Mumbai, India. After a Master’s degree in 1970 that included an award-winning simulation of tumors of the heart that produce murmurs, he completed his Ph.D. in 1975. His thesis involved developing a laser Doppler velocimetry instrument that he used to study the development of flow in the human aorta – an issue then tied to formation of plaques. He did a brief post-doctoral stint at the Lawrence Berkeley Laboratory, studying dynamics of lean combustion – an issue suddenly brought to prominence with the rise of environmentalism. In 1978, he sought new challenges in the field of Oceanography, joining Woods Hole Oceanographic Institution. His interests in high quality measurements lead to the first deep-ocean laser Doppler velocimeter (LDV), autonomous, operating in deep ocean depth of 5,000m. He followed this with measurements of turbulent energy dissipation rates using a near-surface version of the LDV, hung from a tower in Lake Ontario. This work demonstrated enhanced dissipation in the surface when wave-breaking occurs. The work has been widely cited. In 1988, seeking greener pastures, he migrated to the Seattle area and met and retained Chuck Pottsmith as his assistant – a partnership that would endure for 30 years. After brief stints at two companies, he founded Sequoia Scientific, Inc. together with Chuck Pottsmith (as VP). Recognizing the need for particle size distribution (PSD) and settling velocity distribution (SVD) as fundamental inputs to sediment transport models -neither of which could be measured at that time in situ, he proceeded to develop appropriate laser diffraction technology instruments. The first such instrument, LISST-100 was developed with US Navy funding and demonstrated its capacity to produce the desired PSD measurements. Several papers followed, with observations in storms and coasts. This capability remains unmatched to date (May 2021). This instrument was the first product of Sequoia Scientific, Inc..
Founding Sequoia Scientific, Inc.
With the rapid adoption of LISST-100, other instruments quickly followed. The LISST-ST, that measured settling velocity distribution (SVD), was the second product of Sequoia. With the same core technology, a hand-portable instrument LISST-Portable followed. A rapid succession of others followed, notably the LISST-25 (measuring concentration only), it’s variant LISST-25X (concentrations in 2 size classes: total and sand sizes) and LISST-SL, a streamlined version for river sediment hydrology. Recognizing the need for instruments in ocean optics studies, with NASA funding he developed the LISST-VSF – an instrument measuring the volume scattering function and depolarization of water – an inherent optical property. Of the many instruments since developed, the new technology 8MHz acoustic backscatter sensor LISST-ABS is significant, as is its successor that combines optics and acoustics, the Super-turbidityTM sensor LISST-AOBS. The company grew with high caliber engineers and scientists joining along the way. Among these, Dr. Curt Mobley (see this page) added radiative transfer expertise, developing the Hydrolight software. Drs. Ole Mikkelsen and later Dr. Wayne Slade expanded company expertise and continue to develop new instruments and technologies. Partner Chuck Pottsmith continues as VP of Operations, Mr. David Dana as VP of engineering. A wide array of new instruments have been added (see the Products page). In 2018-end, Yogi brought Dr. Ole Mikkelsen, who had spent a few years earlier at Sequoia as VP and returned to his homeland, back from Denmark to replace him as the successor President. With Ole taking command, Yogi retired, staying engaged in technology support. Yogi is proud of creating a company that produces unmatched technologies, firmly grounded in physics, uniquely requiring no fudging or recalibration of data by users.
Along the way, Yogi and friends have planted a few thousand Sequoia trees all over the world. His chartable work involved education and other development work in India. Sequoia is Yogi’s proud legacy.
Curtis Mobley, Emeritus Vice President and Senior Scientist
RETIRED FROM SEQUOIA 1/1/2019
Although my background is physics and meteorology, most of my career has been devoted to research in radiative transfer theory applied to problems in optical oceanography and ocean color radiometry. The widely-used HydroLight software, the textbooks Light and Water: Radiative Transfer in Natural Waters and The Oceanic Optics Book (DOI: 10.25607/OBP-1710), and the Ocean Optics Web Book (www.oceanopticsbook.info) are the best-known products of my efforts.
Early in my career, I was a Fulbright Fellow to Germany, and I have held both regular (at the NOAA Pacific Marine Environmental Lab) and senior (at the Jet Propulsion Lab) National Research Council Resident Research Associateships. I was an oceanographer with the University of Washington Joint Institute for the Study of the Atmosphere and Ocean during the 1980s. From 1989-1991, I was the Program Manager of the Ocean Optics program at the Office of Naval Research. I have also been an associate professor of physics at Pacific Lutheran University, an Affiliate Professor in the School of Oceanography at the University of Washington, and an External Faculty member of the School of Marine Sciences at the University of Maine. I was the 2012 Distinguished Alumnus for the School of Atmospheric and Oceanic Sciences at the University of Maryland. I received the 2016 Jerlov Award, in part for “applications of radiative transfer theory to problems in optical oceanography.” According to Google Scholar Citations, my papers and books have been cited over 16,000 times. I have an H index of 51 (51 papers cited 51 or more times), and 90 papers with ten or more citations. I was Vice President for Science and Senior Scientist at Sequoia from 1997 until I retired at the end of 2018.
Much of my early research at Sequoia sought to improve remote sensing of optically shallow water. That work involved the development and evaluation of spectrum-matching methods for retrieval of bathymetry, bottom classification, and water inherent optical properties from airborne hyperspectral imagery. More recent work was on improving ocean ecosystem models by improving their light calculations (the light both heats the water and drives photosynthesis). One result of that work is the extremely fast EcoLight-S(ubroutine) radiative transfer code, which is designed for use as the optical component of coupled physical-biological-optical ocean ecosystem models.
I also have a fondness for teaching, and I have taught many intensive week-long courses and summer classes (twice at the Univ. of Washington, 10 times at the Univ. of Maine, 3 times in France, twice in Brazil, 3 times in China, and also in Singapore, Sweden, and Korea). I enjoy figuring out something and then explaining it to others, so much of my time is now spend adding new material to the Ocean Optics Web Book.
Starting in graduate school, my wife, Ann Kruse, and I devoted all weekends and vacations to climbing — ice in New England in the winter, rock in California, mountaineering in Alaska, and everything in between. But after 20 years of playing on vertical terrain, all of the climbs started to feel the same. This serious mid-life crisis was resolved when we discovered sea kayaking. Our vacations now find us paddling in exotic locations around the world. Our kayaking expeditions have included Alaska, Greece, arctic Norway, eastern Greenland, Panama, Fiji, Belize, and even Antarctica. Next up is the Galapagos Islands in 2023. You can see photos from recent trips at our Smugmug site.
For almost 20 years I led trips for Wilderness Volunteers, a non-profit organization that does trail maintenance, habitat restoration, archaeological surveys, and similar work in National Parks, wilderness areas, wildlife refuges, and other public lands. I served on the Wilderness Volunteers Board of Directors for six years before “aging off” in 2021. For many years I also led white-water rafting and sea kayaking trips, and cultural trips in China, for the Sierra Club
I’m spending my retirement writing more books, sea kayaking, and developing a native plant garden at my home.
David R. Dana, VP, Engineering & Production
RETIRED 1st JULY 2023, see link below for details.
My research focuses on characterization of oceanic particles and their dynamics using optical methods, especially using multi-spectral, multi-angle, and polarized measurements of inherent optical properties. As a research scientist at Sequoia Scientific, one of my primary aims is the development of instrumentation and methods for measuring particle optical properties and the deployment of these technologies in observing systems, ship-based flowthrough systems, and on autonomous and other challenging platforms. I received a Ph.D. in Oceanography in 2011 focused on ocean particle optics. I am experienced in deploying optical sensors in coastal and open ocean environments, in design and execution of laboratory studies using these same sensors, in the analysis of data from field and laboratory experiments, and in computer modeling of the optical properties of particles. I have additional research experience in signal and image processing and intelligent algorithm design.
Current Research Interests
Improving understanding of the links between optical properties and particle size
Measurement of the volume scattering function and polarization properties of natural waters and links to particle properties
Developing algorithms and validation methods for remote sensing algorithms for estimating biogeochemical quantities such as particulate organic carbon and particle size distribution