A personal tribute to Michael Gadsden

1. Foreword

I first met Michael Gadsden in the late 1970s when he visited our Upper Atmospheric Group at Southampton University, UK. At that time I was a new grad­uate student studying for my Ph.D. under Pamela Rothwell. Mike (as I was later privileged to call him) was inter­ested in developing a collaborative program to study polarization in nocti­lucent clouds (NLC) using our low-light video cameras. Of course at that time I had never even heard of nocti­lucent clouds but what an impression he made on us all! Within a couple of months I found myself heading north for Scotland, with my car packed full of video gear, eager to learn all about these fascinating night shining clouds that only occur during the summer months at higher latitudes. True to his nature, Mike gave me the “royal tour” of the ancient city of Aberdeen and its famous uni­versity, intro­ducing me to the faculty in the Department of Natural Philosophy as a “heathen from the south” (you have to say it with a Scottish accent) who had “come north for the summer to gain a decent education!”

We set up our cameras at the majestic Cromwell Tower Observatory, located in Kings College in the oldest part of the university (circa 1400 AD). Mike had recently refurbished this abandoned observatory and after several weeks of tutoring me while waiting for the Scottish skies to clear, we were eventually re­warded with a wonderful NLC display. It was a most impressive event that lit up the northern sky late at night, with many beautiful iridescent blue-white waves illuminated within the twilight arch. I savored this eerie yet tranquil time, and as the display grew in brightness, it was soon accompanied by a chorus of birds singing as they were tricked by this “false dawn”. I was firmly hooked! Moreover, we gained our first data on circular polarization in NLC on this night and Mike swiftly prepared a letter for pub­lication in Nature [Gadsden, Rothwell, Taylor, 1979. Nature 278]. Therein began a wonderful relation with Mike, first as a mentor and later as a colleague and dear friend.

2. Early career

Mike was born in Harrow, England, in December 1933, the youngest of three brothers. He obtained his bachelor’s degree in Physics (with honors) in 1954 from The Royal College of Science, Imperial College, London. He then cont­inued to do his Ph.D. in Technical Optics, also at Imperial College, with a thesis entitled “The Application of Colorimetry to some Astronomical and Meteorological Phenomena”, awarded in 1957. It was during his student years that he first met and later married his lifelong partner Mavis Upton in 1955. In 1957, Mike and Mavis moved to New Zealand where he took a position as a Scientific Officer at the Auroral Station at Invercargill, making radar and optical measure­ments as a part of the Inter­national Geophysical Year (IGY). Using his knowledge of optics, he was able to develop spectrometers for the study of aurora, twilight and the night sky which led to his first visits to Antarctica. In 1963, Mike, Mavis and their three children (Andrew, Anne and Jonathan) moved to Boulder, CO, to take up a position at the Central Radio Propagation Lab­oratory (now NOAA), where he soon became the Director of Fritts Peak Observatory, and in 1968, was appointed Director of the Aeronomy Lab­oratory. Mike was a happy man, always telling jokes and often making time to tell endless stories and adventures. It always amused him that as an “alien resident” in the USA, he held a high ranking Civil Servant position-something that would be virtually impossible these days. Whilst at Boulder, Mike was involved in a broad range of research activities, with several visits to the South

Pole Station for further spectroscopic studies; he also participated in the NASA Airborne Auroral Exped­itions and made two solar eclipse expeditions: one to the Cook Islands (on a rented yacht that nearly came to grief on some unexpected reefs one night!) and the other to Mexico. He was awarded the US Antarctic Service medal in 1974 for his pioneering work in Antarctica.

3. Return to UK

Mike was a family man and he wanted his children to be raised in his homeland so he gave up a very promising career in the USA and the Gadsden family moved back to the UK where he took up a Senior Lecturer position at the Department of Natural Philosophy (Physics) at Aberdeen University in Scotland. Both Mike and Mavis have very broad interests in the arts and they quickly became immersed in the local culture becoming true “Aberdonians”. At Aberdeen, Mike lectured a wide range of classes. His lectures were always sharp, witty and packed full of information, as were his presentations at scientific meetings and conferences. Indeed, Mike was a truly gifted scientist, able to put his mind to every aspect of a problem from detailed instrument design to developing his own software programs for novel data analyses. Scotland is well situated for the study of NLC and Mike took full advantage of this fact to become an inter­nationally recognized expert in the field of modern NLC research. Together with colleagues George Witt (Sweden), Gary Thomas (USA), Olev Avaste (Estonia/USSR), Eoghagan Roddy (Ireland), and later with Ulf von Zahn and Franz-Josef Lübken (Germany), and Jeff Thayer (USA) he helped spearhead the development of a series of conferences that were initially focused on NLC research but were broadened later to encompass a range of mesopause layer phenomena. As a grad­uate student, I was most fortunate to be able to participate in some of the early meetings held in Tallinn, Estonia, where I was introduced to several famous NLC scientists including Charles Willmann and Oleg Vasilyev. This was possible only because Mike had put my name forward for invitation to visit the (then) USSR. This act epitomizes my best memories of Mike - a very generous and hardworking man, keen to help his students and always promoting new ideas. Mike also believed deeply in the importance of encouraging and supporting amateur involvement in NLC research and in the 1980s he initiated a simultaneous photography program with the British Astronomical Association’s (BAA) Auroral Section members across central Scotland to measure NLC heights. Indeed, Mike gave exemplary service to the BAA throughout his career and actively promoted and utilized data obtained by amateur NLC observers worldwide (Fig. 1.)

Therein lay the “sweet side” of Mike. However, as many of his contemporaries may well remember, Mike was able to combine his formidable intellect with a wicked sense of humor, and was rarely shy to point out a “critical flaw” in a conference presentation. I too have experienced his enormous interrogative capacity. In 1986, Mike was external examiner for my Ph.D. dissertation. After 3 h of “grilling me,” much of the time on the information content in a single photograph of the airglow emission layers, I truly appreciated his immense knowledge. This taught me a life-long lesson on the critical importance of paying close attention to details. After­wards, Mike congratulated me on surviving the ordeal and, in a witty voice, stated “that was the easy part-now your real work begins”. I never forgot those words which are as true today as they were almost two decades ago. Mike loved to write letters and he communicated regularly with many friends and colleagues worldwide. In particular, he always talked very fondly of Rex and Abbey Megill, their life-long family friends since working together at Boulder. In 1984, this friendship led to the successful flight of a getaway special “Space Pac” instrument on the Columbia Space Shuttle, developed jointly by students at Aberdeen University and Utah State University, where Rex then worked. Mike made sure that this event was publicized by the local Aberdeen press, jovially describing their payload as “just a third of a dustbin” in size!

In the late 1980s, I had the privilege of working with Mike on a Forward Scatter Photometric Camera design for studying NLC from the Soviet MIR Space Station. This was a wonderful opportunity to work together with scientists from Estonia and Russia on this joint venture to put a UK instrument onboard MIR. Although we received full funding for a feasibility study, our

Michael Gadsden
Fig. 1. (a) Mike in Prague, during the 5th IAGA Scientific Assembly, 1985. As Secretary General of IAGA (1983-1995), his conference organizing skills were legendary. (b) Intense NLC display containing several bands and whirl-like structures photographed by Mike from Aberdeen University. (c) Mike on the roof of the Cromwell Tower Observatory, Kings College, Aberdeen, summer 1978. (d) Attendees of the International NLC Meeting held at Tallinn, Estonia, 1988. (Mike and Mavis are together on the right side of the photograph).

subsequent application for instrument develop­ment costs was unfortunately declined. This enraged Mike, and I remember sitting with him in his study at home drafting a letter to the Prime Minister (R.H. Margaret Thatcher) expressing the folly of this decision. To our surprise, we received a reply from 10, Downing Street (the Prime Minister’s residence), stating that while the government cannot inter­vene in the decisions of its Research Councils, they were looking into alter­native methods of supporting this pro­gram. Alas, a sudden change in govern­ment led to the eventual demise of our MIR program.

4. Research achievements and service

Mike was an exceptional experimental scientist and during his career he dev­eloped expertise in a number of areas including radio and optical aurora, twi­light measurements, eclipse studies and airglow. However, after moving to Scot­land, his research efforts focussed almost exclusively on NLC which, at that time, were regarded more as a scientific curiosity. His papers were built on careful observations. Initial scattering and polar­ization measurements led to studies of NLC particle size distributions (with implications on mesospheric water vapor content), while later studies focussed critically on the nucleation and growth of the particles to observable sizes. Satellite observations in the 1970-1980s led to the discovery of polar mesospheric clouds (PMC) which led Mike to investigate the effects of winds on the trajectories of PMCs from their polar source regions down to high-mid-latitudes where they could be observed as NLCs. Subsequently, he pioneered the use of geostationary satellite images to investigate the occur­rence and latitudinal extent of NLC/PMC. However, Mike will probably best be remembered for his work utilizing a wealth of amateur observations from North­west Europe that suggested a secular increase in the occurrence of NLCs during the

period 1965-1995. Although contro­versial, this study stimulated considerable scientific and public interest helping raise NLC research to the prominent position that it enjoys today. Indeed, the NASA AIM (Aeronomy of Ice in the Mesosphere) satellite, which is currently under dev­elopment, will specifically investigate the formation, global extent, and seasonal variability of mesospheric clouds. During his career, Mike published many papers on NLC observations, modeling, and theory. He also co-authored a topical book entitled “Noctilucent Clouds” (with W. Schröder), which has become an imp­ortant single reference for the dedicated researcher as well as the enthusiastic amateur. One of Mike’s most important contributions to the inter­national sci­entific community resulted from his many years of dedicated service to the International Association for Geo­mag­netism and Aeronomy (IAGA). He was elected a member of the IAGA Executive Committee (1975-1979), then served as Vice-President (1979-1983), and finally became its long-serving Secretary General (1983-1995). Mike excelled in this latter capacity and his conference organizing skills became legendary. After 20 years of hard work, he was made an IAGA Honorary Member in 1997.

5. Retirement

Following Mike’s retirement from Aberdeen University, he and Mavis moved south to Perth to be closer to their childrens’ families. In Perth, he main­tained a very active NLC research pro­gram (using a small stone cottage in his garden as his laboratory) and attended many meetings in UK and in mainland Europe, especially the new Mesopause Layer Phenomena meetings. Indeed, even during his last year, Mike organized an NLC meeting at Perth to discuss key issues raised by recent studies on changes in the NLC occurrence frequency, and new results related to effects of rocket exhausts on NLC formation. Many leaders in the field attended this meeting from Europe and the USA sitting side-byside with amateur observers from the UK, Denmark and Finland including his great friend David Gavine, Edinburgh (who collates NLC observations in Scotland). When I learned some 6 months later that Mike was in intensive care stricken with cancer, I was dumbfounded. Apparently, his doctor had advised him of his grave ailment before the NLC meeting took place, yet he persevered on driven by his insatiable appetite for research. Together with his spirited support of amateur observers and scientists from developing countries, this made Mike a truly unique and most highly valued member of the inter­national scientific community. I visited Mike in hospital in February 2003. You would have thought he was just in for a routine check up! He seemed his old usual self making jokes with the nurses and telling tall tales to his fellow bed friends in the ward. Even then he took time to discuss his latest thoughts on NLC with me. Mike was always so open-minded about his research. He was concerned about the impact of an increasing number of rocket launches on the mesospheric environment and his last paper (of which I am a proud co-author) discusses future possibilities of observing NLC anywhere and anytime. This layman’s article was published in the Journal of the British Astronomical Association (and includes two beautiful NLC photographs on the front cover). Mike was given a copy of this paper shortly before his untimely death at his home in Perth surrounded by his loving family. To many of his colleagues, he was known as Michael Gadsden but in his numerous messages to me he would often sign himself as “Michael the Great”. He truly was a great man and an even greater scientist.

Center for Atmospheric and Space Sciences and
Physics Department, Utah State University,
Logan, UT 84322, USA
E-mail address: mtaylor@cc.usu.edu