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Symposium Honours Jim Angell on his 80^th Birthday

Silver Spring (MD), USA, November 4, 2003

Dian Seidel, NOAA (R/ARL), Silver Spring, MD, USA ( Dian.Seidel@noaa.gov)

with contributions from B. Hicks, K. Labitzke, J. Lanzante, J. Logan, J. Mahlman, V. Ramaswamy, W. Randel, G. Rasmusson, A. Robock, B. Ross, and S.F. Singer.

Participants at the Jim Angell 80th Birthday Symposium, November 4, 2003, at the NOAA Science Center in Silver Spring, Maryland

Before the establishment of the WCRP in 1980, and well before the organization of the SPARC in 1992, Jim Angell was making pioneering contributions to our understanding of the climate system and the role of stratospheric processes in climate variability. On November 4, 2003, more than 50 colleagues and friends gathered at the NOAA Science Center in Silver Spring (MD), USA, for a one-day symposium reviewing and honouring Jim’s career achievements and celebrating his 80^th birthday (November 2). This article highlights some of Jim’s contributions, both as reviewed during the symposium, and as captured in poems composed in his honour and recited at a birthday dinner celebration. More information about Jim Angell and the Angell Symposium, including photos, some presentations, his publications list and more poems, is online at www.arl.noaa.gov/ss/climate/AngellSymposium.html.

Jim received his Ph.D. in meteorology in 1956 from the University of California, Los Angeles, where he worked as a lab instructor for J. Bjerknes. His dissertation research, under advisor M. Neiberger, addressed atmospheric transport using data from constant level balloons developed by J. Mastenbrook. After graduation, Jim was offered a position in the Special Projects Branch of the U.S. Weather Bureau (now NOAA’s National Weather Service) by L. Machta. That branch evolved into the NOAA Air Resources Laboratory (ARL), where Jim has spent his entire career. Having retired from Federal service in Spring 2000, Jim continues to work on climate and ozone research at NOAA/ARL in Silver Spring, Maryland.

Grounded in Observations, Taken aloft by Balloons

There once was a fine lad named James
Who found that balloons weren’t just games
He pulled out their data
’Cause sooner or lata
They would bring him his multiple fames.
Jerry Mahlman

“The work being done in climate today rests on the early efforts of scientists such as Jim,” said R.D. Rosen, in remarks welcoming participants to NOAA. J. Mahlman gave an overview of Jim’s career, noting his strong focus on analysis of observations, particularly from balloon-borne instruments, to address emerging scientific challenges, ranging from the transport and dispersion of air pollution to long-term climate change and stratospheric ozone depletion. J. Mahlman noted Jim’s “passion for observations with a purpose,” remarking that “he carefully examined the data, acknowledged its flaws and decided whether or not he was seeing new physical insights into atmospheric behaviour.”

Global Temperature Monitoring and Research

Jim with his network of sites, 63,
studies temperature change in the atmosphere-free.
He calmly considers (without any panic)
effects on the change of eruptions volcanic.
His ongoing study of T trends, decadal,
will continue no doubt as long as he’s able.
His service to science is quite an example
so lets give him credit and LOUD APPLAUSE ample.
Becky Ross

Jim set out to monitor the variability and trends of atmospheric temperature three decades ago, when he identified a global network of 63 radiosonde stations, and a methodology of analysis of seasonal anomalies of zonal, hemispheric and global temperature at the surface and in different atmospheric layers, in a seminal paper [Angell and Korshover 1975]. The datasets he developed covered the period from the 1958 expansion of the radiosonde network for the International Geophysical Year to near-present. Jim extended and analysed data from this network to identify numerous climate signals, from short-term seasonal and interannual variations to long-term trends. The network continues to provide meaningful results, although in his most recent paper [Angell 2003], Jim removed nine stations with anomalous trends from the record.

In addition to his work with radiosonde data, Jim was among the first to use data from meteorological rocketsondes to explore temperature variations at higher stratospheric altitudes. His comprehensive explorations of temperature observations often made insightful and original connections with related parameters, including early stratospheric water vapour data, sea surface temperature and pressure observations, Indian monsoon rainfall data, sunshine duration and cloudiness observations, atmospheric carbon dioxide concentrations and, most notably, stratospheric ozone and ozone profile data.

Dubbing Jim “The Monitoring Expert,” V. Ramaswamy noted five hallmarks of his career: incessant research, breadth of exploration, meticulous analyses, prompt reports, and exemplary collegiality. V. Ramaswamy congratulated and thanked him for his contributions to several major assessment activities, including the SPARC Temperature Trends and Ozone Assessment Panels, the WMO/UNEP Scientific Assessments of the Ozone Layer, and the Intergovernmental Panel on Climate Change assessment reports.

Ozone Studies

Jim measured the polar vortex as it would grow,
Though his pencil and calculator made him a little slow,
A true pioneer in the field,
Such insights his statistics would yield,
And he took us where no one else knew where to go.
Jim studied volcanoes, the vortex and QBO,
He put on quite a scientific show,
A gentlemen is he,
A most pleasant person with which to be,
And from his friends, a gracious thanks, we now bestow!
John Lanzante

J. Logan traced the course of Jim’s ozone investigations. His pioneering analyses documented three dominant influences on interannual variability of stratospheric ozone: the quasi-biennial oscillation (QBO), the solar cycle, and major volcanic eruptions. Jim conducted the first comprehensive analysis of the QBO in column ozone [Angell and Korshover 1964]. He turned his attention back to ozone in the early 1970s when concerns were first raised about ozone depletion. In a landmark paper [Angell and Korshover 1973], he: (1) showed the “quasibiennial fluctuations” in ozone as a function of latitude and their relationship to the winds, (2) provided a careful analysis of the relationship between ozone and sunspot number, a controversial subject at the time, (3) analysed long-term trends in column ozone, which was increasing in the 1960s, and (4) found no evidence for a reduction in ozone resulting from nitric oxide produced by nuclear bomb tests.

Jim’s search for trends in ozone later expanded to include the first analyses of trends in the Umkehr and ozonesonde data, after models predicted the vertical profile of ozone loss. Recurring themes in his analyses of ozone over a 35-year period are examination of the relationship of ozone to the QBO, solar cycle and volcanic eruptions. His concern over data quality is another constant, as is his search for consistency among the various ozone records from Dobson, Umkehr and sondes. He laid the groundwork for later work on ozone trends as statisticians entered the field, and as satellite data became available: the QBO and solar cycle are now included as explanatory variables in all regression estimates of ozone trends.

“It is hoped that this discussion has directed the reader’s attention to the complex nature of the total-ozone variation, both in time and space. Because of uncertainty concerning the raison-d’être of much of the variation, it is extremely difficult at this time to evaluate accurately man-made influences on ozone amount. Consequently, when considering the possible effects of the supersonic transport on stratospheric ozone, for example, we must be very careful that any changes noted reflect the human influence and would not have occurred naturally. For conscientious scientists, this may be the most difficult determination of all.” [Angell and Korshover,1973].

Discovery and Characterization of the QBO

Our friend Jim has a strong reputation,
For analysis of data and not speculation,
East winds changing to west,
Were the ones he knew best,
He called it the quasi-biennial oscillation
William Randel

W. Randel reviewed Jim’s contributions to understanding the stratospheric QBO and noted that he was one of the first scientists to recognize its importance in global climate variability. His careful work with sparse data sets documented the global dynamical structure of the QBO and quantified its influence on a variety of meteorological fields and trace constituents. Publications by Angell and Korshover (1962, 1963) quickly followed the 1961 discovery of the biennial oscillation and characterized the propagation characteristics and global structure (including extension into middle latitudes).

In 1964 Angell and Korshover coined the term “Quasi-Biennial Oscillation” and documented correlated variations in global temperatures, ozone and tropopause height. Further original work included quantifying QBO variations in equatorial Kelvin waves and the QBO influence on global ozone variability, and documenting effects on tropical tropopause temperatures and associations with stratospheric water vapour, both topics of current stratospheric water vapour investigations. Jim also documented QBO effects on tropospheric circulation patterns, in particular surface pressure variations in the ‘centers of action’ (the North Atlantic and North Pacific subtropical high pressure systems); his pioneering results agree well with recent estimates of surface QBO effects. Over the past 40 years, Jim has contributed over 20 publications on the structure and global influence of the QBO.

Volcanic Effects on Climate

A. Robock reviewed the fundamentally new understanding of the effects of volcanic eruptions on climate that resulted from Jim’s observational studies of temperature, winds and ozone concentration in the atmosphere. During the past 50 years, which Jim studied, there were three major volcanic eruptions that produced massive stratospheric sulfate aerosol clouds: Agung in 1963; El Chichón in 1982; and Pinatubo in 1991. Jim used radiosonde and rocketsonde data to study the stratospheric temperature response following these large eruptions, accounting for the effects of the stratospheric QBO [Angell and Korshover 1983]. In addition, Jim showed that six major eruptions, starting in 1780, produced a significant surface cooling for a couple years.

Jim was also a pioneer in using the mid-tropospheric thickness (850-300 mb) obtained from radiosondes to measure tropospheric temperature changes. He was the first to notice that volcanic and El Niño influences have about the same amplitude and time scale, and that to delineate the volcanic influence, the El Niño influence needed to be removed. He showed that after doing this, a clear volcanic cooling influence is evident [Angell 1988]. Finally, Jim recognized the impacts of volcanic eruptions on stratospheric ozone, associated with the increasing effect of heterogeneous chemistry on volcanic aerosols to liberate anthropogenic chlorine, which catalyzes ozone destruction [Angell 1997].

Solar Signals in Climate

K. Labitzke reviewed Jim’s contributions to the identification of solar signals in ozone and climate, noting the controversies surrounding this topic. Recognizing the difficulty of separating solar, volcanic and anthropogenic influences, all of which have comparable time scales of variability, Angell and Korshover (1973) noted with characteristic caution and care that “...evidence for a nearly 11-yr periodicity in total ozone directs one’s attention toward the possibility of a relationship with sunspot number.... we plan to reopen this particular Pandora’s box....”. As the length of data record grew, Jim confirmed and explored the details of the solar signal in ozone in subsequent publications in the 1970s, 1980s, and 1990s, in which he stressed the need to consider (and remove) the solar signal in evaluating long-term ozone trends. More recently, Jim identified a possible solar influence in atmospheric circulation patterns, showing that the size of the North Polar vortex varies in association both with El Niño and with sunspot number.

“The rationale for this paper is the belief, nay certainty, that knowledge of past ‘natural’ variations is a prerequisite to detection and comprehension of possible future effects.” [Angell 1980].

El Niño-Southern Oscillation Signals in Climate

G. Rasmusson provided a comprehensive summary of Jim’s El Niño-Southern Oscillation (ENSO) research, initiated during a 1979-80 sabbatical year at CSIRO in Aspendale. His contributions are in three general areas of inquiry: (1) ENSO effects on NH extratropical circulation, (2) the nature and stability of tropical Pacific - monsoon sector relationships, and (3) the impacts of ENSO warm events and volcanic eruptions on interannual tropospheric temperature variability and long-term temperature trends.

Jim’s work in collaboration with B. Elliott: (1) confirmed a high correlation between the Southern Oscillation Index (SOI) and equatorial Pacific sea surface temperature (SST), (2) identified a two-season lag of tropical tropospheric temperature relative to equatorial Pacific SST, (3) identified a two-season lag of tropical Pacific SST relative to monsoon rainfall, and (4) identified a lag of the atmospheric carbon dioxide decrease relative to tropical Pacific SST, which increased from one season in the tropics to three seasons in the polar regions [Angell 1981; Elliott and Angell 1987, 1988]. The team also identified secular changes in the correlation of SST with SOI over the course of the twentieth century. As Jim often notes with irony “You need to know when to stop in correlation studies, because just when the correlations seem to be convincing, a longer data record results in the correlations falling to pieces.”

Jim identified ENSO effects on the NH extratropical circulation, addressing both the four centres of action [Angell and Korshover 1984] and the 300 mb North Polar vortex [Angell 2001], suggesting a link between ENSO and the Arctic Oscillation. Jim also identified and quantified the atmospheric thermal pulse associated with an equatorial Pacific warming and its poleward spread, which allowed him to “back out” the ENSO warming and obtain the volcanic cooling contribution in cases where the two signals overlapped, i.e. Agung (1963) and El Chichón (1982). Using this information, he later evaluated the contribution of ENSO warming to the long-term tropospheric temperature trend [Angell 2000].

Atmospheric Transport and Boundary Layer Research

B. Hicks discussed some of Jim’s early contributions to the understanding of atmospheric dispersion and transport, noting how relevant those studies remain today. Jim’s dissertation research with constant-pressure balloon (transosonde) data and his later work, with constant-volume balloons (the tetrahedral-shaped tetroons) shed light on the long-range transport of air within the United States, and across the Pacific Ocean from Japan. Jim conducted flights to study mesoscale urban and sea-breeze influences on atmospheric circulation, inertial oscillations in the atmosphere, vertical velocities in the atmospheric boundary layer, jet stream velocities and lateral dispersion. Jim spent a sabbatical year in 1961-62 working with F. Pasquill at the British Meteorological Office in Bracknell, and tells of a rather harrowing experience in the field, launching tetroons from open wicker basket suspended below a barrage balloon at 1000 m altitude, in 30 knot winds and near-freezing temperatures.

In addition to all the topics mentioned above, Jim also made significant contributions to the study of climate and air quality in the United States. He developed climatologies of air stagnation, cloudiness and sunshine duration, each of which plays a role as meteorological controls on the formation and duration of air pollution episodes. For many years, he monitored variations and trends in cloudiness and sunshine, until changes in observing systems made continuation of the analyses impossible. With the availability of reanalysis data products, and in collaboration with J. Wang, Jim’s stagnation datasets have been updated and used by NOAA’s National Weather Service as part of its suite of forecast products.

Summary

As J. Mercer wrote, “Fools rush in where angels fear to tread.” But as the symposium made clear, Jim fearlessly treads just about everywhere in the atmospheric sciences. Carried along largely by data from balloons, he has analysed everything from the Earth’s surface to the stratosphere, examining atmospheric variations on hourly to centennial scales, drawing connections among elements as wide-ranging as volcanoes and sunshine, temperature and ozone, cloudiness and water vapour. Jim remains an active contributor to atmospheric science. As the icing on his 80th birthday cake proclaimed, “Long may the time series continue!”

The day after the Angell Symposium, SPARC sponsored a Workshop on “Understanding Seasonal Temperature Trends in the Stratosphere” (see page ). The workshop co-chairs, W. Randel and V. Ramaswamy, noted that, “Many of the details of the workshop trace their origin to Jim's pioneering sonde analyses right from the early days.”

Clickety Clackety
Hail NOAA’s Angell.
Troposphere's guardian,
Stratosphere’s knight.
Environmentally
Data collecting, but
Always concerned about
Getting it right.
S. Fred Singer

Selected References (in chronological order)

Angell, J. K., and J. Korshover, 1962: The biennial wind and temperature oscillations of the equatorial stratosphere and their possible extension to higher latitudes. Mon. Wea. Rev., 90, 127-132.

Angell, J. K., and J. Korshover, 1963: Harmonic analysis of the biennial zonal wind and temperature regimes. Mon. Wea. Rev., Wexler Memorial Volume, 537-548.

Angell, J. K., and J. Korshover, 1964: Quasi-biennial variations in temperature, total ozone and tropopause height. J. Atmos. Sci., 21, 479-492.

Angell, J. K., and J. Korshover, 1973: Quasi-biennial and long-term fluctuations in total ozone. Mon. Wea. Rev., 101(5), 426-443.

Angell, J. K., and J. Korshover, 1975: Evidence for a quasi-biennial variation in eccentricity of the North Polar Vortex. J. Atmos. Sci., 32, 634-635.

Angell, J. K., 1980: Temperature and ozone variations in the stratosphere. Pure Appl. Geophys., 118, 378-386.

Angell, J. K., 1981: Comparison of variations in atmospheric quantities with sea surface temperature variations in the equatorial eastern Pacific. Mon. Wea. Rev., 109(2), 230-243.

Angell, J. K., and J. Korshover, 1983: Comparison of stratospheric warmings following Agung and Chichon. Mon. Wea. Rev., 111, 2129-2135.

Angell, J. K., and J. Korshover, 1984: Some long-term relations between equatorial sea-surface temperature, the four centers of action and 700 mb flow. J. Clim. Appl. Meteorol., 23, 1326-1332.

Elliott, W. P., and J. K. Angell, 1987: The relation between Indian monsoon rainfall, the Southern Oscillation, and hemispheric air and sea temperature: 1884-1984. J. Clim. Appl. Meteorol., 26, 943-948.

Elliott, W. P., and J. K. Angell, 1988: Evidence for changes in Southern Oscillation relationships during the past 100 years. J. Climate, 1, 729-737.

Angell, J. K., 1988: Variations and trends in tropospheric and stratospheric global temperatures, 1958-87. J. Climate, 1, 1296-1313.

Angell, J. K., 1997: Estimated impact of Agung, El Chichón and Pinatubo volcanic eruptions on global and regional total ozone after adjustment for the QBO. Geophys. Res. Lett., 24, 647-650.

Angell, J. K., 2000: Tropospheric temperature variations adjusted for El Niño, 1958-1998. J. Geophys. Res., 105, 11,841-11849.

Angell, J. K., 2001: Relation of size and displacement of the 300 mbar north circumpolar vortex to QBO, El Niño, and sunspot number, 1963-2000. J. Geophys. Res., 106, 31,787-31,794.

Angell, J. K., 2003: Effect of exclusion of anomalous tropical stations on temperature trends from a 63-station radiosonde network, and comparison with other analyses. J. Climate, 16, 2288-2295.