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G. W. Grams, I. H. Blifford Jr., B. G. Schuster, and J. S. DeLuisi

Abstract

On 30 September 1970, the National Center for Atmospheric Research (NCAR) obtained data on the vertical distribution of particulate material over Boulder, Colo., from laser radar soundings and simultaneous airborne particle collections. A layer of particulate material at about 13 km was of special interest. Particles in this layer differed from normal tropospheric particles and were probably fly ash created by forest fires in California during the previous week. A technique for determining the complex index of refraction of atmospheric particles has been applied to the 13-km data. By assuming the real part of the refractive index to be 1.55, the imaginary part (the absorption parameter) is estimated to be 0.044±0.011.

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J. J. DeLuisi, P. M. Furukawa, D. A. Gillette, B. G. Schuster, R. J. Charlson, W. M. Porch, R. W. Fegley, B. M. Herman, R. A. Rabinoff, J. T. Twitty, and J. A. Weinman

Abstract

The experimental results in Part I are used in the theoretical interpretation of the radiation flux measurements which were taken with an aircraft. The absorption term of the complex refractive index of aerosols is estimated to be approximately 0.01 for a real part of 1.5 for the wavelength bandwidth 0.32–0.68 μm. A regional variation in the refractive index is noted.

Atmospheric heating and cooling rates due to aerosol and molecular absorption in the solar and terrestrial wavelengths are determined from the radiation flux measurements. The magnitudes of these rates are compared and their relative importance is discussed.

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J. J. Deluisi, P. M. Furukawa, D. A. Gillette, B. G. Schuster, R. J. Charlson, W. M. Porch, R. W. Fegley, B. M. Herman, R. A. Rabinoff, J. T. Twitty, and J. A. Weinman

Abstract

An exploratory field experiment was undertaken to determine the practicality of a method specifically designed to obtain the optical properties of aerosols as they relate to the earth's radiation balance. The method requires a basic set of data consisting of the vertical distribution of aerosol concentrations, size distribution, optical depth, and net radiation fluxes. From these data radiation absorptions are determined, and effective aerosol refractive indices consistent with the actual absorption are deduced through the application of precision radiative transfer calculations. The results of 11 experiment episodes involving a combined aircraft and surface-based measurement system are described. The episodes took place in an arid desert region located near Blythe, California, and in a semiarid agricultural region located near Big Spring, Texas. Part I deals with the physical-numerical depiction of such aerosol properties as optical depth, size distribution, and vertical profiles of concentration. Part II will deal with the analysis of measurements of the radiation field leading to the deduction of the effective aerosol refractive index compatible with the absorption of solar radiation.

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L. C. Slivinski, G. P. Compo, P. D. Sardeshmukh, J. S. Whitaker, C. McColl, R. J. Allan, P. Brohan, X. Yin, C. A. Smith, L. J. Spencer, R. S. Vose, M. Rohrer, R. P. Conroy, D. C. Schuster, J. J. Kennedy, L. Ashcroft, S. Brönnimann, M. Brunet, D. Camuffo, R. Cornes, T. A. Cram, F. Domínguez-Castro, J. E. Freeman, J. Gergis, E. Hawkins, P. D. Jones, H. Kubota, T. C. Lee, A. M. Lorrey, J. Luterbacher, C. J. Mock, R. K. Przybylak, C. Pudmenzky, V. C. Slonosky, B. Tinz, B. Trewin, X. L. Wang, C. Wilkinson, K. Wood, and P. Wyszyński

Abstract

The performance of a new historical reanalysis, the NOAA–CIRES–DOE Twentieth Century Reanalysis version 3 (20CRv3), is evaluated via comparisons with other reanalyses and independent observations. This dataset provides global, 3-hourly estimates of the atmosphere from 1806 to 2015 by assimilating only surface pressure observations and prescribing sea surface temperature, sea ice concentration, and radiative forcings. Comparisons with independent observations, other reanalyses, and satellite products suggest that 20CRv3 can reliably produce atmospheric estimates on scales ranging from weather events to long-term climatic trends. Not only does 20CRv3 recreate a “best estimate” of the weather, including extreme events, it also provides an estimate of its confidence through the use of an ensemble. Surface pressure statistics suggest that these confidence estimates are reliable. Comparisons with independent upper-air observations in the Northern Hemisphere demonstrate that 20CRv3 has skill throughout the twentieth century. Upper-air fields from 20CRv3 in the late twentieth century and early twenty-first century correlate well with full-input reanalyses, and the correlation is predicted by the confidence fields from 20CRv3. The skill of analyzed 500-hPa geopotential heights from 20CRv3 for 1979–2015 is comparable to that of modern operational 3–4-day forecasts. Finally, 20CRv3 performs well on climate time scales. Long time series and multidecadal averages of mass, circulation, and precipitation fields agree well with modern reanalyses and station- and satellite-based products. 20CRv3 is also able to capture trends in tropospheric-layer temperatures that correlate well with independent products in the twentieth century, placing recent trends in a longer historical context.

Open access
Ian M. Brooks, Margaret J. Yelland, Robert C. Upstill-Goddard, Philip D. Nightingale, Steve Archer, Eric d'Asaro, Rachael Beale, Cory Beatty, Byron Blomquist, A. Anthony Bloom, Barbara J. Brooks, John Cluderay, David Coles, John Dacey, Michael Degrandpre, Jo Dixon, William M. Drennan, Joseph Gabriele, Laura Goldson, Nick Hardman-Mountford, Martin K. Hill, Matt Horn, Ping-Chang Hsueh, Barry Huebert, Gerrit De Leeuw, Timothy G. Leighton, Malcolm Liddicoat, Justin J. N. Lingard, Craig Mcneil, James B. Mcquaid, Ben I. Moat, Gerald Moore, Craig Neill, Sarah J. Norris, Simon O'Doherty, Robin W. Pascal, John Prytherch, Mike Rebozo, Erik Sahlee, Matt Salter, Ute Schuster, Ingunn Skjelvan, Hans Slagter, Michael H. Smith, Paul D. Smith, Meric Srokosz, John A. Stephens, Peter K. Taylor, Maciej Telszewski, Roisin Walsh, Brian Ward, David K. Woolf, Dickon Young, and Henk Zemmelink

Abstract

No Abstract available.

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Ian M. Brooks, Margaret J. Yelland, Robert C. Upstill-Goddard, Philip D. Nightingale, Steve Archer, Eric d'Asaro, Rachael Beale, Cory Beatty, Byron Blomquist, A. Anthony Bloom, Barbara J. Brooks, John Cluderay, David Coles, John Dacey, Michael DeGrandpre, Jo Dixon, William M. Drennan, Joseph Gabriele, Laura Goldson, Nick Hardman-Mountford, Martin K. Hill, Matt Horn, Ping-Chang Hsueh, Barry Huebert, Gerrit de Leeuw, Timothy G. Leighton, Malcolm Liddicoat, Justin J. N. Lingard, Craig McNeil, James B. McQuaid, Ben I. Moat, Gerald Moore, Craig Neill, Sarah J. Norris, Simon O'Doherty, Robin W. Pascal, John Prytherch, Mike Rebozo, Erik Sahlee, Matt Salter, Ute Schuster, Ingunn Skjelvan, Hans Slagter, Michael H. Smith, Paul D. Smith, Meric Srokosz, John A. Stephens, Peter K. Taylor, Maciej Telszewski, Roisin Walsh, Brian Ward, David K. Woolf, Dickon Young, and Henk Zemmelink

As part of the U.K. contribution to the international Surface Ocean-Lower Atmosphere Study, a series of three related projects—DOGEE, SEASAW, and HiWASE—undertook experimental studies of the processes controlling the physical exchange of gases and sea spray aerosol at the sea surface. The studies share a common goal: to reduce the high degree of uncertainty in current parameterization schemes. The wide variety of measurements made during the studies, which incorporated tracer and surfactant release experiments, included direct eddy correlation fluxes, detailed wave spectra, wind history, photographic retrievals of whitecap fraction, aerosolsize spectra and composition, surfactant concentration, and bubble populations in the ocean mixed layer. Measurements were made during three cruises in the northeast Atlantic on the RRS Discovery during 2006 and 2007; a fourth campaign has been making continuous measurements on the Norwegian weather ship Polarfront since September 2006. This paper provides an overview of the three projects and some of the highlights of the measurement campaigns.

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