A. R. Mackenzie

Publications (50) View all

• Source

  Available from: A. R. Mackenzie

  Dataset: phil trans atmos chem 16 with figs

  T A M Pugh, K E Hornsby, L K Whalley, A C Lewis, N Robinson, A Karunaharan, J D Lee, B Langford, P K Misztal, V Nicolas-Perea, [......], D Fowler, T Ingham, G Phillips, A R MacKenzie, J A Pyle, P S Monks, M W Gallagher, K L Furneaux, C N Hewitt, A M Gabey
• Article: Corrigendum to

  C. N. Hewitt, J. D. Lee, A. R. MacKenzie, M. P. Barkley, N. Carslaw, G. D. Carver, N. A. Chappell, H. Coe, C. Collier, R. Commane, [......], R. Pike, J. M. C. Plane, T. Pugh, J. A. Pyle, C. E. Reeves, N. H. Robinson, D. Stewart, D. Stone, L. K. Whalley, X. Yang
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  ABSTRACT: No abstract available.
  ATMOSPHERIC CHEMISTRY AND PHYSICS 12/2009; 10:563-563. · 5.52 Impact Factor
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  Available from: A. R. Mackenzie

  Article: The APE-Theseo Tropical Campaign: An Overview

  L. Stefanutti, R. A. MacKenzie, Santacesaria, A. Adriani, S. Balestri, Borrmann, S, V. Khattatov, P. Mazzinghi, V. Mitev, V. Rudakov, C. Schiller, G. Toci, C.M. Volk, V.A. Yushkov, H. Flentje, C. Kiemle, G. Redaelli, K. S. Carslaw, K. Noone, T. Peter
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  ABSTRACT: The APE-THESEO campaign was held from 15 February to 15 March 1999 from the Seychelles in the western Indian Ocean. APE-THESEO stands for Airborne Platform for Earth observation — (contribution to) the Third European Stratospheric Experiment on Ozone. The campaign aimed to study processes controlling the low water content of the stratosphere, including the mechanisms of cloud formation in the tropical tropopause region, and transport processes, studied using measurements of long-lived trace gases and ozone.Two aircraft were used: the high-altitude research aircraft, M-55 Geophysica, which can fly up to 21 km, and the Falcon of the Deutsches Zentrum fr Luft- und Raumfahrt, a tropospheric aircraft. Seven flights were performed, including the first simultaneous in situ and remote sensing of sub-visible cirrus clouds, the first interception of sub-visible cirrus using in-flight guidance from a path-finding aircraft, and guided descent of a high-altitude research aircraft into the anvil cloud at the top of a tropical cyclone. In this paper we describe the payload used, the objectives for each flight, and the meteorological conditions encountered. First results show that a new type of cloud, which we have dubbed ultra-thin tropical tropopause cloud (UTTC), has been observed frequently, and observed to cover areas of 105 km2. The frequent coincidence of the tropopause and hygropause implies that the western Indian Ocean played an important role in the dehydration of the lower tropical stratosphere during the season of the mission. UTTCs, sub-visible cirrus, and visible cirrus, have all been implicated in the observed dehydration. Tracer measurements indicate little mixing of stratospheric air into the upper tropical troposphere.
  Journal of Atmospheric Chemistry 01/2004; 48(2004):1-33. · 0.99 Impact Factor
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  Available from: A. R. Mackenzie

  Article: Ultrathin Tropical Tropopause Clouds (UTTCs): II. Stabilization mechanisms

  B. P. Luo, Peter Th, Wernli H, Fueglistaler S, Wirth M, Kiemle C, Flentje H, V. A. Yushkov, Khattatov V, Rudakov V, [......], Adriani A, C. M. Volk, Strom J, Noone K, Mitev V, R. A. MacKenzie, K. S. Carslaw, Trautmann T, Santacesaria V, Stefanutti L
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  ABSTRACT: Mechanisms by which subvisible cirrus clouds (SVCs) might contribute to dehydration close to the tropical tropopause are not well understood. Recently Ultrathin Tropical Tropopause Clouds (UTTCs) with optical depths around 10^-4 have been detected in the western Indian ocean. These clouds cover thousands of square kilometers as 200-300 m thick distinct and homogeneous layer just below the tropical tropopause. In their condensed phase UTTCs contain only 1-5% of the total water, and essentially no nitric acid. A new cloud stabilization mechanism is required to explain this small fraction of the condensed water content in the clouds and their small vertical thickness. This work suggests a mechanism, which forces the particles into a thin layer, based on upwelling of the air of some mm/s to balance the ice particles, supersaturation with respect to ice above and subsaturation below the UTTC. In situ measurements suggest that these requirements are fulfilled. The basic physical properties of this mechanism are explored by means of a single particle model. Comprehensive 1-D cloud simulations demonstrate this stabilization mechanism to be robust against rapid temperature fluctuations of +/- 0.5 K. However, rapid warming (Delta T > 2 K) leads to evaporation of the UTTC, while rapid cooling (Delta T < -2 K) leads to destabilization of the particles with the potential for significant dehydration below the cloud
  Atmospheric Chemistry and Physics. 01/2003;
• Article: The impact of local emissions on the formation of secondary pollutants in urban plumes.

  A R MacKenzie, R M Harrison, I Colbeck
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  ABSTRACT: The results of modelling studies are reported together with a further analysis of an existing field measurement dataset. Emphasis is on the maximum ozone concentrations occurring in the urban plume from London, UK, on days of photochemical activity. Nitrogen oxide and volatile organic compound emissions from automotive exhausts are expected to be a large proportion of the total emission of these species, and the effect of their distinct diurnal variation is apparent in the field data. Factorial sensitivity studies on an expanding box model of the urban plume also show the dominance of urban emissions in the determination of plume maxima 100km downwind of the upwind urban boundary. These effects are not additive and depend strongly on the level of other variables.
  Science of The Total Environment 05/1990; 93:245-54. · 3.29 Impact Factor