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On the visibility of airborne volcanic ash and mineral dust from the pilot’s perspective in flight

Weinzierl, Bernadett and Sauer, Daniel and Minikin, Andreas and Reitebuch , Oliver and Dahlkötter, Florian and Mayer, Bernhard and Emde, Claudia and Tegen, Ina and Gasteiger, Josef and Petzold, Andreas and Veira, Andreas and Kueppers, Ulrich and Schumann, Ulrich (2012) On the visibility of airborne volcanic ash and mineral dust from the pilot’s perspective in flight. Physics and Chemistry of the Earth, 45-46, pp. 87-102. DOI: 10.1016/j.pce.2012.04.003.

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Official URL: http://dx.doi.org/10.1016/j.pce.2012.04.003

Abstract

In April 2010, volcanic ash from the Eyjafjalla volcano in Iceland strongly impacted aviation in Europe. In order to prevent a similar scenario in the future, a threshold value for safe aviation based on actual mass concentrations was introduced (2 mg m3 in Germany). This study contrasts microphysical and optical properties of volcanic ash and mineral dust and assesses the detectability of potentially dangerous ash layers (mass concentration larger than 2 mg m3) from a pilot’s perspective during a flight. Also the possibility to distinguish between volcanic ash and other aerosols is investigated. The visual detectability of airborne volcanic ash is addressed based on idealized radiative transfer simulations and on airborne observations with the DLR Falcon gathered during the Eyjafjalla volcanic ash research flights in 2010 and during the Saharan Mineral Dust Experiments in 2006 and 2008. Mineral dust and volcanic ash aerosol both show an enhanced coarse mode (>1 lm) aerosol concentration, but volcanic ash aerosol additionally contains a significant number of Aitken mode particles (<150 nm) not present in mineral dust. Under daylight clear-sky conditions and depending on the viewing geometry, volcanic ash is visible already at mass concentrations far below what is currently considered dangerous for aircraft engines. However, it is not possible to visually distinguish volcanic ash from other aerosol layers or to determine whether a volcanic ash layer is potentially dangerous (mass concentration larger or smaller than 2mgm3). Different appearances due to microphysical differences of both aerosol types are not detectable by the human eye. Nonetheless, as ash concentrations can vary significantly over distances travelled by an airplane within seconds, this visual threat evaluation may contribute greatly to the short-term response of pilots in ash-contaminated air space.

Document Type:Article
Title:On the visibility of airborne volcanic ash and mineral dust from the pilot’s perspective in flight
Authors:
AuthorsInstitution or Email of Authors
Weinzierl, Bernadett bernadett.weinzierl@dlr.de
Sauer, Daniel LMU
Minikin, Andreas DLR
Reitebuch , Oliver DLR
Dahlkötter, Florian DLR
Mayer, Bernhard LMU
Emde, Claudia LMU
Tegen, Ina IfT Leipzig
Gasteiger, Josef LMU
Petzold, Andreas DLR
Veira, Andreas DLR
Kueppers, Ulrich LMU
Schumann, Ulrich DLR
Date:2012
Journal or Publication Title:Physics and Chemistry of the Earth
Refereed publication:Yes
In Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:45-46
DOI:10.1016/j.pce.2012.04.003
Page Range:pp. 87-102
Status:Published
Keywords:Volcanic ash, Saharan mineral dust, Particle size distribution, Visible ash, Ash mass concentration, Radiative transfer simulations
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:ATM and Operation
DLR - Research area:Aeronautics
DLR - Program:L AO - Air Traffic Management and Operation
DLR - Research theme (Project):L - Climate, Weather and Environment
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Lidar
Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Jana Freund
Deposited On:11 Jul 2012 14:52
Last Modified:26 Mar 2013 13:40

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