Research Group
"Optical Remote Measurements - Analysis of Atmospheric Processes with Optical Methods"

INDOEX - INDIAN OCEAN EXPERIMENT

Objectives and goals Three main objectives were identified: Assess the significance of sulfates and other contitental aerosols for global radiative forcing. Assess the magnitude of the solar absorption at the surface and in the troposphere including the ITCZ (intertropical convergence zone) cloud system. Assess the role of the ITCZ in the transport of trace species and pollutants and their resultant radiative forcing. The first objective would contribute to a better understanding of the decadal and longer time scale climate forcing; the second would lead to improved coupled ocean-atmosphere models; and the third would aid the development of tropospheric chemistry models.

The equatorial Indian Oceam during the northeast winter monosoon season is a unique natural laboratory for addressing these objectives. The selected experiment area is probably the only place in the world where an intense source of continental aerosols, anthropogenic trace species and their reaction products (e.g., sulfates and ozone) from the northern hemisphere is directly connected to the pristine air of the southern hemisphere by a cross quatorial monsoonal flow into the intertropical convergence zone (ITCZ). Furthermore, the deep convection within the ITCZ gives rise to extensive mid- and upper-level cloud systems. INDOEX was an international field experiment in the Indian Ocean with participation from France, Germany, India, the Netherlands, and the US.

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Results of our measurements
(Click on picture to enlarge!)

Pollution outbreak above the marine boundary layer during northeast monsoon observed with the IfT six-wavelength lidar; INDOEX, Hulule, Maldives, March 25th, 1999, 1330-1500 UTC (See also Inversion Algorithm!)

Air mass change: transport of aerosols from southeast Asia and India as observed with the IfT six-wavelength lidar; INDOEX, Hulule, Maldives, March 8th-11th, 1999

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Picturesque impressions from the campaign

During INDOEX the IfT lidar, Sun photometer, and radiosonde station were set up on
the airport island of the Maldives, Hulule (Go to Picture Gallery).


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Summary

A detailed summary of INDOEX is given in:

Journal of Geophysical Research, Special Section on INDOEX, Vol. 106, No. D22, 2001
Journal of Geophysical Research, Special Section on INDOEX, Vol. 107, No. D21, 2002

Our group contributed with the following publications to INDOEX:

Ansmann, A., Althausen, D., Wandinger, U., Franke, K., Müller, D., Wagner, F. and Heintzenberg, J. 2000. Vertical profiling of the Indian aerosol plume with six-wavelength lidar during INDOEX: A first case study. Geophys. Res. Lett., 27, 963-966.

Franke, K., Ansmann, A., Müller, D., Althausen, D., Wagner, F. and Scheele, R. 2001. One-year observations of particle lidar ratio over the tropical Indian Ocean with Raman lidar. Geophys. Res. Lett., 28, 4559-4562.

Müller, D., Franke, K., Wagner, F., Althausen, D., Ansmann, A. and Heintzenberg, J. 2001. Vertical profiling of optical and physical particle properties over the tropical Indian Ocean with six-wavelength lidar. 1. Seasonal cycle. J. Geophys. Res., 106, 28567-28575.

Müller, D., Franke, K., Wagner, F., Althausen, D., Ansmann, A., Heintzenberg, J. and Verver, G. 2001. Vertical profiling of optical and physical particle properties over the tropical Indian Ocean with six-wavelength lidar. 2. Case studies. J. Geophys. Res., 106, 28577-28595.

Wagner, F., Müller, D. and Ansmann, A. 2001. Comparison of the radiative impact of aerosols derived from vertically resolved (lidar) and vertically integrated (Sun photometer) measurements: Example of an Indian aerosol plume. J. Geophys. Res., 106, 22861-22870.

Masonis, S. J., Franke, K., Ansmann, A., Müller, D., Althausen, D., Ogren, J. A., Jefferson, A. and Sheridan, P. J. 2002. An intercomparison of aerosol light extinction and 180 backscatter as derived using in-situ instruments and Raman lidar during the INDOEX field campaign.J. Geophys. Res., 107, 2000JD000035.

Franke, K., Ansmann, A., Müller, D., Althausen, D., Venkataraman, C., Reddy, M. S., Wagner, F. and Scheele, R. 2003. Optical properties of the Indo-Asian haze layer over the tropical Indian Ocean. J. Geophys. Res., 108, 2002JD002473.

Müller, D., Franke, K., Ansmann, A., Althausen, D. and Wagner, F. 2003. Indo-Asian pollution during INDOEX: Microphysical particle properties and single-scattering albedo inferred from multiwavelength lidar observations. J. Geophys. Res., 108, 2003JD003538.