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

ACE-2 - NORTH ATLANTIC REGIONAL AEROSOL CHARACTERIZATION EXPERIMENT

During ACE-2 the IfT six-wavelength lidar was set up at the southwestern tip of Portugal, in Sagres. During the observational period in June and July 1997 vertically resolved measurements of aerosol optical properties at six wavelengths between 355 and 1064 nm were performed.

Introduction

ACE-2, the North Atlantic Regional Aerosol Characterization Experiment, was the third experiment co-ordinated by the International Global Atmospheric Chemistry Project (IGAC) that addresses the properties of the atmospheric aerosol relevant to radiative forcing and climate. The objectives of this series of experiments are to provide the necessary data to incorporate aerosols into global climate models and to reduce the overall uncertainty in the calculation of climate forcing by aerosols.

ACE-1 (November-December, 1995) documented the chemical, physical and optical characteristics and determinded the controlling processes of the aerosol in the remote marine atmosphere. TARFOX (June 1996) focussed specifically on the column-integrated direct radiative forcing by anthropegenic aerosols. ACE-2 extended these characteriziation and process studies to the North Atlantic Ocean with an emphasis on the anthropogenic perturbation of the background aerosol. A major focus of ACE-2 was the characterization and evolution of anthropogenic aerosols from the European continent and desert dust from the African continent, as they move out over the North Atlantic Ocean.

ACE-2 was conducted from June 15th to July 31st, 1997, over the subtropical northeastern Atlantic Ocean, with the base of operations on the Canary Islands (see picture below).

Shown here are the positions of the ship and groundbased stations involved,
and a schematic view of the aircraft operations during the intensive campaign in summer 1997.
(Click on picture to enlarge!)

Objectives and goals

The goal of ACE-2 was to determine and understand the properties and controlling factors of the aerosol in the anthropogenically modified atmosphere of the North Atlantic and to assess their relevance for radiative forcing. To achieve this goal, ACE-2 pursued three specific objectives:

1. Determine the physical, chemical, radiative and cloud nucleating properties of the major aerosol types in the North Atlantic regions and investigate the relationships between these properties.
2. Quantify the physical and chemical processes controlling the evolution of the major aerosol types and in particular of their physical, chemical, radiative and cloud nucleating properties.
3. Develope procedures to extrapolate aerosol properties and processes from local to regional and gloabl scales, and assess the regional direct and indirect forcing by aerosols in the North Atlantic region.

The area schown here is selected as the limited study area for ACE-2.
(Click on picture to enlarge!)

Summary

A detailed summary of ACE-2 is given in:

Tellus, Series B: Chemical and physical meteorology, Volume 52B, Number 2, April 2000.

Our group contributed with the following publications to ACE-2:

Ansmann, A., Wagner, F., Althausen, D., Müller, D., Herber, A. and Wandinger, U. 2001. European pollution outbreaks during ACE 2: Lofted aerosol plumes observed with Raman lidar at the Portuguese coast. J. Geophys. Res., 106, 20725-20733.

Ansmann, A., Wagner, F., Müller, D., Althausen, D., Herber, A., Hoyningen-Huene, W. v. and Wandinger, U. 2002. European pollution outbreaks during ACE 2: Optical particle properties inferred from multiwavelength lidar and star/Sun photometry. J. Geophys. Res., 107, 2001JD001109.

ACE-2 related downloads and links

• NOAA/PMEL