PIs: Justus Notholt, Roland Neuber

The Arctic atmosphere changes considerably with latitudes, as do the processes therein. Gradients exist particularly along the land – sea margin and the open – ice covered ocean. Arctic Amplification processes vary accordingly. This project will address the spatial fine structure of important atmospheric components along the latitudinal gradient from northern Europe via Svalbard into the Arctic Ocean and will thereby connect the ship and airborne measurements with those at the German/French Arctic Research station in Ny–Ålesund on Svalbard. Particularly we will assess the latitudinal variability of the important climate drivers water vapour, aerosols, and clouds on the radiative budget.

The aim of the proposal is to investigate the horizontal fine structure of the Arctic atmosphere during a ship cruise from mid–latitudes to the high Arctic, and build the link to the permanent research stationin Ny–Ålesund. We propose to perform a combination of integrated water vapour measurements (IWV) and liquid water path (LWP) using a millimeterwave radiometer HATPRO together with results for trace gases and optically thin clouds measured by a FTIR instrument.

These measurements complement those in the project A01 of the distribution of clouds and aerosols from mid–latitudes to the Arctic across the ice edge to provide a comprehensive picture during the Arctic summer using complementary observations. The observations in the project A01 and within this project will be performed during the same ship cruise onboard the research vessel RV Polarstern.

Parallel to the ship borne measurements from this proposal, similar observations are carried out continuouslyat the Arctic Research Base AWIPEV at Ny–Ålesund, Svalbard, as described in E02. The combined analysis of aerosols, water vapour, and thin cloud parameters will allow to investigate the impact of transport from mid-latitudes on the inner Arctic summer situation and to understand its variability by the continuous land based observations. The observations are closely connected to model studies and will serve as input data for models in A01 and D03.

The outcome of this study will help to:

• understand the impact of long–range transport from mid–latitudes into the Arctic and vice versa

• improve the understanding of the Arctic atmosphere dynamics and meteorology

• determine the vertical and latitudinal distribution of key trace substances during summer and its variability

• assess the actual state of the atmosphere during the ship cruise, complementing the long–term data set available from the Svalbard station (AWIPEV Base)

• combine the aerosol measurements of the campaign (A01) with the long–term observations in Ny–Ålesund providing an assessment of pollution pathways and the efficiency of wet deposition or activation.

In order to test the hypothesis, we will address and contribute to the following central questions exemplarily with the first ship cruise in phase I:

• How large is the latitudinal variability of aerosols, water vapour and thin clouds between the North Atlantic ice edge and the inner Arctic?

• How can the effect of the spatial atmospheric fine structure be parameterized using the time series obtained by the standard measurement stations and the satellite measurements?

• With the help of models, how does the spatial fine structure of the Arctic atmosphere affect the radiative budget of the Arctic atmosphere in summer?

• B06 complements observations in A01 with ship-borne FTIR measurements and Ny-Ålesund long term data
• Data retrieval with E02
• Data analysis and interpretation with A01, B05, and E02, particularly on the radiative budget
• Data provision for model evaluation in B05, D01, E01, and E02
• Satellite validation in B01, B05
• Airborne measurements in B03 supported by ground testing and intensive observational periods in Ny-Ålesund