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Research article - Peer-reviewed, 2020

Using land-based stations for air-sea interaction studies

Rutgersson, Anna; Pettersson, Heidi; Nilsson, Erik; Bergström, Hans; Wallin, Marcus; Nilsson, E. Douglas; Sahlée, Erik; Wu, Lichuan; Mårtensson, E. Monica;

Abstract

In situ measurements representing the marine atmosphere and air–sea interaction are taken at ships, buoys, stationary moorings and land-based towers, where each observation platform has structural restrictions. Air–sea fluxes are often small, and due to the limitations of the sensors, several corrections are applied. Land-based towers are convenient for long-term observations, but one critical aspect is the representativeness of marine conditions. Hence, a careful analysis of the sites and the data is necessary. Based on the concept of flux footprint, we suggest defining flux data from land-based marine micrometeorological sites in categories depending on the type of land influence: 1. CAT1: Marine data representing open sea, 2. CAT2: Disturbed wave field resulting in physical properties different from open sea conditions and heterogeneity of water properties in the footprint region, and 3. CAT3: Mixed land–sea footprint, very heterogeneous conditions and possible active carbon production/consumption. Characterization of data would be beneficial for combined analyses using several sites in coastal and marginal seas and evaluation/comparison of properties and dynamics. Aerosol fluxes are a useful contribution to characterizing a marine micrometeorological field station; for most conditions, they change sign between land and sea sectors. Measured fluxes from the land-based marine station Ostergarnsholm are € used as an example of a land-based marine site to evaluate the categories and to present an example of differences between open sea and coastal conditions. At the Ostergarnsholm site the surface drag is larger for € CAT2 and CAT3 than for CAT1 when wind speed is below 10 m/s. The heat and humidity fluxes show a distinctive distinguished seasonal cycle; latent heat flux is larger for CAT2 and CAT3 compared to CAT1. The flux of carbon dioxide is large from the coastal and land–sea sectors, showing a large seasonal cycle and significant variability (compared to the open sea sector). Aerosol fluxes are partly dominated by sea spray emissions comparable to those observed at other open sea conditions.

Keywords

air–sea interaction; coastal zone; carbon dioxide; micrometeorological measurements; sea spray

Published in

Tellus A: Dynamic Meteorology and Oceanography

2020, volume: 72, number: 1, pages: 1-23

Authors' information

Rutgersson, Anna
Uppsala University
Pettersson, Heidi
Finnish Meteorological Institute
Nilsson, Erik
Uppsala University
Bergström, Hans
Uppsala University
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Nilsson, E. Douglas
Stockholm University
Sahlée, Erik
Uppsala University
Wu, Lichuan
Uppsala University
Mårtensson, E. Monica
Uppsala University

UKÄ Subject classification

Meteorology and Atmospheric Sciences
Oceanography, Hydrology, Water Resources

Publication Identifiers

DOI: https://doi.org/10.1080/16000870.2019.1697601

URI (permanent link to this page)

https://res.slu.se/id/publ/108817