Overview

Within the OCEANET project the fi rst shipborne facility was developed that is able to investigate continuously the transfer of energy and material between ocean and atmosphere. The facility is based on the expertise of the Helmholtz Centre for Ocean Research Kiel (GEOMAR), TROPOS, the Helmholtz Centre Geesthacht, and the Alfred Wegener Institute (AWI), Bremerhaven. State-of-the-art oceanic underway measurement systems observethe CO2 and O2 concentrations, type of plankton, temperature, salinity, nutrients, andturbidity to determine the state of the upper ocean [Petersen et al., 2003; Amann et al.,2011]. Continuous observations of aerosol, cloud, temperature, and humidity pro les, liquid-water path, incident solar and thermal radiation, sensible and latent heat are performed to determine the inuence of the highly variable atmosphere on the radiativeenergy budget between ocean and atmosphere. Additional satellite observations by Meteosat Second Generation (MSG) are used to estimate the radiative energy budget at the top of atmosphere (TOA).


OCEANET is currently operated aboard the German research vessel Polarstern during its meridional cruises to the southern hemisphere and back.

OCEANET at TROPOS

TROPOS contributes to OCEANET by means of the measurement of atmospheric properties above the Ocean surface. The first Polarstern-cruise of Oceanet took place in  October 2009. Since then TROPOS has been participating regularly in the meridional cruises of Polarstern to the southern hemisphere. The equipment provided by TROPOS comprises an in-situ component and the remote-sensing component OCEANET-Atmosphere.

 

OCEANET-Atmosphere:

The OCEANET-Atmosphere facility was developed to cover the atmospheric observations aboard Polarstern. All measurement instruments are mounted on a 20-feet container shown in Fig. 2. Incident solar and thermal radiation are measured with a pyranometer (CMP21) and a pyrgeometer (CGR4), respectively, from Kipp & Zonen (box c in Fig. 2). They are part of the SCalable Automatic Weather Station (SCAWS) [Kleta, 2010], whichwas developed in cooperation with the German Weather Service (DWD). Due to the additional recording of temperature, relative humidity, and wind (box a in Fig. 2), OCEANET-Atmosphere became an offcial DWD station. Box d in Fig. 2.4 shows the instrumentation for turbulence and CO2-flux measurements (METEK USA-1, LICOR 7500), which enables the determination of sensible and latent heat fluxes [Bumke et al., 2002]. Every 15 s a skyimager (box e) takes a picture of the hemisphere above the platform to estimate cloud coverage and cloud type [Kalisch, 2011]. Liquid-water path is calculated from the measurements of the Humidity And Temperature PROfi ler (HATPRO) [Rose et al., 2005] for further cloud investigations (box f). Vertical aerosol and cloud profi ling is performed with the multiwavelength Raman and polarization lidar PollyXT.The lidar cabinet is mounted inside OCEANET-Atmosphere and measures through quartzplates in the roof of the container. The emitted visible green laser light can be seen in the nighttime photograph of the container in Fig. 2. OCEANET-Atmosphere was deployed at the upperdeck, starboard of Polarstern in about 22m asl.

Figure 2: Photograph of the OCEANET-Atmosphere facility during nighttime with
the green beam of the lidar.

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