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| Titel |
Ceilometer measurements in the Southern Ocean |
| VerfasserIn |
Adrian McDonald, Simon Alexander, John French, Mike Harvey, Andrew Ichoja, Andrew Klekociuk, Graeme Plank, Marwan Katurji |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130432
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| Publikation (Nr.) |
 EGU/EGU2016-10688.pdf |
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| Zusammenfassung |
| Current climate models display a consistent deficit of reflected shortwave radiation over the
Southern Ocean which is mainly due to the poor representation of clouds. Recent work has
also shown that reanalysis also perform poorly relative to satellite observations in terms
of cloud fraction. In particular, satellite observations have shown that low-level
clouds (with tops below 3 km) are ubiquitous over the Southern Ocean. But, most
satellite instruments, even the current generation of active satellite instruments,
have difficulties in sampling low level clouds. As part of the New Zealand Deep
South challenge project focussed on improving the representation of clouds in the
Southern Ocean, we have begun to deploy autonomous instruments on ‘ships of
opportunity’.
This study discusses measurements from a Väisälä CL51 laser ceilometer and ancillary
instruments on the first two research voyages in the Southern Ocean and initial results. The
route of the first voyage covers a return trip from Wellington (New Zealand) to Terra Nova
Bay (Antarctica) onboard the R/V Tangaroa and occurred in January to mid-February 2015.
The second deployment is onboard the Aurora Australis Australian Antarctic Division supply
ship and began in October 2015 and is planned to finish at Macquarie Island in March 2016.
The sampling provided by the ships route allows the ceilometer measurements of the height
of the cloud base in a region where limited data apart from, potentially biased, satellite
measurements of low-level cloud exist. Analysis of the boundary layer height derived
from the ceilometer is also presented. The climatological structure derived from the
ceilometer measurements is first detailed. We then compare these measurements
with satellite and ground-based observations. We then examine variations in these
measurements relative to their meteorological context. Details of plans for future
voyages are also detailed. We will also present a preliminary analysis of a case study
of clouds and local meteorological conditions made while the ship was moored
continuously at Davis, Antarctica (69S, 78E) for several days in October 2015. During this
interval, data collected by the ship-based ceilometer, radiometers and an all-sky
camera were supplemented with shore-based wind-profiling radar and radiosonde
observations |
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