Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
06 Sep 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Ocean Science (OS) and is expected to appear here in due course.
Decorrelation scales for Arctic Ocean Hydrography. Part I: Amerasian Basin
Hiroshi Sumata1, Frank Kauker1,2, Michael Karcher1,2, Benjamin Rabe1, Mary-Louise Timmermans3, Axel Behrendt1, Rüdiger Gerdes1,4, Ursula Schauer1, Koji Shimada5, Kyoung-Ho Cho6, and Takashi Kikuchi7 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
2Ocean Atmosphere Systems, Hamburg, Germany
3Yale University, Connecticut, USA
4Jacobs University, Bremen, Germany
5Tokyo University of Marine Science and Technology, Tokyo, Japan
6Korea Polar Research Institute, Incheon, Korea
7Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
Abstract. Abstract. Any use of observational data for data assimilation requires adequate information of their representativeness in space and time. This is particularly important for sparse, non-synoptic data, which comprise the bulk of oceanic in-situ observations in the Arctic. To quantify spatial and temporal scales of temperature and salinity variations, we estimate the autocorrelation function and associated decorrelation scales for the Amerasian Basin of the Arctic Ocean. For this purpose, we compile historical measurements from 1980 to 2015. Assuming spatial and temporal homogeneity of the decorrelation scale in the basin interior (abyssal plain area), we calculate autocorrelations as a function of spatial distance and temporal lag. The examination of the functional form of autocorrelation in each depth range reveals that the autocorrelation is well described by a Gaussian function in space and time. We derive decorrelation scales of 150~200 km in space and 100~300 days in time. These scales are directly applicable to quantify the representation error, which is essential for use of ocean in-situ measurements in data assimilation. We also describe how the estimated autocorrelation function and decorrelation scale should be applied for cost function calculation in a data assimilation system.

Citation: Sumata, H., Kauker, F., Karcher, M., Rabe, B., Timmermans, M.-L., Behrendt, A., Gerdes, R., Schauer, U., Shimada, K., Cho, K.-H., and Kikuchi, T.: Decorrelation scales for Arctic Ocean Hydrography. Part I: Amerasian Basin, Ocean Sci. Discuss.,, in review, 2017.
Hiroshi Sumata et al.
Hiroshi Sumata et al.


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Short summary
We estimated spatial and temporal decorrelation scales of temperature and salinity in the Amerasian Basin in the Arctic Ocean. The estimated scales can be applied to representation error assessment in the ocean data assimilation system for the Arctic Ocean.
We estimated spatial and temporal decorrelation scales of temperature and salinity in the...