Temporal and Spatial Variability of Global Upper Ocean Freshwater Content
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Authors
Chu, Peter C.
Fan, Chenwu
Subjects
Global Temperature and Salinity Profile Program (GTSPP)
Monthly Varying Global (T, S) Field
Optimal Spectral Decomposition (OSD)
Upper Ocean Freshwater Content
Monthly Varying Global (T, S) Field
Optimal Spectral Decomposition (OSD)
Upper Ocean Freshwater Content
Advisors
Date of Issue
2018-05
Date
Publisher
Lupine Publishers
Language
Abstract
Observational salinity data from the Global Temperature and Salinity Profile Program (GTSPP) are used to identify temporal
and spatial variability of the upper ocean freshwater content (FWC). First, the optimal spectral decomposition (OSD) is used to
build up monthly synoptic temperature and salinity data set from January 1990 to December 2009 on 1o×1o grids and the same
33 vertical levels as the World Ocean Atlas 2005. Then, the monthly varying upper layer FWC fields (F) with four different layer
thicknesses (surface to 50, 100, 300, and 700 m depths) are obtained. Second, a composite analysis is conducted to obtain the totaltime mean FWC field ( F ) and the mean annual FWC variability ( F
%), which is found an order of magnitude smaller than F . Third,
an empirical orthogonal function (EOF) method is conducted on the residue data ( Fˆ ), deviating from F + F
% , in order to obtain
non-annual variability of the FWC fields. The first two EOF modes account for 63.6-76.4% and 6.7-6.8% of the variance for the four
layer thicknesses, representing near-global scale (EOF-1, dominant mode) and northern-southern alternative (EOF-2, minor mode)
freshening/salinization events. The near-global scale freshening/salinization has a decadal trend from salinization before 2002 to
freshening after 2002. The northern-southern alternative freshening/salinization does not have evident trend.
Type
Article
Description
The article of record as published may be found at http://dx.doi.org/10.32474/MAOPS.2018.01.000123
Series/Report No
Department
Oceanography
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Office of Naval Research
Naval Postgraduate School
Naval Postgraduate School
Funder
Format
9 p.
Citation
Peter C C, Chenwu F. Temporal and Spatial Variability of Global Upper Ocean Freshwater Content. Mod App Ocean & Pet Sci 1(5)-
2018. 85-93.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.