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Abstract: Strait and inter-ocean transport are of fundamental interest to physical oceanography [Whitehead, 1989; Killworth, 1995; Godfrey, 1996] and ocean climate considerations [Hansen et al., 2001; Gordon et al., 2003], but are poorly understood and difficult to measure because long-term direct measurements of strait circulation is an expensive alternative and their implementation remains logistically challenging. We hypothesize that the magnitude and variability of strait transport varies with sea-surface height (SSH) and ocean bottom pressure (OBP) gradients between two inter-connected oceans. The combined 15-year TP/Jason-1 and other altimetry data has been the great resource of ocean surface topography, and the Gravity Recovery and Climate Experiment (GRACE) mission has been delivering temporal gravity data for five years with some oceanographic applications [e.g., Chambers et al., 2004; Song and Zlotniki, 2004; 2007; Zlotnicki et al., 2006]. Now it is the perfect time to combine the altimetry and gravimetry data for a better estimate of inter-ocean transport, based on the three years time series of Indonesian throughflow (ITF) measurements from the INSTANT program [Sprintall et al. 2004; Gordon et al, 1999], ongoing-projects measuring the throughflows in the Luzon, Mindoro, Karimata and Makassar Straits [Susanto and Gordon, 2005], and modelling support from a high-resolution global model with a terrain-following coordinate system for better resolving the strait geometry. Recently, we have developed a theoretical method by combining the "geostrophic control" formula of Garrett and Toulany [1982] and the "hydraulic control" theory of Whitehead et al. [1974]--allowing the use of SSH and OBP variables for estimating inter-ocean transport and separating the transport into surface and bottom fluxes [Song, 2006], providing a potential use of satellite measurements for operational applications. The problem of strait and inter-ocean transport estimation has not been studied in the previous OSTST program. Here we break new ground by combining satellite and in-situ observations with analytical and numerical models for the challenging problem. Based on the previous studies and the INSTANT-related measurements, we are:
This research will result in: (1) an improved understanding of Indonesian throughflow and Denmark Strait overflow; (2) an innovative methodology for utilizing satellite SSH and OBP; and (3) a demonstration of using future higher-resolution satellite data from OSTM and GRACE follow-on missions. The project addresses the research themes of the OSTST: (1) To support studies in physical oceanography utilizing Jason/OSTM mission data, as well as the combined 15-year TP/Jason data, jointly with other satellite (ERS-1/-2, ENVISAT, GFO) and in situ data and/or models, in support of both basic research and operational applications; and (2) to investigate the use of gravity mission data with altimeter data for improving the understanding of the mean ocean circulation. |
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