Errors in Estimated Temporal Tracer Trends Due to Changes in the Historical Observation Network: A Case Study of Oxygen Trends in the Southern Ocean
1
조회
0
다운로드
0
인용
0
참고문헌
초록
Abstract
Several models predict large and potentially abrupt ocean circulation changes due to anthropogenic greenhouse-gas emissions. These circulation changes drive-in the models-considerable oceanic oxygen trend. A sound estimate of the observed oxygen trends can hence be a powerful tool to constrain predictions of future changes in oceanic deepwater formation, heat and carbon dioxide uptake. Estimating decadal scale oxygen trends is, however, a nontrivial task and previous studies have come to contradicting conclusions. One key potential problem is that changes in the historical observation network might introduce considerable errors. Here we estimate the likely magnitude of these errors for a subset of the available observations in the Southern Ocean. We test three common data analysis methods south of Australia and focus on the decadal-scale trends between the 1970's and the 1990's. Specifically, we estimate errors due to sparsely sampled observations using a known signal (the time invariant, temporally averaged, World Ocean Atlas 2001) as a negative control. The crossover analysis and the objective analysis methods are far less prone to spatial sampling location biases than the area averaging method. Subject to numerous caveats, we find that errors due to sparse sampling for the area averaging method are on the order of several micromoles kg-1. For the crossover and the objective analysis method, these errors are much smaller. For the analyzed example, the biases due to changes in the spatial design of the historical observation network are relatively small compared to the trends predicted by many model simulations. This raises the possibility to use historic oxygen trends to constrain model simulations, even in sparsely sampled ocean basins.
참고문헌 (25)
- "Abrupt climate change", 299(5615), pp.2005~2010 (2003)
- "Decadal changes along an Indian Ocean section at 32oS and their interpretation", 30, pp.1207~1222 (2000)
- "A technique for the objective analysis and design of oceanographic experiments applied to MODE-73", pp.559~582 (1976)
- "Thermohaline circulation, the Achilles heel of our climate system", 278, pp.1582~1588 (1997)
- "World Ocean Database 2001, Volume 1", 42 (2002), U.S. Government Printing Office
- "World Ocean Atlas 2001" (2002), National Oceanographic Data Center
- "Projections of future climate change, Climate Change 2001 - The scientific basis", pp.526~582 (2001), Cambridge University Press
- "WOCE Version 3.0" (2002), University of California
- "Decadal-scale chemical variability in the subtropical North Atlantic deduced from nutrient and oxygen data", 103(2), pp.2817~2830 (1998)
- "On oxygen content variability in the upper ocean", 84(52) (2003), EOS Trans.
- "What story is told by oceanic tracer concentrations?", 290, pp.455~456 (2000)
- "The change in oceanic O2 inventory associated with recent global warming", 99, pp.7848~7853 (2002)
- "Possible biological or physical explanations for decadal scale trends in North Pacific nutrient concentrations and oxygen utilization", 49, pp.345~362 (2002)
- "Tropical stabilization of the thermohaline circulation in a greenhouse warming simulation", 13, pp.1809~1813 (2000)
- "Changes in dissolved oxygen in the Southern Ocean with climate change", 1 (2000)
- "On the meridional extent and fronts of the Antarctic Circumpolar Current", 42(5), pp.641~673 (1995)
- "Temporal trends in deep ocean Redfield ratios", 287, pp.831~833 (2000)
- "Revision of the global carbon budget due to changing air-sea oxygen fluxes", 16 (2002)
- "Nutrient data differences between crossings of WOCE hydrographic lines", 80(49) (1999)
- "Climate field reconstruction under stationary and nonstationary forcing", 16(3), pp.462~479 (2003)
- "Simulated response of the ocean carbon cycle to anthropogenic climate warming.", 393, pp.245~249 (1998)
- "Warming and circulation change in the Eastern South Pacific Ocean", 27(9), pp.1247~1250 (2000)
- "Requirements for WOCE hydrographic programme data reporting" (1994)
- "Resampling hypothesis tests for autocorrelated fields", 10(1), pp.65~82 (1997)
- "Temporal trends in deep ocean Redfield ratios", 289 (2000)
