Accession Number : ADA306400

Title :   Improved Tests for Global Warming Trend Extraction In Ocean Acoustic Travel-Time Data.

Descriptive Note : Final technical rept.,

Corporate Author : MISSION RESEARCH CORP SANTA BARBARA CA

Personal Author(s) : Bottone, Steven ; Gray, Henry L. ; Woodward, Wayne A.

PDF Url : ADA306400

Report Date : 01 APR 1996

Pagination or Media Count : 60

Abstract : A possible indication of the existence of global climate warming is the presence of a trend in the travel time of an acoustic signal along several ocean paths over a period of many years. This report describes new, improved tests for testing for linear trend in time series data with correlated residuals. Previous tests that adjust for the correlation in the residuals tend to have the problem that observed significance levels are higher than nominal for small to moderate realization lengths whenever the residuals are correlated. We introduce a bootstrap based procedure to test for trend in this setting which is better adapted to controlling the significance levels. The procedure is applied to acoustic travel time data generated by the MASIG ocean model. It is shown how to generalize the improved method to multivariate, or vector, time series, which, in the ocean acoustics setting, corresponds to travel time data on many ocean paths. An appendix describes the TRENDS software, which enables the user to perform these calculations using a graphical user interface (GUI).

Descriptors :   *CLIMATE, *UNDERWATER ACOUSTICS, *ACOUSTIC VELOCITY, COMPUTER PROGRAMS, GLOBAL, PATHS, TIME SERIES ANALYSIS, OCEANOGRAPHIC DATA, ACOUSTIC SIGNALS, EXTRACTION, OCEAN MODELS, ACOUSTIC DATA, TRAVEL TIME.

Subject Categories : Meteorology
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE