Recent Climate Change in the Tropical Western Pacific and Indian Ocean Regions as Detected by Outgoing Longwave Radiation Records

Abstract

Abstract Recent climate change in tropical convection in the western Pacific and Indian Ocean regions is inferred from the outgoing longwave radiation (OLR) records. The systematic bias in the OLR series is first corrected and results of the rotated empirical orthogonal function analysis indicate that the bias, to a first approximation, has been corrected. Linear regression analysis and nonparametric Mann–Kendall rank statistics are employed to detect trends. From 1974 to 1992, trend analyses based on the entire consecutive monthly records suggest a significant decrease in OLR over the tropical central–western Pacific and a large portion of the Indian Ocean. In contrast, northern Australia shows the largest increase in OLR over time. The significance of the local linear trend pattern has been determined via a Monte Carlo simulation technique that scrambles OLR time series at each grid point “simultaneously” and results show the field significance. An increase in convection shows a preference to occur in t...