Annual to Inter-Decadal Variability of Surface Air Temperature along the Coast of Tanzania

Abstract

The patterns of atmospheric surface temperature along the coast of Tanzania were investigated for variability and decadal trends over the past 50 years (1960-2009). Various statistical tools were employed in the research, including non-parametric models as well as trend, spectral and wavelet analyses. The effects of large scale climatic systems were investigated through partial correlations. Results show the predominance of annual oscillations, but the El Niño–Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Pacific Decadal Oscillation (PDO) phenomena are also evident in the record. Generally around equinoxes, the surface temperatures are directly influenced by ENSO, and indirectly by the IOD and the PDO. Conversely around solstices, the temperatures are directly influenced by the IOD and PDO, and indirectly by the ENSO. A key finding of this study is the revelation of significant warming trends of surface temperature along the coast. The increases per decade are consistent with global trends, being generally greater in minimum temperature (0.14-0.72^oC) than in maximum temperature (0.07-0.13^oC). Within the last half century, the warmest year in minimum temperature differed slightly between stations but all fell within the last decade (2000-2009). The past decade, which coincided with a warm PDO inter-decadal signal, was also the warmest.