Interannual Variability of Thermal Conditions in the Extratropical Zone of the South Pacific at the Turn of the XX–XXI Centuries

• Published in: Physical Oceanography
• Main Authors: I.D. Rostov, E.V. Dmitrieva, N.I. Rudykh
• Format: Article in Journal/Newspaper
• Language: English
• Published: Federal State Budget Scientific Institution «Marine Hydrophysical Institute of RAS» 2021
• Subjects: south pacific; extratropical zone; current climatic changes; regional features; water and air temperature; warming and cooling trends; climatic parameters; correlations; Oceanography; GC1-1581; New Zealand; Pacific; Subarctic
• Online Access: https://doi.org/10.22449/1573-160X-2021-6-612-631; https://doaj.org/article/dd52fc6c1ddb43ac991dcbc04b9c9b71

Purpose. The aim of the study consists in identifying the spatial-temporal features of interannual changes in the surface air temperature Ta, the sea surface temperature (SST) and the upper 1000-meter water layer temperature Tw in the extratropical zone of the South Pacific Ocean over the past four decades, which are manifested as a result of the planetary changes and a shift in the climatic regime at the turn of the XX–XXI centuries. Besides, the revealed features’ trends and their possible cause-and-effect relationships with the processes in the atmosphere and on the ocean surface are planned to be assessed. Methods and Results. Based on the Global Meteorological Network and Reanalysis data (NOAA), regional features and trends of the water and air temperature interannual fluctuations, and their relation to variations in the pressure and wind fields, intensity of the atmosphere action centers (AAC) and climatic indices (CI) over the past 4 decades have been determined. Applied were the methods of the cluster, correlation and regression analysis, as well as the apparatus of empirical orthogonal functions (EOF). The positive trends in changes of the Ta and SST fields are manifested mainly in the northwestern part of the region, where they are statistically significant and reach their maximum 0.4–0.6°C over 10 years in the Tasman Sea region and to the northeast of New Zealand. The water areas with minimal, negative or insignificant values of the air and water temperature trends are located on the southern and eastern peripheries of the water area under study – in the areas of influence of cold currents. Over the entire investigated water area, the trends in the mean annual SST and Ta were ~ 0.04–0.06°C/10 years that are 2–3 times less than those in the subarctic region of the North Pacific Ocean. The features of spatial-temporal variability of the water temperature trends at different horizons differ significantly from the characteristics of the SST trends. The trends’ spatial distribution is already transformed ...