Century‐scale causal relationships between global dry/wet conditions and the state of the Pacific and Atlantic Oceans

• Published in: Geophysical research letters Vol. 43; no. 12; pp. 6528 - 6537
• Main Authors: Sun, Qiaohong, Miao, Chiyuan, AghaKouchak, Amir, Duan, Qingyun
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.06.2016; Wiley
• Subjects: Atlantic Ocean; Atmospheric forcing; Climate; Climate change; Climate variability; Drought; Droughts; Drying; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; El Niño–Southern Oscillation; Evaluation; Evapotranspiration; Evapotranspiration-precipitation relationships; Flood forecasting; Freshwater; Marine; Meteorology; Multiscale analysis; North Atlantic Oscillation; Ocean currents; Ocean-atmosphere interaction; Ocean-atmosphere system; Oceans; Pacific Decadal Oscillation; Precipitation; River discharge; Southern Oscillation; Standardized precipitation index; Variability; South America; Antarctica; North America; Europe; Africa; ASW, South America; PS, Antarctica; INW, Russia; I, Pacific; AN, North Atlantic, North Atlantic Oscillation; ANE, Europe; IN, Pacific
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2016GL069628

The Granger causality test is used to examine the effects of the El Niño–Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO) on global dry/wet conditions. The results show robust relationships between dry/wet conditions and the ocean states, as assessed through a multi‐index (standardized precipitation evapotranspiration index and standardized precipitation index) and multiscale (3 months and 12 months) evaluation. The influence of ENSO events is widespread, dominating about 38% of the global land surface (excluding Antarctica). Southern and western North America, northern South America, and eastern Russia are influenced by the PDO. The NAO influences not only dry/wet conditions in Europe but also dry/wet conditions in northern Africa. Similarly, climate variability in southern Europe and northern Africa may be due to the concurrence of the ENSO and the NAO. Knowledge of the spatial influence of ocean states on global dry/wet conditions is valuable for improving drought and flood forecasting. Key Points Granger causality test was used to examine the impact of large‐scale climate drivers on regional droughts ENSO dominating about 38% of the global droughts ENSO and PDO can reinforce each other to dominate climate variability