Analysis of the Effect of an Anomalous Convective Longitude Position Difference on Regional Climate Caused by El Niño

Based on NOAA (National Oceanic and Atmospheric Administration) monthly OLR (Outgoing Longwave Radiation) data from 1979 to 2019, NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis), ECMWF (European Centre for Medium-Range Weather Forecasts) ERA5 monthly reanalysis datasets, and East Anglia Climatic Research Unit surface temperature data from 1960 to 2019, the effects of El Niño events with anomalous convection at a different zonal position on regional climate are discussed. The findings show that studying the effects of El Niño events on atmospheric circulation and regional climate anomalies based on the zonal positions of anomalous convection in the tropical Pacific can overcome the limitation that SST anomalies do not fully reflect the atmospheric convection anomalies. In super El Niño events, the anomalous convection is located near 140°W. During the boreal autumn and winter, anomalous subsidence over the tropical western and eastern Pacific moves eastward, resulting in higher temperatures and drought in northeastern Australia and northeastern Brazil, as well as more rainfall along the coasts of Peru and Ecuador. The PNA (Pacific–North American) wave train is located eastward, which significantly weakens the North American trough and brings warmer weather to North America. From Greenland to northwest Europe, the geopotential height is low, making northern Eurasia significantly warmer. The anomalous convection in eastern El Niño is located near 160°W. As a result, from boreal autumn to spring, anomalous subsidence is westward, resulting in dry northwestern Australia, northwestern South America, and wet eastern Australia. The PNA wave train originates in the south of the Aleutian Islands and deepens the North American trough, causing severe cold winters in eastern North America. The anomalous convection is located near 180° in El Niño Modoki. Contrary to super El Niño, the coasts of Peru and Ecuador are dry due to abnormal subsidence, and most of Australia experiences drought from boreal autumn to spring under the control of anomalous anticyclones. The PNA wave train is located westward, resulting in severe cold winters in southeastern America. The Atlantic exhibits a negative North Atlantic Oscillation pattern during the winter of eastern and El Niño Modoki events, and temperatures in the middle latitudes of Eurasia are low.