Influence of ENSO on the Diurnal Cycle of Rainfall over the Maritime Continent and Australia

• Published in: Journal of climate Vol. 26; no. 4; pp. 1304 - 1321
• Main Authors: Rauniyar, Surendra P., Walsh, Kevin J. E.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.02.2013
• Subjects: Anomalies; Australia; Climate cycles; Cluster analysis; Clustering; Continents; Convection; Diurnal; Diurnal cycle; Diurnal variations; Earth, ocean, space; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; Exact sciences and technology; External geophysics; Geography; Gravity waves; Influence; Islands; La Nina; Marine; Maritime; Meteorology; Meteors; Oceans; Offshore; Orography; Phases; Precipitation; Propagation; Rain; Rainfall; Rainfall anomalies; Seasons; Southern Oscillation; Studies; TRMM satellite; Tropical climates; Tropical rainfall; Tropical Rainfall Measuring Mission (TRMM); Tropical regions; Vector quantization; Walker circulation; Water in the atmosphere (humidity, clouds, evaporation, precipitation); Winter; Australia; Asia; South east Asia; New Guinea; Sumatra; Indonesia; Borneo; Sulawesi; Cluster analysis; Teleconnection; rainfall; El Niño Southern Oscillation; atmospheric precipitation; Australasia; Space remote sensing; Satellite observation; K means algorithm; diurnal variations; Spatial distribution; El Nino; Observation data; Reanalysis; TRMM satellite; La Nina
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/jcli-d-12-00124.1

This study examines the influence of ENSO on the diurnal cycle of rainfall during boreal winter for the period 1998–2010 over the Maritime Continent (MC) and Australia using Tropical Rainfall Measuring Mission (TRMM) and reanalysis data. The diurnal cycles are composited for the ENSO cold (La Niña) and warm (El Niño) phases. Thek-means clustering technique is then applied to group the TRMM data into six clusters, each with a distinct diurnal cycle. Despite the alternating patterns of widespread large-scale subsidence and ascent associated with the Walker circulation, which dominates the climate over the MC during the opposing phases of ENSO, many of the islands of the MC show localized differences in rainfall anomalies that depend on the local geography and orography. While ocean regions mostly experience positive rainfall anomalies during La Niña, some local regions over the islands have more rainfall during El Niño. These local features are also associated with anomalies in the amplitude and characteristics of the diurnal cycle in these regions. These differences are also well depicted in large-scale dynamical fields derived from the interim ECMWF Re-Analysis (ERA-Interim).