Atmospheric structure favoring high sea surface temperatures in the western equatorial Pacific

• Published in: Journal of geophysical research. Atmospheres 2016-10, Vol.121 (19), p.11,368-11,381
• Main Authors: Wirasatriya, Anindya, Kawamura, Hiroshi, Shimada, Teruhisa, Hosoda, Kohtaro
• Format: Article
• Language: English
• Subjects: Atmospheric processes; Atmospheric structure; Atmospherics; Case studies; Climatic analysis; Climatology; Cloud cover; Convection; Decay; Decay rate; Evaporation; Geophysics; High seas; Hot Event; Low clouds; Marine; MJO; Ocean currents; Pressure gradients; Radiation; remote convection; Sea level; Sea level pressure; Sea surface; Sea surface temperature; Solar radiation; Strong winds; Surface temperature; Surface wind; topographic effect; Troposphere; Upper troposphere; Water vapor; Water vapour; Westerlies; Wind; Wind speed
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1002/2016JD025268

We investigated the atmospheric processes over high sea surface temperature called Hot Event (HE) in the western equatorial Pacific from climatological analysis and a case study of the HE which began on 28 May 2003 (hereafter, HE030528). Climatological analysis shows that during the development stage of HE, solar radiation inside the HE area is higher than its climatology and wind speed is lower than the decay stage. During the decay stage, strong westerly wind often occurs inside HE area. The case study of HE030528 shows that the suppressed convection above high SST area resulted from the deep convection from the northern and southern areas outside HE. The suppressed convection created a band‐shaped structure of low cloud cover along HE area increasing solar radiation during the development stage. Thus, the theory of “remote convection” was supported for the HE030528 formation mechanisms. The large sea level pressure gradient magnitude between the southern side of the terrain gap and the northern coast of the Solomon Islands, through which strong wind blew, indicated the role of land topography for the increase of wind speed during the decay of HE030528. Moreover, surface wind had an important role to influence the variability of solar radiation during the occurrence of HE030528 by controlling the water vapor supply in the upper troposphere through surface evaporation and surface convergence variation. Thus, surface wind was the key factor for HE030528 occurrence. The representativeness of HE030528 and the possible relation between HE and Madden‐Julian Oscillation are also discussed. Key Points The suppressed phase of MJO may also contribute for the development of HE The suppressed convection generated from the deep convection outside of HE area increase solar radiation during the development stage During the development and decay stage of HE, the variability of convection at the upper layer is influenced by surface wind