Detection of hot event in the equatorial Indo‐Pacific warm pool using advanced satellite sea surface temperature, solar radiation, and wind speed

Abstract

[1] Using advance satellite-derived sea surface temperature (SST), solar radiation and wind speed products, we investigate hot events (HEs) associated with very high SST of around 30°C. Amplitude of the SST diurnal variation (DSST) is obtained by an empirical formula with the downward surface shortwave radiation (DSSR) and the wind speed. The HE is defined as a connected region with SST > the time-dependent SST threshold of about 30°C having a minimum areal size greater than 3 Â 10 6 km 2 and lasting for a period longer than 10 days. Thirty-one hot events were detected from 1993 to 2003 in and around the equatorial Indo-Pacific warm pool. The HE precursor is increase of an area with SST > the time-dependent SST threshold, and the HE starts when the areal size exceeds the areal threshold. It keeps the very high SST for a while, and then its SST decreases with decrease of the HE area toward its ending phase. The HE area and the high-DSST area correspond with each other on timescales of daily and the whole one event period. In the HE period, a clear-sky and low-wind condition becomes the reason for large DSST appearance. Through statistics of the detected 31 HEs, it is indicated that the mean HE period, the mean areal size, and the means of the regional HE areal averaged SST are 24.2 days, 1.57 Â 10 7 km 2 , and 0.25°C above the time-dependent SST threshold, respectively. The HE area shifts with season though they stay within/around the SST contour of 28°C in the Indo-Pacific oceans.Citation: Qin, H., H. Kawamura, and Y. Kawai (2007), Detection of hot event in the equatorial Indo-Pacific warm pool using advanced satellite sea surface temperature, solar radiation, and wind speed,

Climatology of hot events in the western equatorial Pacific

“…Over the course of 10 years (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003), they identified 31 HEs distributed in the tropical oceans, with most of the HEs (68 %) detected in the western equatorial Pacific. This and subsequent studies concluded that the HEs occur when there are high levels of solar radiation and low wind speeds, and that HE development involves a high diurnal SST amplitude Qin et al 2007Qin et al , 2008Kawamura 2009, 2010). However, there are still some problems with their detection method.…”

“…Using this dataset reduced sampling and merging errors. Then we improved the HE detection method proposed by Qin et al (2007) by taking seasonal SST variations into account. The application of this method allowed us to obtain new results on HE climatology in the western equatorial Pacific and to explore the relation of HEs to the western Pacific warm pool, as discussed in this paper.…”

“…In fact, only a few studies have focused on the short-period variability of the SSTs in the western Pacific warm pool. Qin et al (2007) used optimally interpolated daily SST data with a spatial resolution of 0.1° × 0.1° (Kawai et al 2006) to detect well-organized high SSTs (higher than 30 °C) in the equatorial oceans, which correspond to so-called hot events (HEs). Over the course of 10 years (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003), they identified 31 HEs distributed in the tropical oceans, with most of the HEs (68 %) detected in the western equatorial Pacific.…”

“…However, there are still some problems with their detection method. Qin et al (2007) used a time-dependent SST threshold of approximately 30 °C to detect the HEs, and Qin et al (2008) used a fixed SST threshold of 30 °C. Both of these methods are affected by seasonal variation and may underestimate SST variations associated with HEs during the cold season.…”

Detection of the Eastern Edge of the Equatorial Pacific Warm Pool Using Satellite-Based Ocean Color Observations

“…Detection of very high SST (around 30°C) within the warm pool is associated with the strong intraseasonal variability of hot events (Qin et al 2007). Zonal displacement of the warm pool is also important for the onset of the El Niño Southern Oscillation (ENSO) phenomenon (Picaut et al 1996;Ando and Hasegawa 2009).…”