In-situ diurnal sea surface temperature variations and near-surface thermal structure in the tropical hot event of the Indo-Pacific warm pool

Diurnal Sea Surface Temperature (SST) variations and the near-surface thermal structure of the tropical hot event (HE) have been investigated using advanced in-situ equatorial observations with hourly temporal resolution. The information on the HE area defined by the satellite cloud-free SSTs is used to sample the in-situ observations. The in-situ SSTs sampled for the HE conditions show that a maximum (minimum) SST has a histogram mode at 30.8°C (29.0°C), and frequently appears at 15:00 (07:00) local time. The amplitude of the diurnal SST variation (DSST) is defined by the difference between the maximum and minimum SSTs. The mean DSST during HEs is greater than 0.5°C, and has a maximum of about 0.75°C at the HE peak. The time series of mean DSST gradually increases (rapidly decreases) before (after) the peak. The satellite SST has a systematic positive bias against the corresponding daytime SST measured by the Triangle Trans-Ocean buoy Network. This bias is enhanced under conditions of large in-situ DSST. One-dimensional numerical model simulation suggests that the systematic bias is caused by the sharp vertical temperature gradient in the surface layer of HE. The near-surface thermal structure is generated by conditions of high insolation and low wind speed, which is the typical HE condition.

[1]  Brian Ward,et al.  Near‐surface ocean temperature , 2006 .

[2]  M. Mcphaden,et al.  The Relationship between Sea Surface Temperature and Latent Heat Flux in the Equatorial Pacific , 1995 .

[3]  Hiroshi Kawamura,et al.  Validity of sea surface temperature observed with the TRITON buoy under diurnal heating conditions , 2006 .

[4]  Ngar-Cheung Lau,et al.  A Modeling Study of the Relative Roles of Tropical and Extratropical SST Anomalies in the Variability of the Global Atmosphere-Ocean System , 1994 .

[5]  J. Kondo,et al.  Heat and Momentum Transfers under Strong Stability in the Atmospheric Surface Layer , 1978 .

[6]  C. Hepplewhite,et al.  Remote observation of the sea surface and atmosphere The oceanic skin effect , 1989 .

[7]  A. Tompkins.  On the Relationship between Tropical Convection and Sea Surface Temperature , 2001 .

[8]  R. Lukas,et al.  The Near-Surface Layer of the Ocean: Structure, Dynamics and Applications , 2010 .

[9]  R. Evans,et al.  Overview of the NOAA/NASA advanced very high resolution radiometer Pathfinder algorithm for sea surface temperature and associated matchup database , 2001 .

[10]  Duane E. Waliser,et al.  Convective cloud systems and warm-pool sea surface temperatures : coupled interactions and self-regulation , 1993 .

[11]  Hiroshi Kawamura,et al.  Detection of hot event in the equatorial Indo-Pacific warm pool using advanced satellite sea surface temperature, solar radiation, and wind speed , 2007 .

[12]  Ryuzo Yokoyama,et al.  Sea surface effects on the sea surface temperature estimation by remote sensing , 1995 .

[13]  Yign Noh,et al.  Simulations of temperature and turbulence structure of the oceanic boundary layer with the improved near-surface process , 1999 .

[14]  W. McGillis,et al.  Biases in the air‐sea flux of CO2 resulting from ocean surface temperature gradients , 2004 .

[15]  H. Kawamura,et al.  Study on a Platform Effect in the In Situ Sea Surface Temperature Observations under Weak Wind and Clear Sky Conditions Using Numerical Models , 2000 .

[16]  D. Waliser.  Formation and Limiting Mechanisms for Very High Sea Surface Temperature: Linking the Dynamics and the Thermodynamics , 1996 .

[17]  Hiroshi Kawamura,et al.  Spatial and temporal variations of model‐derived diurnal amplitude of sea surface temperature in the western Pacific Ocean , 2005 .

[18]  E. F. Bradley,et al.  Bulk parameterization of air‐sea fluxes for Tropical Ocean‐Global Atmosphere Coupled‐Ocean Atmosphere Response Experiment , 1996 .

[19]  Peter J. Webster,et al.  The role of hydrological processes in ocean‐atmosphere interactions , 1994 .

[20]  P. Poulain,et al.  Near-surface thermal structure and surface diurnal warming in the Adriatic Sea using satellite and drifter data , 2006 .

[21]  Misako Kachi,et al.  Satellite‐based high‐resolution global optimum interpolation sea surface temperature data , 2006 .

[22]  Validation of Daily Amplitude of Sea Surface Temperature Evaluated with a Parametric Model Using Satellite Data , 2003 .

[23]  Yoshimi Kawai,et al.  Diurnal sea surface temperature variation and its impact on the atmosphere and ocean: A review , 2007 .

[24]  R. Lukas,et al.  Observation of large diurnal warming events in the near-surface layer of the western equatorial Pacific warm pool , 1997 .

[25]  Melbourne G. Briscoe,et al.  Diurnal response of sea surface temperature observed at the long‐term upper ocean study (34°N, 70°W) in the Sargasso Sea , 1987 .

[26]  Hiroshi Kawamura,et al.  Comparison of downward surface solar radiation derived from GMS5/VISSR and of reanalysis products , 2006 .