Circulation a publication of the Center for Coastal Physical Oceanography Summer 2007

Recent observations from a satellite-based, microwave SST sensor reveal daily to weekly variation in SST (up to 3 C), which had not been seen with infrared composite measurements. During the winter, Dr. Brian Ward was in the Indian Sea on the French vessel R/V Suroît as part of the CIRENE program. He is using the Air-Sea Interaction Pro-fi ler (ASIP) which he recently designed and constructed. It allows frequent (every 5 m) measurements of water structure in the upper 10 m of the ocean with a vertical resolution of mm's. He is addressing issues of diurnal changes in SST and its effect on the atmosphere along with the effect of organisms on heat trapping in the near-surface. He is testing the capability of ASIP to measure air-sea exchange and upper ocean dynamics. The western Pacifi c and Indian oceans are home to the world's largest pool of warm water (in excess of 28-C). It is also home to the largest region of atmospheric deep convection which plays a key role in the global atmospheric circulation, being the area where air rises within Hadley and Walker cells, and where latent heat is released providing energy to set these global–scale circulations in motion. During the boreal summer, this convection is most active over the In-dian subcontinent, when the monsoon occurs. During the winter the maximum amount of convective activity is found south of the Equator over the Indian Ocean, and is generally referred to as the Madden-Julian oscillation (MJO). Convection in this region is modulated at many temporal scales, the most energetic being the interannual, seasonal and intraseasonal scales. Many studies have shown that there is a clear peak in the spectrum of this deep convective 2 F i g u r e 2. U n d e r w a t e r photograph of ASIP during during one of its descents in the Indian Ocean. activity at timescales between 20 and 60 days. At this time scale, there is also a spatial organization at large scale and a strong sea-sonality of the amplitude and characteristics of the intraseasonal variability of convection. Recent observations have revealed large amplitude (up to 3K) SST variability in relation to the ISVC in the Indian Ocean. These large SST excursions were identifi ed using the Tropical Rainfall Measuring Mission's (TRMM) Microwave Imager (TMI) Sea Surface Temperature (SST) dataset. The advantage of the microwave SST sensor …