Yasuhiro Sugimori

Sediment transport and depth variation study of the Gulf of Kutch using remote sensing

Ocean Colour Monitor (OCM) data gathered onboard Indian Remote Sensing satellite (IRS P4), in eight VNIR bands covering Gulf of Kutch and adjoining regions were digitally processed using an image processing system. False colour composite images of actual data and principal components were generated to study sediment transport, depth variation and associated processes by mapping coastal and underwater geomorphic features and suspended sediment plumes. Submerged shoals, located as deep as 20 m below water level, were correctly marked. By studying turbidity distribution patterns and sediment transport indicators, sediment distribution and dispersion have been inferred. The study demonstrates that OCM data have been derived from up to 20 m water depth in the high-energy tide dominated Gulf and hence are useful for mapping underwater bedforms, sediment plumes, and other geomorphic features. The study indicates that the sediments are transported to the Gulf from the north as well as from the south and are mainly season dependent. It is concluded that the OCM data can be used for depth variation and sediment distribution studies.

Study of the relationship between non-dimensional roughness length and wave age, effected by wave directionality

Relationship between the non-dimensional roughness length and inverse of wave age has been discussed without consideration of wave directions, though wind wave field consists of various directional component waves. In this study we observe wave heights by an array of four wave gauges at the Hiratsuka Tower of (Independent Administrative Institution) National Research Institute for Earth Science and Disaster Prevention (NIED), Japan, and discuss the effect of wave directionality. As a result, the data sets were classified into two different groups according to the directional wave spectrum distribution. In case 1 only swell and wind waves exist and in case 2 there exist wave components from several directions. It is shown that the case of multiple-directional component waves (case 2) may affect the non-dimensional roughness length and friction velocity.

Surface heat fluxes using satellite observations: A case study in the northwest Pacific

Abstract Satellite-observed surface-level meteorological parameters are used to derive 10-day mean surface heat fluxes of solar, longwave, sensible, and latent heat fluxes in the northwest Pacific. Cloud amount in tenths were taken from Geostationary Meteorological Satellite cloud data, published by the Japan Meteorological Agency. Sea surface temperature (SST) was derived from the NOAA Advanced Very High Resolution Radiometer observations using the cross-product SST. Surface wind speed was obtained from the Special Sensor Microwave/Imager (SSM/I). Air temperature and surface level humidity were derived statistically from the SSM/I precipitable water. Synoptic flux estimates using satellite observations are compared with earlier estimates for this region (same season) derived from in situ data and were found to be reasonable. While the Kuroshio regime shows large net heat loss toward the south, it decreases and has heat surplus. For an evaluation of the satellite-derived heat fluxes, these are compared wi...