Application of spatial statistics in zoning and spatial analysis of the sound speed in the Persian Gulf

The aims of this study were to find the distribution of sound speed under the influence of water's physical parameters; to predict spatial analysis in oceanography using geostatistical methods; to forecast value parameters for the Persian Gulf and zoning the sound speed. Sound Speed was calculated using Chen-Millero formula and pressure, salinity, and temperature data. The data extracted from World Ocean Atlas 2013 with regular mesh grid 0.25 degree. Sound speed was calculated using the Chen-Millero formula. Spatial analysis of the sound speed comparison based on three methods Kriging, Co-Kriging and Inverse Distance Weighted. These methods were performed using GS+ software in both warm and cold season. The best method finally used to forcast and prepare the plans of zoning sound speed. The Pearson’s correlation test was performed between independent variables and sound speed showed that the maximum correlation occurs between temperature and sound speed. Therefore, the temperature was considered as the auxiliary variable in Co-Kriging method for spatial analysis of sound speed. Cross-validation results showed that model's forecasting in cold season was better compared to warm season in this region. Results of spatial analysis showed that the sound speed decreased about 20m/s in all layers from the Hormuz Strait toward the northwestern part of the Persian Gulf. Because of the increased salinity the maximum of sound speed was always in the south shallow area. In all investigated stations, sound speed reduced with increasing depth, due to temperature reduction and the sound channel is not also observed.