GOAL hydrographic gridded data set for the Northern Antarctic Peninsula, Southern Ocean

This gridded product was built by optimally interpolate the Brazilian High Latitude Oceanography Group (GOAL) profiles sampled in the Northern Antarctic Peninsula (NAP) during 2003-2019. The profiles were first linearly interpolated onto 114 depth levels, and then optimally interpolated in space using a grid of ~10 km resolution. The grid spacing is 0.09˚ along latitudes and 0.2˚ along longitudes (i.e., 0.09˚ latitude x 0.09˚/cos(63˚S) longitude, where 63˚S is the mean latitude of our domain). A series of tests were made to find the appropriate smoothing lengthscale and the a priori relative error in order to find a balance between smoothness and feature representativeness. The final smoothing lengthscale (i.e. the radius of influence of the interpolation) chosen was 0.8˚ in latitude and longitude, and the a priori relative error allowed was set to 0.1 for the objective interpolation algorithm. The same constants were set for all depth levels and all variables. Regions where the mapping relative error was higher than 0.5 were excluded. The GOAL gridded product can be used for several applications, including input data for ocean and climate models initialization/assessment and ocean reanalysis evaluation, as well as to produce and reconstruct biogeochemical properties. Finally, the GOAL hydrographic gridded product represents the ocean mean-summer-state for the NAP in the early 21st-century.