CoAuthors

Yoichi Ishikawa (Japan Agency for Marine-Earth Science and Technology, Japan); Yosuke Fujii (Meteorological Research Institute, Japan); Norihisa Usui (Meteorological Research Institute, Japan); Kei Sakamoto (Meteorological Research Institute, Japan); Tsurane Kuragano (Meteorological Research Institute, Japan); Masafumi Kamachi (Meteorological Research Institute, Japan); Osamu Isoguchi (Remote Sensing Technology Center of Japan, Japan); JAXA COMPIRA team (Japan Aerospace Exploration Agency, Japan)

The impact of wide-swath altimetry measurements on the quality of ocean mesoscale features retrieved by three dimensional variational data assimilation (3DVar) system is evaluated by using simulated sea surface height data. Simulated data are constructed from MRICOM high resolution ocean circulation model and ground tracks of the Japanese altimeter mission, COMPIRA. In this analysis, emphases are placed on the quality of indirectly retrieved variables, vertical velocities and relative vorticities accompanying mesoscale fronts in the Kuroshio extension region, where the most energetic mesoscale activities in the North Pacific Ocean are observed. Compared to the control case with conventional nadir altimetry measurements, both vertical velocities and relative vorticities can be retrieved with higher accuracy due to a dynamically consistent horizontal geostrophic velocity field provided from wide-swath altimetry measurements. Accuracy of the retrieved fields are sensitive to the high wave number component of measurement error assumed in the simulated sea surface height data. Further investigation is required to evaluate the impact of the measurement error on the 3DVar analysis error.