Is it possible to extract information related to sea-state from an Argo float ?
Abstract
Thanks to the new genera.on of profiling floats and in par.cular to iridium telemetry, the acquisi.on frequency can be drama.cally increased. We inves.gate here the possibility to extract informa.on related to sea-state from the analysis of high-resolu.on measurements of the pressure data. We par.cularly focus on the study of the speed anomaly as compared to a nominal speed expected for a calm sea-state. By comparison between speed anomaly of a float in the Med Sea and concurrent seastate measurements by a weather buoy in the same area, we suggest that float behaviour can be an indicator of sea-state. In the context of remOcean and NOAS projects, we set up a high frequency mode (every 2 s) for the sub-surface layer and for more than fourty floats deployed in various open ocean areas, we present a preliminary analysis of the speed anomaly. observa.on of float behavior : Characteris.cs of the NKE CTS4 float in the upper layer:-when the float passes 10 dbars, it does not ac.vate its pump for a dura.on of 600 sec-ader 600 sec, the float starts to pump 360 sec to emerge-under standard (calm) weather condi.ons, it takes 90-100 sec for the float to rise the surface from 10m.-data acquisi.on from 1m to 0 m: mean value-data acquisi.on from 10 to 1m : raw data @ 2 sec (0.5Hz)-data acquisi.on from 350 to 10m : raw data @ 10 sec (0.1Hz) CTS4, NKE 600 s 4.5 m 80 s 0 m Standard behavior sta.s.c & climagraphs Non Standard behavior MOORED AUTOMATIC WEATHER STATIONS valida.on with weather mooring Time-serie of behavior indicators of two floats compared to meteorological buoy data in the NorthWestern Mediterranean Sea. Even if the distance of the floats to the mooring are greater than 100 km, the comparison of both time series confirms that float behavior indicators can be used with a certain confidence to track sea-state. These indicators can thus be extracted from all the CTS4 floats we manage to date. We now envisage to extract similar float behavior indicators from standard Argo profiles and in particular the information related to big event.. big events > 10m re-dive 0.4% what next Characteris.cs of the NKE CTS4 float in Indicators of float behavior in the upper layer In this poster we explore the idea that the float behavior is related to the sea state. Time spend between 10m and 1m (s) proxy of speed anomaly Maximum re−dive between 10m and 1m [m],
Domains
Ocean, Atmosphere
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