Forecast skill score assessment of a relocatable ocean prediction system, using a simplified objective analysis method

Abstract

Abstract. A relocatable ocean prediction system (ROPS) was employed to an observational data set which was collected in June 2014 in the waters to the west of Sardinia (western Mediterranean) in the framework of the REP14-MED experiment. The observational data, comprising more than 6000 temperature and salinity profiles from a fleet of underwater gliders and shipborne probes, were assimilated in the Regional Ocean Modeling System (ROMS), which is the heart of ROPS, and verified against independent observations from ScanFish tows by means of the forecast skill score as defined by Murphy (1993). A simplified objective analysis (OA) method was utilised for assimilation, taking account of only those profiles which were located within a predetermined time window W . As a result of a sensitivity study, the highest skill score was obtained for a correlation length scale C = 12.5 km, W = 24 h, and r = 1, where r is the ratio between the error of the observations and the background error, both for temperature and salinity. Additional ROPS runs showed that (i) the skill score of assimilation runs was mostly higher than the score of a control run without assimilation, (i) the skill score increased with increasing forecast range, and (iii) the skill score for temperature was higher than the score for salinity in the majority of cases. Further on, it is demonstrated that the vast number of observations can be managed by the applied OA method without data reduction, enabling timely operational forecasts even on a commercially available personal computer or a laptop.

OceanGliders: A Component of the Integrated GOOS

“…Temperature and salinity data from these gliders were assimilated into a state estimate (Todd et al, 2011a(Todd et al, , 2012Zaba et al, 2018), while velocity data were not assimilated so they could be used for verification. In the Mediterranean, Dobricic et al (2010) showed the large-scale impact of the repetition of a glider section and in particular when depth-average currents were also assimilated while Mourre and Chiggiato (2014) and Onken (2017) assimilated glider data for a forecast and verified against data from a ship survey. A state estimate of the tropical Pacific (Verdy et al, 2017) was verified against withheld glider observations on either side of the Pacific basin.…”

Suspended Sediment Concentration and Fluxes in the High-Turbidity Zone in the Macro-Tidal Hangzhou Bay

“…The closer the absolute values of the CCs and WSSs are to 1, the better the results of the simulation. The performance levels of WSS were categorized as: >0.2, some credibility; >0.5, high credibility [67]. The model results for water levels showed excellent agreement with the field data (Figure S1I).…”

High-resolution observations in the western Mediterranean Sea: the REP14-MED experiment

“…Concerning operational forecasting, a relocatable ocean prediction system was applied in hindcast mode to the survey data (Onken, 2017a). More than 6000 temperature and salinity profiles originating from the glider fleet and shipborne CTD probes were assimilated, and the forecasts were verified against observations from the ScanFish tows (Fig.…”