58 FIG. 38. Location of sampling points where calculated 137Cs concentrations in surface water have been compared with measurements. 3.5.2.1. Exercise 4a: Common parameters A comparison of model results with 137Cs measurements in surface water for Exercise 4a (using JCOPE2 water circulation and common model parameters as in Exercise 3) is shown in Figures 39 and 40 for points T1–T8 and the three additional points at far distances from Fukushima, respectively. The general structure of the time series is very similar in all models since the same water circulation is being used and there is also an acceptable agreement with measured concentrations. At large distances from Fukushima, all models agree in producing concentrations below 10 Bq/L (except in E3). Additionally, peaks are generated at approximately the same time periods, except in B1, where a more noisy signal is produced by some models. Model results for sediment 137Cs concentrations have also been compared with measurements and are presented in Figure 41. Modelled activity concentrations at the end of the simulation period (30 June 2011) are shown with TEPCO measurements. Given that the same water circulation was used in all models, the resulting 137Cs distributions in sediment produce similar results, with the highest concentrations in the area nearest to Fukushima and some extension towards the south and northeast. There is consensus in the fact that most of the 137Cs remains in a band along the coast and model results generally agree by order of magnitude with measurements.