public static double absDiff(double[] obs, double[] sim, double missingValue) {
        sameArrayLen(obs, sim);
        double abs = 0;
        for (int i = 0; i < obs.length; i++) {
            if (obs[i] > missingValue) {
                abs += Math.abs(obs[i] - sim[i]);
            }
        }
        return abs;
    }