Air temperature variability and trend analysis by non-parametric test for Kolkata observatory, West Bengal, India

The present study revealed that January, February, March and December indicate decreasing trend in average temperature and rest eight months are with increasing trend. Magnitude of Mann-Kendall (MK) trend statistic Z(c) for these decreasing temperature months are -4.91,-4.47,-6.35 and -0.09 and for Sen's slope estimator (Q(i)) values for these months are -0.0048, -0.065, -0.062 and -0.001, respectively. The magnitude of slope for the months of January, February and December are confirmed at high significance level of alpha = 0.001, 0.01 and 0.1. While the rest eight months have indicated positive trends with different levels of significance. However, overall results show significant warming in all seasons, but more so in the colder months.