Role of sea-level pressure of Arabian Sea on variability of summer monsoon rainfall over Northern Pakistan

The influence of sea-level pressure (SLP) of Arabian Sea on variability of summer monsoon over northern Pakistan has been discussed in this paper. This study will examine the impact of SLP of Arabian Sea on the summer monsoon of northern Pakistan using composite and correlation analysis, principal component analysis (PCA), and singular value decomposition analysis (SVDA). The correlations of SLP index and first principal component of SLP with the regional rainfall over the monsoon season are respectively − 0.43 and − 0.44 (both significant at 5% level). The first leading SVD mode is found to be the most important because it is alone explaining 95.6% of the total square covariance. Moreover, canonical correlation analysis (CCA) has been applied on the regions that have correlations significant at 5% level on heterogeneous correlation maps to construct forecasting equation using canonical correlations. The correlation between the left and right expansion coefficients for the first leading canonical mode is 0.83 which is higher than in the case of the first leading SVD mode. Furthermore, the composites show that the physical mechanisms are consistent with empirically determined relationships.