Correlation coefficients between the tree-ring chronologies and precipitation data (1948–2011).

The chronology of eastern and western zone was correlated with precipitation of Khulna and Shakhira district, respectively. The regional chronology was correlated with regional (average of both districts) precipitation. For current year, the monthly, annual and seasonal, such as monsoon (June–September), pre-monsoon (March–May) and post-monsoon (October–November) precipitation was used for analysis. In case of previous year (PY-), the annual, monsoon, pre-monsoon and post-monsoon precipitation was used. Dotted horizontal lines indicate 95% significance level and solid vertical line is the boundary between current and previous year.