Reconstruction of a reliable long daily rainfall dataset for the Northeast India (NEI) for climate change impact and extreme rainfall studies

For both food security and biodiversity management in NEI, a biodiversity hot spot, is required dependable, consistent estimates of trend and modes of variability of rainfall, so that policy makers have an idea of the rainfall that can be expected during the coming decades. Hence, daily rainfall data over the North East India (NEI) for more than 100 years is required for any climate change impact assessment. However, the region is poorly sampled and none of the weather stations have operated continuously for such a period. This technical note describes combining conventional weather station records with rain-gauge records from a number of sources like privately owned tea estates to create a continuous daily rainfall record from 1 January 1920-31st December 2009 for the north-eastern region of India. We have been successful in creating a daily rainfall data set on a set of 24 well distributed fixed stations. The data extent back into the 1920 and stem from a variety of station observations. Remaining data gaps are less than 3% of the total data in each station. Every effort has been made to reconstruct the data gaps with the aim to improve assessments of the long-term changes in climate variability in NEI. The final reconstructed data set for NEI is well suited to estimate both long-term trend and multi-decadal variability of rainfall over the region.