Objective climate classification of Himachal Pradesh and Punjab: A clustering based approach

Delineation of climatic zones within a wider geographical area assists in understanding
climatic behaviour. Climate categorization is not purely a mathematical objective procedure
as the boundary between climatic divisions is mostly adjusted subjectively. Several climate
classifications have been proposed based on empirical and observational data from stations
or observatories. So far, climate research has mostly concentrated on large areas but has
failed to address climatic zonation at the local scale. As a result, large spatial scale studies fail
to represent true local climate. This is especially true of mountainous areas, where climatic
controls vary significantly due to topographical complexity and the localized influence of
the atmosphere. Therefore, an understanding of local climates is treated important which
may improve global climate impact assessment. In this study, the climatic regions in parts of
north western India were identified. Regularized gridded data (temperature and precipitation)
provided by India Meteorological Department (IMD) was used for regionalization for the
reference period 1986-2015. The climatic regionalization was done through an objective
process of ‘k means clustering’ approach where Himachal Pradesh and Punjab were divided
into five thermal regions and nine precipitation regions. However, the final decision on
number of climatic zones was subjected to visual interpretation by taking into account local
topographic characteristics. This study is based purely on climatic data while the boundaries
were adjusted subjectively with an expertise of local climate.