1. Variation and Source of Equivalent Black Carbon in
The Air of Himalayan Range
Sovan Sau
It is well known that Black Carbon(BC) has a large impact on Earth’s Radiation
Budget. From the literature, BC has found significantly high over the Himalayan
region and mainly transported from other continental regions. However, it is not
clear about the source region of these transported BC across over the Himalayas.
In this study, the sourceregion of BC is being identified using K-Means algorithm
method of seven days back-trajectory of air parcel over Darjeeling.
In this method the source region can be found in the following way. If there is a
set of N data points, X(I) is given, the points can be arranged into few numbers
of clusters, let be K. Each cluster is defined by a point Z(J), the centroid of each
cluster. Energy of each cluster is defined by
𝐸( 𝐽) = {∑ 𝑋(𝐼)
𝐼
} ∗ {|| 𝑋( 𝐼) − 𝑍( 𝐽)||
2
}
Total energy the sum of all the energy of each cluster.
𝑇𝑜𝑡𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 = ∑ 𝐸(𝐽)
𝐽
The motivation is to find out the cluster in such a way that the total energy of all
the clusters will be minimized. To minimize the energy and to assign each point
to the right cluster ‘K-Means Algorithm’ is used which is described as follows.
1. Assign each point to the nearest cluster centroid.
2. Replace the cluster centroid every time after inclusion of new point in a
cluster.
These steps are repeated until no points are moved, or some other termination
criterion is reached.
Forthe back-trajectories of air parcels over Darjeeling during May, 2015 A back-
trajectory model Hysplit Air Trajectory Model has been used. Every Day of the
month, a back-trajectory of initial height 1000m has been retrieved using the
model. From these set of back-trajectories K-Means algorithm is used to find out
the source of the BC over Darjeeling.
The work is in progress and we are expecting to find a good result in future.