Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Clustering and Trend Analysis of Global Extreme Droughts from 1900 to
  2014   Drought is one of the most devastating environmental disasters. Analyzing
historical changes in climate extremes is critical for mitigating its adverse
impacts in the future. In the present study, the spatial and temporal
characteristics of the global severe droughts using Palmer Drought Intensity
Index (PDSI) from 1900 to 2014 are explored. K-means clustering is implemented
to partition the extreme negative PDSI values. The global extreme droughts
magnitude around the world from 1950 to 1980 were less intense compared to the
other decades. In 2012, the largest areas around the world, especially Canada,
experienced their most severe historical droughts. Results show that the most
recent extreme droughts occurred in some regions such as the North of Canada,
central regions of the US, Southwest of Europe and Southeast Asia. We found
that after 1980, the spatial extent of the regions that experienced extreme
drought have increased substantially.

12
The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
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The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th