The tenth IMSC, Beijing, China, 2007 - International Meetings on ...

<strong>The</strong> Energy and Resources Institute, New Delhi
sangeet@teri.res.in
M K Srivastava
Bose Institute, Darjeeling, India
V Chaudhary
Department of Science and Technology, Delhi
S Anand
Center for Atmospheric Sciences, IIT, Delhi
Climate change is becoming a major issue all over the globe due to its wide spread
impacts on various socioeconomic sectors across the regions. It may also render significant
changes in the climate variability leading to abrupt climate regime shifts that can have
considerable impacts at various temporal and spatial scales. <strong>The</strong> identification of such regime
shifts (or “the change points” in the climatic time series) may help us translating these impacts
to adaptation and mitigation policies. Change point detection models (CPDMs) are useful in
detecting abrupt changes in the climatic variability. In essence, a CPDM employs a measure
on stability and persistence of a statistical model of the climate and its variability. <strong>The</strong> problem
to detect and identify a climatic regime shift can be formulated with respect to many statistical
parameters such as mean and variance. <strong>The</strong> most prevalent models are CPDM with respect to
the mean of a variable.
This paper presents a comparative study of two of such methods, one each to the
changes with respect to mean (Model-1) and to variance (Model-2) respectively. Both models
resolve the change point detection problem quite well. Model-1 is sequential change point
analyzer and uses student-t test to detect the changes in the fit of the distribution based on
mean of the segment. Model-2 uses Bayesian Information Criterion (BIC) to identify the
changes in the variances in the time series. However, it is shown that Model-2 is more robust
to the presence of outliers than to changes in mean. In fact Model-2 is computationally more
efficient as well.
Homogenization of daily air pressure, temperature and precipitation series for Southern Moravia
in the period 1848–2006
Speaker: Petr Stepanek
Petr Stepanek
Czech Hydrometeorological Institute, Regional Office Brno, Czech Republic
petr.stepanek@chmi.cz
Rudolf Brazdil
Institute of Geography, Masaryk University, Brno, Czech Republic
Ladislava Reznickova
Institute of Geography, Masaryk University, Brno, Czech Republic
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