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CPS1834 Gumgum D. et al.


                                 Rainfall data modeling by SARIMA based on
                                               Hijriya calendar
                                                                          1
                                                         2
                                           1,2
                                                                                       2
                      Gumgum Darmawan , Dedi Rosadi , Budi N Ruhyana , Danardono ,
                                                             3
                                                  Hermansah
                                              1 Universitas Padjadjaran
                                              2 Universitas Gadjahmada
                                            3 Universitas Riau Kepulauan

                  Abstract
                  ARIMA  modelling  procedure  is    well  known  developed  by  G.E.P.Box  and
                  G.M.Jenkins. Using this procedure, We are able to obtain ARIMA model that
                  can  represent  past  and  future  patterns  of  time  series.  These  patterns  are
                  random, seasonal, trend, cycle, or combination patterns. In standard model,
                  we use Gregorian Calendar to analysis the data in time domain. Here, in this
                  paper we consider the analysis of the data using what we call Hijri calendar In
                  particular  ,we  apply  the  method  to  rainfall  data.  Based  on  the  empirical
                  analysis we found that SARIMA based on Hijri calendar has lower MAPE than
                  SARIMA analysis in Gregorian calendar especially in forecast in three future
                  observations (short-term forecast). However, when we extend the analysis to
                  long-term forecast, the forecast based on Gregorian calendar , SARIMA model
                  has better performance.

                  Keywords
                  Hijriya Calendar; Sarima Modeling; Rainfall; Opensource Software

                  1.  Introduction
                      In  the  time  series  analysis  known  for  various  methods  in  forecasting,
                  several classical forecasting methods such as Moving Average, Exponential
                  Smoothing, ARIMA, and Classical Decomposition are often used in forecasting
                  the  future.  Different  methods  have  advantages and  disadvantages  of  each
                  which  will  be  adjusted  to  the  characteristics  of  the  data  to  be  predicted.
                  Moving  averages  use  the  average  value  in  the  previous  period  data  as  a
                  forecast for future data.
                      The time series data models above are widely used to forecast rainfall such
                  as [1], [2] and [3] using singular spectrum analysis. Whereas [3] and [4] use
                  Ensemble methods and [6] use ARMA method to predict rainfall. [7] build a
                  software to predict rainfall [8] forecast rainfall with Artificial Neural Network.
                  [9] and [10] using probabilistic forecasting and [11], [12], [13] and [14] using
                  other model models such as machine learning to forecast rainfall.
                      From  the  research  above,  rainfall  data  uses  time  series  data  with  the
                  Gregorian calendar. While according to Tsubatsa Kohyama (2016), variations

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