Lok Sabha Question No. 2087 (UNSTARRED), answered on 2017-03-15
Subject: Supercomputer Weather Modelling
Ministry: EARTH SCIENCES
Asked by: G. HARI

## GOVERNMENT OF INDIA

## MINISTRY OF EARTH SCIENCES LOK SABHA

## UNSTARRED QUESTION No. 2087 TO BE ANSWERED ON WEDNESDAY, MARCH 15, 2017

## SUPERCOMPUTER WEATHER MODELLING

## 2087. SHRI G. HARI:

Will the Minister of EARTH SCIENCES be pleased to state:

- (a) whether IMD proposes to shift to a forecast system that relies on a supercomputer led dynamical weather modelling next year and if so, the details thereof;
- (b) whether IMD's weather forecast has been proving wrong constantly in recent times including August, 2016 forecast;
- (c)
- if so, the details thereof and the reasons therefor; and
- (d)
- the steps taken/being taken by the Government in this regard?

## ANSWER

## MINISTER OF STATE FOR MINISTRY OF SCIENCE AND TECHNOLOGY AND MINISTRY OF EARTH SCIENCES (SHRI Y. S. CHOWDARY)

- (a) Yes Madam. From the year 2017, India Meteorological Department (IMD) is planning to implement a seasonal forecasting system that relies  on  a  supercomputer  based  dynamical  modeling  system  in addition to the existing statistical model based seasonal forecasting system.  Both  the  forecasting  systems  will  be  used  to  prepare  the operational  seasonal  forecasts.  It  may  also  be  added  that  IMD  is already  using  dynamical  forecasting  system  for  short  range  and medium range forecasts using super computers.
- (b-c)    No Madam. It is not a fact that IMD's weather forecasts have been proving  wrong  constantly  in  recent  times.  IMD  has  been  able  to correctly  predict  several  extreme weather  and  climate events like cyclones, deficient and excess monsoon rainfall, heat waves, heavy rainfall  etc.  in  recent  years.  For  example,  IMD  has  been  very successful  in  predicting  the  deficient  southwest  monsoon  season rainfall  over  the  country  during  the  recent  two  years  (2014  and 2015)  and  cyclone  PHAILIN,  HUDHUD  and  VARDAH  during  2013, 2014 and 2016 respectively.

IMD's monthly forecast issued for  rainfall  of  August  overestimated the observed rainfall in 2016.

The forecasted and realized seasonal rainfall anomalies during the period  2010-2016  are  given  in  Table  -1.  As  seen  in  the  table,  the signs  of  the  forecasted  rainfall  anomalies  were  same  as  that  of realized  rainfall  anomalies  in  4  years  whereas  the  signs  were different  during 3 years (2011, 2013 & 2016).

## The forecasted and realized seasonal rainfall anomalies during the

Table -1 period 2010-2016.

|   Year |   Actual % departure |   Forecast % departure |
|--------|----------------------|------------------------|
|   2010 |                    2 |                      2 |
|   2011 |                    2 |                     -5 |
|   2012 |                   -7 |                     -4 |
|   2013 |                    6 |                     -2 |
|   2014 |                  -12 |                     -7 |
|   2015 |                  -14 |                    -12 |
|   2016 |                   -3 |                      6 |

- (d) The  present  long  range  forecast  system  based  on  the  statistical models has shown some useful skill in predicting all India seasonal rainfall including the deficient monsoon season rainfall during 2015. However,  in  order  to  overcome  the  limitations  of  the  statistical models  used  so  far,  dynamical  coupled  ocean-atmospheric  model framework  has  been  implemented  under  the  National  Monsoon Mission. IMD is planning to use dynamical forecasting system also to prepare the monthly and seasonal forecasts.

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