IUKWC Workshop Nov16: Developing Hydro-climatic Services for Water Security – Session 6.5 Priya P

1. 11/08/1629 November – 1 December 2016, IITM, Pune, India
Priya P
PhD Student
Email: priya@tropmet.res.in
IUKWC Workshop on
“Developing Hydro-climatic
Services for Water Security”

2. 2010 Pakistan Floods
Introduction Motivation Objective Methodology Results Conclusions
Event could have been predicted two
weeks in advance (Webster et. al. 2011)
Northwest India-Pakistan flood 29 July 2010
TRMM3b42 Precipitation
ERA Interim wind at 700hPa
Webster et al,2011
mm/d

3. Introduction Motivation Objective Methodology Results Conclusions
2010
CLIM
Mean sea level pressure (hPa) for JJAS 2010
 Connection with Russian heat wave–wildfires (Lau and Kim , 2012)
 Interaction between mid-latitude disturbance and monsoon surges (Hong et al., 2011)
 Persistent increase in conditional instabilities (Wang et al. 2011)
Convection of ocean character (Houze et al. 2011)
Westward shift of West Pacific Subtropical High associated with LaNina (Mujumdar et al. 2012)
Hong et al. 2011
Mujumdar et al. (2012)

4. TRMM (Rainfall) & NCEP
(Moisture Transport)
JJAS Climatology
TRMM (Rainfall) & NCEP
(Moisture Transport)
“2010” JJAS Anomalies
• Strong east-west rainfall gradient
over equatorial west Pacific
• Suppressed rainfall over equatorial
Indian Ocean
• Suppressed rainfall activity over
Bay of Bengal and Central India
• Anomalous northward moisture
transport over Arabian Sea
• Enhanced seasonal rainfall over
northwest India-Pakistan region
Anomalous features of 2010 Boreal Summer Monsoon Season
Introduction Motivation Objective Methodology Results Conclusions

5. (0
C)
 Strong SST gradient between
Central & western equatorial
Pacific
 Basin wide type of warming
 Developing Negative IOD over
southeast Indian Ocean
Anomalous SST patterns over
Pacific & Indian Ocean regions were
unique during 2010 La Nina.
SST Anomaly for JJAS 2010
Unique features of 2010 La Nina
Introduction Motivation Objective Methodology Results Conclusions
 Previous studies discussed the
anomalous Atmospheric and Oceanic
features associated with 2010 Indo-
Pak extreme rainfall events.
Though, slowly varying tropical
SSTs can modulate synoptic, sub-
synoptic and meso-scale variabilities,
“specific roles of remote (ENSO)
and regional (ENSO-unrelated)
boundary forcings in the
evolution of 2010 summer
monsoon heavy rainfall events”
was unexplored.

6. Decomposition of 2010 SST (Compo & Sardeshmukh, 2010 personnel communication)
To delineate the role of ENSO and ENSO-unrelated factors, ensemble simulation experiments
were carried out with different SSTs forcing using variable resolution AGCM (LMDZ4).
Introduction Motivation Objective Methodology Results Conclusions
2010
ENSO
ENSO-Unrelated

7. LMDZ grid setup for South Asia (shaded region has grid-size < 35 km)
2012
(0-Equator, 45-110E)
Introduction Motivation Objective Methodology Results Conclusions

8. Extreme convective events & Weibull Distribution
 Statistics of extreme convective events over Indus basin is captured (Priya et al 2015).
ProbabilityDensity
Vertical Velocity (Pa s-1
)
LMDZ4 AGCM
Simulation using
Climatological SST
ensemble mean
Introduction Motivation Objective Methodology Results Conclusions
(Priya et al 2015, J. Climate).
Northwest India-Pakistan region (70°-74°E, 30°-36°N)

9. Introduction Motivation Objective Methodology Results Conclusions
Extreme convective events & Weibull Distribution
 The “large-scale” summer monsoon climatology is realistically simulated (Sabin et al 2013).
 Statistics of extreme convective events over Indus basin is captured (Priya et al 2015).
SST boundary forcings for the different sets of LMDZ simulation experiments
Serial No. Experiment SST boundary condition
1 C-SST Climatological SST
2 R-SST Real SST for 2010
3 E-SST ENSO-related SST for 2010
4 NE-SST ENSO-unrelated SST for 2010
5 NE-IO-SST ENSO-unrelated SST for 2010 over Indian Ocean

10. Rainfall and Moisture Transport Anomalies for JJAS 2010
Observation
TRMM (Rainfall) &
NCEP (Moisture Transport)
Simulation
LMDZ4 AGCM
R-SST ensemble mean
Introduction Motivation Objective Methodology Results Conclusions
Vertical Velocity (Pa s-1
)
ProbabilityDensity
(70-74ºE & 30-36ºN)Weibull Distribution
&
Extreme Convection

11. Introduction Motivation Objective Methodology Results Conclusions
OBS (NCEP) MODEL (R-SST)
Western Indian Ocean
Eastern Indian Ocean
Meridional cell
averaged over
(60°-75°E)
Meridional cell
averaged over
(85°-110°E)
Rainfall and Moisture Transport
Anomalies JJAS 2010 -OBS
Rainfall and Moisture Transport
Anomalies JJAS 2010 -LMDZ

12. Introduction Motivation Objective Methodology Results Conclusions
Near Equatorial region
OBS (NCEP) MODEL (R-SST)
Zonal-cell
averaged
over
(15°S-0°)
?Roles of ENSO and ENSO-unrelated SSTs on the northwest Indo-Pak rainfall events ?
Rainfall and Moisture Transport
Anomalies JJAS 2010 -OBS
Rainfall and Moisture Transport
Anomalies JJAS 2010 -LMDZ
The LMDZ model experiment using 2010 real SST simulates observed
atmospheric circulation features and rainfall anomalies over the Indo-Pak region

13. Introduction Motivation Objective Methodology Results Conclusions
E-SST
NE-SST
NE-IO-SST
NE-SST & NE-IO-SST simulations
reproduces extreme convective activities
and anomalous positive rainfall over
northwest India-Pakistan region.
Vertical Velocity (Pa s-1
)
ProbabilityDensity
Specific roles of Indo-Pacific
SSTs
SST boundary forcings for the different sets of LMDZ simulation experiments
Serial No. Experiment SST boundary condition
1 C-SST Climatological SST
2 R-SST Real SST for 2010
3 E-SST ENSO related SST for 2010
4 NE-SST ENSO-unrelated SST for 2010
5 NE-IO-SST ENSO-unrelated SST for 2010 over Indian Ocean

14. E-SSTNE-SST
Introduction Motivation Objective Methodology Results Conclusions
E-SSTNE-SST
Meridional cell
averaged over
(60°-75°E)
Western Indian Ocean
Near Equatorial region
Zonal-cell
averaged over
(15° S-0°)
E-SST
NE-SST

15. Introduction Motivation Objective Methodology Results Conclusions
Conclusion
This study points to the key-role of Indian Ocean SST anomaliesrole of Indian Ocean SST anomalies in inducing the northward
moisture transport from AS into sub-tropical Indo-Pak region in the background of modulated
large-scale Indo-Pacific summer monsoon circulation by Pacific SST anomalies during 2010.
DD
CC
DD
CC
SST
Precipitation
CC
DD
CC
DDCC
CC
SST
Precipitation
La Nina SST
over Pacific
Westward shift of the West Pacific Subtropical High
Weaker convection over Bay of Bengal
Indian
Ocean SST
Cyclonic convergence over south-eastern Indian Ocean
Divergence over central and western equatorial Indian Ocean
Enhanced convection and northward moisture transport over northern Arabian Sea
Heavy rainfall activity over north-west India Pakistan region during 2010

16. 11/08/16
Introduction Motivation Objective Methodology Results Conclusions
Northwest India-Pakistan flood 29 July 2010
TRMM3b42 Precipitation
ERA Interim wind at 700hPa
Heavy precipitation activity over
Western Himalaya

Midlatitude trough activity 
Southerly wind over Arabian Sea 
Moisture flux convergence over WH 
Trend in frequency of Extreme rain events ( R > 99th
pctl)
APHRODITE Precipitation data 1951-2007

17. 11/08/16
 Weakening trend of the
monsoon large-scale
facilitated the enhancement
of cyclonic trough activity
over the WH and increases
moisture convergence over
the WH region associated
with stronger southerly flows
from the Arabian Sea during
the recent decades.
 These two results suggest an
increasing probability of the
type of extreme precipitation event that results from the combination of large-scale
moisture flux (associated with a westward extended monsoonal trough) and a
southward protruding mid-latitude westerly trough.
Introduction Motivation Objective Methodology Results Conclusions
Results highlight the importance of a detailed monitoring of the Indian Ocean variability andthe importance of a detailed monitoring of the Indian Ocean variability and
conditions,conditions, through dedicated observation systems, for improving the accuracy of “extended-
range” prediction of future heavy rainfall events in the Indian Ocean and adjacent subtropicalprediction of future heavy rainfall events in the Indian Ocean and adjacent subtropical
areasareas, which are projected to be more frequent in the future warming climate
Thank You.!