17th Conference on Air Sea Interaction

12.3

Moist teleconnection between tropical SST and south Asian monsoon‭

Prasanth Appukuttan Pillai, International Pacific Research Center, Honolulu, HI; and H. Annamalai

Deviating from tradition,‭ ‬the observed monsoon rainfall variability over India is classified into three categories,‭ ‬namely:‭ (‬i‭) ‬moderate‭ (> ‬0.5‭ < ‬1.0‭ ‬standard deviation‭); (‬ii‭) ‬strong‭ (> ‬1.0‭ < ‬1.5‭ ‬standard deviation‭) ‬and severe‭ (> ‬1.5‭ ‬standard deviation‭)‬.‭ ‬Each of these categories‭'‬ association with boundary forcing,‭ ‬in particular with tropical SST anomalies,‭ ‬are then examined.‭ ‬While anomalously strong and severe monsoon years are linked with equatorial Pacific SST variations associated with ENSO,‭ ‬the intensity of ENSO does not determine the intensity of monsoon rainfall.‭ ‬The moderate events have no association with ENSO.‭ ‬Due to limited samples from observations,‭ ‬the diagnostics is repeated with the‭ ‬5-member ensemble simulation of the GFDL_CM2.1‭ ‬20th century integrations spanning the period‭ ‬1861-2000.‭ ‬Of the total‭ ‬700-years analyzed,‭ ‬20%‭ ‬strong and‭ ‬15%‭ ‬severe monsoon years are identified.‭ ‬In the model,‭ ‬while most of the strong and severe years‭ (‬80%‭) ‬are associated with ENSO,‭ ‬regional SST anomalies over the Indo-Pacific warm pool also cause severe monsoon years.‭ ‬The severe monsoons associated with these tropical SST anomalies are investigated in detail.‭ ‬For severe monsoon‭ ‬category,‭ ‬the anomalies in monsoon characteristics are noted in late‭ ‬boreal‭ ‬spring,‭ ‬and they‭ ‬persist into‭ ‬fall.‭ ‬To understand‭ ‬the processes involved in the‭ ‬teleconnection,‭ ‬idealized ensemble simulations with the atmospheric component of CM2.1‭ ‬are carried out.‭ ‬We perform moisture and moist static energy budgets in CM2.1‭ ‬and AGCM integrations and‭ ‬note that the interaction of equatorial waves with moist physics‭ ‬is responsible for setting up the teleconnection.‭

wrf recordingRecorded presentation

Session 12, Air-Sea Interaction in the Indo-Pacific Region
Thursday, 30 September 2010, 3:30 PM-5:00 PM, Capitol AB

Previous paper  Next paper

Browse or search entire meeting

AMS Home Page