TY - JOUR
T1 - Indian Summer Monsoon Sub-seasonal Low-Level Circulation Predictability and its Association with Rainfall in a Coupled Model
AU - Sagalgile, Archana P.
AU - Chowdary, Jasti S.
AU - Srinivas, G.
AU - Gnanaseelan, C.
AU - Parekh, Anant
AU - Attada, Raju
AU - Singh, Prem
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We thank the Director of ESSO-IITM and the Ministry of Earth Sciences, Government of India for support. We sincerely thank the Editor and the anonymous reviewer for their valuable comments that helped us to improve the manuscript. Figures are prepared in GrADS. We thank NCEP for providing CFS hindcast data, which are freely available (online available at http://cfs.ncep.noaa.gov). NOAA_OI_SST_V2 data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their web site at http://www.esrl.noaa.gov/psd/.
PY - 2017/10/26
Y1 - 2017/10/26
N2 - This study investigates predictability of the sub-seasonal Indian summer monsoon (ISM) circulation and its relation with rainfall variations in the coupled model National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2). Hindcasts based on CFSv2 for the period of 1982–2009 are used for detailed analysis. Though the model is capable of predicting the seasonal ISM rainfall at long lead months, the predication skill of the model for sub-seasonal rainfall in general is poor for short and long lead except for September. Rainfall over the ISM region/Indian Subcontinent is highly correlated with the low-level jet (LLJ) or Somali jet both in the observations and the model. The model displays improved skill in predicting LLJ as compared to precipitation in seasonal mean and September, whereas the model skill is poor for June and August. Detailed analysis reveals that the model LLJ variations throughout the season are overdependent on the El Niño-Southern Oscillation (ENSO) unlike in the observations. This is mainly responsible for the model’s low skill in predicting LLJ especially in July and August, which is the primary cause for the poor rainfall skill. Though LLJ is weak in September, the model skill is reasonably good because of its ENSO dependency both in model and the observations and which is contributed to the seasonal mean skill. Thus, to improve the skill of seasonal mean monsoon forecast, it is essential to improve the skill of individual months/sub-seasonal circulation and rainfall skill.
AB - This study investigates predictability of the sub-seasonal Indian summer monsoon (ISM) circulation and its relation with rainfall variations in the coupled model National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2). Hindcasts based on CFSv2 for the period of 1982–2009 are used for detailed analysis. Though the model is capable of predicting the seasonal ISM rainfall at long lead months, the predication skill of the model for sub-seasonal rainfall in general is poor for short and long lead except for September. Rainfall over the ISM region/Indian Subcontinent is highly correlated with the low-level jet (LLJ) or Somali jet both in the observations and the model. The model displays improved skill in predicting LLJ as compared to precipitation in seasonal mean and September, whereas the model skill is poor for June and August. Detailed analysis reveals that the model LLJ variations throughout the season are overdependent on the El Niño-Southern Oscillation (ENSO) unlike in the observations. This is mainly responsible for the model’s low skill in predicting LLJ especially in July and August, which is the primary cause for the poor rainfall skill. Though LLJ is weak in September, the model skill is reasonably good because of its ENSO dependency both in model and the observations and which is contributed to the seasonal mean skill. Thus, to improve the skill of seasonal mean monsoon forecast, it is essential to improve the skill of individual months/sub-seasonal circulation and rainfall skill.
UR - http://hdl.handle.net/10754/626108
UR - http://link.springer.com/article/10.1007/s00024-017-1702-z
UR - http://www.scopus.com/inward/record.url?scp=85040229263&partnerID=8YFLogxK
U2 - 10.1007/s00024-017-1702-z
DO - 10.1007/s00024-017-1702-z
M3 - Article
SN - 0033-4553
VL - 175
SP - 449
EP - 463
JO - Pure and Applied Geophysics
JF - Pure and Applied Geophysics
IS - 1
ER -