Transcript Slide 1
Disclaimer The material contained in this PPT is a raw model output and research product. This is meant for scientific use. For any clarification/interpretation, please contact India Meteorological Department. Extended range prediction during 2014 season Using CFS based Grand Ensemble Prediction System (CGEPS) INITIAL CONDITION: 08 September 2014 Strategy: Ensemble Prediction using CFSv2 Ocean and Atmospheric Initial conditions (IC) are obtained from NCEP. Technique was developed to perturb ICs to generate 11 members. (Abhilash et al., 2013) Model has been integrated at low resolution (T126, ~100km, termed as CFS126 hereafter; Abhilash et al. 2014) and high resolution (T382, ~38km, termed as CFS382 hereafter; Sahai et al. 2014) for 45 days for each 11 ICs at five day intervals starting from 16th May (Eg: 16 May, 21 May, 26 May, 31 May, 05 Jun........etc). Climatology has been calculated from 10-year hindcast. Bias correction in daily forecasted SST from CFS126 for each lead time has been done by removing the daily mean bias for corresponding lead time (model climatology-observed climatology) from forecasted daily SST (Sahai et al., 2013; Abhilash et al., 2013). This model is hereafter termed as GFSbc. Generation of CGEPS In the formulation of MME from CGEPS, 21 ensembles of GFSbc, 11 ensembles of CFS126 and 11 ensembles of CFS382 have been used (Abhilash et al. 2014, submitted). Hence, total 43 ensemble members were produced independently from 3 variants of CFS model to generate the CGEPS and forecast consensus is done by making simple average among the members. Real-time forecast based on 08 September 2014 initial condition Daily evolution of rainfall and wind at 850hPa Daily evolution of vorticity at 850hPa and mean sea level pressure Daily evolution of divergence and winds at 200hPa Pentad wise rainfall predicted by MME Area averaged rainfall over homogeneous regions predicted by MME Computation of MISO (Ref: Suhas et al. 2012, Sahai et al. 2013) Extended EOF analysis is carried out similar to Wheeler and Hendon 2004 using standardized rainfall anomalies up to lag -15 days, averaged between 60-95E for the latitudes -12 to 30. The rainfall anomalies for the lag days are appended side by side to create the extended data matrix. The EOF analysis is carried out using IMD-TRMM merged data from 1998-2011. The real time data for 2013 is projected onto the EOFs created from the 14 years of past data. The amplitude of EOF1 and EOF2 (PC1 and PC2 ) are plotted in a PC1/PC2 phase space similar to Wheeler Hendon 2004 to get an idea of the evolution of ISO and its strength. Phase1: Peninsular India; Phase5: Foothills Phase2: Central India; Phase6: South Indian Ocean; Phase3: Central India; Phase7: Indian Ocean; Phase4: North India Phase8: Southern tip MISO monitoring and forecast for next 25 days Key points from the present forecast Although monsoon activity will be normal over northern India (with increased amplitude over northwest India) for the next 5-10 days, conditions of withdrawal is expected to occur 20 September onwards. Large scale MISO forecast indicates that it will be active over the foothills in next 5-10 days and will then start withdrawing from the Indian region.