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Challenge: What Impact would a 30% reduction in ship time… SI Forecasting Perspective

Challenge: What Impact would a 30% reduction in ship time… SI Forecasting Perspective. Arun Kumar Climate Prediction Center NCEP. - JMA Forecast System - 2004-2007 Initialized 4 times a year - Summary based on 7-month predictions.

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Challenge: What Impact would a 30% reduction in ship time… SI Forecasting Perspective

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  1. Challenge: What Impact would a 30% reduction in ship time…SI Forecasting Perspective Arun Kumar Climate Prediction Center NCEP Arun Kumar Climate Prediction Center 28 October 2010

  2. - JMA Forecast System - 2004-2007 Initialized 4 times a year - Summary based on 7-month predictions Based on the Ocean Observing System Experiments (where some data is held back from the assimilation and forecast systems) we kind of know that TAO observations add both the analysis of the ocean state and skill of subsequent predictions Arun Kumar Climate Prediction Center 28 October 2010

  3. David Anderson, 2009, OceanObs ‘09 Arun Kumar Climate Prediction Center 28 October 2010

  4. However, • Because of various reasons, it is hard to put a number from the SI forecasting perspective • Sampling • Errors in modeling and assimilation systems • Evolving data platforms could result in time dependent inferences (impact of TAO of prediction skill may be different for pre/post ARGO) Arun Kumar Climate Prediction Center 28 October 2010

  5. Sampling Issues Skill for Nino34 SST Nino34 Variability Arun Kumar Climate Prediction Center 28 October 2010

  6. Some systematic inter-comparison studies have been done, e.g., a coordinated experiment in 2002-2003 led by Michele Reinecker, and involving GFDL, NASA, NCEP, IRI+LDEO, COLA, • Objective: Observing system impacts - focused on TAO: • Is it effective in its present configuration? • Could it be modified to provide better support for S-I forecasts? Arun Kumar Climate Prediction Center 28 October 2010

  7. Conclusions: • Early stage of the analysis - we have to study the results in more detail • Statistical significance of results - need more ensemble members and more cases of both warm and cold events for robust conclusions • Eastern array definitely improves forecast skill • Western array improves skill in central Pacific • Entire array • best results • probably associated with atmospheric response across the entire Pacific • some indication that get a tighter spread • Results are subtle - complicated by coupled model shocks and drifts Courtesy: Michele Reinecker

  8. …in summary It is hard to quantify the impact of TAO on the forecast skill…needs fair amount of computing resources to do this Has to be a multi-model study…we could make another organized attempt at it In the absence of definitive answers, it may be most prudent to maintain the TAO array the best we can. However, some results indicate that ENSO forecast skill may be most sensitive to errors in the thermocline in the EP, and if resources are limited then… Maintenance of the TAO as a possible “Climate Data Record” Arun Kumar Climate Prediction Center 28 October 2010

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