21st Conference on Climate Variability and Change


NAEFS/GEFS extended forecast

Yuejian Zhu, NOAA/NWS/NCEP/EMC, Camp Springs, MD; and Z. Toth, D. Hou, M. Peņa, Q. Zhang, and J. Gottschalck

The North American Ensemble Forecast System (NAEFS) was established in 2004 by the Meteorological Service of Canada (MSC), the National Meteorological Service of Mexico (NMSM), and the US National Weather Service (NWS) as an operational multi-center ensemble forecast system. Currently it combines the 20-member MSC and NWS ensembles to form a joint ensemble of 40 members twice a day. After bias correction, the joint ensemble is used to generate a suite of products for North America and for other regions of the globe.

NCEP/GEFS (National Centers for Environmental Prediction/Global Ensemble Forecast System) is part of NAEFS. Recently, it has experimentally extended their forecasts from current 16-day to 35-day (at 00UTC only) by using T126/L28 resolution with a stochastic perturbation scheme to represent the model-related uncertainties, 8th order horizontal diffusion (instead of 4th order in current operation). Preliminary results from raw forecasts indicate that, by using the latest GFS/GSI model, the GEFS system outperforms the lagged operational CFS (Climate Forecast System) for week-3 and week-4 based on MJO anomaly correlations and 2mT CRPS assessment. They also show skillful predictions of MJO during winter season. Underway, we are planning to implement the GEFS forecast out to 35-day for 00UTC cycle, applying bias correction, and coupling with ocean model as well.

Session 9A, Prediction of climate on seasonal to decadal timescales - II
Wednesday, 14 January 2009, 10:30 AM-12:00 PM, Room 129A

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