Earth System Prediction with the Subseasonal Experiment (SubX)
Kathy PegionGeorge Mason University, Dept of Atmospheric, Oceanic, and Earth Sciences
Center for Ocean-Land-Atmosphere Studies
Valid Jun 28 – Jul 12
The Subseasonal Experiment (SubX)
From White, C, …. K. Pegion, … 2017, J. Royal. Met. Soc.
Forecasts available in real-time
Research models included
SubX BY THE NUMBERS
7 Global Models
17 Years of weekly
Retrospective Forecasts
~2 Years of weekly
Real-time Forecasts
3-4 week guidance
for Climate Prediction Center Outlooks
CESM-30LCESM1 A,O,I,L 10 45 1999-2016 SEAS/Dec/CC R
CESM-46LCESM1 A,O,I,L 10 45 1999-2016 SEAS/Dec/CC R
The Subseasonal Experiment (SubX)
Pegion et al. 2019, BAMS revised
SubX Multi-model Biases Week-1
2m Temperature Precipitation
Anomaly Correlation 2m Temperature Week 3
Pegion et al. 2019, BAMS revised
SubX Average Anomaly Correlation North America Week 3-4
Overall subseasonal skill is low
But, subseasonal skill varies:RegionSeasonTime
Skill of Week 3 Jan Re-forecasts
Pegion et al. 2019, BAMS revised
For this timescale, focus on forecasts opportunity
• Models fail to predict the MJO convection, associated circulations, and moisture advection processes beyond 10 days
• Models have mean biases across the Indo-Pacific: a drier low troposphere, excess of surface precipitation, frequent occurrence of light precipitation.
Kim, Janiga, Pegion, submitted to JGR
Understanding ProcessesEvaluating Skill
Madden-Julian Oscillation (MJO)
Pegion et al. 2019, BAMS revised
Where to find more information: http://cola.gmu.edu/kpegion/subx/ • SubX BAMS
Paper (revised)
• SubX MJO Paper, (submitted)
• SubX Data Users Guide
• Codes for Downloading and processing data
• Model Evaluation Plots
• Real-time Forecast Plots
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