Ensemble sensitivity analysis Research performed by Minghua Zheng (SBU graduate student) References: Torn and Hakim (2008, 2009)

Initial time 2010 Dec 23 12Z, 84 hour ECMWF ensemble forecast

Dec Z (84-hr fcst) Ensemble meanVariance

Sensitivity of EOF 1 (weak/strong cyclone) to 500 hPa height 0-lag EOF1 positive phase: weaker cyclone Here, J is the principal component of EOF1

T-24hr (26 00Z) T-60hr (24 12Z) T-0hr (27 00Z)

Sensitivity of EOF 2 (SW/NE shift of cyclone) to 500 hPa height 0-lag EOF2 positive phase: southwest shift of cyclone

T-24hr (26 00Z) T-48hr (25 00Z) T-0hr (27 00Z)

T-48 hr (25 00Z) Sensitivity EOF1 EOF2

T-60 hr (24 12Z) Sensitivity EOF1 EOF2

SBU CSTAR future work: –Examine sensitivity for different forecast metric J –Examine sensitivity computed using multi-model ensembles –Relate to ETKF sensitivity