Comparison of Ocean Heat Content from Hy COM

Comparison of Ocean Heat Content from Hy. COM with Satellite Retrievals: Preliminary Results Informal Presentation Weekly HWRF Meeting March 25, 2010 Mark De. Maria, NESDIS/STAR/RAMMB Robert De. Maria, CIRA/CSU Research partially supported by HFIP 1

Ocean Heat Content (OHC) ρw=1030 kg/m 3 cw= 3850 J/kg-o. C D 26 = Depth of 26 o. C isotherm T = temperature (o. C) z = Depth (m) Example: 100 m deep isothermal mixed later with T=29 o. C OHC = 1030*3850*3*100 = 1. 19 x 109 J/m 2 = 119 k. J/cm 2 2

Ocean Heat Content (OHC) • Provides bulk measure of upper ocean structure • More variability than SST • Statistical intensity models show positive correlation with intensity changes • Satellite-altimetry based retrievals available for comparison with ocean model forecasts 3

Datasets • OHC calculated from coupled HWRF-Hy. COM runs – Provided by Hyun-Sook Kim – Hurricane Ike initialized at 00 UTC 2 -13 Sept 2008 – Forecast fields at t=0, 24, …, 120 h – Variable resolution, ~6 to 16 km • Corresponding OHC from satellite retrievals at validation times – Previous 10 to 20 days of Jason, GFO, Envisat – Reynolds weekly SST – 50 km spatial resolution 4

Hy. COM and Satellite Retrieval Grids Every 5 th Hy. COM grid point Every 5 th Satellite OHC retrieval grid Interpolate and smooth Hy. COM to 0. 5 o retrieval grid using Barnes analysis with re=25 km 5

Hy. COM OHC 090208 00 f 000 Hy. COM Smoothed OHC 090208 00 f 000 6

Hy. COM OHC 090208 00 f 000 Satellite OHC 090208 7

Hy. COM OHC 090208 00 f 000 Scaled Satellite OHC 090208 8

Preliminary Results • First Ike forecast – Initialized 00 UTC on 02 Sept 2008 • Compare Hy. COM and satellite OHC – 0, 24, …, 120 h forecasts • 0. 5 deg domain • Match points with OHC and Hy. COM data ~8200 points per validation time 9

Ike 02 Sept 2008 00 UTC , t=0 h forecast 500 R 2 = 0, 7308 Satellite OHC (k. J/cm² 400 300 200 100 0 0 100 200 300 Hycom OHC (k. J/cm²) 400 500 10

Ike 02 Sept 2008 00 UTC t=120 h forecast 500 R 2 = 0, 6947 Satellite OHC (k. J/cm²) 400 300 200 100 0 0 100 200 300 Hycom OHC (k. J/cm²) 400 500 11

Variance Explained (%) or Regression slope 0, 8 0, 7 0, 6 r 2 0, 5 slope 0, 4 0, 3 0, 2 0, 1 0 0 24 48 72 96 120 Forecast Time (hr) 12

Preliminary Conclusions and Next Steps • Basin-wide OHC from Hy. COM and Retrievals highly correlated – Source of offset needs to be determined • • Correlation decreases very slowly with time Perform statistics on complete Ike sample Perform statistics on storm-centric domain Compensate for time composites in satellite retrievals – Only pre- and post-storm retrievals may be useful • Test OHC from Hy. COM in SHIPS statistical intensity model instead of satellite OHC 13

Operational Atlantic Intensity Forecast Model Errors 2007 -2009 Intenstiy Error (kt) 25 20 15 GFDL 10 HWRF SHIPS LGEM 5 0 12 24 36 48 60 72 84 96 108 120 Forecast Interval (hr) 14