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Impact of NOAA18 in the Met Office Global Model. Brett Candy, Steve English and Fiona Hilton. Experiment Details. Trial Details (1). Monitoring of NOAA18 AMSU data shows that the data is of comparable quality to other NOAA platforms
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Impact of NOAA18 in the Met Office Global Model Brett Candy, Steve English and Fiona Hilton
Trial Details (1) • Monitoring of NOAA18 AMSU data shows that the data is of comparable quality to other NOAA platforms • Currently operational global model assimilates AMSU data from N15, N16, Aqua • The time for processing ATOVS data cannot increase therefore we intend to withdraw Aqua and replace it with NOAA-18 • Prior to assimilation we thin data to 1 ATOVS observation per analysis gridpoint. Intention is to give NOAA-18 the priority in the thinning • A near real time trial of duration 1 month has been run to test this strategy
Trial Details (2) • Trial consists of two runs • a) Control as operations (N15, N16, Aqua) + N18 in passive mode to collect bias correction stats • b) Experiment Aqua withdrawn, N18 assimilated • The experiment was switched on after the control had completed 10 days in order to accumulate enough stats for bias correction.
Average Data Assimilated for a Main forecast Run Control Experiment
NOAA18 fit to short range forecast Black – Control runGrey – NOAA18 assimilated
NOAA16 fit to short range forecast Black – Control runGrey – NOAA18 assimilated
Northern Hemisphere: Main impact is in PMSL Red: Control Blue: Exp Overall: 16 parameters improved, 101 neutral, 6 worsened
Tropics: ~Neutral for surface winds Red: Control Blue: Exp Overall: 14 parameters improved, 106 neutral, 3 worsened
Southern Hemisphere: Main impact is again in PMSL Red: Control Blue: Exp Overall: 26 parameters improved, 83 neutral, 14 worsened
Global T+6 fit comparisons using Sondes % Improvement to RMS fit
Verification of the moisture forecasts Red: Control Blue: Exp NH Tropics SH
Conclusions • Forecast impacts due to the switch over from Aqua to Noaa18 are very encouraging. Part of this improvement is probably due to more data arriving in time for the main runs • NOAA18 is now in our parallel suite with the expectation of operational assimilation from 9th August • Use of N18 data in regional models expected from Autumn