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This report examines the performance and technical issues of the Chronos AQHI forecast in Nova Scotia, including lessons learned and conclusions. The evaluation highlights the need for improvement in data ingestion, manual extraction, and communication of forecasted AQHI values. The report suggests automation of Chronos product and clearer presentation of forecasted AQHI values.
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Nova Scotia pilot & evaluation of CHRONOS AQHI Doug E Steeves Atlantic Storm Prediction Centre February 13, 2007
Contents • AQHI Forecasts to Nova Scotia Pilot • Technical Issues • Lessons Learned • Chronos AQHI Verification • Conclusions
AQHI Forecasts • Forecast support July 8 – Sept 30 • Sent once per day at approx 0800 ADT • Maximum AQHI for today and tomorrow for three sites… Halifax, Dartmouth (Lake Major), and Sydney • Manually extracted from FQ (Chronos) files on CMC website.
Sample Forecast FHCN99 CWHX ddhhhh 2006-05-10 07:00:00,Sydney,1,2 2006-05-10 07:00:00,Halifax,2,3 2006-05-10 07:00:00,Dartmouth,1,2 $$$$^^
Chronos Guidance 20061031 AQHI from/de CHRONOS (CTM) Pour/for Sydney P00=00Z A / At 0 m Hres 1-6 7-12 13-18 19-24 25-30 31-36 37-42 43-48 /Hrs Maximum 1.81 1.64 1.82 1.88 1.88 2.49 3.22 3.28 Moy/Mean 1.79 1.62 1.74 1.86 1.80 2.16 2.79 2.10 AQHI from/de CHRONOS (CTM) Pour/for Halifax P00=00Z A / At 0 m Hres 1-6 7-12 13-18 19-24 25-30 31-36 37-42 43-48 /Hrs Maximum 2.03 2.02 2.47 3.15 3.33 2.86 3.32 3.46 Moy/Mean 2.00 1.99 2.27 2.74 2.92 2.38 3.21 2.26 AQHI from/de CHRONOS (CTM) Pour/for Lake Major
~2 t yr-1 • Lake Major Tufts Cove ~400 t yr-1 Shearwater Halifax ~7 t yr-1 Refinery ~250 t yr-1
Technical Issues • July 8-11 -- Forecasts were not properly ingested by NS E&L web site. • July 14-15 -- Wrong date stamp on the data. Likely the form had not been properly updated by the forecaster. The forecast values were likely correct. • Aug 11 – Identified error in manual input of AQHI. Dartmouth forecast “high risk”, Halifax forecast “low risk”. • Aug 23-24 -- AQHI guidance from Chronos unavailable. Forecast sent for day 1on Aug 23 (based on previous days Chronos run) but not for day 2. • Sept 1 -- No forecast. Reason unknown. • Sept 6 -- Forecast late due to network problems. Sent around 12:00 pm. • Sept 9-11 -- No forecast. Likely forecaster error. • Sept 16-17 -- AQHI guidance from Chronos unavailable. Forecast sent for day 1 on Sept 16 (based on previous days Chronos run). No forecast sent on Sept 17.
Lessons Learned • Forecasters should work with pollutant concentrations before calculation of AQHI. • For the purposes of this pilot, automation of product from Chronos would have been better. • Manual extraction introduced errors. • Feedback suggests some confusion over the forecasts because actual AQHI was presented as a number and a risk factor while no number was associated with the forecast.
Conclusions • Error scores (RMSE and bias) are not large but persistence clearly outperformed CHRONOS • There was no clear winner wrt forecasts by category • Diurnal variation to CHRONOS RMSE and bias • CHRONOS had positive bias at L Major and negative bias at Halifax and Sydney. • Possibly explained by gradient of ozone at coast or representation of NOx. • Performance measurement of AQHI provides minimal feedback to the forecast process • Evaluation should be done on the pollutant level
Acknowledgements • NS Department of Environment and Labour • Barb Bryden, Kamila Tomcik, Fran Di Cesare, Jenn Hutchins, Johnny McPherson • CMC • Veronique Bouchet, Jacinthe Racine, Stephane Gaudreault • ASPC • Bruce MacDonald, Geoff Livingstone • Air Quality Prediction • Mike Howe
