Using CCO data to verify Inshore and Shipping

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Inshore Waters Forecast • Issued four times a day − − 0000 GMT 0600

To verify we need to know what really happened…. . WHAT IS TRUTH? www.

CCO observations are available in most areas …but some do not adequately represent the

1 st January – 30 th September 2019 www. metoffice. gov. uk Inshore Waters

Selsey Bill – Lyme Regis 5 locations Use the maximum observation / location /

www. metoffice. gov. uk Sea State Wave Height (m) Smooth <0. 5 Slight 0.

Forecasts use specific key-words… Phrase at times for a time becoming increasing Meaning At

1. 2. 3. 4. Northerly 6 to gale 8. Rough or very rough. Occasional

Selsey Bill to Lyme Regis: South 5 to 7, veering southwest 6 to gale

Slight or moderate… 41% 38% correct 27% 52% > forecast 10% < forecast Example

Slight or moderate… 52% 30% correct 30% BUT slight did not occur! So apply

moderate observed but not forecast slight and moderate both observed All 4 forecast categories

11 am 10 th August 2019 1. 81 m (moderate) reported at Boscombe 98.

Wave height is correct 74% Wave height is 1 category too high 24% Wave

81% correct Lyme Regis – Lands End 70% correct Selsey Bill – Lyme Regis

1 st October 2018 – 30 th September 2019 www. metoffice. gov. uk Accuracy

Enough observations to verify 24 sea areas HUMBER PLYMOUTH www. metoffice. gov. uk ©

2018 © Crown copyright 2017 Shipping Area State Observations (surface)

Accuracy 1 st January - 31 st December 2018 www. metoffice. gov. uk Shipping

VIKING PLYMOUTH Observed > forecast wave height 1 st January – 31 st December

© Crown copyright 2017 Wave height observations 4 th April 2019

Perenporth Penzance Porthleven PLYMOUTH www. metoffice. gov. uk 5 am 19 th January 2019

Wave Height Forecast Accuracy 1 st January – 31 st December 2018 www. metoffice.

Thank you. Dr Michael Sharpe Dip. Stat(Open) FRMet. S. Verification Systems, Met Office Annual

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Using CCO data to verify Inshore and Shipping Forecasts Dr Michael Sharpe Dip. Stat(Open) FRMet. S. Verification Systems, Met Office Annual Review Meeting, National Oceanography Centre, Southampton, 10 th October 2019 www. metoffice. gov. uk © Crown Copyright 2017, Met Office

Inshore Waters Forecast • Issued four times a day − − 0000 GMT 0600 GMT 1200 GMT 1800 GMT Exceptions: • Shetland: 60 nm twice daily • 24 hour forecast • Isle of Man Meteorological Office • 24 outlook • Jersey Met. • 19 coastal areas • 12 nm coastal zone • Sister product – coastal strong wind warnings www. metoffice. gov. uk © Crown Copyright 2017, Met Office

CCO observations are available in most areas …but some do not adequately represent the inshore area © CCO 2019 © Fugro GB Marine Limited www. metoffice. gov. uk Etrometa Stepgauge on Port Isaac breakwater © Crown Copyright 2017, Met Office

CCO observations are available in most areas …but some do not adequately represent the inshore area …so only 7 areas are currently verified © CCO 2019 © Fugro GB Marine Limited www. metoffice. gov. uk Etrometa Stepgauge on Port Isaac breakwater © Crown Copyright 2017, Met Office

Selsey Bill – Lyme Regis 5 locations Use the maximum observation / location / hour Boscombe West Bay Hayling Island Milford Chesil Sandown Bay Bracklesham Bay Weymouth 00: 00 20 th Sept. 2019 www. metoffice. gov. uk © Crown Copyright 2017, Met Office

www. metoffice. gov. uk Sea State Wave Height (m) Smooth <0. 5 Slight 0. 5 - 1. 25 Moderate 1. 25 - 2. 5 Rough 2. 5 – 4 Very rough 4– 6 High 6– 9 Very high 9 – 14 Phenomenal >14 © Crown Copyright 2017, Met Office

Forecasts use specific key-words… Phrase at times for a time becoming increasing Meaning At any time during the forecast Any time after the start and must occur by the end decreasing www. metoffice. gov. uk later Second half of the forecast at first First half of the forecast © Crown Copyright 2017, Met Office

1. 2. 3. 4. Northerly 6 to gale 8. Rough or very rough. Occasional rain. Moderate or good 1. 2. 3. 4. speed/direction sea state weather visibility www. metoffice. gov. uk © Crown Copyright 2017, Met Office

Selsey Bill to Lyme Regis: South 5 to 7, veering southwest 6 to gale 8, occasionally severe gale 9 for a time. Slight or moderate, becoming rough or very rough. Thundery showers. Good occasionally poor. Slight & moderate during hour 1 Slight to very rough during hours 2 -23 Rough and very rough during hour 24 Phenominal Very High Very rough Increasing to rough - very rough thereafter Rough Moderate Slight to moderate from the start Slight Smooth 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 www. metoffice. gov. uk hour 72 inshore waters area forecasts / day Automatic interpretation ~90% Midday forecast on 9 th August 2019 © Crown Copyright 2017, Met Office

Slight or moderate… 41% 38% correct 27% 52% > forecast 10% < forecast Example 1 10% 11% Forecast categories smooth 0 www. metoffice. gov. uk 1 2 3 4 5 Sea State category 6 7 slight moderate rough very rough Observed sea state categories © Crown Copyright 2017, Met Office

Slight or moderate… 52% 30% correct 30% BUT slight did not occur! So apply a penalty; what? • 1%? - too lenient! • Choose ½ of slight / moderate observations so… 18% 70% > forecast Assessed as only 15% correct… Example 2 …with an extra 15% of sea states > forecast Forecast categories smooth 0 www. metoffice. gov. uk 1 2 3 4 5 Sea State category 6 7 slight moderate rough very rough Observed sea state categories © Crown Copyright 2017, Met Office

Wave height is correct 74% Wave height is 1 category too high 24% Wave height is 1 category too low 1% Wave height is ≥ 2 categories too high 1% 1 st January – 31 st December 2018 www. metoffice. gov. uk Inshore Forecast Sea State Performance © Crown Copyright 2017, Met Office

81% correct Lyme Regis – Lands End 70% correct Selsey Bill – Lyme Regis 1 st October 2018 – 30 th September 2019 www. metoffice. gov. uk Accuracy of Inshore Waters Forecast Sea State © Crown Copyright 2017, Met Office

Thank you. Dr Michael Sharpe Dip. Stat(Open) FRMet. S. Verification Systems, Met Office Annual Review Meeting, National Oceanography Centre, Southampton, 10 th October 2019 www. metoffice. gov. uk © Crown Copyright 2017, Met Office

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