Received 2003-11-15 DWF Proudman Oceanographic Laboratory Natural Environment Research Council Bidston Observatory Bidston Hill Prenton Merseyside CH43 7RA United Kingdom David Flater Tel +44 (0) 151 653 8633 Fax +44 (0) 151 653 6269 United States of America www.pol.ac.uk 07 November 2003 Dear David, This letter is to confirm that we are happy for you to download the sea level data from the British Oceanographic Data Centre website and use this in the generation of harmonic constants using the HarmGen software. However there are a couple of things that we would politely ask that you do. 1. Limit the number of harmonic constants you use in the software to a maximum of 40 for any port. This should easily be enough to create very accurate tidal predictions as for nearly all locations, any harmonics left out (i.e. the 41st most significant constants onwards) will have amplitudes of the order of a centimetre. 2. State that the data is derived from sea level data obtained from the British Oceanographic Data Centre based at the Proudman Oceanographic Laboratory, Liverpool. 3. Make it clear that the predictions however are not the same as those computed by the Proudman Oceanographic Laboratory which uses its own sets of harmonic constants. 4. Continue to make your software using the data freely available. Please inform us if you intend to produce a software product that you will be making a charge for. I hope these conditions are acceptable to you and it will be good to see the UK back on the map. Yours sincerely, Colin Bell Head of Applications Group