Gaussian Grids -------------- Full a description of all ECMWF grid types, see: http://www.badc.rl.ac.uk/data/ecmwf-op/grids.html Gaussian grids are nearly regular latitude-longitude grids. These are used in model calculations in preference to regular grids for numerical accuracy reasons. The ECMWF have used an N80 gaussian grid in their operational spectral model since 1 May 1985. They now use a finer resolution N160 gaussian grid in the model runs, but the gaussian gridded data archived at the BADC is all on the N80 grid. The model output on gaussian grids comes in two forms, full gaussian grid and a reduced gaussian grid. A full gaussian grid has a regular interval along a line of latitude of 1.125 degrees, but an irregular interval between latitude lines as listed below. The grid is symmetric about the Equator. A reduced gaussian grid has the same latitude circles as the full gaussian, but a reduced number of points around each latitude circle, thus saving on storage and computer resources when running the model. The operational ECMWF data archive is on a full gaussian grid. The Re-Analysis data is on the reduced gaussian grid. N80 Gaussian Grid ----------------- "Reduced" "Full" No. from pole Lat (degrees) No. of points No. of points on a Lat circle on a Lat circle 1 89.1416 18 320 2 88.0294 25 320 3 86.9108 36 320 4 85.7906 40 320 5 84.6699 45 320 6 83.5489 54 320 7 82.4278 60 320 8 81.3066 64 320 9 80.1853 72 320 10 79.0640 72 320 11 77.9426 80 320 12 76.8212 90 320 13 75.6998 96 320 14 74.5784 100 320 15 73.4570 108 320 16 72.3356 120 320 17 71.2141 120 320 18 70.0927 128 320 19 68.9712 135 320 20 67.8498 144 320 21 66.7283 144 320 22 65.6069 150 320 23 64.4854 160 320 24 63.3639 160 320 25 62.2425 180 320 26 61.1210 180 320 27 59.9995 180 320 28 58.8780 192 320 29 57.7566 192 320 30 56.6351 200 320 31 55.5136 200 320 32 54.3921 216 320 33 53.2707 216 320 34 52.1492 216 320 35 51.0277 225 320 36 49.9062 225 320 37 48.7847 240 320 38 47.6632 240 320 39 46.5418 240 320 40 45.4203 256 320 41 44.2988 256 320 42 43.1773 256 320 43 42.0558 256 320 44 40.9343 288 320 45 39.8129 288 320 46 38.6914 288 320 47 37.5699 288 320 48 36.4484 288 320 49 35.3269 288 320 50 34.2054 288 320 51 33.0839 288 320 52 31.9624 288 320 53 30.8410 300 320 54 29.7195 300 320 55 28.5980 300 320 56 27.4765 300 320 57 26.3550 320 320 58 25.2335 320 320 59 24.1120 320 320 60 22.9905 320 320 61 21.8690 320 320 62 20.7476 320 320 63 19.6261 320 320 64 18.5046 320 320 65 17.3831 320 320 66 16.2616 320 320 67 15.1401 320 320 68 14.0186 320 320 69 12.8971 320 320 70 11.7756 320 320 71 10.6542 320 320 72 9.53270 320 320 73 8.41120 320 320 74 7.28970 320 320 75 6.16820 320 320 76 5.04670 320 320 77 3.92520 320 320 78 2.80370 320 320 79 1.68220 320 320 80 0.56070 320 320