10/25/2011 CERES Ed2.6 and higher products use geodetically weighting to compute global means. This spherical Earth assumption gives the well-known So/4 expression for mean solar irradiance, where So is the instantaneous solar irradiance at the TOA. When a more careful calculation is made by assuming the Earth is an oblate spheroid instead of a sphere, and the annual cycle in the Earth's declination angle and the Earth-sun distance are taken into account, the division factor becomes 4.0034 instead of 4. Consequently, the mean solar irradiance for geodetic weighting is ~1361/4.0034 = 340 Wm-2, compared to 1365/4 = 341.3 Wm-2 for spherical weighting. Spherical earth zonal weighting uses the sin(lat1 lat2), where lat1 and lat2 are the boundaries of the zone geodetic weighting assumes an oblate spheroid, with the equatorial radius = 6378.137000000 km, and the polar radius = 6356.752314245 km. The CERES geodetic 1.0-deg zonal weights are provided here: lat weight -89.50 0.000077 -88.50 0.000231 -87.50 0.000384 -86.50 0.000538 -85.50 0.000691 -84.50 0.000844 -83.50 0.000997 -82.50 0.001149 -81.50 0.001301 -80.50 0.001453 -79.50 0.001604 -78.50 0.001755 -77.50 0.001905 -76.50 0.002054 -75.50 0.002203 -74.50 0.002351 -73.50 0.002498 -72.50 0.002645 -71.50 0.002790 -70.50 0.002935 -69.50 0.003078 -68.50 0.003221 -67.50 0.003363 -66.50 0.003504 -65.50 0.003643 -64.50 0.003781 -63.50 0.003918 -62.50 0.004054 -61.50 0.004189 -60.50 0.004321 -59.50 0.004453 -58.50 0.004584 -57.50 0.004713 -56.50 0.004840 -55.50 0.004966 -54.50 0.005090 -53.50 0.005213 -52.50 0.005333 -51.50 0.005453 -50.50 0.005570 -49.50 0.005686 -48.50 0.005800 -47.50 0.005912 -46.50 0.006023 -45.50 0.006131 -44.50 0.006237 -43.50 0.006342 -42.50 0.006445 -41.50 0.006545 -40.50 0.006643 -39.50 0.006740 -38.50 0.006834 -37.50 0.006927 -36.50 0.007017 -35.50 0.007105 -34.50 0.007191 -33.50 0.007274 -32.50 0.007355 -31.50 0.007434 -30.50 0.007511 -29.50 0.007586 -28.50 0.007658 -27.50 0.007728 -26.50 0.007796 -25.50 0.007861 -24.50 0.007923 -23.50 0.007984 -22.50 0.008042 -21.50 0.008097 -20.50 0.008151 -19.50 0.008201 -18.50 0.008250 -17.50 0.008295 -16.50 0.008339 -15.50 0.008380 -14.50 0.008418 -13.50 0.008454 -12.50 0.008487 -11.50 0.008518 -10.50 0.008546 -9.50 0.008572 -8.50 0.008595 -7.50 0.008615 -6.50 0.008633 -5.50 0.008649 -4.50 0.008661 -3.50 0.008672 -2.50 0.008679 -1.50 0.008685 -0.50 0.008687 0.50 0.008687 1.50 0.008685 2.50 0.008679 3.50 0.008672 4.50 0.008661 5.50 0.008649 6.50 0.008633 7.50 0.008615 8.50 0.008595 9.50 0.008572 10.50 0.008546 11.50 0.008518 12.50 0.008487 13.50 0.008454 14.50 0.008418 15.50 0.008380 16.50 0.008339 17.50 0.008295 18.50 0.008250 19.50 0.008201 20.50 0.008151 21.50 0.008098 22.50 0.008042 23.50 0.007984 24.50 0.007923 25.50 0.007861 26.50 0.007796 27.50 0.007728 28.50 0.007658 29.50 0.007586 30.50 0.007511 31.50 0.007434 32.50 0.007355 33.50 0.007274 34.50 0.007190 35.50 0.007105 36.50 0.007017 37.50 0.006927 38.50 0.006834 39.50 0.006740 40.50 0.006643 41.50 0.006545 42.50 0.006444 43.50 0.006342 44.50 0.006237 45.50 0.006131 46.50 0.006023 47.50 0.005912 48.50 0.005800 49.50 0.005686 50.50 0.005570 51.50 0.005453 52.50 0.005334 53.50 0.005212 54.50 0.005090 55.50 0.004966 56.50 0.004840 57.50 0.004713 58.50 0.004584 59.50 0.004453 60.50 0.004322 61.50 0.004189 62.50 0.004054 63.50 0.003918 64.50 0.003781 65.50 0.003643 66.50 0.003504 67.50 0.003363 68.50 0.003221 69.50 0.003079 70.50 0.002935 71.50 0.002790 72.50 0.002645 73.50 0.002498 74.50 0.002351 75.50 0.002203 76.50 0.002054 77.50 0.001905 78.50 0.001755 79.50 0.001604 80.50 0.001453 81.50 0.001301 82.50 0.001149 83.50 0.000997 84.50 0.000844 85.50 0.000691 86.50 0.000538 87.50 0.000384 88.50 0.000231 89.50 0.000077 ----- end file ----