GISS Land and sea weightings out of balance

18 Jul 2010

Land and sea weight out of balance Posted on July 17, 2010 by Anthony Watts Frank Lanser finds that GISS global temperature trend is warmed up by weighting land data more. Guest post by Frank Lansner http://hidethedecline.eu/pages/posts/gis....l-more-18 6.php and also here.http://wattsupwiththat.com/2010/07/17/ti....nce/#more-22126 It seems that global temps are not only fiddled by extreme selectivity in the location of the surface stations but that the extra weighting given to the land area by GISS in its land+sea data has been steadily increasing over the 20th century. Since land is warmer than ocean this introduces an ever rising warming bias in the global temp. Why do the GISS “adjustments” ALWAYS result in a warm bias, I wonder.? The real land fraction of the Earth is of course 30%, but around 1980 GISS uses 40%, in 1988 55% – and in 1995 no less than 73%. GISS ends up in 2007 using a land weighting of 67%. On the face of it these increasing weightings look dubious. ........ JoNova discusses Frank Lansner's findings further here http://joannenova.com.au/2010/07/did-gis....here/#more-9450 She entitles her article "Did GISS discover 30% more land in the Northern Hemisphere?" Good question, especially since, given the known UHI effect, extra weighting of the land surface data with respect to the total will create EVEN MORE artificial amplification of temperature and thus of the purported upward trend. She also notes that the Satellite measurement of surface temperatures corresponds very closely to the ocean temps rather than the land temps. Hmmm. Why could that be? ....... Frank Lansner adds " I have just made the math and graphs for this issue globally and not only for NH. Result: it's WORSE globally than on NH. Globally by simply mixing land and SST GISS has added around 0,18K in heat trend over the 20th century. Globally GISS end at 66% land use in 2007, but in the 1930s they only use 30-40% land. Amazing!!! Some may not agree, but i think this is something you will hear a lot about, mark my word." "GISS LST+SST equals the used SST graphs for approx 1900-1920. This means that land is weighted around ZERO % to begin with. Around 1920-30 they use 30% land. And then from 1980 – 2007 they go from around 45% land fraction to 66% land fraction – globally. This does add heat to their trend." I think so too, Frank! Thanks.