i'm pretty much one of the most knowlegeable guys you will ever find anywhere concerning athletics ( not braggadocio - it's likelihood from experience )
gravity
per se has little effect on horizontal jumps re: lower
g
the effect of gravity is much more significant a factor thru reduced atmospheric pressure with altitude than variations of 9.81 m/s^2 around globe - it's only fractionally less
g at mexico city
you can ball-park quantify here :
http://myweb.lmu.edu/jmureika/track/wind/index.html
but to save you labour :
compare 10.00s at your chosen altitude with sea-level ( 0 wind each )
the ratio has to be
^2 to gauge advantage ( higher altitude helps once thru greater runway speed & again thru jump phase )
apply that as correction factor
( can also use it for HJ )
the legend is Bob Beamon & Mexico
that jump was screwed by wind gauge judge ( they swapped nationality judges constantly back then due to politics - the guy for Beamon was clueless ) who rounded 2.0 - 3.0 m/s winds to 2.0 when he should have rounded to 0.1, making it something 2.0 ++ m/s & illegal for record purposes ( but of course, still the win - whoever jumps furthest wins ) - it's likely this part-time judge was thrilled to "make" a WR
Beamon had likely wind likely close to 3m/s
the estimate i got for it 0 altitude/0 wind is ~
8.60 - 8.65m
Carl Lewis never broke outdoor WR ( had indoors of 8.79m - vastly superior to beamon )
Mike Powell beat Carl in '91 with existing WR of 8.95m to 8.91m ( albeit the runway was illegally hard, offering more than 65% permitted energy return )
Carl was robbed of a legendary jump in '82 by an incompetent judge who foul-judged him despite no mark on the plastiscine
download jump here ( its 8.3 MB download at "The Perfect Jump" - i back fan call - he got extraordinary height for him, when he was a noted "flat" trajectory guy because of his incredible speed )
http://www.arielnet.com/media/
fan discussion here :
http://mb.trackandfieldnews.com/discussion/viewtopic.php?f=5&t=23788&hilit=ariel
& check wiki :
http://en.wikipedia.org/wiki/Carl_Lewis
He achieved his 10.00 s clocking the same weekend he leapt 8.61 m twice, and the day he recorded his new low-altitude record 8.76 m at Indianapolis, he had three fouls with his toe barely over the board, two of which seemed to exceed Beamon’s record, the third which several observers said reached 30 ft (about 9.15 m). Some say Lewis should have been credited with setting a world record with that jump, claiming the track officials misinterpreted the rules on fouls.[18]
