Subject: [ids.analysis.forum] Re: TOPEX and Jason surface forces, again
From: "John C. Ries" <[email-masked]>
To: Remko Scharroo <[email-masked]>, Nikita Zelensky <[email-masked]>
Cc: "[email-masked]" <[email-masked]>, Cerri Luca <[email-masked]>, Eelco Doornbos <[email-masked]>, Marek Ziebart <[email-masked]>, Frank Lemoine <[email-masked]>, Scott Luthcke <[email-masked]>, Michiel Otten <[email-masked]>, Eric Leuliette <[email-masked]>, "Mercier Flavien (contact)" <[email-masked]>, "[email-masked]" <[email-masked]>
Date: Wed, 3 Mar 2010 18:01:55 -0600

Hi Everyone,

I doubt if I have been able to understand all the information 
supplied so far in the extensive email thread, but perhaps I can get 
some clarification on a few points.

1) The SRP signal is beta-prime dependent, so a full cycle is 120 
days, at least in Z. It's almost a perfect scaling of the beta prime 
angle, including the sign. There shouldn't be a frequency at half 
that...certainly nothing in my test below. So if 60 days is dominant, 
perhaps we should be looking something other than SRP. Because of the 
yaw flip, could something associated with the radiators exhibit a 
half-beta-prime dependency?

2) There was also the mention of S2, whose alias is 58.6 days. How 
much did T/P influence the estimation of S2 in the tide models being 
used? Could S2 have absorbed a T/P perturbation that is now showing 
up in Jason 1 and 2 (and the same in both)? A tide modeling error 
will show up 100% in the sea level time series but will be diluted in 
the orbit differences. For what it's worth, one of the most prominent 
error aliases in the GRACE estimates for C20 is S2.

JR