date: Thu, 01 Jul 2004 09:12:07 -0600 from: Tom Wigley subject: your text to: Sarah Raper Sarah, To expand on my earlier email, the problem is that your text is too brief. Instead of saying DF is the heat flux below the atmosphere, it might be better to relate this to the heat flux into the ocean -- as it is in MAGICC because the other parts of the model have no heat capacity. This then relates to the change in ocean heat content (dH/dt) in my (much) earlier emails), which then links to Levitus.What you say is correct, but it is confusing to give the Murphy idea of running from a instantaneous transient point in time to a rather idealized equilibrium that will not in general be the same equilibrium that the model would go to if allowed to run freely. So this is what is missing. It would be difficult to do the Murphy thing in practice, so using MAGICC (or a simplified EBM picture) to illustrate the concept is I think a better way to go. In this context, the simple analytical solution I sent you a while back helps in understanding how, in anything but a 1-box model, the effective sensitivity can change in time. I am not suggesting you use this, but it is useful. Tom. Grammar: it is '... if .... were ...' not '... if .... was ...' (conditional). See 4 lines above first equation. Also, your last three references are distorted -- come out very weird when I view in or print from Word. Final point, the Watterson idea is garbage. In my flux breakdown version of MAGICC I calculate his parameter and it is unrelated to anything conventional, and adds zero insight. There is a link to effective heat capacity, which we introduce in the Schlesinger book -- but this is off the track.