cc: Phil Jones date: Mon, 14 Sep 2009 16:44:32 +0100 from: Adrian Simmons subject: Re: humidity paper to: Brian Hoskins Brian I'm not sure I could argue that with confidence (or anything else much about convection with any confidence) but it seems you've thought about it, so I would hesitate to argue with you unless I can find good grounds. Adrian Brian Hoskins wrote: > Adrian > The humidity above the boundary layer affects the towers that entrain, > but you could argue that the few towers that get from near surface to > the upper troposphere, and probably set the temperature there may have > little entrainment and therefore be sensitive mainly to the near surface > humidity. > Do you buy that??!! > Best wishes > Brian > > Adrian Simmons wrote: > >> Brian >> >> I'm glad you liked it. I should really have been spending more time on >> GEMS/MACC than writing this up, but the main result was too interesting >> to ignore. We did our best to convince first ourselves and then the >> reviewers that there was a reasonable case that what we presented is >> sound, and it was pleasing when Kate Willett produced the HadCRUH >> extension that showed a similar drop in RH over land than ERA, and when >> I noticed that variations averaged separately over land and sea were >> similar. It all looks to hang together, but ... >> >> I have to get back to the day job for now, but will keep an eye on how >> things unfold, and look a bit more at what happens higher up in a few >> weeks time, I hope. Upper-air water vapour over the ocean is much better >> in ERA-Interim than ERA-40, but not as good as it might be - not >> correlating as well with qsat(SST) as the SSMI retrievals do - and >> shifting radiosonde humidity biases make things tricky over land, so I'm >> not sure quite how much progress can be made with current reanalysis >> products. >> >> All the best >> >> Adrian >> >> >> Brian Hoskins wrote: >> >> >>> Phil >>> The deep convective regions in the tropics would be very sensitive to >>> the low level moisture supply and therefore to boundary layer humidity. >>> Brian >>> >>> .Jones@uea.ac.uk wrote: >>> >>> >>>> Brian, >>>> The paper has now been accepted. I think I asked Tim Osborn to give >>>> you >>>> a copy as I was somewhere else when you were there for UEA degree. I'm >>>> glad you found it interesting and impressive. >>>> What you say sounds possible. It depends how much of the change in the >>>> atmos column is related to changes at the surface? I need to think >>>> about this. I'm supposed to be involved in a break out group here at an >>>> IPCC meeting in Geneva, so it will be later in th week. >>>> I guess a question for Adrian is whether ERA-INTERIM's tropopause >>>> height >>>> is reasonable, and whether any changes have occurred? >>>> >>>> Cheers >>>> Phil >>>> >>>> >>>> >>>> >>>>> Dear Adrian & Phil >>>>> >>>>> Phil left me your paper when I was visiting UEA. Impressive and >>>>> interesting! >>>>> >>>>> If the tropical near surface specific humidity over tropical land has >>>>> not gone up (Fig 5) presumably that could explain why the expected >>>>> amplification of the warming in the tropics with height has not really >>>>> been detected. >>>>> >>>>> Best wishes >>>>> Brian >>>>> >>>>> >>>>> >>>> >>>> >>>> >>> >> >> >> > > -- -------------------------------------------------- Adrian Simmons European Centre for Medium-Range Weather Forecasts Shinfield Park, Reading, RG2 9AX, UK Phone: +44 118 949 9700 Fax: +44 118 986 9450 --------------------------------------------------