Surely the efficacy of solar radiation management is based on the difference in albedo between 1) summer and winter - for cooling, white in summer and dark in winter is needed (anti-snow, if you like) 2) day and night - for cooling, it should be dark at night and white in the day (smoke tends to be emitted in the day, when people are busy) 3) infra-red versus visible light - 'black body' radiation is, I beleive specific to the part of the spectrum the emission occurs in.
The above suggests that 'albedo' modification is a lot more complicated than it first seems. Can someone explain this to me/the list. A 2008/12/29 Albert Kallio <[email protected]>: > I am fortunate to put forward some ideas answering partially your query: > > "In fact, if the water uncovered is relatively warm, it could result in a > greater loss of heat into space than would otherwise be the case. > Can the clever people (or the people with clever computers) estimate the > significance of this effect?" > > This effect is very significant one, I am not the one who says how much loss > of heat it into space results, but there is definitely a very significant > loss of steam into aerospace below when the Arctic Ocean water is uncovered. > > Therefore, it is no coincidence that the 2007 record Arctic Ocean > summer-time sea ice melting was followed by all-time record snowfall > percipitation in the Northern Hemisphere. By February 2008 the snowcover had > stretched across the Northern Hemisphere to the largest ever seen northern > hemisphere terrestrial snow cover stretching over China to the vicinity of > Vietnamese borders. Huge temperature fluctuations destroyed 60% of > subtropical trees in China when the Arctic air headed towards Vietnamese > border before turning east and dumping its cold into the vastness of > Northern Pacific Ocean. > > From the thickness and spread of snow we could perhaps estimate the energy > the ocean thus released knowing the evaporated volume Norht of Himalayas > that mop up effectively most of he southern humidity. In 2008 the Finnish > Lapland has again seen record snowfalls as the Barents Sea is quite warmed. > > The loss of Arctic sea ice cover leads to massive autumn and winter time > percipitations until the Arctic Ocean becomes ice covered. The record summer > time melts and sea water warmings will be accompanied equally record > winter-time snowfalls on the periphery of the Arctic Ocean. While the > terrestrial snow cover is an excellent reflector of sun shine, it rests on > increasingly warmer soils. Previously the snow cover was supported by the > permafrost ground under it, no the ground under snow is increasingly clogged > by warm autumn time rainfall, not frosted and full of microbial activities. > When the insulating snow cover falls over the soil, the heat of the warmer > ground remains under and when warm spells come in the spring the snow cover > disappears melting record early like in Yakutia in 2008 when snow departed > in record short time. The microbial activity on warm ground under snow and > frosted surface also generate heat that stays trapped under the snow and > there is major soil warming as a result of thickened insulating snow blanket > and microbial activities. > > As a result the loss of sea ice leads into heat and steam pulses that pile > up first lots of rain wettening the grounds and then deposits snowfall on > the top. By the spring all that massive snow blanket released and deposited > quickly melts back into ocean. When the massive melt water pulse from > Siberia returns to the sea, this brings back with it an additional heat > pulse melting the sea ice earlier where the riparian discharges are disposed > to the Arctic Ocean. This situation has been worsening and remain rather > useless as in case of Yakutia the snow blanket despite of its increased > thickeness and spread was lost a month earlier than before. So, when the > snowless spring started month earlier the overall feedbacks were all but > entirely negative, helping for earlier sea ice melt as the warm water and > then the warmed air masses started pouring from the land onto the Arctic > Ocean record early, a month earlier to 2007. > > The Arctic Ocean only lost tiny bit of the melt water pulse when some of the > southernmost rainfall fell to Chinese rivers that then took the water back > to east rather to the Pacific Ocean rather than the north like the Russian > rivers do. > > So, I would look into heat transported into system by the rain as perhaps > the best indicator as it may be cumulatively rather easily measurable due to > energy required for its evaporation and deposition. I hope this comment on > this newly amplified winter snow pulse would be of some use to your query. > > Rgs, > > Albert Kallio > >> Date: Mon, 29 Dec 2008 17:49:02 +0000 >> From: [email protected] >> To: [email protected] >> Subject: [geo] Re: arctic engineering needs and sea-ice science >> CC: [email protected]; [email protected]; [email protected]; >> [email protected]; [email protected] >> >> >> There's an effect which I've not seen discussed here, but without >> doubt it's important. >> Ocean NOT covered by sea ice will radiate heat into space far more >> effectively than will the white ice it replaces. >> Ocean ice loss is potentially less significant than has been assumed. >> In fact, if the water uncovered is relatively warm, it could result >> in a greater loss of heat into space than would otherwise be the case. >> >> Can the clever people (or the people with clever computers) estimate >> the significance of this effect? >> >> A >> >> 2008/12/29 Mike MacCracken <[email protected]>: >> > I would respond with two hopefully clarifying comments: >> > >> > 1. While there is a lot of focus on when the ice will be gone in summer, >> > this will have little effect on the weather as the surface temperature >> > and >> > water availability are similar for no ice and melting ice. Indeed, more >> > solar is absorbed, but that does not significantly raise ocean >> > temperatures. >> > What really matters is what happens in the fall into winter, because as >> > long >> > as there is no ice or thin ice, there will be a lot of heat transport to >> > the >> > atmosphere and so the near surface air cannot cool to –40 C and so >> > create >> > cold, dense air masses that spread out from the Arctic and influence >> > weather >> > around the midlatitudes. With all the extra heat going up into the >> > atmosphere (the solar heat absorbed during the time with lower albedo), >> > the >> > atmospheric circulation will be altered—causing, as Jennifer notes, the >> > "large-scale influence on winter weather patterns over much of the >> > northern >> > hemisphere." So, while the retreat of summer sea ice is an easy metric, >> > what >> > really affects the weather is the delayed formation of thick ice that >> > can >> > insulate the atmosphere from the heat contained in the ocean. >> > >> > 2. On the characteristics of low clouds, I thought the intent was to >> > raise >> > the albedo when the Sun was out, not to raise the IR emissivity. During >> > the >> > polar summer one wants the clouds with a high albedo (once the surface >> > starts to melt and its albedo comes down to below that of low clouds). >> > Then, >> > during the polar night, one would want to decrease the cloud emissivity >> > so >> > the surface can more rapidly radiate to space (the clouds tend to retard >> > the >> > cooling process that allows ice to form, as Jennifer notes). >> > >> > Mike MacCracken >> > >> > >> > On 12/29/08 11:26 AM, "Andy Revkin" <[email protected]> wrote: >> > >> > hi all, >> > >> > >> > I consulted with a few sea-ice wizards on the exchanges here related to >> > Arctic trends, and Jennifer Francis at Rutgers weighed in with the >> > following >> > thoughts. Note the importance of the boundary layer changes as well. >> > There >> > are many important factors besides albedo and ocean solar absorption. >> > >> > Winter cloudiness etc important factor. But also note the importance of >> > not >> > over-interpreting short-term wiggles as trends. Much more on Dot Earth >> > and >> > in my earlier coverage of the sea-ice question. This post (shortcut) is >> > a >> > good starting point: http://tinyurl.com/dotIceTrends >> > >> > Here's jennifer's comment (I sent her that sea-ice graph that was making >> > the >> > rounds here)> >> > >> > >> > >> > Hi Andy -- >> > >> > The first figure you attached with the extrapolation from the 2007 >> > summer >> > ice loss is very unrealistic, in my opinion. Both the observed record >> > and >> > model simulations of ice extent exhibit a great deal of interannual >> > variability, and most sea ice researchers would expect this behavior to >> > continue superimposed on a continuing downward trend. Some years the >> > decline >> > will be dramatic, as it was in 2007, and some years there will likely be >> > a >> > recovery, as random atmospheric patterns act on the ice cover. What's >> > different now as opposed to 2 decades ago is that the ice is now so thin >> > that any unusual forcing -- be it a persistent wind pattern, cloud >> > cover, >> > heat transfer from lower latitudes -- will have a much bigger effect on >> > the >> > ice, as thin ice is more easily moved by wind and/or melted by increased >> > heating. The small ice cover of recent years allows more solar energy to >> > be >> > absorbed by the open surface during summer, but exactly how that extra >> > heat >> > affects >> > the system over the following months is still being worked out. Some >> > recent >> > research suggests that during falls after low-ice summers the lower >> > atmosphere warms, the atmospheric boundary layer gets deeper, and low >> > clouds >> > increase, all of which tend to retard regrowth of sea ice in the fall >> > and >> > early winter. It also appears there's a large-scale influence on winter >> > weather patterns over much of the northern hemisphere. The reason I'm >> > telling you all this is that it appears there is no obvious mechanism >> > for >> > the ice to rebound significantly unless there is a multi-year period of >> > colder-than-normal temperatures, but this is not likely as greenhouse >> > gases >> > continue to increase at rates even faster than the most pessimistic IPCC >> > scenario. >> > >> > Regarding water temperatures, the main effect is through the added >> > absorption of solar energy in summer, which accelerates the melt during >> > late >> > summer. Warmer winter temperatures in the Atlantic sector also appear to >> > be >> > responsible for most of the retreat of the ice edge during winter in >> > that >> > region, but not on the Pacific side. >> > >> > Maybe this is more info that you needed and much of it you already know, >> > but >> > it's not a simple explanation. Regarding the shipping text you sent, it >> > looks like a bunch of hooey to me. 51 ships in the area will not have a >> > perceptible effect on the clouds. The "good" low clouds they're talking >> > about are already almost 100% emissive of infrared energy, and adding >> > ship >> > smoke to them is not going to matter. >> > >> > Hope this helps -- Happy New Year!! >> > Jennifer >> > >> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> > Jennifer Francis, Ph.D. >> > Institute of Marine and Coastal Sciences, Rutgers University >> > Co-Director of the Rutgers Climate and Environmental Change Initiative >> > 74 Magruder Rd, Highlands NJ 07732 USA -- Tel: (732) 708-1217, Fax: >> > (732) >> > 872-1586 >> > [email protected] | http://marine.rutgers.edu/~francis/ >> > >> > At 9:14 AM -0700 12/29/08, [email protected] wrote: >> > >> > Re Arctic ice, the issue is not just albedo, but also thermai >> > inertia. The effective heat capacity of the exposed ocean is >> > hugely greater than the ice. >> > >> > Tom. >> > ++++++++++++++ >> > >> > >> > >> > > >> > >> >> >> > > > ________________________________ > Get Windows Live Messenger on your Mobile. Click Here! --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
