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Messages - guygee

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Any analysis of global temperatures without including an analysis of the current ENSO state is incomplete, for example see:

https://www.osti.gov/pages/servlets/purl/1511151

https://journals.ametsoc.org/jcli/article/7/11/1719/36167/The-Signature-of-ENSO-in-Global-Temperature-and

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From guygee in the melting thread:

<snip>

yes, the contrails, if they act like clouds, might have a net warming effect on air temperatures, so if they're gone, then it should cool air temperatures. However, the strength of the melt season is driven primarily by insolation, not air temps, so the great reduction of the clouds should increase the melting, because it allows more sunlight to hit the ice.

As to the effect of some difference due the number of contrails this year as opposed to previous years, I  lack sufficient information to have any informed opinion. Considering all other factors, I doubt the lack of contrails has a large effect.

I don't mean to belittle your statement on insolation, but rather point out that it is not only insolation that drives summertime sea ice melting, but rather a large number of factors including increased warm air intrusion from continental warming, breaking the near-surface inversion over the ice by strong subsidence under the persistent high pressure this year, increased water temperatures both from continental sources and early melting, increased exchange of waters between the Arctic, Atlantic and Pacific, breaking of the halocline due to increased upwelling and strong atmospheric pressure gradients, and probably other positive ongoing feedbacks not mentioned.

In particular, this year, strong subsidence under the center of the high pressure, and strong pressure gradients around the periphery of the high have served to reduce the predominance of the usual near-surface temperature inversion over the ice. Also, over the open water, the inversion lifts. This increases the importance of air temperature in ice melt as opposed to 'more usual' conditions that have prevailed during the satellite era. Granted the persistent high this year also greatly increased direct insolation. As to the relative importance of all of these factors in this melting season, I would welcome any further information you can provide.

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Arctic sea ice / Re: The 2020 melting season
« on: July 20, 2020, 04:24:53 PM »
Apologies for the OT on clouds, but I've seen the same error here repeatedly regarding the effect of high altitude clouds. These clouds raise temperatures both day and night, since  they are relatively transparent to incoming short wave radiation but tend to reflect outgoing long wave radiation. So their effect on warming is positive both in the day, and, like all clouds, at night. See, for example,
https://earthobservatory.nasa.gov/features/Clouds/clouds3.php

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Arctic sea ice / Re: The 2020 melting season
« on: April 20, 2020, 08:23:52 AM »
Ozone.
I prefer that this regular update be posted in a new thread, as it does not affect the current melting season as far as I can tell.
Oren - I see you are listed as Moderator and thus you decide "what goes where". However, consider that the ozone level animations are a kind of proxy for the polar stratospheric circulation, also that the stratospheric ozone in the polar vortex will increase rather dramatically at the onset of a Sudden Stratospheric Warming (SSW). Such events do have relevance in the melting season. For a simple example please see:

]https://ozonewatch.gsfc.nasa.gov/facts/warming_NH.html

Actually it is a bit more complicated than the simple view expressed above, see:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/jgrd.50651
https://arxiv.org/abs/1807.11750

Thus, I think that the ozone measurement animations are relevant to melting, at least in the early part of the melting season.

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Arctic sea ice / Re: Arctic Image of the Day
« on: August 26, 2018, 12:58:50 AM »
Paper describing extent of the Ward Hunt Ice shelf and major calving, 1961-1962:
https://www.igsoc.org/journal/4/34/igs_journal_vol04_issue034_pg415-424.pdf

Major crack in Ward Hunt Ice shelf reported by NASA:
https://www.nasa.gov/missions/earth/f_iceshelf.html

Discussion of state of Ward Hunt Ice shelf on this forum, 2013, unfortunate that many image links are broken:
https://forum.arctic-sea-ice.net/index.php?topic=219.0

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Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 16, 2018, 03:35:20 AM »
I created an account here:
https://search.earthdata.nasa.gov/search
Searched on cryosphere->sea ice->extent and AMSR2,
there is a data set:
AMSR2 DAILY L3 12.5 KM TB AND SEA ICE CONCENTRATION POLAR GRIDS V0
The latest file can be displayed, it is this one, from today:
AMSR_2_L3_SeaIce12km_P00_20180815.he5

I don't have the software to display it myself. I'm not sure why other sites are not updating.
Hope that helps.


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Arctic sea ice / Re: The 2018 melting season
« on: July 24, 2018, 11:26:12 PM »
Pretty sure this was not relevant to the immediate prior discussion but it got me thinking about Kelvin waves propagating along the shore in the Arctic Ocean, where subsequent upwelling (downwelling) could certainly affect melting. I found this reference interesting,

E.C. Carmack and E. A. Kulikov, (cited by 72)
"Wind-forced upwelling and internal Kelvin wave generation in Mackenzie Canyon, Beaufort Sea", J. of Geophsyical Research, V.103, No.9, pp. 18447-18458, Aug. 1998.

"We here first describe two major upwelling events observed in Mackenazie Canyon in Autumn 1987 (S.3). We then use spectral methods to establish a correlation between upwelling events and a wind field (S.4). Finally, we argue that upwelling within the the canyon generates an internal Kelvin (coastal trapped free) wave that subsequently propagates northeastward along the continental margin."

Reading on to section 5: "The negative correlation for alongshore winds means that the alongshore wind in the northeast (southwest) direction causes isopycnal elevation (depression)."
..."The maximum response of ED to wind forcing is about 4.5 m/(km h^-1) at site SS4 in Mackenzie Canyon."

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