Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - pleun

Pages: [1]
Arctic sea ice / Re: MOSAiC news
« on: September 05, 2020, 09:09:15 PM »
Mosaic itself provides only the sketchiest details of the expedition written from the perspective of a future large format coffee table book. On past voyages, the Polarstern always posted a very informative weekly ship's log.

About 1% of the 600 scientists involved have supplemented 'Follow Mosaic' with blogs and twitter commentary, most notably the co-originator M Shupe. He posts quite regularly to the AGU and Cires sites, though often with a month's delay with undated pictures by others from the AWI photo gallery. The most recent is 8/4/20 but that was written on 9/17/20. He also posts youtubes that are basically zoom lectures on clouds, boundary layer processes and ice (not watched).

I extracted items of scientific interest from the AGU posts into 11 dense pages in the text attachment below, leaving out musings and miscellany. He is quite a good writer and openly discusses various problems they've had with abandoned and crushed equipment, lost data, flag litter, dirty ice (pebbles), lost weeks resupplying, and idling in the Fram. The blogs give a good sense of what it is like to be on such an expedition (minus inter-personal shipboard interactions).

Low-level mixed-phase clouds in a complex Arctic environment
R Gierens S Kneifel MD Shupe K Ebell M Maturilli U Löhnert
Atmospheric Chemistry and Physics doi: 10.5194/acp-20-3459-2020

Low-level mixed-phase clouds (MPCs) are common in the Arctic. Both local and large-scale phenomena influence the properties and lifetime of MPCs. Arctic fjords are characterized by complex terrain and large variations in surface properties. Yet, not many studies have investigated the impact of local boundary layer dynamics and their relative importance on MPCs in the fjord environment.

In this work, we used a combination of ground-based remote sensing instruments, surface meteorological observations, radiosoundings, and reanalysis data to study persistent low-level MPCs at Ny-Ålesund, Svalbard, for a 2.5-year period. Methods to identify the cloud regime, surface coupling, and regional and local wind patterns were developed. We found that persistent low-level MPCs were most common with westerly winds, and the westerly clouds had a higher mean liquid (42 g m−2) and ice water path (16 g m−2) compared to those with easterly winds.

The increased height and rarity of persistent MPCs with easterly free-tropospheric winds suggest the island and its orography have an influence on the studied clouds. Seasonal variation in the liquid water path was found to be minimal, although the occurrence of persistent MPCs, their height, and their ice water path all showed notable seasonal dependency. Most of the studied MPCs were decoupled from the surface (63 %–82 % of the time).

The coupled clouds had 41 % higher liquid water path than the fully decoupled ones. Local winds in the fjord were related to the frequency of surface coupling, and we propose that katabatic winds from the glaciers in the vicinity of the station may cause clouds to decouple.

We concluded that while the regional to large-scale wind direction was important for the persistent MPC occurrence and properties, the local-scale phenomena (local wind patterns in the fjord and surface coupling) also had an influence. Moreover, this suggests that local boundary layer processes should be described in models in order to present low-level MPC properties accurately.

Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 05:40:08 PM »
You are right the unit is actually Exajoule (EJ). Damn km2 to SI unit conversion.

For the central Arctic the daylight intensity drops in August to below melting conditions for a solid ice pack. Extensive meltponds can delay this point somewhat, but generally not as much as a very dispersed icepack as we have seen in 2012 and 2016. Currently the ice is just compacted against Canada/Greenland as a solid icepack. I wouldn't count on a strong melt in August.
I am glad to see that I am not the only one known to have screwed up with a conversion ratio. 

Attached is the graph of the Central Arctic Sea** concentration, which dropped like a stone and has since recovered. Note it was in 2016, not 2012 , when concentration dropped the most. 2016 minimum area was only 200k greater than 2012, while 2016 extent was 750k greater than 2012.
Central Arctic Sea** - is the NSIDC defined area of 3.22 million km2, mostly above 80 North.
See map from MASIE attached.
The CAB as used by Wipneus in his PIOMAS output is 4.6 million km2

Arctic sea ice / Re: The 2020 melting season
« on: May 31, 2020, 06:07:14 PM »
If the forecast holds, the Beaufort is going to look quite different in ten days. Steady winds blowing parallel to the coast are going to augment the spin of the gyre and the region will get a steady diet of warmth. i envision lots of open water and steep area drop.

Edit: Growing evidence of >0C SST's on the Pacific side as well.
Don't forget the inflow of hot pacific water with the Alaskan Coastal Current!!,91.24,2304/loc=-165.460,63.479

The rest / Re: Astronomical news
« on: October 02, 2019, 12:34:09 AM »
Scientists Are Starting to Take Warp Drives Seriously, Especially One Specific Concept

Warp drive, as Star Trek fans know, is the ability to fly through space at speeds faster than light. A report on University of Alabama in Huntsville student Joseph Agnew’s work succinctly explained the value of speeds like that: Unless we can do it, we’re not going very far from home.

In recent years, the scientific community has become understandably excited and skeptical about claims that a particular concept – the Alcubierre Warp Drive – might actually be feasible.

This was the subject of a presentation made at this year's American Institute of Aeronautics and Astronautics Propulsion and Energy Forum, which took place from August 19th to 22nd in Indianapolis.

This presentation was conducted by Joseph Agnew – an undergraduate engineer and research assistant from the University of Alabama in Huntsville's Propulsion Research Center (PRC).

As part of a session titled "The Future of Nuclear and Breakthrough Propulsion", Agnew shared the results of a study he conducted titled "An Examination of Warp Theory and Technology to Determine the State of the Art and Feasibility".

... "Mathematically, if you fulfill all the energy requirements, they can’t prove that it doesn’t work"

"Warp drive theory is at the point where the mathematics needs more development and the technologies need more development," Agnew says.

The field is where radio, television, radar, microwaves, computing, cellular communications, human flight, space exploration and travel by automobile all once were. It’s ahead of the current cutting edge, theoretically possible, but limited by its prodigious energy requirements and scalability issues as well as the current state of supporting technologies.

But even if it has doubters, that doesn’t mean it can’t be done.

... Engage!

J. Agnew, An Examination of Warp Theory and Technology to Determine the State of the Art and Feasibility, AIAA Propulsion and Energy 2019 Forum


Maybe they could tap into the energy all around us ...

Physicist Suggests 'Quantum Foam' May Explain Away Huge Cosmic Energy

... Conventional theory suggests that spacetime should be filled with a huge amount of energy—perhaps as much as 10120 more than seemingly exists. Over the years, many theorists have suggested ideas on why this may be—most have tried the obvious approach, trying to figure out a way to make the energy go away. But none have been successful. In this new effort, Carlip suggests that maybe all that energy really is there, but it does not have any ties to the expansion of the universe because its effects are being canceled out by something at the Planck scale.

The new theory by Carlip is based very heavily on work done by John Wheeler back in the 1950s—he suggested that at the smallest possible scale, space and time turn into something he called "spacetime foam." He argued that at such a small scale, defining time, length and energy would be subject to the uncertainty principle. Since then, others have taken a serious look at spacetime foam—and some have suggested that if a vacuum were filled with spacetime foam, there would be a lot of energy involved. Others argue that such a scenario would behave like the cosmological constant.

Thus, to explain their ideas, they have sought to find ways to cancel out the energy as a way to make it go away. Carlip suggests instead that in a spacetime foam scenario, energy would exist everywhere in a vacuum—but if you took a much closer look, you would find Planck-sized areas that have an equal likelihood of expanding or contracting. And under such a scenario, the patchwork of tiny areas would appear the same as larger areas in the vacuum—and they would not expand or contract, which means they would have a zero cosmic constant. He notes that under such a scenario, time would have no intrinsic direction.

S. Carlip. Hiding the Cosmological Constant, Physical Review Letters (2019).

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 07, 2019, 05:13:59 PM »
It's a pity this one ends in 2015, but never mind. This is volume at maximum, and the amount of ice up to 3.3 meters stays about the same over the entire period.

So one way to understand this is to say that every year, the same amount of ice is generated (the under 3.3) while every summer more and more of the older ice (over 3.3) melts away. It doesn't really tell us much about the minimum or the average trend, but never mind that.

But my point would be that when the over 3.3 meter ice is finally gone, the under 3.3 should start to show some serious losses and the minimum should take a nosedive.

Consequences / Re: Places becoming less livable
« on: August 29, 2019, 06:30:37 PM »
Nope, my brain will create a nice illusion where I'll be fine. So would most people's brain. It's a defense mechanism. The same applies to the climate change argument at all scales.

Once the climate reality superimposes over the illusion I create, then I'll run.

Pages: [1]