Hi Jim Thanks for sharing this nice paper. The ideas you develop do seem very consistent with some of my earlier work, and indeed you do reference Hood et al (2009) (doi: 10.1051/0004-6361/200912285) - thank you! We showed here that even very smooth and simple motions in the photosphere can produce a very complex field in the corona with multiple fragmented current sheets. Whether one calls this "turbulence" or not is a matter of nomenclature, but it is certainly not classic Kolmogorov. Your statement "It nonetheless has a complex structure that bears no direct relationship to the pattern of driving" sums this up very nicely. Prior to this, Browning and Van der Linden (2003) (doi 10.1051/0004-6361:20021887) proposed that a repeated series of energy release triggered by kink instability could produce a distribution of nanoflares - this was verified by Bareford et al (2010, 2011) (10.1051/0004-6361/201014067) where we show you can actually get a power law distribution from a random twistings. These were simple semi-analytical models, but I think there is scope to follow through on some of these ideas with simulations. Of course the reality involves ongoing and more complex patterns of driving- and the possibility of avalanching, as we showed in Hood et al (2016) (10.3847/0004-637X/817/1/5) and pursued in the interesting recent work of Knizhnik et al of course. It seems one localised kink instability can generate a lot of current sheets and energy release! Best wishes Philippa
-----Original Message----- From: Loops loops-bounces@solar.physics.montana.edu On Behalf Of loops-request@solar.physics.montana.edu Sent: 18 May 2021 19:00 To: loops@solar.physics.montana.edu Subject: Loops Digest, Vol 6, Issue 2
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Today's Topics:
1. Is the corona turbulent? (Klimchuk, James A. (GSFC-6710))
----------------------------------------------------------------------
Message: 1 Date: Tue, 18 May 2021 13:24:09 +0000 From: "Klimchuk, James A. (GSFC-6710)" james.a.klimchuk@nasa.gov To: " (Loops@solar.physics.montana.edu)" Loops@solar.physics.montana.edu Subject: [Loops] Is the corona turbulent? Message-ID: BY3PR09MB857890CB88D737802F4BB975B02C9@BY3PR09MB8578.namprd09.prod.outlook.com Content-Type: text/plain; charset="us-ascii"
Dear "loops" friends,
You might be interested in the paper that Spiro and I just published concerning the role of turbulence in forming the current sheets that spawn nanoflares in the magnetically closed corona:
http://journal.frontiersin.org/article/10.3389/fspas.2021.662861/full?&u...<https://gcc02.safelinks.protection.outlook.com/?url=http%3A%2F%2Flinks.email... g6QSXzWA2wXgA4DkQrYG8zw9-2BrhOoZY5D8wkA-3D-3D&data=04%7C01%7Cjames.a.klimchuk%40nasa.gov%7C5e1b386e3d2042eee27f08d919b402e2%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C637569083199946822%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=hjrQ5rwifhz4O8XDZt6jIUTLTdxEi45UOl%2FQuFGWNOU%3D&reserved=0>
We argue that the sheets form primarily from other processes, unrelated to turbulence. Localized temporary bursts of turbulence may nonetheless be generated when the sheets reconnect.
Abstract: We argue that the magnetically closed corona evolves primarily quasi-statically, punctuated by many localized bursts of activity associated with magnetic reconnection at a myriad of small current sheets. The sheets form by various processes that do not involve a traditional turbulent cascade whereby energy flows losslessly through a continuum of spatial scales starting from the large scale of the photospheric driving. If such an inertial range is a defining characteristic of turbulence, then the magnetically closed corona is not a turbulent system. It nonetheless has a complex structure that bears no direct relationship to the pattern of driving.
Cheers, Jim
******************************************************************************** James A. Klimchuk NASA Goddard Space Flight Center Solar Physics Lab, Code 671 Bldg. 21, Rm. 158 Greenbelt, MD 20771 USA
Phone: 1-301-286-9060tel:%28301%29%20286-9060 Fax: 1-301-286-7194tel:%28301%29%20286-7194 E-mail: James.A.Klimchuk@nasa.govmailto:James.A.Klimchuk@nasa.gov Homepage: http://science.gsfc.nasa.gov/sed/bio/james.a.klimchukhttp://science.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&&iPhonebookId=15844
No endorsement by NASA is implied for any correspondence related to my official role in professional organizations.
********************************************************************************
Hi Philippa,
Thanks! Yes, the formation of current sheets by kink instability - that you, Alan, and your colleagues have modeled so beautifully - is just one of the several mechanisms for producing current sheets that do not involve a turbulent cascade. We also point to three others in the paper:
1. simple driver flows acting on coronal separatrices and QSLs that result from the clumping of the field in the photosphere (what Eric called "coronal tectonics";
2. complex driver flows involving things like stagnation points;
3. current driven filamentation that results from patchy reconnection.
Also, Hugh pointed out in an e-mail the current sheets are also produced when new flux emerges into pre-existing flux. This could be very important in the low-lying magnetic carpet of the quiet Sun, but probably is not so important in active regions, which are unipolar over large areas.
Thanks again, Jim
-----Original Message----- From: Loops loops-bounces@solar.physics.montana.edu On Behalf Of Philippa Browning Sent: Wednesday, May 19, 2021 5:44 AM To: loops@solar.physics.montana.edu Subject: [EXTERNAL] Re: [Loops] Loops Digest, Vol 6, Issue 2
Hi Jim Thanks for sharing this nice paper. The ideas you develop do seem very consistent with some of my earlier work, and indeed you do reference Hood et al (2009) (doi: 10.1051/0004-6361/200912285) - thank you! We showed here that even very smooth and simple motions in the photosphere can produce a very complex field in the corona with multiple fragmented current sheets. Whether one calls this "turbulence" or not is a matter of nomenclature, but it is certainly not classic Kolmogorov. Your statement "It nonetheless has a complex structure that bears no direct relationship to the pattern of driving" sums this up very nicely. Prior to this, Browning and Van der Linden (2003) (doi 10.1051/0004-6361:20021887) proposed that a repeated series of energy release triggered by kink instability could produce a distribution of nanoflares - this was verified by Bareford et al (2010, 2011) (10.1051/0004-6361/201014067) where we show you can actually get a power law distribution from a random twistings. These were simple semi-analytical models, but I think there is scope to follow through on some of these ideas with simulations. Of course the reality involves ongoing and more complex patterns of driving- and the possibility of avalanching, as we showed in Hood et al (2016) (10.3847/0004-637X/817/1/5) and pursued in the interesting recent work of Knizhnik et al of course. It seems one localised kink instability can generate a lot of current sheets and energy release! Best wishes Philippa
-----Original Message----- From: Loops loops-bounces@solar.physics.montana.edu On Behalf Of loops-request@solar.physics.montana.edu Sent: 18 May 2021 19:00 To: loops@solar.physics.montana.edu Subject: Loops Digest, Vol 6, Issue 2
Send Loops mailing list submissions to loops@solar.physics.montana.edu
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You can reach the person managing the list at loops-owner@solar.physics.montana.edu
When replying, please edit your Subject line so it is more specific than "Re: Contents of Loops digest..."
Today's Topics:
1. Is the corona turbulent? (Klimchuk, James A. (GSFC-6710))
----------------------------------------------------------------------
Message: 1 Date: Tue, 18 May 2021 13:24:09 +0000 From: "Klimchuk, James A. (GSFC-6710)" james.a.klimchuk@nasa.gov To: " (Loops@solar.physics.montana.edu)" Loops@solar.physics.montana.edu Subject: [Loops] Is the corona turbulent? Message-ID: BY3PR09MB857890CB88D737802F4BB975B02C9@BY3PR09MB8578.namprd09.prod.outlook.com Content-Type: text/plain; charset="us-ascii"
Dear "loops" friends,
You might be interested in the paper that Spiro and I just published concerning the role of turbulence in forming the current sheets that spawn nanoflares in the magnetically closed corona:
https://gcc02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fjournal.fro...<https://gcc02.safelinks.protection.outlook.com/?url=http%3A%2F%2Flinks.email... g6QSXzWA2wXgA4DkQrYG8zw9-2BrhOoZY5D8wkA-3D-3D&data=04%7C01%7Cjames.a.klimchuk%40nasa.gov%7C5e1b386e3d2042eee27f08d919b402e2%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C637569083199946822%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=hjrQ5rwifhz4O8XDZt6jIUTLTdxEi45UOl%2FQuFGWNOU%3D&reserved=0>
We argue that the sheets form primarily from other processes, unrelated to turbulence. Localized temporary bursts of turbulence may nonetheless be generated when the sheets reconnect.
Abstract: We argue that the magnetically closed corona evolves primarily quasi-statically, punctuated by many localized bursts of activity associated with magnetic reconnection at a myriad of small current sheets. The sheets form by various processes that do not involve a traditional turbulent cascade whereby energy flows losslessly through a continuum of spatial scales starting from the large scale of the photospheric driving. If such an inertial range is a defining characteristic of turbulence, then the magnetically closed corona is not a turbulent system. It nonetheless has a complex structure that bears no direct relationship to the pattern of driving.
Cheers, Jim
******************************************************************************** James A. Klimchuk NASA Goddard Space Flight Center Solar Physics Lab, Code 671 Bldg. 21, Rm. 158 Greenbelt, MD 20771 USA
Phone: 1-301-286-9060tel:%28301%29%20286-9060 Fax: 1-301-286-7194tel:%28301%29%20286-7194 E-mail: James.A.Klimchuk@nasa.govmailto:James.A.Klimchuk@nasa.gov Homepage: http://science.gsfc.nasa.gov/sed/bio/james.a.klimchukhttp://science.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&&iPhonebookId=15844
No endorsement by NASA is implied for any correspondence related to my official role in professional organizations.
********************************************************************************
Sorry, the third mechanism is actually called "reconnection driven current filamentation." It's something that Judy Karpen, Spiro, and colleagues pointed out some years ago.
Jim
-----Original Message----- From: Loops loops-bounces@solar.physics.montana.edu On Behalf Of Klimchuk, James A. (GSFC-6710) Sent: Wednesday, May 19, 2021 9:13 AM To: Philippa Browning philippa.browning@manchester.ac.uk; loops@solar.physics.montana.edu Subject: Re: [Loops] [EXTERNAL] Re: Loops Digest, Vol 6, Issue 2
Hi Philippa,
Thanks! Yes, the formation of current sheets by kink instability - that you, Alan, and your colleagues have modeled so beautifully - is just one of the several mechanisms for producing current sheets that do not involve a turbulent cascade. We also point to three others in the paper:
1. simple driver flows acting on coronal separatrices and QSLs that result from the clumping of the field in the photosphere (what Eric called "coronal tectonics";
2. complex driver flows involving things like stagnation points;
3. current driven filamentation that results from patchy reconnection.
Also, Hugh pointed out in an e-mail the current sheets are also produced when new flux emerges into pre-existing flux. This could be very important in the low-lying magnetic carpet of the quiet Sun, but probably is not so important in active regions, which are unipolar over large areas.
Thanks again, Jim
-----Original Message----- From: Loops loops-bounces@solar.physics.montana.edu On Behalf Of Philippa Browning Sent: Wednesday, May 19, 2021 5:44 AM To: loops@solar.physics.montana.edu Subject: [EXTERNAL] Re: [Loops] Loops Digest, Vol 6, Issue 2
Hi Jim Thanks for sharing this nice paper. The ideas you develop do seem very consistent with some of my earlier work, and indeed you do reference Hood et al (2009) (doi: 10.1051/0004-6361/200912285) - thank you! We showed here that even very smooth and simple motions in the photosphere can produce a very complex field in the corona with multiple fragmented current sheets. Whether one calls this "turbulence" or not is a matter of nomenclature, but it is certainly not classic Kolmogorov. Your statement "It nonetheless has a complex structure that bears no direct relationship to the pattern of driving" sums this up very nicely. Prior to this, Browning and Van der Linden (2003) (doi 10.1051/0004-6361:20021887) proposed that a repeated series of energy release triggered by kink instability could produce a distribution of nanoflares - this was verified by Bareford et al (2010, 2011) (10.1051/0004-6361/201014067) where we show you can actually get a power law distribution from a random twistings. These were simple semi-analytical models, but I think there is scope to follow through on some of these ideas with simulations. Of course the reality involves ongoing and more complex patterns of driving- and the possibility of avalanching, as we showed in Hood et al (2016) (10.3847/0004-637X/817/1/5) and pursued in the interesting recent work of Knizhnik et al of course. It seems one localised kink instability can generate a lot of current sheets and energy release! Best wishes Philippa
-----Original Message----- From: Loops loops-bounces@solar.physics.montana.edu On Behalf Of loops-request@solar.physics.montana.edu Sent: 18 May 2021 19:00 To: loops@solar.physics.montana.edu Subject: Loops Digest, Vol 6, Issue 2
Send Loops mailing list submissions to loops@solar.physics.montana.edu
To subscribe or unsubscribe via the World Wide Web, visit https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsolar.phys... or, via email, send a message with subject or body 'help' to loops-request@solar.physics.montana.edu
You can reach the person managing the list at loops-owner@solar.physics.montana.edu
When replying, please edit your Subject line so it is more specific than "Re: Contents of Loops digest..."
Today's Topics:
1. Is the corona turbulent? (Klimchuk, James A. (GSFC-6710))
----------------------------------------------------------------------
Message: 1 Date: Tue, 18 May 2021 13:24:09 +0000 From: "Klimchuk, James A. (GSFC-6710)" james.a.klimchuk@nasa.gov To: " (Loops@solar.physics.montana.edu)" Loops@solar.physics.montana.edu Subject: [Loops] Is the corona turbulent? Message-ID: BY3PR09MB857890CB88D737802F4BB975B02C9@BY3PR09MB8578.namprd09.prod.outlook.com Content-Type: text/plain; charset="us-ascii"
Dear "loops" friends,
You might be interested in the paper that Spiro and I just published concerning the role of turbulence in forming the current sheets that spawn nanoflares in the magnetically closed corona:
https://gcc02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fjournal.fro...<https://gcc02.safelinks.protection.outlook.com/?url=http%3A%2F%2Flinks.email... uZJdPZTjkOw5Lex1j5mMrGLJYOspWWklOaNS4utGQaNCq2OdltDGuiihne27nWtTLT-2FLAzoK-2Fkf-2FaLFgyfGWAKkiFfNpZq3CX0TzZ1RqgJyRmmFYdTNf0hlVVLNisVNAwaj28XBH0jBA-3D-3DG1xp_q-2BdpEcq7WJfuCP40fqxszBBzhAI51DRrBlYKLHUwAsqlRze16Lb99F10xZ8oOHQsitylB-2ByLaxFU2I43-2FK3Y3sTeYZ-2BK3KIkhWpSX6mhmQlu9tLJf6gn2QevfPNmlh-2FzdWe1205-2BgPyGUGHtH9g5hOi4TbpLQEZS7JBcgq-2FvNEjwhPXApPQFawnRYiz1oOfmEDqJO1rIUA3B0xv94si9cELzoijSFWeBOTzl0UtUtxqTiEhy1 g6QSXzWA2wXgA4DkQrYG8zw9-2BrhOoZY5D8wkA-3D-3D&data=04%7C01%7Cjames.a.klimchuk%40nasa.gov%7C5e1b386e3d2042eee27f08d919b402e2%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C637569083199946822%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=hjrQ5rwifhz4O8XDZt6jIUTLTdxEi45UOl%2FQuFGWNOU%3D&reserved=0>
We argue that the sheets form primarily from other processes, unrelated to turbulence. Localized temporary bursts of turbulence may nonetheless be generated when the sheets reconnect.
Abstract: We argue that the magnetically closed corona evolves primarily quasi-statically, punctuated by many localized bursts of activity associated with magnetic reconnection at a myriad of small current sheets. The sheets form by various processes that do not involve a traditional turbulent cascade whereby energy flows losslessly through a continuum of spatial scales starting from the large scale of the photospheric driving. If such an inertial range is a defining characteristic of turbulence, then the magnetically closed corona is not a turbulent system. It nonetheless has a complex structure that bears no direct relationship to the pattern of driving.
Cheers, Jim
******************************************************************************** James A. Klimchuk NASA Goddard Space Flight Center Solar Physics Lab, Code 671 Bldg. 21, Rm. 158 Greenbelt, MD 20771 USA
Phone: 1-301-286-9060tel:%28301%29%20286-9060 Fax: 1-301-286-7194tel:%28301%29%20286-7194 E-mail: James.A.Klimchuk@nasa.govmailto:James.A.Klimchuk@nasa.gov Homepage: http://science.gsfc.nasa.gov/sed/bio/james.a.klimchukhttp://science.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&&iPhonebookId=15844
No endorsement by NASA is implied for any correspondence related to my official role in professional organizations.
********************************************************************************
loops@solar.physics.montana.edu