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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Dear Loops Friends,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal> Given all the recent work on the subject, I think it would be useful to establish some definitions regarding the repetition frequency of nanoflares (on a given strand). The current bimodal classification of high frequency versus low frequency is no longer adequate. We can all agree that when the repetition time, t_rep, is much longer than or much shorter than the cooling time, t_cool, then the frequency can be straightforwardly classified as low or high, respectively. But what if t_rep and t_cool are not greatly different? Recent studies seem to fall within this intermediate regime (e.g., results presented at the SPD meeting by Inaki and by Amy’s student Scott Ripperda, and results presented at ISSI by Peter). I fear it is misleading to classify nanoflares as low or high frequency if t_rep is only marginally different from t_cool. I therefore suggest the following classification scheme:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>High frequency: t_rep < 0.5 * t_cool<o:p></o:p></p><p class=MsoNormal>Intermediate frequency: 0.5 * t_cool < t_rep < 2 * t_cool<o:p></o:p></p><p class=MsoNormal>Low frequency: t_rep > 2 * t_cool<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>In these ranges, the temperature variation in the strand will be approximately:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>High frequency: deltaT < 39%<o:p></o:p></p><p class=MsoNormal>Intermediate frequency: 39% < deltaT < 86%<o:p></o:p></p><p class=MsoNormal>Low frequency: deltaT > 86%<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I would be interested in your thoughts on this suggestion.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks,<o:p></o:p></p><p class=MsoNormal>Jim<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>********************************************************************************</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>James A. Klimchuk</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>NASA Goddard Space Flight Center</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Solar Physics Lab, Code 671</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Bldg. 21, Rm. 158</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Greenbelt, MD 20771</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>USA</span><o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Phone: 1-301-286-9060</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Fax: 1-301-286-7194</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>E-mail: <a href="mailto:James.A.Klimchuk@nasa.gov"><span style='color:blue'>James.A.Klimchuk@nasa.gov</span></a> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Homepage: </span>http://science.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&&iPhonebookId=15844<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>No endorsement by NASA is implied for any correspondence related to my official role in professional organizations.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>********************************************************************************<o:p></o:p></span></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>