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Re: [John Muir Trail] Cumulative Elevation gain Hi to Whitney

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  • ravi_jmt2013
    I think that the main limitation of the spreadsheet, and the reason that the cumulative elevation gain is lower than many figures I have read, is that the book
    Message 1 of 32 , Jun 30, 2013
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      I think that the main limitation of the spreadsheet, and the reason that the cumulative elevation gain is lower than many figures I have read, is that the book only presents elevations at various intervals along the trail. It is possible to calculate the net elevation gain or loss between any two of the intervals presented but there could be both elevation gain and loss *within* those intervals that goes unrecorded. So some of that detail is inevitably lost when relying on net gain/loss between two of the waypoints.

      For planning purposes I believe that these limitations are not that important since the book does include a very large number of waypoints. My main goal was to get a sense of the elevation gain or loss I would be facing on any given day. For this purpose, whether the elevation gain is off by 5-10% doesn't make that big of a difference (exertion and hiking time required is not going to be that different with a gain of 3,000 feet vs. 3,300).

      For my specific hike plan, the greatest estimated elevation gain for a day is 3,590 going from Quail Meadows to Marie Lake over 13 miles. But I think that the hardest day will be the 3,132 estimated gain over 11.7 miles going from Arrowhead Lake to Center Basin over Glen Pass due to the higher elevations involved.



      --- In johnmuirtrail@yahoogroups.com, Roleigh Martin <roleigh@...> wrote:
      >
      > John is right, I'm wrong. I misread the columns. Where are my glasses?
      > -------------------------------------------------
      > Visit my Google Profile (lots of very interesting research
      > links)<https://plus.google.com/104440166440169700478/about>
      > _
      >
      >
      >
      > On Sat, Jun 29, 2013 at 6:58 PM, John <johndittli@...> wrote:
      >
      > > **
      > >
      > >
      > >
      > > Roleigh, 38,478 is the cumulative loss, 42,773 is the gain if I'm reading
      > > that right?
      > >
      > > John
      > >
      > >
      >
    • longritchie
      Okay, now I see. I checked the box that hides both my email AND my IP address. I was in a suspicious mood when I checked that. Why do they need my IP address,
      Message 32 of 32 , Jul 10, 2013
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        Okay, now I see. I checked the box that hides both my email AND my IP address. I was in a suspicious mood when I checked that. Why do they need my IP address, I wondered? It doesn't appear that I can chose one or the other, it's got to be neither or both. So I went with neither.

        But feel free to email me: longritchie AT yahoo DOT com


        --- In johnmuirtrail@yahoogroups.com, Roleigh Martin <roleigh@...> wrote:
        >
        > Your postings, come across like this:
        > longritchie <no_reply@yahoogroups.com>
        >
        > It means you asked Yahoo not to display your email address. It's fine, it
        > just means people can't contact you individually, even moderators.
        >
        > I'm replying via the group even though you spelled out your email address
        > so that others understand the same implication of making that
        > choice.
        >
        > Elizabeth Wenks created the XLS except for the advertisement page which she
        > asked me to do to please the publisher and get their permission.
        >
        > She created the other two spreadsheet tabs in that file.
        > -------------------------------------------------
        > Visit my Google Profile (lots of very interesting research
        > links)<https://plus.google.com/104440166440169700478/about>
        > _
        >
        >
        >
        > On Wed, Jul 10, 2013 at 8:14 PM, longritchie <no_reply@yahoogroups.com>wrote:
        >
        > > **
        > >
        > >
        > > "Longritchie, you make it impossible for people to reach you offline
        > > since your handle is not associated with an email address."
        > >
        > > How did I make this impossible?
        > >
        > > I'm new to this group. I signed up with a yahoo email: longritchie AT
        > > yahoo DOT com.
        > > What else was I supposed to do exactly?
        > >
        > > I checked the "_Elizabeth Wenk Master Spreadsheet for JMT.xls" file
        > > which I obtained from the JMT Yahoo files section and found that she did
        > > have an errata regarding the location of Island Pass. But on the "Data"
        > > page in the spreadsheet there are in fact two seperate entries for
        > > Island Pass. And that is where Ravi got his data. His value of 42,773
        > > feet total gain from Yosemite to Whitney, based on Wenk's data, should
        > > be reduced by 165 feet to 42,608 feet. Yeah, I know, big deal.
        > >
        > > I can send an email to Ms. Wenk if it was in fact her hand that created
        > > the XLS file. Was it?
        > >
        > >
        > > --- In johnmuirtrail@yahoogroups.com, Roleigh Martin wrote:
        > > >
        > > > Longritchie, you make it impossible for people to reach you offline
        > > since
        > > > your handle is not associated with an email address. I wanted to
        > > reply
        > > > offline that Elizabeth provides contact information for error
        > > corrections
        > > > in that spreadsheet listed below:
        > > >
        > > > When you post the spreadsheet and errata to the websites, you can go
        > > ahead
        > > >
        > > > and give the following e-mail address for me, asking people to
        > > contact me
        > > > only with errors
        > > >
        > > > they have found or information they'd like included in future
        > > editions:
        > > >
        > > > wenk [dot] jmtbook [at] gmail [dot] com.
        > > >
        > > >
        > > > -------------------------------------------------
        > > > Visit my Google Profile (lots of very interesting research
        > > > links)
        > > > _
        > > >
        > > >
        > > >
        > > > On Wed, Jul 10, 2013 at 7:04 PM, Roleigh Martin roleigh@ wrote:
        > > >
        > > > > Did you look at the errata page Elizabeth Wenk provided us in the
        > > master
        > > > > spreadsheet in our file library?
        > > > >
        > > > >
        > > > >
        > > http://groups.yahoo.com/group/johnmuirtrail/files/Planning%20and%20Trans\
        > > portation/_Wilderness%20Press%20and%20Other%20Data%20Points/<http://groups.yahoo.com/group/johnmuirtrail/files/Planning%20and%20Transportation/_Wilderness%20Press%20and%20Other%20Data%20Points/>
        > >
        > > > >
        > > > > _Elizabeth Wenk Master Spreadsheet for JMT.xls
        > > > >
        > > > > If she did not correct the error, I can send you her email address,
        > > I'm
        > > > > sure she'd like to update the errata page. I'll do this offline but
        > > I
        > > > > might not be able to do it immediately as I'm leaving for my JMT
        > > hike
        > > > > tomorrow (at least the fly to CA part).
        > > > > -----------------------------------------------
        > > > > Visit my Google Profile (lots of very interesting research links)
        > > > > _
        > > > >
        > > > >
        > > > >
        > > > > On Wed, Jul 10, 2013 at 5:18 PM, longritchie
        > > no_reply@...:
        > > > >
        > > > >> **
        > >
        > > > >>
        > > > >>
        > > > >>
        > > > >>
        > > > >>
        > > > >> I borrowed an altimeter watch and walked the first 50 miles of the
        > > JMT.
        > > > >> Here is the reported altimeter elevation compared to the Wenk data:
        > > > >>
        > > > >>
        > > > >> (http://imageshack.us/a/img29/5526/0ojq.jpg)
        > > > >>
        > > > >> I set the elevation at Happy Isles and then set it again at
        > > Tuolumne. The
        > > > >> altimeter read low between Yosemite Valley and Tuolumne. I suspect
        > > that
        > > > >> this was due to the fact that it was a very hot day. High
        > > temperature means
        > > > >> lower aid density which results in a smaller change in pressure per
        > > change
        > > > >> in elevation. Although the pressure sensor in the altimeter is
        > > temperature
        > > > >> compensated I don't think the firmware attempts to adjust its model
        > > of the
        > > > >> atmosphere based on the ambient temperature. One of the pitfalls of
        > > > >> barometric altimetry.
        > > > >>
        > > > >> Beyond Tuolumne the altimeter tracked the map elevation reasonably
        > > well,
        > > > >> both on the way out and on the return trip. When returning to the
        > > > >> sweltering hell that is Yosemite the altimeter again under-reported
        > > the
        > > > >> elevation change.
        > > > >>
        > > > >> Here is the cumulative gain reported by the altimeter, compared to
        > > the
        > > > >> Wenk data:
        > > > >>
        > > > >>
        > > > >> (http://imageshack.us/a/img198/967/wz5d.jpg)
        > > > >>
        > > > >> The altimeter matched the Wenk data between Yosemite and Tuolumne
        > > despite
        > > > >> reporting about 6% less net elevation change. Beyond Tuolumne the
        > > agreement
        > > > >> is again fairly good until around mile 43 when they diverge. This
        > > is
        > > > >> because of insufficient Wenk data points between 1000 Island Lake
        > > and
        > > > >> Garnet Lake. The Wenk/Ravi calculation is for a total gain of 70
        > > feet here.
        > > > >> The altimeter reported 390 feet (both heading out and on the return
        > > trip).
        > > > >> A trace in TOPO! suggests 330 feet.
        > > > >>
        > > > >> By the way, I also came across an error in the original Wenk data.
        > > She
        > > > >> somehow inserted a second copy of "Island Pass" at the same mile
        > > point as
        > > > >> Donahue Pass. Ravi carried this error over to his spreadsheet
        > > resulting in
        > > > >> an additional 165 feet of gain where there is actually little or
        > > none.
        > > > >>
        > > > >> The cumulative gain determined by the altimeter was about 5%
        > > greater than
        > > > >> that from Wenk. If one were to attempt to compensate for the
        > > > >> under-reporting of elevation change between YV and TM the
        > > difference would
        > > > >> be something like 8-10%, but this is assuming that the altimeter
        > > was
        > > > >> otherwise accurate in determining cumulative gain. I do not know
        > > the
        > > > >> details of its accumulation algorithm.
        > > > >>
        > > > >> For what it's worth.
        > > > >>
        > > > >>
        > > > >>
        > > > >
        > > > >
        > > >
        > >
        > >
        > >
        >
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