|Top of the Hill||Boots and Blisters||Business as Usual:Meeting Minutes|
|Pinching Pennies||Who's Who and New||Mini Lesson|
|Top of the Hill||by Larry Mervine , President|
See you out there.
|Boots and Blisters||by Tony Gaier, Training Officer|
The July's search techniques training went well with 6 team members showing for the event. Thank you to everyone who came out. As I mentioned in the last newsletter, this is a new training period and everyone is currently training deficient. There are only 6 scheduled training events remaining between now and December 31st.
The following is a list of the trainings remaining.
There is only one training opportunity between now and the next business meeting. August 15th, at 9:00AM there will be a Land Navigation Training at Three Gun Springs Trailhead.
If you have any questions concerning training events please call me at home or on my cellular phone.
|Business as Usual:Meeting Minutes||by Aidan Thompson, Secretary|
The meeting kicked off at 19:23.
Tony announced that a Search Techniques training will be held at the east end of Indian School, Embudo trail head. Most forest areas are currently closed, limiting training area as well as missions. He asked new attendees to bring water, sunblock, sturdy shoes, and members to bring full SAR packs.
Tony mentioned that the first 6 month period for the year is over, and encouraged members to check the web site and monitor number of trainings left to plan out the rest of the year and not be training deficient unexpectedly. He said that lots of other teams have shown an interest in the mock search comming up in early September. He asked for volunteers for planning, but encouraged the membership to participate in the field rather than having all of CSAR behind the scenes.
Bob announced we had two potential prospectives from the web site, one will not be available to attend until the August meeting. He also said we lost two members, Kevin Mohr joined the Peace Corps and will be in Africa until 2006 when he plans to return to New Mexico and rejoin, and Jennifer Hall has been completing her doctorate out of state and will also rejoin when she returns. Bob also congratulated Brian Wilcox as our newest prospective member. For other new folks, he also announced that a PACE exam will be available on July 10th in Taos, and also Larry Mervine is putting together another PACE in August. Bob also reported that he talked to Base sources to see if we can be included in the 'welcome' packet, but it is difficult to achieve. He also talked to the 1st Airmans center about volunteer opportunities.
Mark reported that Carl Gilmore demonstrated some tie-in ideas at the June litter training at REI, but we need some more follow up before ordering. Tony Mentioned that the CMI Catalog had some quick tie-ins for litters, and the group agreed to look at them. He also mentioned that Kevin turned in one of the team radios, and it is available for loan out if anyone is interested.
Adam reminded the group that orange jackets are available for $25 including the the logo stitching. Also Polo shirts in grey or blue for less than $20. He encouraged the group to get their favorite items stitched with the Cibola logo and to wear it on 'off hours' to help promote the team. He also asked for volunteers for the July 31st Mountain Discovery Day at the Sandia Ski Area from 10:00 am to 3:00 pm.
Mike reported that he received his re-cert card and hoped that the other members that took the recertification classes also received theirs by now. He also congratualted Joyce Rumschlag for receiving her EMT Basic certification which brings the total medically certified members on the team to six.
Larry mentioned that some members are not calling in to the hotline when they decide to attend missions, and this is an important function for Pager 1 to know who is in the field and who to contact if the mission is cancelled prematurely. He asked members to leave a voice mail to indicate whether you were participating or not, so Pager 1 can be sure everyone was contacted and accounted for.
Larry mentioned that Cibola has the largest number of ICS trained members on the team, and we might be able to take the lead in taking NASAR classes. Many are web based and the certifications would improve the team credibility and recognition. He said that most of our team training standards are based on NASAR training, and he speculated that we might even become instructors for NASAR classes for our state.
Larry also reminded the group that he is willing to hand over his calling tree to another member. No one volunteered at that time.
Tony Gaier reminded the group to get updated callout information to him to ensure the callout list is up to date.
|Pinching Pennies||by Lili Ziesmann, Treasurer|
Reimbursements for the gas vouchers have still not been received as of this date, but I have a call in to James Newberry to see if there is a problem with the last submissions.
Below is the cumulative percentage of the annual budget spent so far so that each committee can see how they are doing:
|% Of Annual Budget||Jan||Feb||Mar||Apr||May||Jun||Jul|
|Who's Who and New||by Bob Baker, Membership Officer|
|Mini Lesson||by Tom Russo|
[Note: While the text of this article is my own, most of the projection images in this article are copyright 1994 by Professor Peter H. Dana of the department of geography at the University of Texas at Austin, and are used with his permission from Map Projections lecture notes on the Geographer's Craft Project web site from the University of Colorado at Boulder. Please visit those web sites for more detailed information and references on this material.]
The purpose of this article is to introduce some basic concepts of map production, specifically the concept of projection. It is my hope that by the end of the article you'll have a slightly deeper understanding of these pieces of paper we play with every so often, and a clearer picture of the meanings of the various coordinate systems we use in the field.
The Latitude/Longitude (or "lat/lon") system is based on angles from two specific reference planes cutting the Earth. The circles on the surface of the Earth cut by these planes are called "Great Circles" because they have the same diameter as the Earth itself. The "Prime Meridian" is the great circle that passes through the north and south poles, and through Greenwich, England. This meridian is given the arbitrary coordinate of 0 degrees Longitude. The circle we call the "Equator" is given the coordinate of 0 degrees Latitude.
Ignoring the fact that the Earth is not actually spherical (and thereby sweeping the difference between "geodetic" and "geocentric" latitude under the carpet), one can define a "polar" coordinate system based on these reference planes. Referring to Professor Dana's graphic below, the longitude is the angle marked as "theta" (the Greek letter that looks like an "O" with a horizontal bar), and the latitude is the angle "phi" (circle with vertical line through it). The Equatorial plane is the "X-Y" plane in this figure, and the plane in which the prime meridian lies is the "X-Z" plane.
To avoid negative coordinates, longitudes always have value between 0 and 180 degrees and are given an additional designation of "West" or "East" depending on their position relative to Greenwich. Similarly, latitudes are always between 0 and 90 degrees, and are given an "North" or "South" designation based on their position relative to the Equator.
Unfortunately, the unprojected lat/lon maps suffer from serious deficiencies: scale, area, and shape are all distorted. The distortion is worst near the poles, but is present everywhere. Since we often need maps that reflect accurately some quality of the real world, we need to find a different way of preparing them for those uses.
The mathematical process of mapping a curved surface onto a plane is called "projection." It is simplest (though not accurate) to imagine the process as if one were to place a light bulb at the center of a globe, and shine the light through the globe ("project" it) onto a map surface. One can imagine several ways to do this, but here are two of the more common projection types:
For each type of projection (conic, cylindrical, transverse cylindrical), there are many ways of making the mathematical mapping of details onto the projection surface, but some distortion always results from the process. If the projection is such that the distance scale at any point is the same in any direction, the projection is called "conformal." If the projection is such that all mapped areas have the same ratio to their area in the real world, the projection is called "area preserving." A mapping can not be both conformal and area preserving.
Note how the lines of latitude become farther and farther apart as one gets away from the Equator. The mapping being conformal, in any region of the map the scale is constant in all directions, but you can see how the scale must be different at the top of the map than it is at the Equator.
The Transverse Mercator projection is just like the Mercator projection, only the circle of tangency is a meridian of longitude (the "central meridian" of the projection) instead of the Equator. A transverse Mercator projection is subject to all the same distortion of a Mercator projection, turned on its side. What makes it convenient is that the distortion is minimized near the central meridian, and maps can be prepared for each area using a central meridian close enough that the distortion is not so important.
For illustration, here is a figure of the Western hemisphere, in Transverse Mercator projection with central meridian of 90 degrees West:
Note how the distortion increases dramatically as one gets farther from the central meridian. In this figure, lines of longitude are drawn every fifteen degrees. Note the shape of the region inside the first pair of longitude lines. We'll return to that later.
The Universal Transverse Mercator (UTM) projection is just a specific use of the Transverse Mercator projection. UTM "zones" of six degree width are defined, and maps of regions inside those zones are prepared in Transverse Mercator projection using the meridian at the center of the zone. The width of the zone is small enough that distortion is within reasonable limits --- in fact one could use a given UTM projection for a zone extending as far as 4 degrees from the central meridian (a fact sometimes used for UTM projected maps that straddle zone boundaries). If you refer back to the image of the Transverse Mercator projection of the Western hemisphere, the 30 degree swath nearest the central meridian wasn't that badly distorted --- so a six (or even eight) degree swath must be even less distorted. The distortion is not significant for our purposes over the span of a seven and a half minute (i.e. one-eighth of a degree) USGS quadrangle map within that zone.
The first UTM zone (zone 1) extends from 180 degrees West longitude to 174 degrees West, with a central meridian of 177 degrees West. UTM Zone 13 (in which Albuquerque lies) has a central meridian of 105 degrees West longitude, and extends from 108 degrees West to 102 degrees West. Below is a figure showing the UTM zones and the alphabetic designators used within them.
Note, by the way, that this image of UTM zones is an unprojected map of the world. Observe how it compares to the map of the world in Mercator projection and the map of the Western Hemisphere in Transverse Mercator projection.
While you're looking at the UTM zone chart, notice that there are in fact some exceptions to the rule that zones are 6 degrees wide. Look at UTM zone 32V, and zones 31X-37X, for example. This choice is made so that certain countries be mapped using one specific projection instead of straddling a zone boundary. That close to the North pole, widening a zone doesn't really lead to severe distortion of features, so this makes sense.
I include this projection here only because it is commonly used for aeronautical charts. We don't use them a lot in ground SAR, but those of you who are ICS section chiefs may well encounter them on air missions. The Lambert Conformal Conic projection is a secant conic projection, and you will find the projection parameters ("standard parallels") marked on the title page:
(Note: the GEOTIFF file itself has been reprojected into the UTM projection by USGS --- the distortion created by transforming the digital image is apparent even in the tiny image above --- it explains why all the text has been rotated.) Even though the map projection used in these old maps has no bearing on how we use them (there is still both a UTM and lat/lon grid drawn on the map that we can use), it is important to realize that the map was prepared differently than others in the state. If you are working on a search in an area that straddles the boundary of one whose USGS map hasn't been updated recently, you might find not only that you're going to have incompatibility between map datum (NAD27 vs. NAD83), but also map projection. In this case, butting the two maps together and trying to tile them will not serve you well!
While we're familiar with the term "UTM" and use it as the name of a coordinate system, it is important understand that the coordinate systems we use is based on the projection used to prepare our maps. It is also important to understand the nature of the distortion created by map projection and how this distortion limits the utility to particular applications.
I have mentioned map coordinate systems only briefly. In a future article I will present a more technical discussion of the UTM coordinate system and its relation to latitude/longitude, and also introduce some other odd-ball coordinate grids that are present (and usually ignored by SAR grunts) on every USGS topo map.
|Public Relations||by Adam Hernandez|
|Disclaimer and Copyright notice||the Editors|