You can also view a slide show of Dr. Cottons's trip here.

Mesa Verde Field Project October 2009


The purpose of this field project is to measure cloud-forming aerosol particles called cloud condensation nuclei(CCN) and total aerosol particle concentrations which I will call CN or cloud nuclei. CCN represent a subset of the total aerosol population which are soluble and large in size. We have chosen the Mesa Verde site for its excellent exposure to air flowing into the San Juan mountains. Based on our modeling studies, we anticipate that aerosol pollution will have a larger impact on wintertime orographic precipitation in the San Juan’s than in the northern Colorado Mountains. This is because high concentrations of CCN result in numerous smaller droplets which have a lower efficiency of capture by ice particles. In other words the riming process is inhibited. Because riming can account for 40% or more of ice particle growth, any inhibition of riming should result in reduced precipitation or at least a shift in precipitation downstream as the unrimed ice crystals have smaller fall velocities and thereby drift further downstream before settling onto the surface. It is well known that winter storms in the San Juan’s are wetter than those in northern Colorado on average. Thus we anticipate that given the same concentrations of pollution aerosols the San Juan’s will be more susceptible to inhibition of snowfall by aerosol pollution.  But at this time we have no measurements of CCN concentrations in this part of the State. Thus we are making CCN measurements in a region that is well exposed to airflow into the San Juan mountains. In December we will be making aircraft measurements of CCN along the western Colorado Mountains to further our understanding of the variability of CCN flowing into the mountains from Northern Colorado to Southern Colorado.

 Beginning in mid-Sept PhD candidate Dan Ward spent three weeks measuring CCN and CN. Now on October 6 I am spelling Dan and measuring CCN until 16 October. The instruments used are those generally located at the Storm Peak Laboratory run by the Desert Research Institute.  Ian McCubbin of DRI brought the instruments down in early September and we set them up in a shack used for Ozone sampling at the research campus at Mesa Verde. The instrument had been refurbished by the vender, DMT,  in Boulder. At first we couldn’t get it working as a pump power cable had been disconnected during testing and had not be replugged. After that hiccup, the instruments operated fine. Dan reported that measured CCN and CN concentrations were generally higher than the SPL in northern Colorado being typically 300/cc at 0.5% supersaturation and 200/cc at 0.3% supersaturation and CN being around 1000/cc. Some very high peaks of CCN over 1500/cc were observed. One concern was that during a dust event CCN concentrations increased but CN remained low. Was this a sampling artifact?

 This represents my journal for the period of 6 October to 16 October.

Trip to Mesa Verde

 My drive down began at our cabin near Gore Pass. Vollie and I woke to find an inch or so of fresh snow on the deck. What will our respective drives be like through the passes that we encounter? Well Vollie experienced snowpacked icy roads going over Cameron Pass whereas I did not find any snow on the roads at all even over neighboring Gore Pass. My drive took me through some of the most beautiful mountain country in Colorado including the Dallas Divide with a view of Mount Snoffels and Lizard Head Pass with a view of the mountains around Telluride. Moreover, while the aspen had passed their prime in fall colors I still expected to see patches of colorful aspen. Unfortunately, that was not to be as I encountered heavy snowfall and reduced visibility on all passes. I couldn’t even determine if some of the aspen were in full color. Only in the lower Dolores Canyon could I see colorful aspen but since it was raining heavily I didn’t get any pictures as the lighting was far from ideal.

  I stopped by Cortez and visited a Walmart to pick up frozen food and other things that we had not already packed. One thing I learned is never get in the check out line behind a couple of Indians. They did not pay the normal way with credit cards or checks but must have used something like food stamps which required a lot of paperwork to get their purchases processed. It took over 35 minutes to get through the check out line!

 I arrived at the cabin we had rented near our observation site about 4PM. Dan was nearly all packed and was obviously ready to get out of there as soon as he could after checking me out on things in the morning. After sitting in the car all day I suggested we take a jog to get the kinks out. So Dan took me on a social trail that runs from the cabins to the museum. Once there he showed me a trail called the Spruce Canyon trail. I said let’s take it. It was a nicely maintained trail that descended into the depths of the canyon and then rose steeply back up to the mesa top. It was definitely a 2.8 mile strenuous jog! 


 After breakfast Dan and I walked to the instrument shack where he checked me out on what to check on and how to download data onto a memory stick.

 The instruments were showing CN concentrations of 800/cc and
CCN of 275/cc@0.5% SS and 200/cc@0.3%SS. Winds were NE@2mph.

After that I helped Dan load the car and off he went back to Fort Collins. I then worked on an NSF proposal and at noon decided to bike up to the visitors center to get tickets for guided tours to the Balcony and Cliff Palace ruins. The ride was merely 4.5miles but it involved a 900’ elevation gain. I also stopped to view the Far View ruins on the mesa top. These included a tower and a large reservoir(dry) that the Ancestral Pueblos used. After getting tickets one for 3PM in the afternoon and the other for Thursday at the same time, I did the fast but cool downhill ride back to the cabin. After lunch I continued working on the proposal.

  Then I drove over to the Balcony ruin. Our guide had a strong Boston accent and made derogatory comments about Yankee fans and tooted the Redsocks. The Balcony ruin tour is noted for being the most strenuous of tours. After descending a paved trail we encountered a double wood latter that brought us up to the ruin. It is called the Balcony ruin because there is an extension off some of the ruins like a ledge with plastered stone over wood logs that extended out of the stone house. The tour took us past several kivas and then we had to crawl through a narrow rock tunnel to exit the ruin. It is believed it was built that way for defensive purposes. Then we had to climb a single latter back to the mesa top.

Measurements afterwards at 1632 were:

 CN 850/cc at 1430 increased to 2000/cc at 1630.

CCN 300/cc@0.5%SS and 225/cc@0.3%SS

Winds S@4mph winds went from S@2mph to W@2-4mph during period; change mainly in direction

After an early dinner I wanted around the area including a short hike on short Farming Terrace loop, then a social trail that parallels the road to the museum area and returning by trail that Dan showed me last night. I returned just after sunset.


 I awoke today with partly cloudy skies. By the time I walked over to the instrument shack the ground was wet and the clouds filled in to total overcast. I heard thunder on my walk over.

 Readings at 0855:

CN -1500/cc with a few spikes to 15,000 to 20,000/cc

CCN 350 to 380/cc@0.5%SS with a few spikes to 800-900/cc

Temp = 50F
Winds SSE@4mph.

 I made my first attempt to download data. I hope it worked. After looking at the downloaded files I changed my procedure to filling a daily folder in which I imported the day’s readings and then moved the folder onto my laptop. This seemed to work just fine. I will follow this procedure from now on.

 My lunch break amounted to jogging over to the trailhead for the petroglyph trail. I guess this is about 0.75 miles. Then I jogged the 2.8 mile trail. It is a lot of up and down with several rock stairs to ascend and descend. I must have passed 3- 4 four couples that started 30 minutes to an hour before me. They seemed impressed that I could jog it. It is a nice trail with a number of open views of the canyon below. I really enjoy the pinion/juniper ecology. At the apex of the trail I finally encountered the rather small petroglyphs(at least compared to Hidden Valley trail near Moab. The trail then ascended steeply to a point with nice overlooks of the canyons below. The remainder of the trail meandered along the top of the mesa following the edge to the canyons below. It was a rather strenuous run overall. I estimate the distance as over 4 miles with perhaps 400 feet of elevation gain. Elevation wise it was easier than the Spruce Canyon run.

  Back to working on the NSF proposal and then I edited a paper Gustavo Carrio and I are working to get through the review process.

 At 1600h I took my second set of observations for the day.

CN rose again from 2000/cc at around 1400h to over 7000/cc 30min ago and then dropped to 4000 to 5000/cc at the observation time.

CCN@0.5% SS have risen from 400/cc to 900/cc during the same period. CCN@0.3% rose from 250/cc to 459/cc during the same period.

 Winds at the time of observation were SSE@4mph
The temperature was 50F.

  After the observations I biked over to the Spruce Tree ruin trailhead. This is the only self-guided tour of a ruin in the park. A couple of rangers hang about to make sure you don’t walk were you are not supposed to and answer stupid questions. This has a reconstructed kiva where you can climb down into it. After my walk through it I toured the museum. Gee this is only my second day and I have done most of what is accessible on this end of the park! Actually the cloudy wet weather in the morning gave way to sunny skies, Even though it never got out of the 50’s it seemed quite comfortable.

 As I ascended from the Spruce Tree ruin I encountered a couple that was probably in their 50’s who had done the Petroglyph trail in 2 hours 49 minutes compared to my 40 minute slow jog. The over weight woman from Florida was exhausted. But they were troupers and had done the Spruce Canyon loop the day before and also the Balcony ruin.

 I returned to the cabin and split some wood for the stove in the cabin. I brought along a mall and my gloves. The day’s workout merited a New Belgium Abby beer! After a Mexican style tortilla dinner I walked around the area at sunset. I am a bit disappointed at the lack of wildlife. I actually see more in my neighborhood along the Spring Creek trail in Fort Collins.

  Things are not as tidy as when Vollie is around in the cabin. The coffee table in the living room is strewn with cameras, binoculars, and waste packs. My bike is next to the wood stove. In a chair by the door are all my jackets and my shoes and hiking boots are beneath it. In the second bed in the bedroom are my fluffed up sleeping bag and down jacket as well as a few other things. It is beginning to look like a batchelor pad!

 It was mostly cloudy this morning but it cleared by 0900.

0830 observations:

T=42F; Td=29.5;  winds N@2mph

CN counts just below 1000/cc, ranging from 930 to 980/cc

CCN @0.5% 400 to 450/cc
           @ 0.3% 300 to 375/cc

Today I worked on the NSF proposal and spring class notes.
At 2PM I took a break and biked to the Cliff Palace which is mostly downhill for 4.5 miles where I went on a tour. Our guide was an Indian from Arizona, and I think he is Apache by something he said. The cliff palace has several round towers, something like those at Hovenweep, at least to my naïve eyes. No one knows for sure why they were constructed. The climb our involved several ladders and lots of stone steps but it was not as demanding as Balcony House. I actually preferred Balcony House.

 While the ride back was uphill with the wind in my face it was not nearly as challenging as the ride I took to the visitors center. It might have been due to the fact it was shorter and cooler. There are still some scattered flowers out, mostly showy daisies and some like-sized yellow flowers.

1631 observations

CN rose steadily from 1500h with values of 800-900/cc to now where it is 2200/cc with some recent spikes to 2700/cc. I suspect this afternoon rise is due to gas-to-particle(gtp) conversion in the mid-day sun.

CCN@0.5% 550/cc
          @0.4% 420/cc

It is generally overcast with Cbs to the west and south.
T= 56F; Td=19.7F; winds W@8mph.


  Weather at 0825:

 T=38; Td= 17.5

Winds NNW@5mph
Severe clear!

CN =700/cc; cleanest I have seen it so far

CCN@0.5% 650/cc
          @0.3% 489-500/cc 

Very high CCN/CN ratios

 I worked on the NSF proposal all morning. At noon I ran along the mesa top part of the Petroglyph trail. From the cabin over and back it still must have been almost 4 miles and it took me over an hour. It was sunny and short sleeve weather with temperatures in the upper 50’s. It was ideal running conditions and the scenery was great too!

 Back to the proposal.


CN fairly constant at 800/cc

CCN@0.5%  480-520/cc
          @0.3% 325-300/cc

Continues severe clear

Winds SW@4-5kts

After a day of concentrating on that proposal I was ready for a break. I decided to drive into Cortez. I needed to pick up a few things at the grocery store and hoped to download some office stuff I couldn’t with the dial-up mode. The drive took me about 40 minutes which included a stop in the one-way construction zone.

  I encountered a coyote on the way down who insisted on crossing right in front of me. It was nice enough to drive with the windows open and sunroof open too. I followed Dan’s instruction and found the internet cafe. It was a real funky place that was like a mercantile store selling everything from eggs and fresh veges to tools and hardware. Of course they served coffee and tea as well as sandwiches. They even had a greenhouse on the south side.  I attempted my down-loads but most didn’t go through there either. So I gave up and did my grocery shopping and found the local brew pub. The beers were good and I had quesadillas which were quite good. The barmaid was a bit overwhelmed and in a real bitchy mood. After a while she calmed down and we chatted a bit. I also talked to the owner who used to be a partner in Nico’s in Fort Collins, a high-end restaurant that went under recently after being in business for 30 years or so. He gave me the distinct impression that partnering with Nico was not a good decision!

 I headed back to the Mesa trying to get up there before total darkness so at least I could see the deer before I hit them. I did see 4 deer, two right next to the road and two crossed in front of me. Three were does, one looked like a yearling, and the other was a buck with an impressive rack. Finally I got to see some wildlife as I had been disappointed not to see anything but some squirrels and not even hear a coyote at sunset.

 So here I am back at the cabin writing this journal listening to some old John Denver songs on my i-Pod and drinking a glass of wine. Life is good, but I wish Vollie were with me.


 I felt like farmer Bill getting up at 5AM to do his chores before heading out for the days adventures.


CN= 900/cc

CCN@0.5% 325/cc
         @0.3% 225/cc
T=26; Td= 15
Winds ENE@6mph

I arranged to get a tour in the Ute Mountain Reservation 20 miles south of Cortez. There were 4 woman and me in the van. The guided tour was at first up Manca Canyon and then rose up on to a mesa. Our guide was a 61 year old Ute and the driver was a younger heavy set woman Ute. It was a little hard to here Tommy sometimes as he spoke rather softly. We were first showed some ruins in the valley that were not much more than a pile of rubble. The distinguishing thing from Mesa Verde was there were pot shards everywhere. You couldn’t step without stepping on some.  Up on the mesa top we came to a trailhead and we climbed down ladders and walked along a trail to 4 ruins. Now these ruins were pretty similar to Mesa Verde although they had not been reconstructed much. So the kivas often still had some of the original roof beams. Another difference from Mesa Verde was that you could get up close and personal with the ruins. We actually walked into several of the original ruins not reconstructed ones with concrete walkways like Spruce Tree House in Mesa Verde.  

 There were some fantastic old growth spruce trees near one of the ruins. At one of the ruins there were worn grooves in the rocks and in the grooves were the names of two of the Wetherill brothers and the dates which was in the late 1800s. Generally the trail was easy to walk but there was one ladder that must have been 30’ or so. A couple of the woman chickened out on that one. After about a three hour walk we returned and had our lunches at a site on the mesa top.

 On our return we stopped at a site where there were a number of petroglyphs. Many had recent graffiti over them but the panels were much more extensive than Mesa Verde. Further down the road we were shown petroglyph circles in the rocks above where the sun shown directly on then during fall equinox, an other location for winter and summer solstice and another 15’ high pointed rock which cast a shadow at a specific rock groove during the summer solstice.

  I would say our guide was not as knowledgeable as those in Mesa Verde but he did just  fine. It was a little costly at $55 but it was good to get a chance to see what else is out there outside of the park boundaries.

Afternoon 1632 observations:

 CN decreased from 700 to between 500/cc and 600/cc in the afternoon.

CCN@0.5% was generally 550/cc but there was a local peak near 700/cc
         @0.3% counts were generally about 325/cc but local peak to 550/cc

T= 63      Td=14.6
Winds: W@8mph


 Well I woke up to a cold house this morning. The furnace was out! I noticed on Friday that the igniter was trying to start at  least a dozen times before it caught. I thought at that time that is not good.

  So I called several numbers including dispatch and they said they would try to get someone to fix it. Fortunately I had brought my mall and split some wood. So I built a fire. That warmed the living area up but didn’t do much for the rest of the house.


 CN= 1600/cc with a spike over 1800/cc.

CCN@0.5% 450-480/cc
          @0.3% 325 to 340/cc

T=45; Td= 18.3

Winds NE@3mph

Scattered altocu

After breakfast I packed up my hiking gear and drove down to the Morrison Campground where the Prater Ridge trailhead is. It is the only remaining long trail in the park that is not closed off. There are two loops like a figure 8 with a short section(0.2mi) connection trail in the middle. I did the full 7.8 mile north and south loops under 4 hours including a 30 minute lunch stop. The trail steadily climbed to the mesa top and then generally meandered along the rim of a while rock escarpment. The north loop had nice overviews of the Mancos Valley below. It got to around 8100’ elevation. Most of the trails went through burn areas but there were some nice pinon/juniper trees as well. The nicest spots were overloops with live trees below. The temperature was in the mid-60’s and for the most part the winds were not too bad. Certainly better than cloudy, snowy conditions in trying to reach 30 in Fort Collins. I took advantage of the access to cell coverage up there and that is how I found out what it was like there. She is ready to go down to Arizona for the winter.

 When I returned I couldn’t see any evidence a furnace repairman was here. I called dispatch again and they said it was a holiday weekend and that it would probably be Tuesday before someone came out. So much for Civil Service! I guess I’ll be keeping a fire going for the next couple of days.

1639 Measurements

CN= 1000 but recently built up to over 1400/cc

CCN@0.5%  550 to 600/cc
          @0.3% 400 to 425/cc

RAMS server down so can’t use Dan’s link to Mesa Verde Measurements
But Cortez is T=67; Td= 16

Winds SW@14mph.


House was cold again this morning. The temporary fix didn’t work. So the only hotwater I have is what is in the system right now. The wood stove is keeping the living area toasty.


CN= 950/cc

CCN@0.5% 700-750/cc
          @0.3% 500-525/cc

T=47; Td=33.4

Winds ENE@4mph

 I jogged the 2.6 mile over 500’ elevation gain Spruce Canyon trail this noon. I did it in reverse to the direction Dan took me on last Monday. The ascent is much more gradual. It is sunny and in the 60’s. There still was enough hot water in the system for me to get a hot shower.

I am working in the living room in shorts and T-shirt with the door wide open because the wood stove is still putting out heat.



CN is quite variable. At 1430 it rose to over 9000/cc and now it is around 8000/cc and dropping to 6500/cc

CCN@0.5% 600 to over 700/cc
          @0.3% 450 to over 500/cc

T=63;  Td= 22

Winds S@6mph

Partly cloudy with thin cirrus.

I took an evening drive but didn’t see any wildlife.


I heard quite a bit of thunder during the night and then about 0400 there was a close one that rattled all the windows in the house and fully woke me up. It was drizzling when I got up and the ground and roads were wet.

 I biked over to make the measurements as I suspected the walking trail would be muddy. My afternoon walk confirmed that as there were plenty of muddy tracks.


CCN@0.5% 250 to 275/cc with a spike to 400/cc
         @0.3% 125 to 175/cc with spikes to 275/cc

Sky is generally overcast but rain has ended at least for now. Forecast is for isolated showers this morning and winds becoming SE@10-15mph

Current conditions: T= 44; Td=42.9

Winds ENE@3mph

  I worked on the NSF proposal and then class notes most of the morning and afternoon.

At noon I took a bike ride around both the Mesa Top Loop and the Cliff Palace Loop. In the Cliff Palace Loop I did the Soda Canyon overlook trail which is about 1.2 miles. I think I have done every road and trail that doesn’t require a back country permit. I even looked into biking over to Wetherill Mesa as it has been closed since we have been here. But it required a back country permit which means a lot of going through the hoops that takes probably more time than I have here. I must admit I am getting kind of bored with the place.

 When I returned the plumber was working on my furnace and now I have hotwater heat plus gas so I can stop building fires. I must admit I kind of like running around in shorts and a T-shirt but it is messy and I have to somehow clean up the place without a vacuum cleaner.


CN over 900/cc for a while this afternoon but dropped to 8000/cc at the time of measurement

CCN@0.5% 400/cc to 650/cc
         @0.3% climbed from 300/cc to 350/cc

T=61 ; Td= 36.5

Winds SSW@6mph

I am pooped at 1700h. I tend to run or bike further than normal just because it gets me outside. I also work non-stop since there are no distractions. So but late afternoon I am both brain dead and physically exhausted!



CN steady at ~2200/cc

CCN@0.5% 280 t0 300/cc
            @0.3% 160 to 200/cc

Low clouds early but dissipating and patches of thin cirrus
T=50; Td= 35.8
Winds E@2mph


  I ran the top-side of the Petroglyph trail this noon. Afterward I stopped at the Park supervisors office and suggested that since nearly 90% of the park was closed off to visitors that they train people like the Utes to give day walking tours and overnight tours in the backcountry on a fee basis like $15 per person day tours and $25 per person backpacking. I am sure many Utes would be enthusiastic about being back country tour guides. But all they talked about was trying to get more rangers to do that. It ain’t going to happen! That is the trouble with the Park Service they are too much into promoting their inside people and not looking at alternate solutions using training not Park Service people.


 I checked the clocks of the CN and CCN counters as Doug Lowenthal had suggested and it was a good thing. The CCN read 1425 while the CN read 1524; over an hour difference!

CN rose to over 10,000/cc and currently reads 3500/cc.

CCN@0.5% ~225/cc
         @0,3% ~150/cc


 Mostly sunny with some alto cu patches

T=54; Td=36
Winds: S@4mph

After working to after 3PM and finding our server down, I decided to escape the Mesa. I drove down to Mancos and then to Mancos State Park. It has a small lake which this time of year is about half full. Had it been nearly full it would have been quite scenic as the cotton woods in the foreground were yellow and the mountains in the background had fresh snow on them.

 I drove back and made supper of a mix of things that needed to be used before I hit the road on Friday. Ian McCubbin gave me the disappointing news it might be noon before he gets here to help me shut thing down on Friday.



CN –constant at about 1000/cc

CCN@0.5% 180 to 200/cc
         @0.3% 140-150/cc
T= 52; Td= 40.6
Winds N@6mph

 I worked on finalizing the NSF proposal

I ran the Spruce Canyon Loop over lunch. It was warm and sunny. I spied a tarantula on the trail; my second one here.

 I cleaned up the cabin this afternoon in preparation for departure. I burrowed a vacuum cleaner from maintenance and got the rugs looking better. But they are pretty ratty.


CN—rose from 2500/cc at 1530; dropped to 2000/cc at 1545; rose to 2700/cc now

CCN@0.5% 325 to 400/cc
         @0.3% 250 to 300/cc

Sky clear
T=65; Td=31
Winds NW@8mph

 I encountered a doe on the trail returning from my afternoon observations.