Trip Report on WMO Workshop on "Measurement of Cloud Properties for Forecasts of Weather, Air Quality and Climate", June 1997
By: William R. Cotton

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This is my first trip to Mexico City. It is also the first time I have used the $4/day shuttle parking at DIA. You get dropped off at the main terminal but it takes another 20 to 30 minutes over close-in parking. This is also the first time I have flown American West. No fancy meals but the seats are as small as United. Who said United has fancy meals? Except for overseas and flights, to and from Boston most of their meals have been yucky snacks. American West provides bag lunches which we picked up from a cart upon entering the gate, and on return supplied by an attendant from a cart in the plane. American West must contract with Continental to provide check-in counters and gates at Mexico City, as they don't have any of their own.

Arrived Mexico City about 2:40PM. Found the taxi and survived the ride to the hotel. The hotel is on a tree-lined side street. It is fairly up-class but not all that modern. Our room, is not air conditioned but we can open the windows. We look out on a rooftop courtyard. Not pretty but then it doesn't have the street noise either.

To begin getting oriented we took a walk along a main thoroughfare toward a large park, that we later found out is called Chapeultipec Park. The park was closed but the walk along the way was park-like with date palms and flowers.

Temperatures were upper 70's but humid. Pollution was not all that bad.

Near the hotel is a pedestrian mall with loads of aggressive street vendors and entertainers. This included pantomime acts, a group of teens singing beetles and other 50's Anglo music. T hey were pretty good. There was even a lone 7 or 8 year old playing an accordion.

We had supper at an outdoor, sidewalk seafood restaurant. I ordered Papano a la Vercrusana and Vollie also ordered papano steamed in an herbal sauce and wrapped in grape leaves. They were both excellent, especially with a smooth domestic cabernet sauvignon.

Bob had loaned me an aeronautical chart which he used to show me the volcanic mountains in the area of Mexico City. Then Chris Clarke loaned me a climbers guide to Mexico's volcanoes So, I decided to start things off by trying to get to one of them. My first choice was Ixtaccihuattl but it is off limits because it is active. Instead we headed to Nevado de Toluca. After breakfast at McDonalds[cheap and fast], we survived the metro to the bus station. On Saturday morning it wasn't very crowded. The Metro is rather modern and fairly clean. The bus to Toluca is like a Greyhound. Nice roomy seats, snacks provided as we enter, no chickens or goats, and seats like first class airline. All for about $6/person round trip.

I would have preferred to rent a car but Vollie wanted no part of our driving through Mexico City.

Arriving at Teluca we asked how to get to Norvedo de Toluca. We were told to get on another bus. No chickens or goats, but this bus was very crowded. We had to standup for the 40 minute ride. I showed the bus driver where we wanted to go, and he gave me a nod in the mirror when we were to get out. Where we got out there were no signs, roads or anything. But back down the road a hundred yards was a dirt road.

We started walking up the road where there was a sign for Nevado de Taluca. The road is lined by densely covered pines, that resemble ponderosa. Many interesting flowers also lined the roadway. For example, there were giant lupine, the plants being three feet or so tall. The actual flowers are six to eight inches long. In Colorado the same flowers are maybe two inches long and the plants a whopping 8 inches or so.

After a mile or so a VW beetle came along with two mountain bikes on the back. Two guys in there 20's were going in part way to mountain bike along the road. We squeezed into the backseat of the bug; Vollie couldn't even put her feet on the floor! The driver was French who now worked in Mexico. They dropped us off about 10km in at a picnic/campsite. We then started hiking again, and to my dismay, a sign said the summit[of the road] was 17km in. We just decided to hike along the road and see if we could get a ride. There did not seem to be any public transportation into the area. Chris' guide book gave nice directions for driving but none for public transport. Now I know why. In Mexico City they have excursion buses to ruins, etc but nothing to the volcanoes. They don't seem to appreciate these great mountains.

After another mile or so walking and being passed by several cars chuck full of extended families, two guys came along in a ten year old Ford. The driver was in his thirties and with him was his 18 year old cousin. I'll call them 'rum and Coca Cola tours', as the driver continually sipped his rum and Coke! They were very friendly and liked to talk, mostly in Spanish to Vollie, but some broken English too. I had a hard time understanding the English with new-age music blasting in the speakers behind me as well as road noise. He drove very slowly, about 10mph on the rough road. It took about an hour to reach the crater, what with pee stops every twenty minutes or so. Among other things discussed, we found out the driver was big into religion and asked us about our beliefs.

When we reached the crater rim at about 13.5K MSL I noticed a crude trail going up the higher levels of the rim. I asked the driver if we could get out to hike. No problem they said, they were going ahead to the floor of the crater and would meet us about 4PM. So, Vollie and I began hiking up this so-called trail. At first it wasn't very steep and we were even passed by some trail bikes. No rules here, the ride where they liked through the fragile tundra.

Eventually the trail got quite steep on the cinder surface. Vollie told me to go ahead as she was uncomfortable with it. Eventually she made it up to a saddle at 14.2K. I continued on rock scrambling until at 14.4K I found an impenetrable[for me] rock wall that extended for quite some distance. I was disappointed as I had hoped to break 15K. Had I tried the other side of the road at the rim, I might have been able to get higher. But when you are bushing it with no signs or anything but primitive tracks you never know what you are going to get into. I took some pictures of some small alpine red flowers that were in clusters as high as I went. I don't know what they were but they sure were pretty!

Upon descending to the road, we hiked down to the crater floor where there was a rather sizeable lake. Our driver was sitting on a rock standing out in the water meditating or praying[is there a difference?]. We hung out there enjoying the views, as our driver continued to nip on rum and coke, getting high in celebration of passing his engineering exams the week before. Finally about 5PM we started back. I wasn't sure if his car would make it over the rim. The carburetor was flooding due to the altitude and the fact he lugged the engine down as he crawled along. By, slipping the clutch [I could smell it burning] and after a few wrong turns by our now very inebriated driver, we finally made it to the crater rim and began to descend. By this time I had a splitting headache, probably from not drinking enough water at such high altitude. At times I would experience periods of shaking chills! Also, I was a bit stressed out for being at the mercy of our polluted driver. At this hour there was little chance of getting a ride with someone else off the mountain.

As our driver sped along, the twisty, rough road at speeds approaching 10MPH, it took us forever to get down to the main road. This took even longer because we often stopped to enjoy the view which was mostly clouded over, and every 20 minutes for a pee stop. Some philosophical discussions were thrown in for good measure too! Me, with my splitting head, I just wanted to lose altitude. At about 7PM we finally made it to the paved road 30min after the last bus back to Toluca. Our gracious and very inebriated host wanted to take us down to the bus depot. What choice did we have? So on the paved road we revved up to 25MPH. Now mind you I didn't want him to drive very fast in his condition anyway as we wove down the road.

After about the 20th pee stop, followed by discussions and eventually a crying spell, I guess because I didn't look to happy, I noted I was concerned we would miss our bus in Toluca. I told him it was at 8:30 but the last bus was really at 10:30 if we could get on it. Remember I was in pain with a headache and a wee bit concerned about ever getting to Toluca in one piece.

We entered Toluca at 8:10 and all of a sudden our slow driver began driving like a taxi cab driver, speeding more than twice the speed than any time previously, changing lanes, almost wiping out a VW bug, and getting us there about 8:20. After we shook hands, hugged, and heard the 100th "I'm sorry", we headed into the bus station. I swear, this non-Catholic crossed himself and said 10 hail Mary's for delivering us in one piece. Vollie took it all in stride saying that she had faith that someone up there was looking after our driver and presumably us as well.

The 8:30 bus was full but we got on the 9:00. While we waited we had some supper of huevos rancheros, which was the only non-meat dish available. Our bus back to Mexico City was pleasant enough and arrived at 10:15. We took the subway which had few people on board, mainly families. We didn't feel threatened at all. Boy were we pooped by the time we got back to the hotel.

I decided to take a fast today as I talk first thing Monday morning. We played tourista and took a guided tour of the city. We imagined it would be a big bus--not! It was a VW van with one guide for us in English and another in Spanish for a Colombian couple that went with us. We saw the University of Mexico and then went to the hanging gardens. The water reminded me of the canals in Miami with the same algae coating. There seems to be thousands of these flat-bottomed, red yellow and white boats, that were poled along. It was like bumper cars on water as they ran into each other. Along the way there were other boats that would bump into you trying to sell their wares. This included roast corn and tortillas with who knows what in those drinks, Mariachi bands, marimba, flowers, hats and other clothes.

The shores were generally overgrown with uncultivated plants and brush, and populated with many dogs, kids, with an occasional greenhouse type place selling cultivated plants such as geraniums. We even paid to be serenaded with a Mariachi band. This was definitely a Mexican experience.

We were then driven to a tourist trap store which Vollie and I didn't particularly appreciate and dropped off to go on our own tour. We first headed to a large park. That is a must on a Sunday. It is filled with extended families, hawkers selling you name it, lots of food smells everywhere, some people preaching with no one listening, and lovers all over the place in the grass. We met up with Roger Reinking from Boulder, NOAA ETL. He was taking a picture of this Mexican lying on his back with a hat over his face taking a nap(me!). We headed together for a guided tour of the Aztec ruin Templo Mayor. Followed by a long walk back to the hotel, we rested and went to registration and cash bar. I was told several times over I missed a 3PM speakers briefing that I must have not printed out from my E-mail or I didn't get the message.

Monday was work day. Following the general introductions by the organizers and local VIPs, I led off with my talk related to mesoscale forecast models and microphysics with discussions of observational needs. I used RAMS as an example of where microphysics in forecast models is going. I said that where RAMS leads. the ewes and lambs are not far behind. I emphasized the need to have a network of observations of CCN spectra. This was generally appreciated but Gabor Vali didn't appreciate the need. He thinks that if one observes droplet concentration then why infer CCN spectra? He argues that because of chemical reactions and sources and sinks, a network of CCN measurements would not be useful. My response is that is moisture really any different? We generally recognize the need to measure moisture soundings in a network yet it is very stratified, has numerous sources and sinks as well. I will persist in my avocation of direct and remote sensing of CCN.

I added a section of discussion of the need to measure w-spectra and w correlations with microstructure for developing parameterizations of cloud-scale updraft/downdraft forcing in mesoscale and larger scale models. This I noted is important for getting droplet concentrations right and time scales for precipitation processes and sedimentation correct.

Overall, I think my talk was well received. I talked about 50 minutes and the question and answer session lasted for at least 35 minutes. I had a lot of people come up afterward and congratulate me for an excellent talk. I was really exhausted afterwards!

Following me, Gabor Vali gave a talk on airborne in situ measurements of cloud microstructure. Then he discussed his pet topic of cloud radar measurements of cloud microstructure.

Then Tony DelGenio gave the GCM modelers perspective of cloud microphysics needs. He emphasized the need for measurements of cloud fractional coverage and the need to develop better parameterizations of cloud coverage. He also advocated PDFs of cloud w's in relation to cloud LWCs.

Pat Minnis overviewed satellite cloud retrievals of various cloud parameters.

Tony Illingworth presented an overview of radar-observations of cloud microstructure. He showed some graphs which demonstrated little correlation between cloud radar-derived radar reflectivity and LWC for maritime clouds presumably because of the ubiquitous presence of drizzle drops. From the discussion that followed, this is a common experience of cloud radar observers. A few drizzle drops, not what one would call rain, really dominate Z. From the cloud dynamics perspective, I ask how much influence do these sparsely-populated drops have on the fluxes, energetics of the cloud-topped boundary layer? In middle latitudes, Ken Sassen has shown that there is a good Z-LWC correlation, presumably because of the absence of drizzle drops. This does not seem to be the case in central Pennsylvania as Bruce Albrecht has shown drizzle below bases of most stratus there.

That evening Vollie and I went to a Andulucian restaurant in the neighborhood of the hotel. Had some great seafood and a bottle of excellent domestic wine. It was a covered[canvassed] sidewalk cafe style place.

Today we had a guided tour of the Tiatihuacan Pyramids. This is in a 7300ft basin about an hours bus ride north of Mexico City. Our first stop was at a large modern design cathedral on the way out of the city. I really liked the design and feeling of openness of the church. Behind it was the old church dating back to the 16th century. It has been settling and is all tilted all which ways. it is closed to the public for obvious reasons.

Then on to the pyramids. Actually, just outside the entrance we stopped at a store that specialized in obsidian. They had black, brown, and varieties with gold/silver textures. They had an outside mill where they worked the stones into quite an array of Aztec-type figures. They also demonstrated extracting liquid from century plants for making pulta [a beer-like drink] and tequila.

Finally we got to the pyramids. This is the largest prehistoric complex I have seen including Chichen Itza, Tulum, Coba, and Chaco Canyon. First we toured some restored buildings then climbed the moon pyramid. It was about 80 feet tall. The sun pyramid was to the west and set back to the east of a 1/4 mile wide grassy corridor. The corridor was about 1 mile long with a continuous line of smaller restored pyramids. Scattered throughout the plateau are mounds that are unrestored pyramids. Then we climbed the 120ft high pyramid of the sun. It was a good workout getting up there; Quite a view of the plateau and surrounding volcanic peaks. Near the top, Vollie and I found a spot a bit out of the way of the crowds of tourists and school kids, and ate our box lunches while enjoying the great views. Imagine that the Aztec priests would sacrifice men, children (a favorite of Tlaloc!) and an occasional women within 20 feet of where we were having lunch.

As you walk through this beautiful, prehistoric landscape, you are continually confronted by locals selling Abyssinian carvings, yelling with the object in their outstretched hands. "Abyssinian only $1!"

As in the Yucatan, many of the pyramids have one layer built upon one or more earlier period pyramids. The oldest dates to 200BC-600AD, and the peoples are called Teotihuacan. When the Aztecs arrived they found the abandoned pyramids, and considered them to be the homes of the gods. They occupied them and built over them until the Spanish conquests. Virtually nothing is known about the Teotihuacan's; who they were, where they went, and how they used the pyramids.

Following the tour we had a couple hour break at the hotel then back to the conference center for a poster session with drinks and snacks few of which could I eat. We returned to the hotel about 9:00PM, stepped out for a light Mexican meal and then to bed very tired.

Today was a work day. I was co-chair of one working group. We worked from 9AM to 7PM with a working lunch, about half of which I could eat. We were busy defining cloud measurement needs to support forecasting and climate models.

Returning to the hotel by 8PM, Vollie and I went to a nice Italian restaurant for supper. We chose it because it was one of the few places that did not have the soccer game with Bolivia blasting away on the TV.

I began the day with my usual run along the park-like lane alongside of Reforma Avenue in the dark. I finally found my way into Chapeultepec Park and ran along its well lit central corridor. I tried to run along some side lanes, but it was too dark.

Another day of workshop until 1:00PM and then back to the hotel for lunch and a break until 4:00PM when we were off to the anthropological museum on a group tour. Actually Vollie and I virtually race walked 30 minutes to get there just as our group started the tour. The tour was useful because it put all the pre-Columbian civilizations in perspective. Our walk back was in the rain. It has rained after 5PM every day since the weekend. Today was the warmest since the weekend as well, with a high in the low 80's. Most of the week it has been cloudy with highs in the middle 70's.

We ended the day with a working dinner for the group leaders, organizers, and invited speakers. The dinner was at a Mexican-style restaurant with good tasting food. For a true vegetarian, forget it! Even being able to eat fish, I am lucky to find a single item on the menu of all the restaurants I visited that I can eat. Even then I have been hit enough with something in the dishes--lard, chicken broth, or ?? that I am aching all over and in worse shape than I have been in over a year. At that I am lucky as several of our group have been visited by Montezuma's revenge! Pat Minnis ate a hot dot sold by a street vendor outside the museum and looked like crap on Friday.

I decided to go on a fast today. I think it will have to be at least a 3-day fast considering how I feel.

This is our final meeting day. Darrel has regrouped the working groups into three instead of four. I'm not sure what we are to accomplish today.

Overall the organization of the workshop has been very good as far as facilities are concerned. It is a nice working environment at the campus conference center. Very nice lunches have been provided, organized tours, and so forth. On the down side is the 1-hour bus ride each way to and from the hotel. This, with some working days from 9 to 7, I find very confining. Then we have "executive" working group lunches and dinners, so there is little time for one's self. I need that time to myself. They also have made very little provisions for spouses. Even the poster session/cocktail finger food evening there was no specific invitation to spouses. Many of us brought them along anyway. Last evenings working dinner was very awkward. I brought Vollie along as I didn't think she should be expected to go to dinner on her own. Then special reservations had to be made for her. They should have asked if we wanted to bring spouses. If they told me not to I wouldn't have gone. These are the kind of oversights that one has to be careful of when organizing meetings.

Our workshop ended at 1:00PM following the presentations of working group leaders summarizing our recommendations and priority list. I presented the priority list for model initialization and assimilation as well as data priorities for both forecast and climate model testing and validation. Tony DelGenio presented data priorities for development and testing of physical parameterization schemes for both climate and weather forecast models. The other two groups presented their recommendations for insitu aircraft and remote sensor studies.

George Isaac mentioned some work in his group relating sulfate source inventories to droplet concentration estimates or CCN estimates. We'll have to track that work down. Perhaps Hong Lin who is working with Laich either is involved in that work or knows who is.

We arrived at the airport after only a 30 minute taxi ride from the conference center. I think that is much faster than from the hotel in spite of its being closer to the airport. The limited access beltway is the reason. The airport terminal is quite modern and contains a mix of U.S. fastfood shops as well as Mexican chains. The remainder of the trip was uneventful, We arrived home about midnight.

For a description of my talk please see it on this homepage. I plan to apend the workshop draft recommendatioions to this as soon as I receive them.