Thursday, July 24, 2014

Hot Stuff

Here's four hot stuff factoids for your Pioneer Day enjoyment:

  • Yesterday's high at the Salt Lake City International Airport was 103ºF, which is tied with July 14th for the hottest day of the year so far.
  • Climatologically, this is the hottest period of the year.  From 18 July to 2 August, the average high temperature at the Salt Lake City International Airport is 94ºF and the average low is 66ºF. 
  • The overnight (through 6 AM) minimum temperature at the Salt Lake City International Airport was only 80ºF, although temperatures did dip to 79ºF just after 7 AM.  I woke up in the middle of the night and heard the air conditioning cranking and thought, whoa, it must be hot!
  • Globally, June was the hottest recorded in the instrumented record.
Source: NCDC
The heat miser is winning.

Wednesday, July 23, 2014

Early Results: Perspectives on Daylight Savings Time

As some of you are aware, the Utah Legislature is presently investigating whether or not to put an end to daylight savings time, the setting of clocks forward in the spring so that the sun rises and sets at a hour of the day during the spring, summer, and fall months. I am a fan of the later sun rise and set relative to the local-time clock, but others out there may feel differently.

The Utah Governor's Office of Economic Development is currently conducting an online survey on views on daylight savings time that can be completed at by both Utah residents and non-residents (yes, the latter is important as we have a big tourism economy).  You can vote and add comments until August 15th.  I wonder if that means August 15 defined using UTC, MDT, or MST?

Results and comments through yesterday morning are now available on the GOED website and they show that the daylight time lovers are currently getting slaughtered.  With over 26,000 responses, a whopping 67% of the respondents wish to align with Arizona and stay on standard time all year.  Only 15% want to maintain current practice.  18% say stay on daylight savings time all year.

Of course, this is a voluntary survey, which tends to invoke response from those with the strongest opinions.  It would be interesting to see what the results would be of a random sample of Utah residents and non-residents.  Ultimately, the decision to could be put up for a vote, and that might be even more interesting.

For your entertainment purposes, more than 13,000 specific comments are available here.  Here are a few I've self selected just for fun.  I especially like the third and fourth.
"Changing time by legislation is so silly to me. Time should never change, it's a cosmic reality, not a law of men. Fooling ourselves about the real time of day is a bit insane." 
"Daylight Savings is silly for a country which calls itself free. If you want to get up an hour earlier for an hour more of sunlight, then do it; it is your prerogative. But it is a form of totalitarianism to force everyone to get up an hour earlier." 
"If DST was a face, I would punch it as hard as I could." 
"I have not changed my clocks in 4 years. I have hated daylight savings for years. What is the point. "
One thing is apparent from reading the comments, everyone hates the change twice a year.  At least we an agree on something!

Monday, July 21, 2014

Clear Views, Clean Air

After several days of smoke inundation, it was great to wake up this morning to clear views and clean air.

In addition to yesterday's storms, we've had a shift in the large-scale wind direction after several days of northwesterly flow, as evident in wind observations from the top of the Collins chair at Alta Ski Area.  The transition to southwesterly flow has resulted in a smoke-free airstream for the Wasatch Front.

Overnight PM2.5 observations from the University of Utah showed the lowest PM2.5 levels in a few days, with values sitting near 0.

Enjoy the clean air!

Sunday, July 20, 2014

The Pots o' Gold Are on Campus

A spectacular rainbow display could be seen looking toward the east bench this evening.  From my vantage point, the pots o' gold produced by the primary and secondary bows were on the University of Utah Campus, including one near Rice-Eccles Stadium.  No word on whether or not President Pershing was scouring the grounds hoping to add to the U's endowment.

The primary bow was spectacular and featured at least one and possibly two supernumerary bows, purple arcs on the inside of the bow. I've had to doctor-up the photo below to bring the most obvious supernumerary bow out.

Saturday, July 19, 2014

Coast to Coast Smoke

Smoke from the western fires of the U.S. and Canada has now spread coast-to-coast.  If you look closely, you can see it in the visible satellite image below over eastern Canada and Maine.
The National Environmental Satellite, Data and Information Service (NESDIS) provides a nice interactive map for examining fire and smoke hazards.  The screenshot below shows the active fires (red dots), areas with moderately dense smoke (yellow) and areas with thin smoke (green).  Coast to coast coverage is achieved thanks to a fire near the California coast and then large-scale transport of smoke from fires in the western U.S. and Canada across the continent.

Some views of the smoke from MODIS follow (source: NASA).

Smoke plumes over Oregon 
Dense smoke over the Columbia Basin
Smoke over the northern Plains (Lakes Superior and Michigan at right for reference)
Smoke over Labrador, Canada
Sadly, fires have destroyed an estimated 100 homes in north-central Washington.

Friday, July 18, 2014

Ask and You Shall Receive: Insights from a New Ozone Sensor

After belly aching in yesterday's post about the need for more real-time air quality monitoring stations in the Salt Lake Valley, I learned that my colleagues in the mountain meteorology group here at the University of Utah have just installed PM2.5 and ozone sensors at our mountain meteorology lab (MTMET) on upper campus (click here to access).  At an elevation of 4996 ft, this site should make for good comparisons with the DAQ sensors at Hawthorne Elementary near the valley floor and almost 700 feet lower.  MTMET is influenced by outflow from Red Butte Canyon, and this is already proving to be quite interesting.  

Data from the past 24 hours at MTMET (courtesy shows very nicely the gradual rise in temperature during the day yesterday, with a high just above 90ºF.  Just before 2000 (8 PM) MDT, temperatures dropped abruptly to 75ºF with the onset of easterly canyon outflow, after which temperatures held steady until about midnight when the temperatures jumped abruptly when the outflow weakened. The strength of the outflow varied for the rest of the night, with temperatures bottoming out in the low 70s just before 0800 (8 AM) MDT.   

Ozone for the period spiked briefly from 1300–1400 (1–2 PM) MDT yesterday, hitting ~80 parts per billion (ppb).  Ozone overnight, even with the supposedly "clean" canyon outflow, stayed near about 50 ppm until about 0800 (8 AM) MDT when the outflow weakened and winds gradually shifted to southwest. 

We can compare this data with that from Hawthorne, which thankfully is available online again.  It shows a similar spike in ozone in the early afternoon, but lower ozone concentrations than observed at MTMET overnight.  In other words, from the standpoint (solely) of ozone concentrations, the outflow from Red Butte was "dirtier" than the air at Hawthorne.  
Source: Utah Division of Air Quality
That may sound surprising, but it is likely the result of a curious oddity of meteorology and air chemistry.  Profiles of ozone in other regions (e.g., the Los Angeles Basin illustrated below) often show the highest ozone concentrations are aloft and not at the surface (note: this doesn't necessarily mean the air at the surface is "clean"!).  
Ozone concentrations over the Los Angeles Basin from 05-07 local time, 25 June 1987.  Source: Dayan and Koch (1996).  
This may seem strange since one expects the pollution to be worst near the ground where the emissions are, but ozone is a secondary pollutant and the complexities of ozone photochemistry and meteorological turbulence lead to the strange distribution.  Further, this effect is most pronounced at night and in the early morning.   The Los Angeles data above was collected from 5-7 AM local time when ozone concentrations were less than 50 ppb near the surface, but exceeded 250 ppb aloft.

So, one hypothesis for the higher ozone at MTMET last night is that the ozone levels dropped in the valley, but the outflow from Red Butte was tapping into the higher ozone air further aloft.  

Of course, this is an are educated guess.  Comprehensive observations of meteorology and atmospheric chemistry are needed to better understand these local characteristics of our pollution.