Updraft Category Archive: Urban Heat Island

Twin Cities Urban Heat Island study wants you!

Posted at 3:38 PM on November 11, 2011 by Paul Huttner (1 Comments)
Filed under: Urban Heat Island

Here's your chance to get involved in a significant Urban Heat Island (UHI) study right here in the Twin Cities.

The "Islands in the Sun" project is the brain child of Peter Snyder and Tracy Twine at the University of Minnesota's Soil, Water and Climate Department. The 4 year project will be the most detailed ever on the Twin Cities UHI.

"Most urban areas are warming at twice the rate of the planet as a whole, thanks to a phenomenon known as the urban heat island effect. Heat waves are expected to become increasingly frequent as climate changes.

1.quantifying factors that contribute to urban heat islands in the world's 100 largest metropolitan areas;
2.developing a model to assess heat-island-mitigating landscape design strategies; and
3.evaluating the effectiveness of different engineering and landscape design solutions in the Twin Cities metropolitan area."

Heat Waves. This hypothetical graph shows how daytime and nighttime temperature vary in the vicinity of a large city. Notice how daytime temperature is higher over heat-reflecting buildings and lower over a water body, which acts as a heat sink. Illustration courtesy of U.S. Environmental Protection Agency Heat Island Reduction Program

Here's the scoop on how to volunteer from the Islands in the Sun website.

"We are setting up a dense network of temperature sensors around the Twin Cities Metro Area to measure the spatial and temporal variability of temperatures in a variety of urban and suburban environments. The goal of the project is to learn more about the behavior of the urban heat island effect in a large northern latitude metropolitan area. We are currently determining sites based on location and land characteristics.

If selected, we will install a temperature sensor outside your house somewhere on your property and ask that it remain for 2-4 years. There is nothing required of you--the sensor is self-contained and automatically logs readings. We must have access to the sensor every 2-3 months to download data. We will be happy to provide the data for your site to you if you are interested."

MPR listener and weather spy Justin Heideman signed up to volunteer and his location was selected. He sent me this shot of the sensor at his home.

"Hey Paul,

I saw your post on Updraft a couple weeks ago and signed up for the Islands in the Sun study. I thought I'd let you know that it was a piece of cake signing up and getting the sensor installed. Installation by the grad or under-grad student took about 5 minutes. They installed it on my clothesline pole and it's totally out of the way. I hope that this study is able to provide some useful data about the UHIE."

It will be great to watch this study unfold over the next few years. I've often observed temps easily 10 degrees warmer in the inner Twin Cities on clear calm nights when UHI is maximized.

I've also spoken many times with University of Arizona Geography and Climate specialist Dr. Andrew Comrie about the UHI in Tucson. As expected, his studies have found large differences around Tucson, especially in spring.

PH

Comment on this post

Warmer in the Cities

Posted at 4:15 PM on October 21, 2011 by Craig Edwards
Filed under: Climate, Climate change, Drought, Microclimates, Urban Heat Island

The urban heat island is well observed in the climate records of metropolitan areas. If you reside in downtown Minneapolis/St. Paul you experienced a minimum temperature that was near or even above the thawing point of 32 degrees this morning. The International Airport recorded a low of 32 degrees, while Saint Anthony checked in with 34 degrees. All official temperatures are taken about five feet above ground level.

Meanwhile, it was a different story away from the urban region. Here is a sample of some other minimum temperatures recorded this morning: Chanhassen, Crystal, and Buffalo all at 27 degrees, Further away from downtown, it was a very nippy 23 degrees at Waseca, 25 at St. Cloud and one of the coldest readings of 21 degrees in Princeton. Temperatures in the middle twenties were observed in western Wisconsin as well, with a frosty 25 degrees in Eau Claire.

Obviously the the exact location of the thermometer has some bearing on the temperature, particularly when winds are calm and the sky is clear. But the reality is, we were all under the umbrella of the same air mass. When meterorologists predict lows from the middle 20s to the middle 30s, they are not hedging. They are bracketing the temperatures that can be different in a small radius.

Click here to explore the overnight low temperatures.

Peter Synder of the University of Minnesota has embarked on additional research to capture the magnitude of the urban heat island in the Twin Cities. He is in particular need for observers within the Interstate 494/694 beltway. If you would be able to assist Peter and his work, he can be contacted at pksynder@umn.edu. Here's the website for more information; http://www.islands.umn.edu/

I spoke with Greg Spoden at the Minnesota State Climate Office this afternoon and he related how some of his research has shown that with a slight north wind the urban heat island can expand to Farmington. Invaluable research here, especially when scientists are trying to resolve the human impact on global warming.

Greg also confirmed that the latest seasonal outlook for this winter, issued by NOAA yesterday, is using the new normals when defining regions that favor above or below normal temperatures.

Another nice day is in store for Saturday before the opportunity for moisture arrives on Saturday night. It felt quite comfortable in the sunshine this afternoon. We topped out at 60 degrees at the Twin Cities international Airport.

Often meteorologists refer to the prospect of showers as the "threat of rain". When you have been as dry as some locations in Minnesota, you call it an opportunity for rain.

Here's a look at how sparse rainfall has been since late July. As Greg noted, southern Minnesota is seeing moisture shortages that are extremely rare. Being in the zero percentile is not where you'd like to be if you're looking for soil moisture recharge for next year's growing season.

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This afternoon's weather graphic from the National Weather Service in Chanhassen. Hopefully we can play out a win-win in the weather world, with precipitation falling overnight on Saturday.

Twin Cities' Urban Heat Island visible from space

Posted at 5:22 PM on January 21, 2011 by Paul Huttner
Filed under: Urban Heat Island

On the coldest night of the winter, you could see the strong Urban Heat Island effect in the Twin Cities from space.

Check out the NWS GOES infrared satellite image below. You can clearly see the brighter colors over the metro, which represent the "warmer" temperatures in the core of the Twin Cities metro last night.

From Twin Cities NWS:

"Cold Temperatures Seen From Space The temperatures Friday morning were so cold that they were similar to normal cloud top temperatures between 10 and 20thousand feet this time of year. With no clouds over Minnesota and thus no blocking, satellite infrared channel (which detects temperatures) could sample temperatures at the surface. Because of the frigid temperatures, the infrared image values resembled that of cloud top temperatures."

A look at minimum temperatures around the core of the metro morning make show that the greatest metro UHI effect was about +13 degrees early Friday morning.

MSP Airport -16
St. Paul (Holman Field) -17
Eden Prairie -21
St. Paul (UM Campus) -22
Crystal -22
Chanhassen (NWS_ -25
Chaska -29
Lakeville -29

"Air mass" temperatures clearly supported -29 Friday morning, even south of the metro.

Also of note are the warmer temperatures over Lake Superior and the colder cloud tops in South Dakota.

Next Snow Sunday & Monday?

The weekend looks cold, but not nearly as barbaric as what we endured Friday. Temperatures should hover a few degrees either side of zero most of the weekend.

The next clipper appears to be on track to bring us more snow Sunday & Monday. Early indications are that much of Minnesota could see another shot of 1" to 3" by late Monday. That could also set up another slick Monday morning rush hour.

Stay warm, and have a great weekend!

PH