A Look into the Phoenix Urban Heat Island Issue

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#1 UMeoswald on 08.07.08 at 5:42 pm

Overnight “thermal snapshots” are being used in several studies (including one i am working on) to show heat islands….or more specifically neighborhoods or parts of cities that lose less of the heat acquired during the daytime heating. I have two questions, and I am wondering if anyone has good insight into them.

First, how would one go about translating the “thermal snapshot” (which is a representation of the “skin temperature” of the surface) into “temperature experienced” (2 m above ground) by someone who is in a heat event?

Secondly, I understand fully why some neighborhoods, or parts of cities, ‘retain’ heat overnight better than other neighboorhoods (daytime heating, material properties, ect….) and thus when we take one of these “thermal snapshots” we get “urban heat islands”. But my question is about daytime “thermal snapshots” and more specifically warehouses. Every time I look at a “thermal snapshot” of a city during the daytime…an area of “very hot” always sticks out and it almost always is an area with many warehouses (and one sees the black roof tops). In using “thermal snapshots” to help locate areas where more heat is present during a heat wave, one would probably do an amount of spatial averaging and then use the map to locate areas with more heat (thus more dangerous during a heat wave). My question is this: a rooftop of a warehouse (or 20 warehouses) gets hot, and re-emits the heat into the air above it (typically)….but does that, now warmer, air sink (wouldn’t it rise!?) to the level of citizens or at least mix significantly enough to effect the common person? can daytime “thermal snapshots” be used in determining dangerous areas during heat waves??

please help! or contact at eoswald@umich.edu

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