New USGS Study Shows Heat Retaining Concrete and Asphalt Have Encroached Upon US Climate Stations

By Anthony Watts – Re-Blogged From http://www.WattsUpWithThat.com

A new study from USGS by Keven Gallo and George Xian verifies what we’ve already learned and published on via the Surface Stations project; that concrete and asphalt (aka impervious surfaces) have increased near weather stations that are used to monitor climate. In this case, it is the much studied USHCN, that climate network I presented a poster on at AGU 2015. Details here.

What is most important about this paper is that it quantifies the percentage of stations that have had increased amounts of impervious surface area getting closer to the stations. As I have long since maintained, such things act as heat sinks, which increase the night-time temperature when they released the stored energy from the sun that was absorbed during the day as infrared, warming the air near the thermometer, and thus biasing the minimum temperature upwards.

Tucson-USHCN

The University of Arizona Tucson USHCN station, in the middle of a parking lot. It was closed just a few months after this photo was released on WUWT. Note the impervious surface area all around it.

In this study, they have observed over 32% of the USHCN stations exhibited an increase in impervious surface area of ⩾20% between 2001 and 2011. When the 1000 m radius associated with each station was examined, over 52% (over 600) of the stations exhibited an increase in ISA of ⩾20% within at least 1% of the grid cells within that radius.

What this suggests, is that like Las Vegas, which has had huge infrastructure boosts in the last 50 years, that the minimum temperature is creeping upwards, and that biases the mean temperature used to look for the “global warming signal”.  NOAA would do well to remove stations that have been encroached upon like this, but they stubbornly hold onto this flawed data, insisting they can “adjust” it to be accurate. I say bollocks to that. Since the USA is so highly over-sampled with thousands of weather stations, it is far better to discard noisy and imperfect data, and use only those stations that have not been biased by infrastructure increases, but retain only the best stations with pristine data.

This is what you get when we did exactly that, and found a statistically significant lower 30 year trend.

figure4-poster1

Here is the new paper:

Changes in satellite-derived impervious surface area at US historical climatology network stations

Kevin Gallo,  George Xian

Abstract

The difference between 30 m gridded impervious surface area (ISA) between 2001 and 2011 was evaluated within 100 and 1000 m radii of the locations of climate stations that comprise the US Historical Climatology Network. The amount of area associated with observed increases in ISA above specific thresholds was documented for the climate stations. Over 32% of the USHCN stations exhibited an increase in ISA of ⩾20% between 2001 and 2011 for at least 1% of the grid cells within a 100 m radius of the station. However, as the required area associated with ISA change was increased from ⩾1% to ⩾10%, the number of stations that were observed with a ⩾20% increase in ISA between 2001 and 2011 decreased to 113 (9% of stations). When the 1000 m radius associated with each station was examined, over 52% (over 600) of the stations exhibited an increase in ISA of ⩾20% within at least 1% of the grid cells within that radius. However, as the required area associated with ISA change was increased to ⩾10% the number of stations that were observed with a ⩾20% increase in ISA between 2001 and 2011 decreased to 35 (less than 3% of the stations). The gridded ISA data provides an opportunity to characterize the environment around climate stations with a consistently measured indicator of a surface feature. Periodic evaluations of changes in the ISA near the USHCN and other networks of stations are recommended to assure the local environment around the stations has not significantly changed such that observations at the stations may be impacted.

http://dx.doi.org/10.1016/j.isprsjprs.2016.08.006

Kevin Gallo is the Corresponding author at: USGS, Earth Observations and Science (EROS) Center, 47914 252nd Street, Sioux Falls, SD 57198-0001, USA.

Note from Anthony: Full disclosure, I was an invited reviewer for this paper, and I submitted reviews that caused improvements (according to the editor) to the paper.

CONTINUE READING –>

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2 thoughts on “New USGS Study Shows Heat Retaining Concrete and Asphalt Have Encroached Upon US Climate Stations

  1. OMG. This article is just ignorant.

    Neither asphalt nor concrete GENERATE heat. They have a physical property called “latency of heat” which is quite high. Meaning that it is hard to heat, and when heated, releases heat slowly.

    Concrete would simply moderate the temperature near the sensors. When the air is heating, concrete is cooler than the air while it catches up. When the air cools, concrete is warmer than the air, until the concrete cools. It smooths the average – it doesn’t shift it.

    What might be interesting, would be to note whether asphalt or concrete absorb heat better or worse than the material they replaced.

    if they absorb less, the temperature readings are scarier because they went up anyway.
    If they absorb more, then the net increase of paved surfaces are a global warming indicator (and man-made to boot)
    If they make no difference, it was an ignorant article.

    The article makes no sense.

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  2. It makes sense if you look at the urban stations vs the rural stations. Urban have daytime highs about where they’ve been for decades, while the lows have increased dramatically. Rural stations’ highs and lows have changed very little. Sometimes what you might expect is wrong.

    BTW, part of the UHI argument talks about the albedo of asphalt/blacktop vs that of trees, etc and also mentions that evapo-transpiration from paved surfaces is zero while greenery always cools the locale through this process.

    Like

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