Chinese UHI study finds 0.34C/century inflation effect on average temperature estimate.

Posted: May 14, 2019 by tallbloke in Analysis, climate, Dataset, Surfacestation, Temperature, UHI

New study published by Springer today makes interesting reading. Phil Jones’ ears will be burning brightly.

Historical temperature records are often partially biased by the urban heat island (UHI) effect. However, the exact magnitude of these biases is an ongoing, controversial scientific question, especially in regions like China where urbanization has greatly increased in recent decades. Previous studies have mainly used statistical information and selected static population targets, or urban areas in a particular year, to classify urban-rural stations and estimate the influence of urbanization on observed warming trends. However, there is a lack of consideration for the dynamic processes of urbanization. The Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD) are three major urban agglomerations in China which were selected to investigate the spatiotemporal heterogeneity of urban expansion effects on observed warming trends in this study. Based on remote sensing (RS) data, urban area expansion processes were taken into consideration and the relationship between urban expansion rates and warming trends was investigated using data from 975 meteorological stations throughout China.

Although urban areas constitute less than 1% of land in China, more than 90% of the meteorological stations experienced urban land use change and the average urban expansion rate was 0.33%/a. There was also a significant positive relationship between observed warming trends and urban expansion rates. Background warming, without the influence of urbanization and extra warming induced by urbanization processes, was estimated using a linear regression model based on observed warming trends and urban expansion rates. On average, urbanization led to an additional annual warming of 0.034 ± 0.005 °C/10a. This urbanization warming effect was 0.050 ± 0.007 °C/10a for minimum temperatures and 0.008 ± 0.004 °C/10a for maximum temperatures. Moreover, it appeared that urbanization induced greater warming on the minimum temperature during the cold season and maximum temperature during the warm season.

  1. Nothing new but good to see it was published in a biased climate journal for all the alarmists to mull over.

  2. Or am I confused? What on earth does °C/10a mean?

  3. oldbrew says:

    What’s Wrong with the Surface Temperature Record? (Guest: Dr. Roger Pielke Sr.)

    Dr. Roger Pielke Sr. explains how the Intergovernmental Panel on Climate Change (IPCC) is incorrectly explaining climate change to the media and public. Pielke highlights how the IPCC ignores numerous drivers of climate aside from CO2, leading to numerous factual inaccuracies in the IPCC reports. Host Anthony Watts and guest Dr. Roger Pielke Sr. also cover what is wrong with the surface temperature record – specifically why many temperature readings are higher than the actual temperature.

  4. JB says:

    I really question whether urban temperature detectors are good for 0.00XºC resolution. Last I checked, most sensors had an absolute error at least 10X this. Silicon devices, such as Microchip’s TC1133 has an accuracy of±3ºC @ 25ºC, with a linearity of 0.8ºC. The age-old LM135 a calibrated error of ±0.5ºC & linearity of 0.3ºC; the LM34 accuracy of 1ºF, linearity of ±0.5ºF.

    Thermocouple and platinum sensors are somewhat better with sophisticated linearizing circuitry, but need periodic service and recalibration to get into the 0.0Xº range, which necessarily includes the accuracy of the associated electronics amplifying the signal and the digitization errors. It just doesn’t seem reasonable that the Chinese would install expensive and high maintenance sensors around their population centers. That’s not consistent with the Chinese mfg I was involved with for the last 2 decades.

    Back in college we were taught about the fallacy of decimal point precision, but apparently in this crazed climate frenzy nobody remembers that. But what do I know?

  5. tallbloke says:

    Howard: Or am I confused? What on earth does °C/10a mean?

    I took it to mean degrees celcius per 10 annum (decadal)