Dear Jenny,

very interesting question! But I don't as yet fully understand your query: The UHI will always be calculated RELATIVE to other temperatures, e.g. surrounding rural areas as you mention. So where do the two different figures you cite come from? Of course, there are significant temperature variations also within an urban area. Perhaps this causes you to have a larger gradient when looking at the built-up/city area only compared to a full urban-rural transect?

PS: Are you performing calculations por la ciudad de Mexico?

Best,

Julius

Hey,

have a look here:

https://www.sciencedirect.com/science/article/abs/pii/S0048969721051123

https://www.sciencedirect.com/science/article/abs/pii/S0048969722016631

if you have questions, do not hesitate to ask

Enjoy!

Luis

PS if you cant dowload them, you can find those publications on my profile :)

Are you analyzing the satellite-based surface temperature UHI or the weather-station based surface air temperature UHI? They are rather different in diurnal and intra seasonal variations. In any cases, however, UHI intensity could be calculated for any stations and any areas in a city (except for UHI intensity of the whole built-up region of the city), and the key issue would be how to select rural/reference stations or pixies/areas. We developed a few procedures to determine rural/reference stations for calculating UHI intensity of a city, and for evaluating surface air temperature data bias for a large regional observational network, and you may find them helpful.

UHI is defined as the temperature difference between an urban area and its rural reference.

For air temperature UHI, we generally do not have spatially continuous observations.

For surface temperature UHI, we have continuous measurements from satellites.

Note that these two UHIs can be quite different (Article Crowdsourced air temperatures contrast satellite measures of...

For surface UHI, which I think is what you are referring to, the important thing is consistency and the specific use case.

The chapter on heat islands here goes into a few standard methods, including the use of normalized buffers, to calculate the surface UHI: https://docs.google.com/document/d/1MIPIFMJakC6eNGOhlkXLcwjUKFyY6QJLHElzBCOfyn4/edit

PS: I would generally be careful about using surface UHI for quantifying human heat exposure: Article Lower Urban Humidity Moderates Outdoor Heat Stress

I thank you all very much, I still don't have a clear answer but all of you have given me very valuable ideas.

I am quantifying the intensity of the heat islands, but this value changes a bit according to the cropping of the image (Landsat) with formula 2 (UHI)> https://www.sciencedirect.com/science/article/pii/ S2405844022014736#bib5

https://youtu.be/OGX8oVgS-QE

Here you can find some answers.

The procedure is as follows, when you edit the Landsat TIR images, they must be vectorized and then classified. It is interesting to overlay the classified LULC or NDVI maps so that you can determine the broadcast temperature for each purpose (LULC). If you do not succeed in QGiS to determine the classified excel table, try the command from ArcMap "tabulate spatial". If you still need help, get in touch.

In our recent research, the rural area was proposed using the NDVI index, and areas greater than 0.5 are preferred. The buffer zone was determined to reach 5 km, taking into account the neighboring urban centers, and then that area was excluded, due to the influence of urban centers that may reach this distance. Also, any body of water and its surrounding areas, up to half a kilo, were removed. In addition to removing any urban buildings, even if it was a very small town, all these areas were excluded in order to produce a pure and accurate rural area without any urban or water impact.

Article Satellite-Based Discrimination of Urban Dynamics-Induced Loc...

Dear Jenny Lizeth Flores Zuñiga Islam Hamdi Tomislav Djordjevic Tirthankar 'TC' Chakraborty

I would like to share with our research articles focusing on enhancing the green roof applications for mitigating Urban Heat Island effects. We kindly request your recommendations for making our findings visible to fellow researchers as well:

Article Feasibility study for estimating optimal substrate parameter...

Article Green roof substrates—A literature review

Roofs can basically have a cooling role, so why use them as a mitigation factor through cultivation?