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SKOPJE’S FIRST THERMAL MAP! Are Urban Heat Islands Real?

How I became part of this project?

After more than four years of doing researches all over the World as a GIS and Remote Sensing researcher, a chance was given to me to be a part of a project related to my hometown. There was no way I was going to say NO to that!

In May 2018, together with my colleagues, we wrote a conference paper about the Urban Heat Island effect in Skopje based on satellite images. This was not our first research on this topic, and we also worked on some projects related to this topic. But this time, I was more connected to the topic, it was my hometown!


The paper got big attention from the local people, since a small number of satellite imagery studies have been conducted over Skopje, and the topic of Global Warming and Urban Heat Island effects is a trendy topic. It was no long until I got an invitation to be a part of a project, “ICT for Urban Resilience”, implemented jointly by the City of Skopje and UNDP.

What are the “famous” Urban Heat Islands?

The easiest way for me to explain the phenomena of Urban Heat Islands is through a simple example;

Often people go away for the weekend, away from the city, in a more green environment. Well, it is no secret that those areas are cooler than the center of the cities, so there it is, that’s what Urban Heat Island presents, the differences in the air temperatures between the urban and the rural temperatures. Of course, the reason for this condition are the anthropogenic activities.


So, what was my part in the project?

While the great team of the Faculty of Computer Science and Engineering of Skopje was responsible for the data collection, our team took part in processing the collected data. Thus, the data collection was performed on 24 August 2018, using an aircraft Cessna 172, in the afternoon hours, when the temperatures are expected to be high. The air temperature was also recorded on the same day, and it was noted that the air temperatures were varying from 29 to 32.5 ⁰C in the period between 11:00 and 16:00 o’clock. The data collection was made with two different cameras, one as we know it, capturing what we can see, and one collecting thermal data, or the capturing the heat of the surface. Data collection resulted with 20.000 separate images that needed to be merged into one map! Even though everything seemed easy at the start, and we already had experience in this kind of projects, our team had very exciting twenty days of hard work. First, in order to process 20.000 images, a very good Hardware is needed. One of the computers that we worked on had 128 GB RAM, GPU NVIDIA Quadro K4200, and Intel(R) Xeon(R) CPU E5–2643 @ 3.40 GHz. I must say that the first part of the data collected with the RGB (normal) camera was processed in three days together with its 3D model, and we thought, “well this is going to be easy!”, well, it wasn’t. The data from the thermal camera did not have geographical information (coordinates), so we had to process the data in a local coordinate system, and then transform them in the national grid using the RGB data. On the top of it, the thermal camera did not collect the temperature of the surface, but the radiance, so additional conversions needed to be done.

Our Results

After approximately three weeks, we were happy to see the results from our hard work. The first product was the high-resolution map of Skopje. With 50 cm per pixel, we also created Skopje’s first high-resolution 3D model! You can find a simulated flight over the 3D model on the following link:

Our main product in this project was, of course, the thermal map. The thermal map is with 1.5 m resolution and presents real surface temperature of the city of Skopje of 24 August 2018.

The final product of this project was the Urban Heat Analysis. These analyses were made using GIS tools. Similar to the results from our previous research, results showed that, yes, there is an Urban Heat Island effect in the city of Skopje. Areas affected by UHI are usually dense urban areas and non-vegetated agricultural areas.


Gordana Kaplan, Ph.D. candidate

Gordana (Jovanovska) Kaplan received her MSc degree in geodesy from St. Kiril and Metodij University, Skopje, Macedonia, in 2014. In February 2015, she started her Ph.D. studies at Anadolu University, Eskisehir, Turkey, as a winner of the Turkiye Burslari Scholarship. Currently, she is working as a researcher at the Earth and Space Scientific Institute at Anadolu University. Her current research interests include Remote Sensing techniques and Geo-Information Systems, mapping and monitoring of water and wetland areas using image fusion techniques and remote sensing data, as well as Land Surface Temperature and Urban Heat Island analyses.

Being a part of the “ICT for Urban Resilience” Project, SkopjeLab — City of Skopje Innovation Centre has the pleasure to share Ph.D. candidate Gordana Kaplan’s research paper on Urban Heat Islands in the City of Skopje and will continue to partner up with academic institutions in order to implement innovation and technology in the public sector.

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