Free satellite data and open-source tools for urban green spaces and temperature pattern analysis in Algiers

• Algiers experienced increasing urbanisation and decreasing urban green spaces (UGSs) between 2004 and 2022. • Integration of static landscape metrics and dynamic Land Surface Temperature (LST) trends showed persistent warming trends. • Analysis of landscape metrics identified 600 m as the optimal scale for assessing UGSs-LST relationships in Algiers. • The vegetation cover metric, PLAND, explained 61% of LST variability; larger, contiguous UGS enhanced cooling. • A novel open-source framework — PyQGIS LMs calculator, GEE and RStudio — facilitates analysis in resource-limited settings. Rapid urbanization and global climate change are intensifying the Urban Heat Island (UHI) effect in cities worldwide, with consequences for human health and well-being. Urban green spaces (UGSs) mitigate extreme temperatures, but their cooling potential depends on spatial configuration, size, shape, and distribution. This study fills a geographic gap by providing one of the first detailed analyses of UGSs-Land Surface Temperature (LST) dynamics in a North African context. It combines spatial pattern analysis with temporal trend detection to comprehensively evaluate UGSs-LST relationships in Algiers from 2004 to 2022, addressing a common limitation in the literature where these approaches are often treated separately. Using freely available satellite data and open-source tools—including Landsat data from Google Earth Engine (GEE), QGIS, and RStudio—we integrate supervised classification, landscape metrics (LMs) computation via our custom PyQGIS LMs calculator, and Mann-Kendall trend analysis to quantify the static spatial configuration of green spaces and their dynamic thermal impacts over time. Findings reveal a 38% decrease in green spaces and a 10% reduction in agricultural land, accompanied by increased urbanization. Strong negative correlations between some LMs and LST were observed, with PLAND (Percentage of Landscape) explaining 61% of LST variability at an optimal 600-meter scale. This medium-sized scale differs from previous findings in other regions, highlighting the importance of context-specific analysis. LST trend analysis identified specific heat-resistant zones characterized by large, contiguous green patches. Despite greening initiatives, UGSs in Algiers continue to decline, underlining the need to preserve and strategically expand UGSs to combat rising temperatures.