# Assessing Spatiotemporal LST Variations in Urban Landscapes Using Diurnal UAV Thermography
## 4 Results
### Frequency Distributions and Descriptive Statistics Analysis  
The frequency distributions of LST across different LULC classes and temporal periods revealed distinct thermal behavior patterns, with histograms showing notable variations in distribution shapes and temperature ranges (Figure 5). During morning hours, bare soil and grassland exhibited relatively symmetric distributions centered around 7 \({}^{\circ}\)C, while building and paved road surfaces showed positively skewed distributions with peaks at lower temperatures (2-3 \({}^{\circ}\)C). Afternoon distributions indicated maximum thermal differentiation, with bare soil, grassland, and paved roads displaying broad, multi-modal distributions spanning 15-25 \({}^{\circ}\)C, whereas water bodies maintained a distinctive narrow, concentrated distribution (6-10 \({}^{\circ}\)C), reflecting their thermal stability. Evening patterns revealed interesting urban thermal characteristics, particularly in paved roads showing a platykurtic distribution across 5-15 \({}^{\circ}\)C, suggesting prolonged heat retention. The midnight distributions were especially noteworthy, with grassland exhibiting a pronounced normal distribution centered at \(-\)2.5 \({}^{\circ}\)C, while water bodies and paved surfaces maintained positive temperature ranges with right-skewed distributions.  
Figure 4: Box-and-whisker plots depicting the diurnal LST distribution across five LULC classes (bare soil, building, grassland, paved road, and water body) measured during four temporal periods (morning, afternoon, evening, and midnight).  
Descriptive statistics of LST by LULC class and temporal period are presented, offering a comprehensive analysis of diurnal LST variations across five distinct LULC classes (\(n=463\)) as presented in Table 1. The results reveal significant temporal and spatial heterogeneity in thermal patterns. Notably, bare soil and grassland exhibited the highest afternoon temperatures (\(20.39\pm 4.50\,\mathrm{\SIUnitSymbolCelsiusC}\) and \(20.57\pm 5.13\,\mathrm{\SIUnitSymbolCelsiusC}\), respectively), while water bodies demonstrated remarkable thermal stability across all temporal periods (SD range: 0.79-2.85 \(\,\mathrm{\SIUnitSymbolCelsiusC}\)). The maximum thermal amplitude was observed in buildings (\(\Delta T=21.28\,\mathrm{\SIUnitSymbolCelsiusC}\) during afternoon) and paved roads (\(\Delta T=20.31\,\mathrm{\SIUnitSymbolCelsiusC}\) during afternoon), indicating strong urban surface heating. Conversely, water bodies maintained the most moderate temperature fluctuations (maximum \(\Delta T=10.88\,\mathrm{\SIUnitSymbolCelsiusC}\) during morning period), consistent with their high thermal inertia. The midnight period revealed distinct cooling patterns, with grassland showing the lowest temperatures (\(-2.45\pm 0.31\,\mathrm{\SIUnitSymbolCelsiusC}\)), while paved roads and water bodies retained higher temperatures (\(2.25\pm 1.51\,\mathrm{\SIUnitSymbolCelsiusC}\) and \(2.39\pm 1.25\,\mathrm{\SIUnitSymbolCelsiusC}\), respectively), suggesting significant human-induced heat retention in urban materials.  
Figure 5: Frequency distributions of LST across five LULC classes (bare soil, building, grassland, paved road, and water body) during four diurnal periods (morning, afternoon, evening, and midnight). The histograms with overlaid kernel density estimates illustrate distinct thermal signatures and temporal evolution patterns.