Characterizing sea ice melt pond fraction and geometry in relation to surface morphology

Abstract. Melt ponds play a crucial role in modulating the energy balance of Arctic sea ice by reducing surface albedo. While Arctic sea ice is becoming younger and smoother, this raises questions about how these changes affect melt pond characteristics, as the effect of ice deformation features, such as pressure ridges, on pond development on large spatial scales remains insufficiently understood. Here, we analyze 70 km² of high resolution airborne optical imagery and coincided laser altimeter data from three research flights north of Greenland to investigate the relationship between ridge fraction and melt pond properties. Our results reveal that high melt pond fractions are not exclusive to smooth ice but can also occur on heavily deformed multi-year ice. Furthermore, we find that ridge fraction influences both the size distribution and geometry of melt ponds on various typical ice types. Whether ridges constrain pond geometry in a way that increases or decreases pond shape complexity depends on pond size: small ponds are on average more complex in the presence of ridges, whereas large ponds are restricted in their complexity. This shift in behavior occurs around the characteristic size scale of 10² m² that coincides with the transition in pond fractal dimension. These results demonstrate the role of ice morphology in shaping melt pond characteristics and provide valuable insights for improving melt pond parameterizations in sea ice models.