DIAL and GNSS observations of the diurnal water‐vapour cycle above Iqaluit, Nunavut

Atmospheric water vapour is the dominant gas in greenhouse effect and its diurnal cycle an essential component of hydrological cycle. High-quality water-vapour measurements are critical observations for numerical weather prediction (NWP) models, which encounter difficulties Arctic due to unique weather. Accurate can improve precipitation rate type predictions. In this study, we use a preproduction Vaisala broad-band differential absorption lidar (DIAL), installed Iqaluit, Nunavut (63.75°N, 68.55°W), calculate seasonal height-resolved cycles from 100–1,500 m altitude. We also surface mixing ratio integrated (IWV) using co-located station global navigation satellite system (GNSS) measurements. find that first 250 DIAL agrees within 0.02 g · kg − 1 with surface-station amplitudes, 0–2 hr phase. diurnal-cycle R 2 values close at surface, between 0.25 0.95 depending on altitude season. The phases shift amplitudes increase summer, all instruments observe strong 24-hr amplitude decreases solar cycle, such 12-hr begins influence total significantly by winter. IWV has large throughout year, could be superposition two components different altitudes or increasing contributions higher than those measured DIAL. have shown provides deeper understanding achieved GNSS alone.