A Multi-Year Evaluation of Doppler Lidar Wind-Profile Observations in the Arctic

Abstract

Doppler light detection and ranging (lidar) wind profilers have proven their capability to measure vertical wind profiles with an accuracy comparable to anemometers and radiosondes. However, most of these comparisons were performed over short time periods or at mid-latitudes. This study presents a multi-year assessment of the accuracy of Doppler lidar wind-profile measurements in the Arctic by comparing them with coincident radiosonde observations, and excellent agreement was observed. The suitability of the Doppler lidar for verification case studies of operational numerical weather prediction (NWP) models during the World Meteorological Organization’s Year of Polar Prediction is also demonstrated, by using Environment and Climate Change Canada’s (ECCC) global environmental multiscale model (GEM-2.5 km and GEM-10 km). Since 2016, identical scanning Doppler lidars were deployed at two supersites commissioned by ECCC as part of the Canadian Arctic Weather Science project. The supersites are located in Iqaluit (64°N, 69°W) and Whitehorse (61°N, 135°W) with a third Halo Doppler lidar located in Squamish (50°N, 123°W). Two lidar wind-profile measurement methodologies were investigated; the velocity-azimuth display method exhibited a smaller average bias (−0.27 ± 0.02 m/s) than the Doppler beam-swinging method (–0.46 ± 0.02 m/s) compared to the sonde. Comparisons to ECCC’s NWP models indicate good agreement, more so during the summer months, with an average bias < 0.71 m/s for the higher-resolution (GEM-2.5 km) ECCC models at Iqaluit. Larger biases were found in the mountainous terrain of Whitehorse and Squamish, likely due to difficulties in the model’s ability to resolve the topography. This provides evidence in favor of using high temporal resolution lidar wind-profile measurements to complement radiosonde observations and for NWP model verification and process studies.

Evaluation of Arctic Water Vapor Profile Observations from a Differential Absorption Lidar

“…Overall, the performance of the DIAL in Iqaluit is similar to previous evaluations in southern latitudes using the same DIAL and a Raman lidar [29] and for the prototype DIAL, RSs, and a Raman lidar [26]. In particular, the shape of the DIAL's positive mean bias profile and the larger bias and STDE below 400 m (including oscillations in the WVMR profile) were also found in these studies.…”

“…The site was a designated supersite for the WMO YOPP project. It has been equipped with a suite of co-located remote-sensing and in-situ instruments for meteorological observations since 2015 [28,29]. With the enhanced meteorological observations conducted at the site, international NWP modeling centers, including ECCC, provided model output data at the model time-step in a 7 × 7 grid centered on Iqaluit and other YOPP-designated supersites during the YOPP (https://yopp.met.no/node/54 (accessed on 13 November 2020)).…”

“…ECCC's operational NWP models are based on the Canadian global environmental multiscale (GEM) model [36][37][38][39]. The regional deterministic prediction system (RDPS, 10 km grid spacing) is a limited area model (LAM) that covers North America and the entire Arctic region (see Section 3.2 in Reference [29] for the experimental setup and a map of the domain). It is nested within the Global Deterministic Prediction System (GDPS, 25 km resolution), which is fully coupled with the global ice and ocean prediction system (GIOPS) [40].…”

“…Using a similar experimental design as the NWP model verification case study via Doppler lidar wind profiles [29], almost one year of comparisons (7 September 2018 to 22 August 2019) between the RDPS, HRDPS, and CAPS model output and the DIAL WVMR profile observations were performed. The goal of these comparisons was to verify NWP model WVMR output as part of the YOPP project.…”

“…This study presents a detailed evaluation of the new pre-production Vaisala DIAL system currently operating at the Canadian Arctic Weather Science (CAWS) Iqaluit supersite (63.74 • N, 68.51 • W) [27] during the World Meteorological Organization's (WMO) Year of Polar Prediction (YOPP) project (core phase: mid-2017 to mid-2019) [28,29]. Comparisons between the new pre-production DIAL system and RS observations were conducted over almost one year of continuous observations (7 September 2018 to 22 August 2019), and Raman lidar comparisons were conducted over six months (7 September 2018to 27 February 2019.…”