NWT RESEARCH DATABASE

Tags: physical sciences, climatology, climate change, glaciology, atmospheric sciences, meteorology, cloud

Objective(s): To improve the understanding of the cloud-related processes in the Arctic atmosphere and to use these measurements to improve the performance of regional and global climate models of the Arctic; and to obtain a snapshot of ice thickness in this region of the Arctic, to create an inventory of Arctic sea ice volume, and to provide background information needed for the cloud studies.

Project Description: Climate change and sea ice change affects all who live in the north. The aim of this project is to improve understanding of the physical processes in Arctic clouds and their contribution to the current changes in the polar environment, and thereby reducing uncertainties in regional and global model simulations important for future weather and climate prediction. These research activities combine investigations of clouds and sea ice in the Beaufort Sea. The main aim of the cloud studies is to improve the understanding of the cloud-related processes in the Arctic atmosphere and to use these measurements to improve the performance of regional and global climate models of the Arctic. The aim of the sea ice studies is to obtain a snapshot of ice thickness in this region of the Arctic, to create an inventory of Arctic sea ice volume, and to provide background information needed for the cloud studies. The target of the cloud studies will be low-level stratiform clouds (1000–6000 ft / 300–2000 m). The scientific objective is to observe (from above) and probe (from inside) those clouds. To this purpose, two kinds of flight strategies are required, one for “remote sensing” using solar radiation (observing) and one for “in-situ probing” of the cloud particles (concentration, size, phase, shape), respectively. Both kinds of strategies may be combined in any given science flight, and are briefly described now: a) Remote-sensing flight legs will be typically performed at a constant altitude above the cloud top (typically near the maximum aircraft altitude; 10,000 ft / 3,000 m). These legs are straight lines up to 100 km long. Circles (1–2 km radius) at a defined bank (roll) angle will be inserted at defined locations to determine the full Stokes vector of the reflected polarized radiance. The instrumentation for these observations (SMART-Albedometer, AISA Eagle, Sun Photometer, AMALi) is almost entirely located inside the under-floor compartments of the aircraft, which are closed by roller doors when not operated. Only the sun photometer and parts of the SMART-Albedometer are mounted on the roof of the aircraft: While the sun photometer is installed within the large glass dome, the SMART-albedometer optical inlets are mounted at the view port close to the door. AMALi, the lidar system, can also be configured to measure in zenith direction, for which a second viewport on top of the fuselage is used. Legs at 10,000 ft (3 km) altitude will include launches of drop sondes over uninhabited areas to determine the vertical structure of the atmosphere. The lidar system will be operated in nadir direction only above altitudes of 9,000 feet. In zenith configuration it will be operated at all altitudes. b) In-situ flight legs typically consist of ramps (ascending and descending, at a rate of 500 to 1000 ft per minute) through the cloud layer as well as horizontal sections just above the cloud top (to remove aircraft icing) and just below the cloud bottom (background aerosol characterization). The instrumentation used during these legs will be installed in standard PMS canisters under the wings. The lidar will be switched off during these legs. The aerosol characterization is partly realized by systems (ALABAMA) that suck air through an aerosol inlet fixed on the top of the aircraft. For the typical cloud study, the Polar 5 aircraft will take off from Inuvik airport and fly at high altitude (approx. 3000 m) into the target area and perform the described science flight legs there. In addition, horizontal legs may be performed over the sea ice at the lowest possible altitude (500 ft in general; only for measurements of the ice thickness: 200 ft) to characterize the surface properties. No drop-sonde launches; no nadir laser operations; only if visibility permits. For the sea-ice studies, low-level flights at 200 ft (61 m) over the frozen Beaufort Sea will be conducted to measure the thickness of the sea ice. One or two flights of this kind will be conducted between 20 April and 23 April 2012 (depending on weather conditions) from Inuvik airport. The aircraft will not fly at low altitudes until it is safely away from the coast of the mainland and Banks Island. After each research mission, the aircraft will fly back to Inuvik at high altitudes (up to 3,000 m) measuring solar radiation and aerosols. No landing of the aircraft will take place during each mission. The aircraft will avoid the floe edge and bird/wildlife sanctuaries. The crew on board the aircraft will look for marine mammals on the sea ice, and if encountered during low altitude flight, the aircraft will change course to avoid them. If the proposed flight plan is not suitable, the crew will take a different route based on the recommendation of the local Hunters and Trappers Committees. The Polar 5 research aircraft is a Canadian Basler BT–67 (call sign C–GAWI) and will be equipped with the following instruments: cloud-particle probes NIXE/CCP/CAS (cloud particle size distribution), Small Ice Detector (characterization of ice particles in clouds), SMART-Albedometer (measurement of the solar radiation spectrum), AISA Eagle (hyperspectral camera), broadband sensors for solar and infrared radiation, AMALi lidar system, AIMMS-20 (winds and turbulence), electromagnetic bird (sea ice thickness), ALABAMA (aerosol particles mass spectrometer), sun photometer (optical thickness of aerosol column), digital video cameras, and meteorological sensors. A summary report will be submitted to the Aurora Research Institute, Inuvik. The fieldwork for this study will be conducted from April 20, 2012 to May 20, 2012.