Simultaneous profiling of the Arctic Atmospheric Boundary Layer S. Mayer, M. Jonassen, Jonassen, and J. Reuder Geophysical Institute, University of Bergen, Norway
Introduction
The SUMO system
Simultaneous profiles over land and open water April 02, 06:23 Local Time
The structure and diurnal development of Arctic Atmospheric Boundary Layer (AABL) is not well understood yet. The key to better knowledge of the AABL is the detailed information on its vertical structure and horizontal variability with respect to temperature, humidity and wind. In this study, the small unmanned meteorological observer (SUMO) as described by Reuder et al. (2008) is used under Arctic conditions in Longyearbyen, Spitsbergen. SUMO has been operated in different missions, mainly vertical profile flights and horizontal surveys. For the first time two SUMO aircrafts have been operated simultaneously over snow-covered land and open water of Isfjorden (see map) to determine synchronized atmospheric profiles. The measured profiles document the detailed structure of the stable AABL.
• Cost-efficient ‘recoverable radiosonde’: ~ 150 € for model airplane construction kit FunJet from Multiplex including an advanced brushless motor ~ 500 € for required electronic boards and components communication hardware
• Longyear airport, Spitsbergen. • March-April 2009. • more than 90 flights: - 60 single profiles up to 1500 m agl. - 25 horizontal surveys. - 8 simultaneous profiles.
Length Wingspan Weight Average airspeed Maximum airspeed Average ascent rate Maximum ascent rate Maximum altitude above ground Endurance
• Autonomous navigation, with Paparazzi, an open source autopilot system. • Attitude detection in x-, y- and z-direction by 3 pairs of infrared thermopiles.
75 cm 80 cm 580 g 1212-18 m/s 35 m/s 7-10 m/s 15 m/s 3.5 km+ Up to 30min
’.
• Meteorological data and aircraft position are transmitted continuously with an update frequency of 4 Hz. • Profiles of wind speed and direction can be determined from the GPS speed above ground by operating SUMO in a helical flight pattern with constant throttle and pitch.
Measured temperature, humidity and wind profiles of two simultaneously descending SUMOs. The horizontal distance between the profiles is 1 km. Above the open water of Isfjorden close to Longyear airport a very stable surface layer has been observed. Water vapor was evaporating from the relatively warm water (T > -2°C) into the -20°C cold AABL. At a height of 600 m agl the water vapor was condensating visible by the evolution of a thin layer of stratocumulus clouds. The arrows indicate the top of the stratocumulus layer.
Technical details of the FunJet airframe used as SUMO platform.
• Pressure sensor is mounted inside the fuselage. • The combined temperature humidity sensor is mounted at the side of the fuselage in a radiation shield tube.
Field campaign
The FunJet construction kit.
• Meteorological sensors for temperature (SHT75 by Sensirion ) humidity (SHT75 by Sensirion) pressure (SCP1000 by VTI Technologies)
The measured profiles document the detailed structure of the stable AABL, characterized by numerous layers of differing stability.
Flight paths of two simultaneous profiles over land and open water at Longyearbyen airport.
1. The AABL above water is marginally warmer (∆T ≈ 0.5K). 2. Above water a significant accumulation of water vapor has been observed at the top of the mixed layer. Above this level the humidity profiles show almost identical behaviour; below great variability. 3. The wind profiles show almost no difference between land and see. Acknowledgements
Isfjorden
The authors are thankful for the work of Martin Müller, Christian Lindenberg and the other Paparazzi members that have made the SUMO project possible through their assistance and provision of their system as a whole with aircraft, hardware and software. The main financial support for the development of SUMO was provided by the Meltzer University Foundation, Bergen, Norway. The field campaign was financed by Svalbard Science Forum (SSF), Arctic Field Grant 2009, RiS ID 3346.
References
Longyearbyen
Contact:
Geophysical Institute, University of Bergen Allegaten 70, N-5007 Bergen, Norway
[email protected] [email protected]
Screenshot of the open source Paparazzi application. Google Earth is used as underlying map information.
Brisset P.: The Paparazzi solution http://www.recherche.enac.fr/paparazzi/papers 2006/mav06 paparazzi.pdf, 2006. Jonassen, M.: The Small Unmanned Meteorological Observer (SUMO) - Characterization and test of a new measurement system for atmospheric boundary layer research, Master’s thesis at Geophysical Institute, University of Bergen, 2008. Reuder J., Brisset P., Jonassen M., Müller M., Mayer S.: The Small Unmanned Meteorological Observer SUMO: A new tool for atmospheric boundary layer research, Meteorologische Zeitschrift, in press, 2009. Mayer S., Sandvik A., Jonassen M., Reuder J.: Atmospheric profiling with the UAS SUMO: A new perspective for the evaluation of fine-scale atmospheric models, Meteorology and Atmospheric Physics, submitted 2009.
