Monday, 28 August 2023
Boundary Waters (Hyatt Regency Minneapolis)
The European ICE GENESIS project (https://www.ice-genesis.eu/) aims to better measure, understand and model the properties and the mechanisms of snow particles responsible for icing of rotor-craft and aircraft. As a milestone of this project, an international field experiment took place in the Swiss Jura Mountains in January 2021, with the aim to collect observations of clouds and snowfall at a prescribed range of temperatures (-10°C to +2°C), dictated by test conditions.
The campaign is a multi-sensor deployment featuring ground-based and airborne, remote sensing and in-situ measurements, during a two-week time frame in January 2021. While some instruments collected data over a longer period of a few months, this intensive observation period included overpasses of an instrumented scientific aircraft (Safire-ATR42), critical to sample precipitating systems in the temperature range of interest. The flight plans consisted of relatively short (15-25 km) legs in the vicinity of the ground-based platform. The sampling legs were performed at different constant-altitude flight levels, which were chosen depending on the temperature profile and within the authorized flight paths, constrained by the topography.
On-board the Safire ATR 42 was a suite of in-situ instruments including airborne probes and imagers, able to sample liquid and ice particles from the micron to the centimeter size range, as well as icing sensors and cameras. The aircraft payload also comprised a combination of two multi-beam W-band radars profiling above and across the aircraft path.
At the ground level, the main measurement site included: a high-sensitivity X-band Doppler spectral profiler, a K-band Doppler spectral profiler, a dual-polarization W-band Doppler spectral zenith profiler complemented with an 89 GHz radiometer, an additional W-band profiler and a scanning system composed of a W-band radar and a 808 nm micro-pulse lidar. A multi-angle snowflake camera (MASC) was also deployed about 500 m from this main site, together with a 3D sonic anemometer. In a secondary site, an X-band polarimetric radar deployed about 5 km away performed 5-minute scanning cycles with RHI (Range-Height-Indicator) scans in the direction of the main instrumental suite.
The synoptic situation during the campaign was dominated by a succession of lows over North-Western Europe, which maintained mostly dynamic and wet conditions over Switzerland.
Between January 23 and January 27, the weather was cold enough to bring snowfall at ground level, while the last days of January were characterized by warmer temperatures with rainfall at ground level and a melting layer around 1500 to 2000 m amsl. 140 mm of total precipitation were recorded during this period and about 120 hours of precipitation of which 70 hours with snowfall at the ground level at the main site.
The campaign showed its full potential during five multi-hourly flights during which precipitation was monitored from cloud to ground. The originality of this campaign resides in the targeted specific temperature range for snowfall and in the synchronization between the ground-based remote sensing and the aircraft trajectories designed to maximize the collection of in-situ observations within the column above the radar systems. In spite of its relatively short duration, the ICE GENESIS campaign provides a rich dataset (publicly available at the portal https://ice-genesis.aeris-data.fr/catalogue/), with detailed in-situ information on cloud and precipitation microphysics at various temperatures and down to ground level, collocated with multi-frequency radar observations including high-resolution Doppler spectra. The set-up is therefore ideal to find evidence of microphysical signatures of many processes affecting precipitation and the composition of the hydrometeor populations in given observation volumes. The ICE GENESIS dataset opens up possibilities for new or improved radar-based retrievals of snowfall microphysical properties and process-oriented studies, that can be validated with in-situ observations. The data also offers opportunities in the field of numerical weather prediction, for example for the improvement and validation of microphysical schemes in meteorological models, through the comparison of model outputs with in-situ measurements or radar retrievals in a region of complex orography.
The campaign is a multi-sensor deployment featuring ground-based and airborne, remote sensing and in-situ measurements, during a two-week time frame in January 2021. While some instruments collected data over a longer period of a few months, this intensive observation period included overpasses of an instrumented scientific aircraft (Safire-ATR42), critical to sample precipitating systems in the temperature range of interest. The flight plans consisted of relatively short (15-25 km) legs in the vicinity of the ground-based platform. The sampling legs were performed at different constant-altitude flight levels, which were chosen depending on the temperature profile and within the authorized flight paths, constrained by the topography.
On-board the Safire ATR 42 was a suite of in-situ instruments including airborne probes and imagers, able to sample liquid and ice particles from the micron to the centimeter size range, as well as icing sensors and cameras. The aircraft payload also comprised a combination of two multi-beam W-band radars profiling above and across the aircraft path.
At the ground level, the main measurement site included: a high-sensitivity X-band Doppler spectral profiler, a K-band Doppler spectral profiler, a dual-polarization W-band Doppler spectral zenith profiler complemented with an 89 GHz radiometer, an additional W-band profiler and a scanning system composed of a W-band radar and a 808 nm micro-pulse lidar. A multi-angle snowflake camera (MASC) was also deployed about 500 m from this main site, together with a 3D sonic anemometer. In a secondary site, an X-band polarimetric radar deployed about 5 km away performed 5-minute scanning cycles with RHI (Range-Height-Indicator) scans in the direction of the main instrumental suite.
The synoptic situation during the campaign was dominated by a succession of lows over North-Western Europe, which maintained mostly dynamic and wet conditions over Switzerland.
Between January 23 and January 27, the weather was cold enough to bring snowfall at ground level, while the last days of January were characterized by warmer temperatures with rainfall at ground level and a melting layer around 1500 to 2000 m amsl. 140 mm of total precipitation were recorded during this period and about 120 hours of precipitation of which 70 hours with snowfall at the ground level at the main site.
The campaign showed its full potential during five multi-hourly flights during which precipitation was monitored from cloud to ground. The originality of this campaign resides in the targeted specific temperature range for snowfall and in the synchronization between the ground-based remote sensing and the aircraft trajectories designed to maximize the collection of in-situ observations within the column above the radar systems. In spite of its relatively short duration, the ICE GENESIS campaign provides a rich dataset (publicly available at the portal https://ice-genesis.aeris-data.fr/catalogue/), with detailed in-situ information on cloud and precipitation microphysics at various temperatures and down to ground level, collocated with multi-frequency radar observations including high-resolution Doppler spectra. The set-up is therefore ideal to find evidence of microphysical signatures of many processes affecting precipitation and the composition of the hydrometeor populations in given observation volumes. The ICE GENESIS dataset opens up possibilities for new or improved radar-based retrievals of snowfall microphysical properties and process-oriented studies, that can be validated with in-situ observations. The data also offers opportunities in the field of numerical weather prediction, for example for the improvement and validation of microphysical schemes in meteorological models, through the comparison of model outputs with in-situ measurements or radar retrievals in a region of complex orography.
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