Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project

Beswick, K.M.; Gallagher, Martin; Webb, Ann R.; Norton, E. G.; Perry, Felicity

doi:10.5194/acp-8-5449-2008

Cited by 78 publications

(67 citation statements)

References 23 publications

(19 reference statements)

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“…Again, this measures the flow velocity relative to the aircraft (at the instrument location), with a separate combined GPS-inertial system to measure Earth-relative velocity, attitude and attitude-rate information. The instrument carried on the FAAM aircraft differs from that described by Beswick et al [56] in that its nose probe is de-iced. In order to remove any melt-water that has entered the differential pressure sensor lines, these are connected to a pressure system that can be operated periodically to blow out the lines.…”

Section: Instrumentationmentioning

confidence: 98%

“…Technical limitations due to the need to avoid interference with the operation of the aircraft's standard weather radar mean that the system cannot be de-iced. The second system is an Aventech AIMMS-20 (Airborne Integrated Meteorological Measurement System [56]). This is an instrument package, the external components of which are carried in a standard underwing canister of the kind normally used to carry cloud and aerosol probes.…”

Section: Instrumentationmentioning

confidence: 99%

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Mountain Waves in High Resolution Forecast Models: Automated Diagnostics of Wave Severity and Impact on Surface Winds

Sheridan

Brown

2017

Atmosphere

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An automated method producing a diagnostic of the severity of lee waves and their impacts on surface winds as represented in output from a high resolution linear numerical model (3D velocities over mountains (3DVOM)) covering several areas of the U.K. is discussed. Lee waves involving turbulent rotor activity or downslope windstorms represent a hazard to aviation and ground transport, and summary information of this kind is highly valuable as an efficient 'heads-up' for forecasters, for automated products or to feed into impact models. Automated diagnosis of lee wave surface effects presents a particular challenge due to the complexity of turbulent zones in the lee of irregular terrain. The method proposed quantifies modelled wind perturbations relative to those that would occur in the absence of lee waves for a given background wind, and diagnoses using it are found to be quite consistent between cases and for different ranges of U.K. hills. A recent upgrade of the operational U.K. limited area model, the U.K. Variable Resolution Model (UKV) used for general forecasting at the Met Office means that it now resolves lee waves, and its performance is here demonstrated using comparisons with aircraft-and surface-based observations and the linear model. In the future, automated diagnostics may be adapted to use its output to routinely produce contiguous mesoscale maps of lee wave activity and surface impacts over the whole U.K.

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Section: Instrumentationmentioning

confidence: 98%

Section: Instrumentationmentioning

confidence: 99%

Mountain Waves in High Resolution Forecast Models: Automated Diagnostics of Wave Severity and Impact on Surface Winds

Sheridan

Brown

2017

Atmosphere

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“…In parts of the cloud that are not at their level of neutral buoyancy, the in-cloud temperatures may be up to a few degrees Celsius warmer or cooler due to the energies associated with changes in the phase of water molecules (Wang and Geerts, 2009). A de-iced Aventech aircraft-integrated meteorological measurement system (AIMMS)-20 turbulence probe (Beswick et al, 2008) was used to measure the 3-D wind vector at 20 Hz. The stated accuracy of the AIMMS vertical wind (W ) is ∼ 0.75 m s −1 , though intercomparisons between the AIMMS and the BAe-146's radome-mounted five-port turbulence sensor agreed within around 0.5 m s −1 .…”

Section: Meteorological Instrumentationmentioning

confidence: 99%

Observations of cloud microphysics and ice formation during COPE

et al. 2016

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Abstract. We present microphysical observations of cumulus clouds measured over the southwest peninsula of the UK during the COnvective Precipitation Experiment (COPE) in August 2013, which are framed into a wider context using ground-based and airborne radar measurements. Two lines of cumulus clouds formed in the early afternoon along convergence lines aligned with the peninsula. The lines became longer and broader during the afternoon due to new cell formation and stratiform regions forming downwind of the convective cells. Ice concentrations up to 350 L −1 , well in excess of the expected ice nuclei (IN) concentrations, were measured in the mature stratiform regions, suggesting that secondary ice production was active.Detailed sampling focused on an isolated liquid cloud that glaciated as it matured to merge with a band of cloud downwind. In the initial cell, drizzle concentrations increased from ∼ 0.5 to ∼ 20 L −1 in around 20 min. Ice concentrations developed up to a few per litre, which is around the level expected of primary IN. The ice images were most consistent with freezing drizzle, rather than smaller cloud drops or interstitial IN forming the first ice.As new cells emerged in and around the cloud, ice concentrations up to 2 orders of magnitude higher than the predicted IN concentrations developed, and the cloud glaciated over a period of 12-15 min. Almost all of the first ice particles to be observed were frozen drops, while vapour-grown ice crystals were dominant in the latter stages. Our observations are consistent with the production of large numbers of small secondary ice crystals/fragments, by a mechanism such as Hallett-Mossop or droplets shattering upon freezing. Some of the small ice froze drizzle drops on contact, while others grew more slowly by vapour deposition. Graupel and columns were seen in cloud penetrations up to the −12 • C level, though many ice particles were mixed habit due to riming and growth by vapour deposition at multiple temperatures.Our observations demonstrate that the freezing of drizzle/raindrops is an important process that dominates the formation of large ice in the intermediate stages of cloud development. As these frozen drops were the first precipitation observed, interactions between the warm-rain and secondary ice production processes appear to be key to determining the timing and location of precipitation.

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“…The CO concentration was measured using an AeroLaser VUV fluorescence monitor model AL5002 (Gerbig et al, 1999), and the 3-D wind vector was measured with a deiced Aventech aircraft-integrated meteorological measurement system (AIMMS)-20 turbulence probe (Beswick et al, 2008). A Stratton Park Engineering Company SPEC 2DS stereo probe was used to derive ice concentration, using the data processing rules described by Taylor et al (2016).…”

Section: Aircraft Measurementsmentioning

confidence: 99%

Aerosol measurements during COPE: composition, size, and sources of CCN and INPs at the interface between marine and terrestrial influences

et al. 2016

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Abstract. Heavy rainfall from convective clouds can lead to devastating flash flooding, and observations of aerosols and clouds are required to improve cloud parameterisations used in precipitation forecasts. We present measurements of boundary layer aerosol concentration, size, and composition from a series of research flights performed over the southwest peninsula of the UK during the COnvective Precipitation Experiment (COPE) of summer 2013. We place emphasis on periods of southwesterly winds, which locally are most conducive to convective cloud formation, when marine air from the Atlantic reached the peninsula. Accumulation-mode aerosol mass loadings were typically 2-3 µg m −3 (corrected to standard cubic metres at 1013.25 hPa and 273.15 K), the majority of which was sulfuric acid over the sea, or ammonium sulfate inland, as terrestrial ammonia sources neutralised the aerosol. The cloud condensation nuclei (CCN) concentrations in these conditions were ∼ 150-280 cm −3 at 0.1 % and 400-500 cm −3 at 0.9 % supersaturation (SST), which are in good agreement with previous Atlantic measurements, and the cloud drop concentrations at cloud base ranged from 100 to 500 cm −3 . The concentration of CCN at 0.1 % SST was well correlated with non-sea-salt sulfate, meaning marine sulfate formation was likely the main source of CCN. Marine organic aerosol (OA) had a similar mass spectrum to previous measurements of sea spray OA and was poorly correlated with CCN.In one case study that was significantly different to the rest, polluted anthropogenic emissions from the southern and central UK advected to the peninsula, with significant enhancements of OA, ammonium nitrate and sulfate, and black carbon. The CCN concentrations here were around 6 times higher than in the clean cases, and the cloud drop number concentrations were 3-4 times higher.Sources of ice-nucleating particles (INPs) were assessed by comparing different parameterisations used to predict INP concentrations, using measured aerosol concentrations as input. The parameterisations based on total aerosol produced INP concentrations that agreed within an order of magnitude with measured first ice concentrations at cloud temperatures as low as −12 • C. Composition-specific parameterisations for mineral dust, fluorescent particles, and sea spray OA were 3-4 orders of magnitude lower than the measured first ice concentrations, meaning a source of INPs was present that was not characterised by our measurements and/or one or more of the composition-specific parameterisations greatly underestimated INPs in this environment.

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Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project

Cited by 78 publications

References 23 publications

Mountain Waves in High Resolution Forecast Models: Automated Diagnostics of Wave Severity and Impact on Surface Winds

Mountain Waves in High Resolution Forecast Models: Automated Diagnostics of Wave Severity and Impact on Surface Winds

Observations of cloud microphysics and ice formation during COPE

Aerosol measurements during COPE: composition, size, and sources of CCN and INPs at the interface between marine and terrestrial influences

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