Isokinetic Total Water Content Probe in a Naturally Aspirating Configuration: Initial Aerodynamic Design and Testing

Davison, Craig R.; MacLeod, J. D.; Strapp, J. W.; Buttsworth, David

doi:10.2514/6.2008-435

Cited by 33 publications

(22 citation statements)

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“…borne radar measurements with regions of HIWC. TWC was measured by an Isokinetic probe (IKP2) that was specifically designed to measure very high TWC (Davison et al, 2008). Alternatively, IWC was estimated from the measured PSDs with the D-M parameterization tuned using IKP2 measurements.…”

Section: In Situ Datamentioning

confidence: 99%

Determination of ice water content (IWC) in tropical convective clouds from X-band dual-polarization airborne radar

2019

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This paper presents a methodology for ice water content (IWC) retrieval from a dual-polarization sidelooking X-band airborne radar. Measured IWC from aircraft in situ probes is weighted by a function of the radar differential reflectivity (Z dr ) to reduce the effects of ice crystal shape and orientation on the variation in IWC -specific differential phase (K dp ) joint distribution. A theoretical study indicates that the proposed method, which does not require a knowledge of the particle size distribution (PSD) and number density of ice crystals, is suitable for high-ice-water-content (HIWC) regions in tropical convective clouds. Using datasets collected during the High Altitude Ice Crystals -High Ice Water Content (HAIC-HIWC) international field campaign in Cayenne, French Guiana (2015), it is shown that the proposed method improves the estimation bias by 35 % and increases the correlation by 4 % on average, compared to the method using specific differential phase (K dp ) alone. Wolde and Vali, 2001). It has been shown that the radar-Published by Copernicus Publications on behalf of the European Geosciences Union.

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Section: In Situ Datamentioning

confidence: 99%

Determination of ice water content (IWC) in tropical convective clouds from X-band dual-polarization airborne radar

2019

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“…The IKP2 probe is a downsized version of a prototype isokinetic evaporator designed especially to make measurements in the high IWC/high speed/high-altitude environment up to at least 10 g m 23 at 200 ms 21 with a target accuracy of 20% (Davison et al 2008). The probe measures total condensed water content and is close to a first-principles method due to the simple method of operation, the lack of empirical estimation, and the direct measurement of humidity to provide TWC.…”

Section: ) Ikp2 Probe and Data Processingmentioning

confidence: 99%

Ice Crystal Sizes in High Ice Water Content Clouds. Part II: Statistics of Mass Diameter Percentiles in Tropical Convection Observed during the HAIC/HIWC Project

Leroy

Fontaine

Schwarzenböeck

et al. 2017

Journal of Atmospheric and Oceanic Technology

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High ice water content (IWC) regions in mesoscale convective systems (MCSs) are a potential threat to commercial aviation, as they are suspected to cause in-service engine power-loss events and air data probe malfunctions. To investigate this, the high-altitude ice crystals (HAIC)/high ice water content (HIWC) projects set up a first field campaign in Darwin (Australia) in 2014. The airborne instrumentation was selected to provide the most accurate measurements of both the bulk total water content (TWC), using a specially developed isokinetic evaporator, and the individual ice crystals properties, using particle imaging probes. This study focuses on determining the size ranges of ice crystals responsible for the mass in high IWC regions, defined here as cloud regions with IWC greater than 1.5 g m−3. It is shown that for high IWC areas in most of the encountered MCSs, median mass diameters (MMDs) of ice crystals range from 250 to 500 μm and decrease with increasing TWC and decreasing temperature. At the same time, the mass contribution of the smallest crystals (below 100 μm) remains generally low (below 15%). In contrast, data from two flight missions in a long-lasting quasi-stationary tropical storm reveal that high IWC values can also be associated with MMDs in the range 400–800 μm and peak values of up to 2 mm. Ice crystal images suggest a major growth contribution by vapor deposition (columns, capped columns) even for such larger MMD values.

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“…Bulk TWC measurements were made with an isokinetic evaporator probe (IKP) first designed and developed by the National Research Council of Canada (NRC) and then reengineered as the IKP2 by Science Engineering Associates (SEA) Inc. and NRC to operate within the constraints of the Falcon 20 aircraft (Davison et al, 2008Strapp et al, 2016b). The probe was designed specifically for the measurement of high-altitude, high-IWC conditions, with a target accuracy of 20 %.…”

Section: Observationsmentioning

confidence: 99%

A ubiquitous ice size bias in simulations of tropical deep convection

et al. 2017

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Abstract. The High Altitude Ice Crystals -High Ice Water Content (HAIC-HIWC) joint field campaign produced aircraft retrievals of total condensed water content (TWC), hydrometeor particle size distributions (PSDs), and vertical velocity (w) in high ice water content regions of mature and decaying tropical mesoscale convective systems (MCSs). The resulting dataset is used here to explore causes of the commonly documented high bias in radar reflectivity within cloud-resolving simulations of deep convection. This bias has been linked to overly strong simulated convective updrafts lofting excessive condensate mass but is also modulated by parameterizations of hydrometeor size distributions, single particle properties, species separation, and microphysical processes. Observations are compared with three Weather Research and Forecasting model simulations of an observed MCS using different microphysics parameterizations while controlling for w, TWC, and temperature. Two popular bulk microphysics schemes (Thompson and Morrison) and one bin microphysics scheme (fast spectral bin microphysics) are compared. For temperatures between −10 and −40 • C and TWC > 1 g m −3 , all microphysics schemes produce median mass diameters (MMDs) that are generally larger than observed, and the precipitating ice species that controls this size bias varies by scheme, temperature, and w. Despite a much greater number of samples, all simulations fail to reproduce observed high-TWC conditions (> 2 g m −3 ) between −20 and −40 • C in which only a small fraction of condensate mass is found in relatively large particle sizes greater than 1 mm in diameter. Although more mass is distributed to large particle sizes relative to those observed across all schemes when controlling for temperature, w, and TWC, differences with observations are significantly variable between the schemes tested. As a result, this bias is hypothesized to partly result from errors in parameterized hydrometeor PSD and single particle properties, but because it is present in all schemes, it may also partly result from errors in parameterized microphysical processes present in all schemes. Because of these ubiquitous ice size biases, the frequently used microphysical parameterizations evaluated in this study inherently produce a high bias in convective reflectivity for a wide range of temperatures, vertical velocities, and TWCs.

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Isokinetic Total Water Content Probe in a Naturally Aspirating Configuration: Initial Aerodynamic Design and Testing

Cited by 33 publications

References 0 publications

Determination of ice water content (IWC) in tropical convective clouds from X-band dual-polarization airborne radar

Determination of ice water content (IWC) in tropical convective clouds from X-band dual-polarization airborne radar

Ice Crystal Sizes in High Ice Water Content Clouds. Part II: Statistics of Mass Diameter Percentiles in Tropical Convection Observed during the HAIC/HIWC Project

A ubiquitous ice size bias in simulations of tropical deep convection

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