HAIC - High Altitude Ice Crystals

Dezitter, Fabien; Grandin, Alice; Brenguier, Jean‐Louis; Hervy, Franck; Schläger, Hans; Villedieu, Philippe; Zalamansky, G.

doi:10.2514/6.2013-2674

Cited by 73 publications

(36 citation statements)

References 3 publications

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“…2 in Leroy et al, 2017), thereby avoiding red aircraft radar echoes at normal gain as commercial aircraft would also do. More details on HAIC/HIWC projects and implemented flight strategy can be found in Dezitter et al (2013), Leroy et al (2016Leroy et al ( , 2017, Protat et al (2016), and .…”

Section: Data Processingmentioning

confidence: 99%

“…During the High Altitude Ice Crystals (HAIC; Dezitter et al, 2013)/High Ice Water Content (HIWC; Strapp et al, 2016) airborne field campaign performed out of Darwin, the from SAFIRE (Service des Avions Français Instrumentés pour la Recherche en Environnement) measured on the same aircraft 94 GHz Z, PSD, aspect ratios of hydrometeors, and independently CWC. The objective of our study is to use this comprehensive HAIC/HIWC dataset to evaluate the method presented by Fontaine et al (2014).…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of radar reflectivity factor simulations of ice crystal populations from in situ observations for the retrieval of condensed water content in tropical mesoscale convective systems

Fontaine

Leroy²,

Schwarzenböeck³

et al. 2017

Atmos. Meas. Tech.

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Abstract. This study presents the evaluation of a technique to estimate cloud condensed water content (CWC) in tropical convection from airborne cloud radar reflectivity factors at 94 GHz and in situ measurements of particle size distributions (PSDs) and aspect ratios of ice crystal populations. The approach is to calculate from each 5 s mean PSD and flight-level reflectivity the variability of all possible solutions of m(D) relationships fulfilling the condition that the simulated radar reflectivity factor (T-matrix method) matches the measured radar reflectivity factor. For the reflectivity simulations, ice crystals were approximated as oblate spheroids, without using a priori assumptions on the mass-size relationship of ice crystals. The CWC calculations demonstrate that individual CWC values are in the range ±32 % of the retrieved average CWC value over all CWC solutions for the chosen 5 s time intervals. In addition, during the airborne field campaign performed out of Darwin in 2014, as part of the international High Altitude Ice Crystals/High Ice Water Content (HAIC/HIWC) projects, CWCs were measured independently with the new IKP-2 (isokinetic evaporator probe) instrument along with simultaneous particle imagery and radar reflectivity. Retrieved CWCs from the T-matrix radar reflectivity simulations are on average 16 % higher than the direct CWC IKP measurements. The differences between the CWC IKP and averaged retrieved CWCs are found to be primarily a function of the total number concentration of ice crystals. Consequently, a correction term is applied (as a function of total number concentration) that significantly improves the retrieved CWC. After correction, the retrieved CWCs have a median relative error with respect to measured values of only −1 %. Uncertainties in the measurements of total concentration of hydrometeors are investigated in order to calculate their contribution to the relative error of calculated CWC with respect to measured CWC IKP . It is shown that an overestimation of the concentration by about +50 % increases the relative errors of retrieved CWCs by only +29 %, while possible shattering, which impacts only the concentration of small hydrometeors, increases the relative error by about +4 %. Moreover, all cloud events with encountered graupel particles were studied and compared to events without observed graupel particles. Overall, graupel particles seem to have the largest impact on high crystal number-concentration conditions and show relative errors in retrieved CWCs that are higher than for events without graupel particles.

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Section: Data Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of radar reflectivity factor simulations of ice crystal populations from in situ observations for the retrieval of condensed water content in tropical mesoscale convective systems

Fontaine

Leroy²,

Schwarzenböeck³

et al. 2017

Atmos. Meas. Tech.

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“…This study utilizes data collected from the High Altitude Ice Crystals -High Ice Water Content (HAIC-HIWC) joint field campaign (Dezitter et al, 2013;Strapp et al, 2016a). The first HAIC-HIWC phase was conducted in and around Darwin, Australia, from January to March in 2014 during the wet monsoon season.…”

Section: Introductionmentioning

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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“…Mason [94] has derived a model for the melting rate of hailstones by assuming that the heat (Q conv ) absorbed from the surrounding air minus the heat (ṁ ev L ev ) that is used for the evaporation of the liquid film results in the heat (ṁ m L m ) available for the actual phase change. For the energy conservation equation this yields: 26) where T m is the melting temperature,ṁ ev is the evaporation rate,ṁ m is the melting rate, L ev is the latent heat of evaporation and L m is the latent heat of melting. The latent heats can be approximated by a relation that depends on the particle temperature.…”

Section: Meltingmentioning

confidence: 99%

“…The EU research project HAIC, High Altitude Ice Crystals, has been organized in order to acquire that knowledge. This project was started in August 2012 for a duration of 4.5 years and has received funding from the EU seventh framework program (FP7 ing to the European Aeronautical industry Acceptable Means of Compliance (test facilities and numerical tools) and appropriate detection/awareness technologies to be fitted on aircraft and able to alert the flight crew in order to enhance safety when an aircraft is flying in such weather conditions" [26]. Within HAIC a collaboration between 34 European companies, institutes and universities and 5 partners from outside Europe, namely Australia, Canada and the United States, has been established.…”

Section: Haic: High Altitude Ice Crystalsmentioning

confidence: 99%

Eulerian method for ice crystal icing in turbofan engines

Norde¹

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HAIC - High Altitude Ice Crystals

Cited by 73 publications

References 3 publications

Evaluation of radar reflectivity factor simulations of ice crystal populations from in situ observations for the retrieval of condensed water content in tropical mesoscale convective systems

Evaluation of radar reflectivity factor simulations of ice crystal populations from in situ observations for the retrieval of condensed water content in tropical mesoscale convective systems

A ubiquitous ice size bias in simulations of tropical deep convection

Eulerian method for ice crystal icing in turbofan engines

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