Response of the Nevzorov hot wire probe in clouds dominated by droplet conditions in the drizzle size range

Schwarzenböeck, Alfons; Mioche, Guillaume; Armetta, A.; Herber, Andreas; Gayet, Jean-François

doi:10.5194/amt-2-779-2009

Cited by 25 publications

(23 citation statements)

References 24 publications

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“…Because airflow diverges in the vicinity of the LWC collector, LWC NEV may be underestimated by as much as 30 % in droplet populations with VMD less than 8 µm since particles with insignificant mass are unable to cross the divergent streamlines and impact collector elements (Korolev et al, 1998). Collection efficiency also departs from unity for droplets with VMD greater than 30 µm because larger droplets tend to splatter on impact, leading to incomplete evaporation (Schwarzenboeck et al, 2009). …”

Section: Constant Temperature Hot-wire Probesmentioning

confidence: 99%

Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP)

2018

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Abstract. Laboratory and in-flight evaluations of uncertainties of measurements from a Cloud Droplet Probe (CDP) are presented. A description of a water-droplet-generating device, similar to those used in previous studies, is provided along with validation of droplet sizing and positioning. Seven experiments with droplet diameters of 9, 17, 24, 29, 34, 38, and 46 µm tested sizing and counting performance across a 10 µm resolution grid throughout the sample area of a CDP. Results indicate errors in sizing that depend on both droplet diameter and position within the sample area through which a droplet transited. The CDP undersized 9µm droplets by 1-4 µm. Droplets with diameters of 17 and 24 µm were sized to within 2 µm, which is the nominal CDP bin width for droplets of that size. The majority of droplets larger than 17 µm were oversized by 2-4 µm, while a small percentage were severely undersized, by as much as 30 µm. This combination led to an artificial broadening and skewing of the spectra such that mean diameters from a near-monodisperse distribution compared well (within a few percent), while the median diameters were oversized by 5-15 %. This has implications on how users should calibrate their probes. Errors in higher-order moments were generally less than 10 %. Comparisons of liquid water content (LWC) calculated from the CDP and that measured from a Nevzorov hot-wire probe were conducted for 17 917 1 Hz in-cloud points. Although some differences were noted based on volume-weighted mean diameter and total droplet concentration, the CDP-estimated LWC exceeded that measured by the Nevzorov by approximately 20 %, more than twice the expected difference based on results of the laboratory tests and considerations of Nevzorov collection efficiency.

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Section: Constant Temperature Hot-wire Probesmentioning

confidence: 99%

Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP)

2018

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“…-ε LWC,l = 0.76; see Schwarzenboeck et al (2009); -ε LWC,i = 0.11, following Korolev et al (1998); -ε TWC,l = 1, according to Korolev et al (1998) for droplets with size around 25 µm; and -ε TWC,i = 1, following Schwarzenboeck et al (2009). It should be noticed that taking ε TWC,i = 3 (as assumed in Korolev et al, 2013) instead of 1 induces an increase of LWC by 10 % only.…”

Section: Appendix A: Data Processing Of In Situ Measurementsmentioning

confidence: 99%

Vertical distribution of microphysical properties of Arctic springtime low-level mixed-phase clouds over the Greenland and Norwegian seas

et al. 2017

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Abstract. This study aims to characterize the microphysical and optical properties of ice crystals and supercooled liquid droplets within low-level Arctic mixed-phase clouds (MPCs). We compiled and analyzed cloud in situ measurements from four airborne spring campaigns (representing 18 flights and 71 vertical profiles in MPCs) over the Greenland and Norwegian seas mainly in the vicinity of the Svalbard archipelago. Cloud phase discrimination and representative vertical profiles of the number, size, mass and shape of ice crystals and liquid droplets are established. The results show that the liquid phase dominates the upper part of the MPCs. High concentrations (120 cm −3 on average) of small droplets (mean values of 15 µm), with an averaged liquid water content (LWC) of 0.2 g m −3 are measured at cloud top. The ice phase dominates the microphysical properties in the lower part of the cloud and beneath it in the precipitation region (mean values of 100 µm, 3 L −1 and 0.025 g m −3 for diameter, particle concentration and ice water content (IWC), respectively). The analysis of the ice crystal morphology shows that the majority of ice particles are irregularly shaped or rimed particles; the prevailing regular habits found are stellars and plates. We hypothesize that riming and diffusional growth processes, including the WegenerBergeron-Findeisen (WBF) mechanism, are the main growth mechanisms involved in the observed MPCs. The impact of larger-scale meteorological conditions on the vertical profiles of MPC properties was also investigated. Large values of LWC and high concentration of smaller droplets are possibly linked to polluted situations and air mass origins from the south, which can lead to very low values of ice crystal size and IWC. On the contrary, clean situations with low temperatures exhibit larger values of ice crystal size and IWC. Several parameterizations relevant for remote sensing or modeling studies are also determined, such as IWC (and LWC) -extinction relationship, ice and liquid integrated water paths, ice concentration and liquid water fraction according to temperature.

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“…Korolev et al, 1998, Isaac et al, 2006Schwarzenboeck et al, 2009;Lance et al, 2010). Korolev et al (1998) found that the integrated collection efficiency of the Novzorov probe for the sensor of LWC varied between 0.9 and 1 without drops larger than 100 µm in diameter, but the efficiency for drops smaller than 5 µm could be as low as 0.6.…”

Section: Instrumentsmentioning

confidence: 99%

“…Korolev et al (1998) found that the integrated collection efficiency of the Novzorov probe for the sensor of LWC varied between 0.9 and 1 without drops larger than 100 µm in diameter, but the efficiency for drops smaller than 5 µm could be as low as 0.6. Schwarzenboeck et al (2009) further studied the response of the Nevzorov hot wire probe and found that droplets smaller than 20-30 µm partly tend to curve around the LWC sensor. Isaac et al (2006) pointed out that the Nevzorov total water probe and other similar hot-wire sensors provided underestimates possibly liquid water content in the presence of large drops.…”

Section: Instrumentsmentioning

confidence: 99%

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Aircraft measurements of wave clouds

et al. 2012

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Abstract. In this paper, aircraft measurements are presented of liquid phase (ice-free) wave clouds made at temperatures greater than −5 • C that formed over Scotland, UK. The horizontal variations of the vertical velocity across wave clouds display a distinct pattern. The maximum updraughts occur at the upshear flanks of the clouds and the strong downdraughts at the downshear flanks. The cloud droplet concentrations were a couple of hundreds per cubic centimetres, and the drops generally had a mean diameter between 15-45 µm. A small proportion of the drops were drizzle. The measurements presented here and in previous recent studies suggest a different interaction of dynamics and microphysics in wave clouds from the accepted model. The results in this paper provide a case for future numerical simulation of wave cloud and the interaction between wave and cloud.

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Response of the Nevzorov hot wire probe in clouds dominated by droplet conditions in the drizzle size range

Cited by 25 publications

References 24 publications

Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP)

Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP)

Vertical distribution of microphysical properties of Arctic springtime low-level mixed-phase clouds over the Greenland and Norwegian seas

Aircraft measurements of wave clouds

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