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

Faber, Spencer; French, Jeffrey R.; Jackson, Robert

doi:10.5194/amt-11-3645-2018

Cited by 49 publications

(41 citation statements)

References 27 publications

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“…For cases with LWC larger than 0.3 g m −3 , the agreement becomes worse, implying the decreasing reliability of the King probe. Figure 2 also suggests that the LWCs from the two probes agree much better for liquid‐phase clouds than for mixed‐phase clouds, simply because the ice in the mixed‐phase clouds may affect the King probe by possible contamination (Faber et al, 2018). To avoid this potential contamination error, the LWC from CDP is used in this study.…”

Section: Methodsmentioning

confidence: 97%

“…The Cloud Droplet Probe (CDP) is an optical probe which measures cloud droplet size distribution in 30 size bins ranging from 2 to 50 μm in diameter ( D ) (Lance et al, 2010) with an uncertainty of 20% (Faber et al, 2018). The Two‐Dimensional Stereo Particle Imaging Probe (2DS) is an optical array probe which uses images to get cloud particle size distribution with D ranging from 10 to 1,260 μm (Lawson, 2011; Lawson et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

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Evaluation of Cloud Microphysical Properties Derived From MODIS and Himawari‐8 Using In Situ Aircraft Measurements Over the Southern Ocean

Zhao

Wang

et al. 2020

Earth and Space Science

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Cloud microphysical properties from aircraft measurements during the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study are used to evaluate the cloud products from the geostationary satellite Himawari-8 (H-8) and the polar-orbiting satellite the Moderate Resolution Imaging Spectroradiometer (MODIS). Compared to the in situ aircraft observations when aircraft flew horizontally near cloud tops, the cloud droplet effective radius (r e ) and number concentration (N d ) from H-8 (MODIS) are 33% (26%-31%) and 2% (9-13%) larger. Both the H-8 and MODIS retrievals behave similarly for liquid-only and mixed-phase low-level clouds, indicating the weak sensitivity of the satellite cloud retrieval performance to cloud phase. The r e and N d of the cloud profiles from aircraft measurements were also used to compare with the satellite product. It shows that H-8 r e and N d agree better with aircraft measurements when considering only the in situ data acquired in the upper portions (highest 20%) of the clouds. Roughly, the r e overestimation by H-8 decreases from 18% to 3% when considering the upper portions of clouds compared to all cloud layer averages, except for one case with drizzles appeared. In addition, the performance of MODIS r e and N d is highly dependent on the wavelengths the retrieval method uses. The droplet r e retrievals using wavelength of 1.6 μm have much larger biases than that using the other two channels. The potential effects of the cloud vertical variation and the photon penetration depth, the cloud heterogeneity, the cloud droplet size spectra, and the drizzle on satellite retrievals have also been discussed. is a co-corresponding author with Chuanfeng Zhao Key Points:• Himawari-8 (MODIS) cloud product overestimates r e near cloud top by 33% (26-31%) over Southern Ocean • Himawari8 r e and N d agree better with aircraft measurements when considering only the in situ data acquired in the upper portions of clouds • The performance of MODIS retrievals depends on the wavelength, with larger biases at 1.6 μm than 2.1 and 3.7 μm

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Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Evaluation of Cloud Microphysical Properties Derived From MODIS and Himawari‐8 Using In Situ Aircraft Measurements Over the Southern Ocean

Zhao

Wang

et al. 2020

Earth and Space Science

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“…Cloud liquid water content (LWC) was derived from the third moment of the size distribution measured by the CDP. Comparisons between CDP-derived LWC and that from various bulk methods including a DMT LWC-100 hot-wire, a Nevzorov probe (Korolev et al, 1998), and a Gerber Particle Volume Monitor-100A (PVM; Gerber, 1993) show agreement generally within 10 to 15 % over the entire COPE campaign (Sulskis and French, 2016;Faber et al, 2018). Two optical array probes (OAPs) were used to derive information about hydrometeors larger than a few tens of microns.…”

Section: Uwka In Situ Measurementsmentioning

confidence: 99%

“…Korolev et al (2013) and Jackson et al (2014) estimated that shattering can cause particle number concentrations to be overestimated by up to an order of magnitude and recommended that mitigation approaches should include both modified probe tips coupled with processing algorithms to identify and remove shattered artifacts. The CIP was equipped with modified "anti-shatter" tips and the interarrival time algorithm of Field et al (2006) was applied during processing of the OAP data. In order to determine the threshold used to identify shattered artifacts, an analysis of inter-arrival times was first applied to time periods where only ice was seen in the CIP imagery and the CDP number concentrations were < 1 cm −3 in order to ensure that liquid particles were not present.…”

Section: Oap Processing Strategymentioning

confidence: 99%

Observations of the microphysical evolution of convective clouds in the southwest of the United Kingdom

et al. 2018

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Abstract. The COnvective Precipitation Experiment (COPE) was designed to investigate the origins of heavy convective precipitation over the southwestern UK, a region that experiences flash flooding due to heavy precipitation from slow-moving convective systems. In this study, the microphysical and dynamical characteristics of developing turrets during 4 days in July and August 2013 are analyzed. In situ cloud microphysical measurements from the University of Wyoming King Air and vertically pointing W-band radar measurements from Wyoming Cloud Radar are examined, together with data from the ground-based NXPol radar. The 4 days presented here cover a range of environmental conditions in terms of wind shear and instability, resulting in a similarly wide variability in observed ice crystal concentrations, both across days as well as between clouds on individual days. The highest concentration of ice was observed on the days in which there was an active warm-rain process supplying precipitation-sized liquid drops. The high ice concentrations observed (>100 L−1) are consistent with the production of secondary ice particles through the Hallett–Mossop process. Turrets that ascended through remnant cloud layers above the 0 ∘C level had higher ice particle concentrations, suggesting that entrainment of ice particles from older clouds or previous thermals may have acted to aid in the production of secondary ice through the Hallett–Mossop process. Other mechanisms such as the shattering of frozen drops may be more important for producing ice in more isolated clouds.

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“…Mertes et al, 2001;Bukarel et al, 2002;Henning et al, 2002;Eugster et al, 2006;Lihavainen et al, 2008;Loyd et al, 2015) and airborne measurements (e.g. Knollenberg et al,1981;Heymsfeld et al, 2004;Bromwich et al, 2012;Johnson et al, 2012, Jones et al, 2012, Briswick et al, 2014Korolev et al, 2014;Petäjä et al, 2016;Webke et al, 2016;Vogt et al, 2017;Faber et al, 2018) In addition to above mentioned experiments, many studies were done to quantify biases, uncertainties and limitations of 20 cloud spectrometers while they were used in measurement campaigns. Uncertainties were usually a result of different meteorological conditions.…”

Section: Introductionmentioning

confidence: 99%

In-situ cloud ground based measurements in Finnish sub-Arctic: Intercomparison of three cloud spectrometers

Doulgeris¹,

Komppula²,

Romakkaniemi³

et al. 2020

Preprint

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Abstract. Continuous, semi-long term, ground based, in-situ cloud measurements were conducted during the Pallas Cloud Experiment (PaCE) in 2013. The measurements were carried out in Finnish sub-Arctic region at Sammaltunturi station (67°58'N, 24°07'E, and 560 m a.s.l.), the part of Pallas Atmosphere – Ecosystem Supersite and Global Atmosphere Watch (GAW) programme. The main motivation of the campaign was to conduct in-situ cloud measurements with three different cloud spectrometer probes and perform an evaluation of their ground based setups. Therefore, we mutually compared the performance of the Cloud and Aerosol Spectrometer (CAS), the Cloud Droplet Probe (CDP) and the Forward Scattering Spectrometer Probe (FSSP-100), (DMT, Boulder, CO, USA). We investigated how different meteorological parameters affect each instrument operation and quantified possible biases and discrepancies of different microphysical cloud properties. Based on obtained results we suggested limitations for further use of the instruments in campaigns where focus is on investigating aerosol cloud interactions. Measurements in this study were made by Finnish Meteorological Institute owned instruments and results concern their operation in sub-Arctic conditions with frequently occurring super-cooled clouds. Measured parameter from each instrument was the size distribution and additionally we derived the number concentration, the effective diameter, the median volume diameter and the liquid water content. A complete intercomparison between the CAS probe and the FSSP-100 and additionally between the FSSP-100 and the CDP probe was made and presented. Unfortunately, there was not sufficient amount of common data to compare all three probes together due to operational problems of the CDP ground setup in sub-zero conditions. The CAS probe that was fixed to one direction lost significant number of cloud droplets when the wind direction was out of wind iso axial conditions in comparison with the FSSP-100 and the CDP which were both placed on a rotating platform. We revealed that CAS and FSSP-100 had good agreement in deriving sizing parameters (effective diameter and median volume diameter from 5 to 35 µm) even though CAS was losing a significant amount of cloud droplets. The most sensitive derived parameter was liquid water content which was strongly connected to the wind direction and temperature.

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

Cited by 49 publications

References 27 publications

Evaluation of Cloud Microphysical Properties Derived From MODIS and Himawari‐8 Using In Situ Aircraft Measurements Over the Southern Ocean

Evaluation of Cloud Microphysical Properties Derived From MODIS and Himawari‐8 Using In Situ Aircraft Measurements Over the Southern Ocean

Observations of the microphysical evolution of convective clouds in the southwest of the United Kingdom

In-situ cloud ground based measurements in Finnish sub-Arctic: Intercomparison of three cloud spectrometers

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