Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP)
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 experime...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-06-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/11/3645/2018/amt-11-3645-2018.pdf |
| _version_ | 1817984150239444992 |
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| author | S. Faber J. R. French R. Jackson R. Jackson |
| author_facet | S. Faber J. R. French R. Jackson R. Jackson |
| author_sort | S. Faber |
| collection | DOAJ |
| description | 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
9 µm 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. |
| first_indexed | 2024-04-13T23:41:53Z |
| format | Article |
| id | doaj.art-ad08862d364e4e01bdb2e8c788313225 |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-04-13T23:41:53Z |
| publishDate | 2018-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-ad08862d364e4e01bdb2e8c7883132252022-12-22T02:24:29ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482018-06-01113645365910.5194/amt-11-3645-2018Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP)S. Faber0J. R. French1R. Jackson2R. Jackson3Department of Atmospheric Science, University of Wyoming, Laramie, WY 82071, USADepartment of Atmospheric Science, University of Wyoming, Laramie, WY 82071, USADepartment of Atmospheric Science, University of Wyoming, Laramie, WY 82071, USApresent address: Argonne National Laboratory, Environmental Science Division, Argonne, IL 60439, USALaboratory 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 9 µm 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.https://www.atmos-meas-tech.net/11/3645/2018/amt-11-3645-2018.pdf |
| spellingShingle | S. Faber J. R. French R. Jackson R. Jackson Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP) Atmospheric Measurement Techniques |
| title | Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP) |
| title_full | Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP) |
| title_fullStr | Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP) |
| title_full_unstemmed | Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP) |
| title_short | Laboratory and in-flight evaluation of measurement uncertainties from a commercial Cloud Droplet Probe (CDP) |
| title_sort | laboratory and in flight evaluation of measurement uncertainties from a commercial cloud droplet probe cdp |
| url | https://www.atmos-meas-tech.net/11/3645/2018/amt-11-3645-2018.pdf |
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