Snow microphysical retrieval from the NASA D3R radar during ICE-POP 2018
<p>A method is developed to use both polarimetric and dual-frequency radar measurements to retrieve microphysical properties of falling snow. It is applied to the Ku- and Ka-band measurements of the NASA dual-polarization, dual-frequency Doppler radar (D3R) obtained during the International Co...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-03-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/15/1439/2022/amt-15-1439-2022.pdf |
| _version_ | 1828876478262018048 |
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| author | S. J. Munchak S. J. Munchak R. S. Schrom R. S. Schrom C. N. Helms C. N. Helms A. Tokay A. Tokay |
| author_facet | S. J. Munchak S. J. Munchak R. S. Schrom R. S. Schrom C. N. Helms C. N. Helms A. Tokay A. Tokay |
| author_sort | S. J. Munchak |
| collection | DOAJ |
| description | <p>A method is developed to use both polarimetric and dual-frequency radar measurements to retrieve microphysical properties of falling snow. It is applied to the Ku- and Ka-band measurements of the NASA dual-polarization, dual-frequency Doppler radar (D3R) obtained during the International Collaborative Experiments for PyeongChang 2018 Olympic and Paralympic winter games (ICE-POP 2018) field campaign and incorporates the Atmospheric Radiative Transfer Simulator (ARTS) microwave single-scattering property database for oriented particles. The retrieval uses optimal estimation to solve for several parameters that describe the particle size distribution (PSD), relative contribution of pristine, aggregate, and rimed ice species, and the orientation distribution along an entire radial simultaneously. Examination of Jacobian matrices and averaging kernels shows that the dual-wavelength ratio (DWR) measurements provide information regarding the characteristic particle size, and to a lesser extent, the rime fraction and shape parameter of the size distribution, whereas the polarimetric measurements provide information regarding the mass fraction of pristine particles and their characteristic size and orientation distribution. Thus, by combining the dual-frequency and polarimetric measurements, some ambiguities can be resolved that should allow a better determination of the PSD and bulk microphysical properties (e.g., snowfall rate) than can be retrieved from single-frequency polarimetric measurements or dual-frequency, single-polarization measurements.</p>
<p>The D3R ICE-POP retrievals were validated using Precipitation Imaging Package (PIP) and Pluvio weighing gauge measurements taken nearby at the May Hills ground site. The PIP measures the snow PSD directly, and its measurements can be used to derived the snowfall rate (volumetric and water equivalent), mean volume-weighted particle size, and effective density, as well as particle aspect ratio and orientation. Four retrieval experiments were performed to evaluate the utility of different measurement combinations: Ku-only, DWR-only, Ku-pol, and All-obs. In terms of correlation, the volumetric snowfall rate (<span class="inline-formula"><i>r</i>=0.95</span>) and snow water equivalent rate (<span class="inline-formula"><i>r</i>=0.92</span>) were best retrieved by the Ku-pol method, while the DWR-only method had the lowest magnitude bias for these parameters (<span class="inline-formula">−31</span> % and <span class="inline-formula">−8</span> %, respectively). The methods that incorporated DWR also had the best correlation to particle size (<span class="inline-formula"><i>r</i>=0.74</span> and <span class="inline-formula"><i>r</i>=0.71</span> for DWR-only and All-obs, respectively), although none of the methods retrieved density particularly well (<span class="inline-formula"><i>r</i>=0.43</span> for All-obs). The ability of the measurements to retrieve mean aspect ratio was also inconclusive, although the polarimetric methods (Ku-pol and All-obs) had reduced biases and mean absolute error (MAE) relative to the Ku-only and DWR-only methods. The significant biases in particle size and snowfall rate appeared to be related to biases in the measured DWR, emphasizing the need for accurate DWR measurements and frequent calibration in future D3R deployments.</p> |
| first_indexed | 2024-12-13T08:21:06Z |
| format | Article |
| id | doaj.art-27f09e952f2b47f5b3be4d1089c8e81f |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-12-13T08:21:06Z |
| publishDate | 2022-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-27f09e952f2b47f5b3be4d1089c8e81f2022-12-21T23:54:00ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482022-03-01151439146410.5194/amt-15-1439-2022Snow microphysical retrieval from the NASA D3R radar during ICE-POP 2018S. J. Munchak0S. J. Munchak1R. S. Schrom2R. S. Schrom3C. N. Helms4C. N. Helms5A. Tokay6A. Tokay7Mesoscale Atmospheric Processes Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USAnow at: The Tomorrow Companies, Inc., Boston, MA, USAMesoscale Atmospheric Processes Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USAUniversities Space Research Association, Columbia, MD, USAMesoscale Atmospheric Processes Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USAUniversities Space Research Association, Columbia, MD, USAMesoscale Atmospheric Processes Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USAJoint Center for Earth Systems Technology, University of Maryland, Baltimore County, Catonsville, MD, USA<p>A method is developed to use both polarimetric and dual-frequency radar measurements to retrieve microphysical properties of falling snow. It is applied to the Ku- and Ka-band measurements of the NASA dual-polarization, dual-frequency Doppler radar (D3R) obtained during the International Collaborative Experiments for PyeongChang 2018 Olympic and Paralympic winter games (ICE-POP 2018) field campaign and incorporates the Atmospheric Radiative Transfer Simulator (ARTS) microwave single-scattering property database for oriented particles. The retrieval uses optimal estimation to solve for several parameters that describe the particle size distribution (PSD), relative contribution of pristine, aggregate, and rimed ice species, and the orientation distribution along an entire radial simultaneously. Examination of Jacobian matrices and averaging kernels shows that the dual-wavelength ratio (DWR) measurements provide information regarding the characteristic particle size, and to a lesser extent, the rime fraction and shape parameter of the size distribution, whereas the polarimetric measurements provide information regarding the mass fraction of pristine particles and their characteristic size and orientation distribution. Thus, by combining the dual-frequency and polarimetric measurements, some ambiguities can be resolved that should allow a better determination of the PSD and bulk microphysical properties (e.g., snowfall rate) than can be retrieved from single-frequency polarimetric measurements or dual-frequency, single-polarization measurements.</p> <p>The D3R ICE-POP retrievals were validated using Precipitation Imaging Package (PIP) and Pluvio weighing gauge measurements taken nearby at the May Hills ground site. The PIP measures the snow PSD directly, and its measurements can be used to derived the snowfall rate (volumetric and water equivalent), mean volume-weighted particle size, and effective density, as well as particle aspect ratio and orientation. Four retrieval experiments were performed to evaluate the utility of different measurement combinations: Ku-only, DWR-only, Ku-pol, and All-obs. In terms of correlation, the volumetric snowfall rate (<span class="inline-formula"><i>r</i>=0.95</span>) and snow water equivalent rate (<span class="inline-formula"><i>r</i>=0.92</span>) were best retrieved by the Ku-pol method, while the DWR-only method had the lowest magnitude bias for these parameters (<span class="inline-formula">−31</span> % and <span class="inline-formula">−8</span> %, respectively). The methods that incorporated DWR also had the best correlation to particle size (<span class="inline-formula"><i>r</i>=0.74</span> and <span class="inline-formula"><i>r</i>=0.71</span> for DWR-only and All-obs, respectively), although none of the methods retrieved density particularly well (<span class="inline-formula"><i>r</i>=0.43</span> for All-obs). The ability of the measurements to retrieve mean aspect ratio was also inconclusive, although the polarimetric methods (Ku-pol and All-obs) had reduced biases and mean absolute error (MAE) relative to the Ku-only and DWR-only methods. The significant biases in particle size and snowfall rate appeared to be related to biases in the measured DWR, emphasizing the need for accurate DWR measurements and frequent calibration in future D3R deployments.</p>https://amt.copernicus.org/articles/15/1439/2022/amt-15-1439-2022.pdf |
| spellingShingle | S. J. Munchak S. J. Munchak R. S. Schrom R. S. Schrom C. N. Helms C. N. Helms A. Tokay A. Tokay Snow microphysical retrieval from the NASA D3R radar during ICE-POP 2018 Atmospheric Measurement Techniques |
| title | Snow microphysical retrieval from the NASA D3R radar during ICE-POP 2018 |
| title_full | Snow microphysical retrieval from the NASA D3R radar during ICE-POP 2018 |
| title_fullStr | Snow microphysical retrieval from the NASA D3R radar during ICE-POP 2018 |
| title_full_unstemmed | Snow microphysical retrieval from the NASA D3R radar during ICE-POP 2018 |
| title_short | Snow microphysical retrieval from the NASA D3R radar during ICE-POP 2018 |
| title_sort | snow microphysical retrieval from the nasa d3r radar during ice pop 2018 |
| url | https://amt.copernicus.org/articles/15/1439/2022/amt-15-1439-2022.pdf |
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