Weather Types Affect Rain Microstructure: Implications for Estimating Rain Rate
Quantitative precipitation estimation (QPE) through remote sensing has to take rain microstructure into consideration, because it influences the relationship between radar reflectivity Z and rain intensity R. For this reason, separate equations are used to estimate rain intensity of convective and s...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-10-01
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| Series: | Remote Sensing |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-4292/12/21/3572 |
| _version_ | 1797549188079157248 |
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| author | Wael Ghada Joan Bech Nicole Estrella Andreas Hamann Annette Menzel |
| author_facet | Wael Ghada Joan Bech Nicole Estrella Andreas Hamann Annette Menzel |
| author_sort | Wael Ghada |
| collection | DOAJ |
| description | Quantitative precipitation estimation (QPE) through remote sensing has to take rain microstructure into consideration, because it influences the relationship between radar reflectivity Z and rain intensity R. For this reason, separate equations are used to estimate rain intensity of convective and stratiform rain types. Here, we investigate whether incorporating synoptic scale meteorology could yield further QPE improvements. Depending on large-scale weather types, variability in cloud condensation nuclei and the humidity content may lead to variation in rain microstructure. In a case study for Bavaria, we measured rain microstructure at ten locations with laser-based disdrometers, covering a combined 18,600 h of rain in a period of 36 months. Rain was classified on a temporal scale of one minute into convective and stratiform based on a machine learning model. Large-scale wind direction classes were on a daily scale to represent the synoptic weather types. Significant variations in rain microstructure parameters were evident not only for rain types, but also for wind direction classes. The main contrast was observed between westerly and easterly circulations, with the latter characterized by smaller average size of drops and a higher average concentration. This led to substantial variation in the parameters of the radar rain intensity retrieval equation Z–R. The effect of wind direction on Z–R parameters was more pronounced for stratiform than convective rain types. We conclude that building separate Z–R retrieval equations for regional wind direction classes should improve radar-based QPE, especially for stratiform rain events. |
| first_indexed | 2024-03-10T15:10:24Z |
| format | Article |
| id | doaj.art-a3d0475050434973ae28d72a98b050dc |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T15:10:24Z |
| publishDate | 2020-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-a3d0475050434973ae28d72a98b050dc2023-11-20T19:23:20ZengMDPI AGRemote Sensing2072-42922020-10-011221357210.3390/rs12213572Weather Types Affect Rain Microstructure: Implications for Estimating Rain RateWael Ghada0Joan Bech1Nicole Estrella2Andreas Hamann3Annette Menzel4TUM School of Life Sciences, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising, GermanyDepartment of Applied Physics-Meteorology, University of Barcelona, C/ Marti i Franques 1, 08028 Barcelona, SpainTUM School of Life Sciences, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising, GermanyDepartment of Renewable Resources, University of Alberta, 733 General Services Building, Edmonton, AB T6G 2H1, CanadaTUM School of Life Sciences, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising, GermanyQuantitative precipitation estimation (QPE) through remote sensing has to take rain microstructure into consideration, because it influences the relationship between radar reflectivity Z and rain intensity R. For this reason, separate equations are used to estimate rain intensity of convective and stratiform rain types. Here, we investigate whether incorporating synoptic scale meteorology could yield further QPE improvements. Depending on large-scale weather types, variability in cloud condensation nuclei and the humidity content may lead to variation in rain microstructure. In a case study for Bavaria, we measured rain microstructure at ten locations with laser-based disdrometers, covering a combined 18,600 h of rain in a period of 36 months. Rain was classified on a temporal scale of one minute into convective and stratiform based on a machine learning model. Large-scale wind direction classes were on a daily scale to represent the synoptic weather types. Significant variations in rain microstructure parameters were evident not only for rain types, but also for wind direction classes. The main contrast was observed between westerly and easterly circulations, with the latter characterized by smaller average size of drops and a higher average concentration. This led to substantial variation in the parameters of the radar rain intensity retrieval equation Z–R. The effect of wind direction on Z–R parameters was more pronounced for stratiform than convective rain types. We conclude that building separate Z–R retrieval equations for regional wind direction classes should improve radar-based QPE, especially for stratiform rain events.https://www.mdpi.com/2072-4292/12/21/3572Thiesdisdrometerweather circulationsconvectivestratiformrain spectra |
| spellingShingle | Wael Ghada Joan Bech Nicole Estrella Andreas Hamann Annette Menzel Weather Types Affect Rain Microstructure: Implications for Estimating Rain Rate Remote Sensing Thies disdrometer weather circulations convective stratiform rain spectra |
| title | Weather Types Affect Rain Microstructure: Implications for Estimating Rain Rate |
| title_full | Weather Types Affect Rain Microstructure: Implications for Estimating Rain Rate |
| title_fullStr | Weather Types Affect Rain Microstructure: Implications for Estimating Rain Rate |
| title_full_unstemmed | Weather Types Affect Rain Microstructure: Implications for Estimating Rain Rate |
| title_short | Weather Types Affect Rain Microstructure: Implications for Estimating Rain Rate |
| title_sort | weather types affect rain microstructure implications for estimating rain rate |
| topic | Thies disdrometer weather circulations convective stratiform rain spectra |
| url | https://www.mdpi.com/2072-4292/12/21/3572 |
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