GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL)
The marine atmospheric boundary layer (MABL) has a profound impact on sensible heat and moisture exchanges between the surface and the free troposphere. The goal of this study is to develop an alternative technique for retrieving MABL-specific humidity (<i>q</i>) using GNSS-RO data in de...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-06-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/13/6/953 |
| _version_ | 1797490077689970688 |
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| author | Dong L. Wu Jie Gong Manisha Ganeshan |
| author_facet | Dong L. Wu Jie Gong Manisha Ganeshan |
| author_sort | Dong L. Wu |
| collection | DOAJ |
| description | The marine atmospheric boundary layer (MABL) has a profound impact on sensible heat and moisture exchanges between the surface and the free troposphere. The goal of this study is to develop an alternative technique for retrieving MABL-specific humidity (<i>q</i>) using GNSS-RO data in deep-refracted signals. The GNSS-RO signal amplitude (i.e., signal-to-noise ratio or SNR) at the deep straight-line height (<i>H<sub>SL</sub></i>) was been found to be strongly impacted by water vapor within the MABL. This study presents a statistical analysis to empirically relate the normalized SNR (<i>S<sub>RO</sub></i>) at deep <i>H<sub>SL</sub></i> to the MABL <i>q</i> at 950 hPa (~400 m). When compared to the ERA5 reanalysis data, a good linear <i>q</i>–<i>S<sub>RO</sub></i> relationship is found with the deep <i>H<sub>SL</sub></i> <i>S<sub>RO</sub></i> data, but careful treatments of receiver noise, SNR normalization, and receiver orbital altitude are required. We attribute the good <i>q</i>–<i>S<sub>RO</sub></i> correlation to the strong refraction from a uniform, horizontally stratiform and dynamically quiet MABL water vapor layer. Ducting and diffraction/interference by this layer help to enhance the <i>S<sub>RO</sub></i> amplitude at deep <i>H<sub>SL</sub></i>. Potential MABL water vapor retrieval can be further developed to take advantage of a higher number of <i>S<sub>RO</sub></i> measurements in the MABL compared to the Level-2 products. A better sampled diurnal variation of the MABL <i>q</i> is demonstrated with the <i>S<sub>RO</sub></i> data over the Southeast Pacific (SEP) and the Northeast Pacific (NEP) regions, which appear to be consistent with the low cloud amount variations reported in previous studies. |
| first_indexed | 2024-03-10T00:26:45Z |
| format | Article |
| id | doaj.art-83961e23abf04e0fab8c2874047c3023 |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-10T00:26:45Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-83961e23abf04e0fab8c2874047c30232023-11-23T15:33:19ZengMDPI AGAtmosphere2073-44332022-06-0113695310.3390/atmos13060953GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL)Dong L. Wu0Jie Gong1Manisha Ganeshan2NASA Goddard Space Flight Center, Greenbelt, MD 20771, USAGESTAR-II, University of Maryland, Baltimore County, Baltimore, MD 21228, USAGESTAR-II, Morgan State University, Baltimore, MD 21251, USAThe marine atmospheric boundary layer (MABL) has a profound impact on sensible heat and moisture exchanges between the surface and the free troposphere. The goal of this study is to develop an alternative technique for retrieving MABL-specific humidity (<i>q</i>) using GNSS-RO data in deep-refracted signals. The GNSS-RO signal amplitude (i.e., signal-to-noise ratio or SNR) at the deep straight-line height (<i>H<sub>SL</sub></i>) was been found to be strongly impacted by water vapor within the MABL. This study presents a statistical analysis to empirically relate the normalized SNR (<i>S<sub>RO</sub></i>) at deep <i>H<sub>SL</sub></i> to the MABL <i>q</i> at 950 hPa (~400 m). When compared to the ERA5 reanalysis data, a good linear <i>q</i>–<i>S<sub>RO</sub></i> relationship is found with the deep <i>H<sub>SL</sub></i> <i>S<sub>RO</sub></i> data, but careful treatments of receiver noise, SNR normalization, and receiver orbital altitude are required. We attribute the good <i>q</i>–<i>S<sub>RO</sub></i> correlation to the strong refraction from a uniform, horizontally stratiform and dynamically quiet MABL water vapor layer. Ducting and diffraction/interference by this layer help to enhance the <i>S<sub>RO</sub></i> amplitude at deep <i>H<sub>SL</sub></i>. Potential MABL water vapor retrieval can be further developed to take advantage of a higher number of <i>S<sub>RO</sub></i> measurements in the MABL compared to the Level-2 products. A better sampled diurnal variation of the MABL <i>q</i> is demonstrated with the <i>S<sub>RO</sub></i> data over the Southeast Pacific (SEP) and the Northeast Pacific (NEP) regions, which appear to be consistent with the low cloud amount variations reported in previous studies.https://www.mdpi.com/2073-4433/13/6/953atmospheric boundary layerspecific humiditydiurnal variationGNSS-ROsignal-to-noise ratiodeep refraction |
| spellingShingle | Dong L. Wu Jie Gong Manisha Ganeshan GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL) Atmosphere atmospheric boundary layer specific humidity diurnal variation GNSS-RO signal-to-noise ratio deep refraction |
| title | GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL) |
| title_full | GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL) |
| title_fullStr | GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL) |
| title_full_unstemmed | GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL) |
| title_short | GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL) |
| title_sort | gnss ro deep refraction signals from moist marine atmospheric boundary layer mabl |
| topic | atmospheric boundary layer specific humidity diurnal variation GNSS-RO signal-to-noise ratio deep refraction |
| url | https://www.mdpi.com/2073-4433/13/6/953 |
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