Academic Journal
A layer-averaged relative humidity profile retrieval for microwave observations: design and results for the Megha-Tropiques payload
| العنوان: | A layer-averaged relative humidity profile retrieval for microwave observations: design and results for the Megha-Tropiques payload |
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| المؤلفون: | Sivira, R. G., Brogniez, H., Mallet, C., Oussar, Y. |
| المصدر: | eISSN: 1867-8548 |
| سنة النشر: | 2018 |
| المجموعة: | Copernicus Publications: E-Journals |
| الوصف: | A statistical method trained and optimized to retrieve seven-layer relative humidity (RH) profiles is presented and evaluated with measurements from radiosondes. The method makes use of the microwave payload of the Megha-Tropiques platform, namely the SAPHIR sounder and the MADRAS imager. The approach, based on a generalized additive model (GAM), embeds both the physical and statistical characteristics of the inverse problem in the training phase, and no explicit thermodynamical constraint – such as a temperature profile or an integrated water vapor content – is provided to the model at the stage of retrieval. The model is built for cloud-free conditions in order to avoid the cases of scattering of the microwave radiation in the 18.7–183.31 GHz range covered by the payload. Two instrumental configurations are tested: a SAPHIR-MADRAS scheme and a SAPHIR-only scheme to deal with the stop of data acquisition of MADRAS in January 2013 for technical reasons. A comparison to learning machine algorithms (artificial neural network and support-vector machine) shows equivalent performance over a large realistic set, promising low errors (biases < 2.2%RH) and scatters (correlations > 0.8) throughout the troposphere (150–900 hPa). A comparison to radiosonde measurements performed during the international field experiment CINDY/DYNAMO/AMIE (winter 2011–2012) confirms these results for the mid-tropospheric layers (correlations between 0.6 and 0.92), with an expected degradation of the quality of the estimates at the surface and top layers. Finally a rapid insight of the estimated large-scale RH field from Megha-Tropiques is presented and compared to ERA-Interim. |
| نوع الوثيقة: | text |
| وصف الملف: | application/pdf |
| اللغة: | English |
| Relation: | https://amt.copernicus.org/articles/8/1055/2015/ |
| DOI: | 10.5194/amt-8-1055-2015 |
| الاتاحة: | https://doi.org/10.5194/amt-8-1055-2015 https://amt.copernicus.org/articles/8/1055/2015/ |
| رقم الانضمام: | edsbas.6ECF54A |
| قاعدة البيانات: | BASE |
| DOI: | 10.5194/amt-8-1055-2015 |
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