Preprints
https://doi.org/10.5194/nhess-2019-185
https://doi.org/10.5194/nhess-2019-185

  22 Jul 2019

22 Jul 2019

Review status: a revised version of this preprint was accepted for the journal NHESS and is expected to appear here in due course.

Wet and dry spells in Senegal: Evaluation of satellite-based and model re-analysis rainfall estimates

Cheikh Modou Noreyni Fall1, Christophe Lavaysse2, Mamadou Simina Drame1, Geremy Panthou2, and Amadou Thierno Gaye1 Cheikh Modou Noreyni Fall et al.
  • 1Laboratoire de Physique de l'Atmosphère et de l'Océan – Simeon Fongang, ESP, Univ. Cheikh Anta Diop, Dakar, Senegal
  • 2Institut des Géosciences de l'Environnement IGE, Univ. Grenoble Alpes, IRD, CNRS, Grenoble INP, 38000 Grenoble, France

Abstract. In this study, wet and dry spells over Senegal provided by four datasets based on satellite data (TRMM-3B42 V7, TAMSAT V3, CMORPH V1.0, CHIRPS V2.0), two fully based on (re)analyses (NCEP-CFSR, ERA5) and one was fully based on gauge observations (CPC Unified V1.0/RT) are compared with respect to observation datasets derived from 65 rain gauge network. All datasets were converted to the same temporal and spatial scales with 0.25 × 0.25 as resolution. Ordinary kriging (OK) and block kriging (BK) were used for the spatial interpolation of the gauge data. Despite a spatial coherence of the seasonal rainfall accumulation between all products, more variability with intra-seasonal features are shown in this paper. The seasonal cycle of dry days shows that TRMM, CPC, ERA5, NCEP and OK record more dry days (from 45 % to 55 % of dry days in August) while TAMSAT, CHIRPS, CMORPH and BK record less dry day (from 40 % to 30 % of dry days in August). All datasets highlighted an agreement that dry spell indicator underscore often false start and early cessation of the rainy Season in Senegal. Although, it can rarely occurs during intensification of West African monsoon (August–September). The most contrast is found on the detection of wet indicators intensity. Wet spell (defined as period with precipitation higher than a certain percentile of historical precipitation) are more severe in OK and TRMM than in other datasets. However, a great similarity is shown on their temporal frequencies.

Cheikh Modou Noreyni Fall et al.

 
Status: closed
Status: closed
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Cheikh Modou Noreyni Fall et al.

Cheikh Modou Noreyni Fall et al.

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Short summary
Extreme wet and dry rainfall periods over Senegal provided by satellite, reanalyses and observation datasets are examined and compared. Despite a spatial coherence of the seasonal rainfall accumulation between all products, more variability with intra-seasonal features are shown. All datasets highlighted that dry spell indicator underscore often false start and early cessation of the rainy season. Finally, wet spells are more severe in observation and TRMM than in other datasets.
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