@article{fdi:010052970,
  title = {{R}egional-scale convection patterns during strong and weak phases of the {S}aharan heat low},
  author = {{L}avaysse, {C}. and {F}lamant, {C}. and {J}anicot, {S}erge},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {W}est {A}frican heat low, which is defined as a thermal depression generally below 700 h{P}a over {W}est {A}frica, is stationary over the {S}ahara during the summer season and is often referred to as the {S}aharan heat low ({SHL}). {T}his {SHL} displays synoptic and intra-seasonal pulsations of its intensity on time scales under 60 days. {I}n this study, we analyse the regional-scale pattern of low troposphere dynamics and convective activity associated with weak and strong phases of the {SHL} during the summer, using 18 years (1984-2001) of concomitant {E}uropean {C}entre for {M}edium-range {W}eather {F}orecasts re-analysis data and satellite observations of brightness temperature provided by the {E}uropean {U}nion-funded {C}loud {A}rchive {U}ser {S}ervice. {S}trong {SHL} phases, defined by an increase of low-level atmospheric thickness, are accompanied by (1) a positive anomaly of temperature in the low layers, (2) a strengthening of the monsoon flow, (3) both a negative anomaly of the divergence flux and an enhancement of the moisture advection over the central {S}ahel, (4) an intensification of the {A}frican easterly jet and (5) enhanced upward vertical motions located south of the inter-tropical discontinuity ({ITD}). {T}hese conditions appear to be favourable for the occurrence of convection over the central {S}ahel. {T}he strongest, most widespread convective activity over the central and eastern {S}ahel occurs on the day when the {SHL} intensity is the strongest. {I}n contrast, a significant decrease of the convective activity was detected over {S}enegal and to the {W}est of the {J}os {P}lateau. {O}pposite patterns are found during weak {SHL} phases, with a negative anomaly of convection over the central and eastern {S}ahel connected with anomalous subsidence south of the {ITD} and a negative moisture advection anomaly. {C}onversely, convection is seen to be enhanced along the {A}tlantic coast and particularly over {S}enegal.},
  keywords = {{W}est {A}frican {M}onsoon ; convective activity ; precipitation ; synoptic ; circulation ; {AMMA} ; {SENEGAL} ; {SAHEL} ; {SAHARA}},
  booktitle = {},
  journal = {{A}tmospheric {S}cience {L}etters},
  volume = {11},
  numero = {4},
  pages = {255--264},
  ISSN = {1530-261{X}},
  year = {2010},
  DOI = {10.1002/asl.284},
  URL = {https://www.documentation.ird.fr/hor/fdi:010052970},
}