Orographic effects of the subtropical and extratropical Andes on precipitating clouds

VIALE M., G.ZALAZAR, AND E. BIANCHI,; CO-AUTOR, GUALBERTO ZALAZAR

Reykjavík, Iceland,

Conferencia; 34th International Conference on Alpine Meteorology, Reykjavík, Iceland, 18-23 June 2017; 2017

Universidad de Islandia

p { margin-bottom: 0.25cm; direction: ltr; line-height: 120%; text-align: left; }p.western { font-family: "Courier",serif; font-size: 12pt; }p.cjk { font-family: "Times New Roman"; font-size: 12pt; }p.ctl { font-family: "Courier"; font-size: 10pt; }Orographiceffects of the subtropical and extratropical Andes on precipitatingclouds MaximilianoViale IANIGLA-CONICET,Mendoza, Argentina, and Departamento de Geofísica, Universidad deChile, Santiago, Chile. maxiviale@mendoza-conicet.gob.ar,+54 261 5244268GualbertoZalazarIADIZA-CONICET,Mendoza, ArgentinaEmilioBianchiINTA-CONICET,Bariloche, ArgentinaAbstractThe orographic effectof the Andes (35°S-50°S) on precipitating clouds from midlatitudefrontal systems is investigated using surface and CloudSat satellitedata. The Andes is a long mountain chain that extends in thenorth-south direction on the west coast of South America. Its crestdescent from the subtropics to extratropics and its perpendiculardisposition to the westerly makes this barrier an excellent naturallaboratory to investigate orographic effects on frontal precipitationsystems. Seven transects of hourly rain gauges between 35°S and 45°Sfrom the windward side (Chile) to the lee side (Argentina) wereinstalled as part of a project initiated in 2016. Installed raingauges were complemented with daily precipitation data managed byArgentinean and Chilean Weather and Water agencies, although thesedatasets do not sample well near the crest and in the immediate leesectors of the Andes. Surface precipitation observations indicateorographic enhancement and suppression in annual total amount fromthe Pacific coast to the leeward slopes that varies with latitude.Hourly gauges and instantaneous satellite observations show that thecross-barrier increase and decrease in annual precipitation respondsto increase and decrease in both the intensity and frequency ofprecipitation. In addition, CloudSat satellite data revealcross-barrier variations in precipitating cloud properties thatsuggest orographic influences on the airflow dynamics andmicrophysical processes that will be discussed in the presentation.