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Moisture Recycling in the Andes of Colombia
  • Juan Mauricio Bedoya-Soto,
  • German Poveda
Juan Mauricio Bedoya-Soto
Universidad Nacional de Colombia

Corresponding Author:[email protected]

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German Poveda
Universidad Nacional de Colombia
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Abstract

Evapotranspiration from land surface and vegetation plays an important role as a source of precipitation at continental scale in South America, and more so over the Andes cordillera. We evaluate the local recycling of moisture in a complex orography region located in the Central Andes of Colombia (CAC; 4.5N to 7.5N, 78.6W to 71.4W), comprising the East, Central and West Andean ranges and the two inter-Andean valleys of the Magdalena and Cauca Rivers. To this end, we apply the offline atmospheric moisture tracking model, WAM-2layers (Water Accounting Model-2layers). The model input data comes from the ERA-Interim Reanalysis spanning the period 1980-2016 and at 0.125 x 0.125 degrees resolution. We estimate the spatial distribution of the evaporation recycling ratio εc (source moisture zones) and the precipitation recycling ratio ρc (sink moisture zones) at annual and seasonal timescales. According with our results, up to 63% of the average annual evapotranspiration returns as local precipitation in the CAC. Some specific zones of the Western Cordillera and the eastern hillside of the Central Cordillera are “hot spots” for local moisture recycling given the high values of both εc and ρc. At seasonal timescales, there is more activity of the identified source moisture zones during March-April-May (MAM) and June-July-August (JJA). The higher moisture recycling activity in those seasons interconnects two source regions of moisture: the eastern piedmont of the Eastern Cordillera with the eastern piedmont of the Central Cordillera. Both piedmonts also show high intensity rainfall rates. Finally, our work confirms the fundamental role of local recycled moisture to enhance the midnight and early morning peak of the diurnal cycle of precipitation in the CAC during JJA.