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.