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High-Elevation Monsoon Precipitation Processes in the Central Andes of Peru

Publication ,  Journal Article
Chavez, SP; Silva, Y; Barros, AP
Published in: Journal of Geophysical Research: Atmospheres
December 27, 2020

Measurements at the high-elevation Lamar Observatory in the Mantaro Valley (MV) in the Central Andes of Peru demonstrate a diurnal cycle of precipitation characterized by convective rainfall during the afternoon and nighttime stratiform rainfall with embedded convection. Wet season data (2016–2018) reveal long-duration (6–12 hr) shallow precipitating systems (LDPS) that produced about 17% of monsoon rainfall in 2016 and 2018 associated with El Niño and La Niña, respectively. The LPDS fraction of monsoon rainfall doubles to 35% with weekly recurrence in 2017 under El Niño Costero (coastal) conditions. LDPS occur under favorable moisture conditions dictated by the South America (SA) Low-Level Jet (SALLJ) and Cold Air Intrusions (CAIs). Backward trajectory analysis shows that precipitable water sustains >80% of seasonal precipitation and ties the LPDS to particular moisture source regions in the eastern Andes foothills 1–2 days in advance, enhanced by increased moisture supply in the midtroposphere. Higher frequency of CAIs and enhanced midlevel moisture convergence along CAI fronts explain the increased LDPS frequency during the 2017 El Niño Costero. These findings highlight the functional role of the Andes morphology in organizing moisture supply to high-elevation precipitation systems on the orographic envelope. Analysis of the Global Precipitation Measurement (GPM) mission satellite-based radar observations points to challenges to precipitation detection and estimation in this region as the GPM clutter-free height (~1–2 km AGL) exceeds the depth of shallow precipitation systems in the MV.

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Published In

Journal of Geophysical Research: Atmospheres

DOI

EISSN

2169-8996

ISSN

2169-897X

Publication Date

December 27, 2020

Volume

125

Issue

24

Related Subject Headings

  • 3702 Climate change science
  • 3701 Atmospheric sciences
  • 0406 Physical Geography and Environmental Geoscience
  • 0401 Atmospheric Sciences
 

Citation

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Chavez, S. P., Silva, Y., & Barros, A. P. (2020). High-Elevation Monsoon Precipitation Processes in the Central Andes of Peru. Journal of Geophysical Research: Atmospheres, 125(24). https://doi.org/10.1029/2020JD032947
Chavez, S. P., Y. Silva, and A. P. Barros. “High-Elevation Monsoon Precipitation Processes in the Central Andes of Peru.” Journal of Geophysical Research: Atmospheres 125, no. 24 (December 27, 2020). https://doi.org/10.1029/2020JD032947.
Chavez SP, Silva Y, Barros AP. High-Elevation Monsoon Precipitation Processes in the Central Andes of Peru. Journal of Geophysical Research: Atmospheres. 2020 Dec 27;125(24).
Chavez, S. P., et al. “High-Elevation Monsoon Precipitation Processes in the Central Andes of Peru.” Journal of Geophysical Research: Atmospheres, vol. 125, no. 24, Dec. 2020. Scopus, doi:10.1029/2020JD032947.
Chavez SP, Silva Y, Barros AP. High-Elevation Monsoon Precipitation Processes in the Central Andes of Peru. Journal of Geophysical Research: Atmospheres. 2020 Dec 27;125(24).

Published In

Journal of Geophysical Research: Atmospheres

DOI

EISSN

2169-8996

ISSN

2169-897X

Publication Date

December 27, 2020

Volume

125

Issue

24

Related Subject Headings

  • 3702 Climate change science
  • 3701 Atmospheric sciences
  • 0406 Physical Geography and Environmental Geoscience
  • 0401 Atmospheric Sciences