SNOWFALL EVENT CHARACTERISTICS IN THE
CORDILLERA VILCANOTA, PERU
Baker Perry1, Richard Poremba1, Anton Seimon1,2,
Daniel Martin1, Ginger Kelly1, and Alfredo Tupayachi3
1Department
2Climate
of Geography and Planning, Appalachian State University
Change Institute, University of Maine, 3Universidad Nacional de San Antonio
de Abád de Cusco
71st Eastern Snow Conference
Boone, NC USA
5 June 2014
Cordillera Vilcanota
Background and Significance

Cordillera Vilcanota has been the site of significant research
focused on:




Precipitation variability is a fundamental influence on past and
current changes in the tropical Andes (Garreaud et al. 2003)



Paleoclimatic reconstructions from Quelccaya ice cores (e.g., Thompson
et al. 1985, Seimon 2003, Thompson et al. 2006 )
Past glaciations and climate-glacier interactions (e.g., Mark et al. 2002)
Ecological response to climate change (e.g., Seimon et al. 2007)
Precipitation type, amount, and timing controls surface albedo, which is
critical to glacier mass balance (e.g., Francou et al. 2003)
Precipitation processes play a dominant role in influencing stable
oxygen isotope ratios (δ18O) preserved in snow/ice stratigraphy (e.g.,
Vuille et al. 2008, Vimeux et al. 2009)
However, considerable uncertainty remains on the timing,
precipitation type, and trajectories during events
Descriptions of Central Andean Regional Precipitation
Climatic Feature
Previous Studies
Precipitation
diurnality
Unimodal daytime
precipitation maximum
Precipitation
character
Exclusively deep,
moist convection
Precipitating
moisture
trajectory
Moisture source
regions
ENSO-related
precipitation
anomalies
This Study
Bimodal: broad nighttime maximum
peaking near midnight LST with
secondary late-afternoon maximum
Primarily stratiform (nighttime) with
secondary deep moist convection
(daytime)
?
E from Amazon basin
Primarily NW, but with 95 % tied to
trajectories from the Amazon basin
Amazon basin exclusively
Dominantly Amazon basin, but also 5%
from Pacific Ocean
Negative anomalies with El Niño;
positive anomalies with La Niña
Positive anomalies with El Niño;
negative anomalies with La Niña
Research Questions

What are the predominant precipitation types at ~ 5,000 m asl
and how do they vary by season?



Snow, graupel (phati in Quechua), rain/snow mix, rain
What is the daily timing of snowfall events in the Cordillera
Vilcanota? When is heavy snowfall most likely to occur?
What are the dominant wind directions and antecedent
upstream air trajectories associated with snowfall events?
Cusco International
Airport: Hourly
Precip Observations
SENAMHI Stations:
2x Daily Observations
0000 and 1200 UTC
Perry et al. 2014, Int J Clim
Don Pedro Godfredo with Precipitation Gauge
(At Murmurani Alto 5,050 m asl)
Quelccaya Icecap
August 2010
10 cm diameter
manual gauge
Murmurani Alto (5,050 m)
Sonic Snow Depth
April 2012
Temp &
Relative
Humidity
Parsivel Present Weather
Osjollo Anante Icecap (5,540 m)
RM Young 05103
Alpine Wind Sensor
Vaisala WXT 510
Multisensor with
Sonic Wind,
Temperature,
Relative Humidity,
and Pressure
April 2012
Snow and Graupel
are the Primary
Precipitation Types
Rain is Very
Infrequent, Less
than 4% of Hours
Rapid Snow Ablation in Murmurani Alto
April 2012
Frequency of Event Maturation Time
(All Cusco Precipitation Events, 2004-2010)
10%
5.9 mm/event
68% of total
=Stratiform?
9%
8%
3.3 mm/event
32% of total
=Convective?
Percent
7%
6%
5%
4%
Sunrise
3%
2%
1%
0%
0
1
2
3
4
5
6
Night
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Hour (UTC)
Day
Perry et al. 2014, Int J Clim
73% of heavy events
occur at night
59% of light events
occur during day
Perry et al. 2014, Int J Clim
Sunrise
Night
Day
Cluster 5
8% of events
3.3 mm/event
Composite Trajectory Clusters
for All Events in Cusco, 2004-2010
Cluster 1
50% of events
4.7 mm/event
58% of precipitation
events at Cusco exhibit
trajectories out of the
NNW
Cluster 3
19% of events
4.8 mm/event
Cluster 2
14% of events
3.6 mm/event
83% of events are tied
to weak low-level flow
out of NNW, NE, and E
Infrequent, yet heavy
Cluster 6
5% of events
8.7 mm/event
Cluster 4
5% of events
4.8 mm/event
Perry et al. 2014, Int J Clim
Wind Speed and Direction
During All Precipitation
Events: 2012-2013
Wind Observations
from Osjollo Anante
Precipitation
Observations
from Murmurani Alto
Wind Speed and Direction
During DJF Precipitation
Events: 2012-2013
Wind Observations
from Osjollo Anante
Precipitation
Observations
from Murmurani Alto
Descriptions of Central Andean Regional Precipitation
Climatic Feature
Previous Studies
Precipitation
diurnality
Unimodal daytime
precipitation maximum
Precipitation
character
Exclusively deep,
moist convection
Precipitating
moisture
trajectory
Moisture source
regions
ENSO-related
precipitation
anomalies
E from Amazon basin
Amazon basin exclusively
Negative anomalies with El Niño;
positive anomalies with La Niña
This Study
Bimodal: broad nighttime maximum
peaking near midnight LST with
secondary late-afternoon maximum
Primarily stratiform (nighttime) with
secondary deep moist convection
(daytime)
Primarily NW, but with 95 % tied to
trajectories from the Amazon basin
Dominantly Amazon basin, but also 5%
from Pacific Ocean
Positive anomalies with El Niño;
negative anomalies with La Niña
(Not shown)
Perry et al. 2014, Int J Clim
Summary and Conclusions

Precipitation primarily falls as snow above 5,000 m, with
graupel and heavily rimed snow crystals common. Rain and
mixed precipitation are rare, accounting for less than 5% of
total precipitation hours.
•

There were a total of 281 events between April 2012 and July
2013, with most of the heavy events occurring at night.



How will these values change in 2014-2015, with the possibility of a
major El Niño and an associated elevated freezing level?
No hourly precipitation totals available, only present weather.
What are the meteorological mechanisms responsible for the heavy
nighttime stratiform precipitation?
Most precipitation events are associated with W and NW flow
at Murmurani Alto and NW trajectories at Cusco.

In contrast to E flow as reported at other sites in the Central Andes,
including Quelccaya.
Paleoclimatic Implications


Much of the inference from the nearby Quelccaya ice core
record presumes that the central Andean precipitation
meteorology is fairly well understood. Our findings call that into
question.
A reconsideration of the climatological inferences derived from
Quelccaya (and possibly other tropical Andean ice cores) may
be needed.


May result in improved paleoclimatic understanding?
Improved correlation with other paleoclimatic proxy records?
Research Activities: July to November 2014




Install precipitation monitoring stations on the Quelccaya
Icecap and at Chacaltaya (Cordillera Real), Bolivia.
Recruit and train additional citizen science precipitation
observers in the Cordilleras Vilcanota and Cordillera Real.
Investigate the vertical structure of precipitation with weather
balloon releases and a vertically-pointing radar.
Categorize snow particle type and degree of riming, which may
provide insight to cloud microphysical processes.
Minder et al. (2012)
Questions?
Acknowledgments



Sandra Yuter, Doug Hardy, Nelson Quispe, Marcos Andrade, Tracie Seimon,
Jon Webb, Preston Sowell, Brooks Fisher, Karina Yager, Charles Rodda,
Skylar Haines, Nico Robles, Ben Boore, Paul Carr, Dan Slayback, Don Pedro
Godfredo, and Crispin family
Appalachian State University Board of Trustees International Research
Travel Grant (2009), Office of International Education and Development
(2010, 2012), Justin Brooks Fisher Foundation (2012), College of Arts &
Sciences (2012)
NSF Grant AGS-1347179 (CAREER: Multiscale Investigations of Tropical
Andean Precipitation)