The More Extreme Nature of North American Monsoon Precipitation in the Southwestern United States as Revealed by a Historical Climatology of Simulated Severe Weather Events
Por:
Luong, Thang M., Castro, Christopher L., Chang, Hsin-I, Lahmers, Timothy, Adams, David K., Ochoa-Moya, Carlos A.
Publicada:
1 sep 2017
Categoría:
Atmospheric science
Resumen:
Long-term changes in North American monsoon (NAM) precipitation
intensity in the southwestern United States are evaluated through the
use of convective-permitting model simulations of objectively identified
severe weather events during ``historical past'' (1950-70) and
``present day'' (1991-2010) periods. Severe weather events are the
days on which the highest atmospheric instability and moisture occur
within a long-term regional climate simulation. Simulations of severe
weather event days are performed with convective-permitting (2.5 km)
grid spacing, and these simulations are compared with available observed
precipitation data to evaluate the model performance and to verify any
statistically significant model-simulated trends in precipitation.
Statistical evaluation of precipitation extremes is performed using a
peaks-over-threshold approach with a generalized Pareto distribution. A
statistically significant long-term increase in atmospheric moisture and
instability is associated with an increase in extreme monsoon
precipitation in observations and simulations of severe weather events,
corresponding to similar behavior in station-based precipitation
observations in the Southwest. Precipitation is becoming more intense
within the context of the diurnal cycle of convection. The largest
modeled increases in extreme-event precipitation occur in central and
southwestern Arizona, where mesoscale convective systems account for a
majority of monsoon precipitation and where relatively large modeled
increases in precipitable water occur. Therefore, it is concluded that a
more favorable thermodynamic environment in the southwestern United
States is facilitating stronger organized monsoon convection during at
least the last 20 years.
Filiaciones:
Luong, Thang M.:
Univ Arizona, Dept Hydrol & Atmospher Sci, Tucson, AZ 85721 USA
Univ Nacl Autonoma Mexico, Ctr Ciencias Atmosfera, Mexico City, DF, Mexico
King Abdullah Univ Sci & Technol, Phys Sci & Engn Div, Thuwal, Saudi Arabia
Castro, Christopher L.:
Univ Arizona, Dept Hydrol & Atmospher Sci, Tucson, AZ 85721 USA
Chang, Hsin-I:
Univ Arizona, Dept Hydrol & Atmospher Sci, Tucson, AZ 85721 USA
Lahmers, Timothy:
Univ Arizona, Dept Hydrol & Atmospher Sci, Tucson, AZ 85721 USA
Adams, David K.:
Univ Nacl Autonoma Mexico, Ctr Ciencias Atmosfera, Mexico City, DF, Mexico
Ochoa-Moya, Carlos A.:
Univ Nacl Autonoma Mexico, Ctr Ciencias Atmosfera, Mexico City, DF, Mexico
|