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
AuthorLuong, Thang M.
Castro, Christopher L.
Adams, David K.
Ochoa-Moya, Carlos A.
AffiliationUniv Arizona, Dept Hydrol & Atmospher Sci
MetadataShow full item record
PublisherAMER METEOROLOGICAL SOC
CitationThe More Extreme Nature of North American Monsoon Precipitation in the Southwestern United States as Revealed by a Historical Climatology of Simulated Severe Weather Events 2017, 56 (9):2509 Journal of Applied Meteorology and Climatology
Rights© 2017 American Meteorological Society.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractLong-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.
Note6 month embargo; published online: 5 September 2017
VersionFinal published version
SponsorsStrategic Environmental Research and Development Program (SERDP) through the U.S. Departments of Defense and Energy [RC-2205]; U.S. Environmental Protection Agency; UNAM-PAPIIT Projects [IA103916, IA100916]; Consortium for Arizona-Mexico Arid Environments (CAZMEX); Consejo Nacional de Ciencia y Technologia de Mexico; University of Arizona; University of Arizona Transboundary Aquifer Assessment Program (TAAP)