Isotopic variability (δ18O, δ2H and d-excess) during rainfall events of the north American monsoon across the Sonora River Basin, Mexico

2021 ◽  
Vol 105 ◽  
pp. 102928
Author(s):  
Juan Pérez Quezadas ◽  
David Adams ◽  
Ricardo Sánchez Murillo ◽  
Alejandro Jiménez Lagunes ◽  
José Luis Rodríguez Castañeda
2020 ◽  
Vol 33 (7) ◽  
pp. 2663-2680 ◽  
Author(s):  
Michael D. Sierks ◽  
Julie Kalansky ◽  
Forest Cannon ◽  
F. M. Ralph

AbstractThe North American monsoon (NAM) is the main driver of summertime climate variability in the U.S. Southwest. Previous studies of the NAM have primarily focused on the Tier I region of the North American Monsoon Experiment (NAME), spanning central-western Mexico, southern Arizona, and New Mexico. This study, however, presents a climatological characterization of summertime precipitation, defined as July–September (JAS), in the Lake Mead watershed, located in the NAME Tier II region. Spatiotemporal variability of JAS rainfall is examined from 1981 to 2016 using gridded precipitation data and the meteorological mechanisms that account for this variability are investigated using reanalyses. The importance of the number of wet days (24-h rainfall ≥1 mm) and extreme rainfall events (95th percentile of wet days) to the total JAS precipitation is examined and shows extreme events playing a larger role in the west and central basin. An investigation into the dynamical drivers of extreme rainfall events indicates that anticyclonic Rossby wave breaking (RWB) in the midlatitude westerlies over the U.S. West Coast is associated with 89% of precipitation events >10 mm (98th percentile of wet days) over the Lake Mead basin. This is in contrast to the NAME Tier I region where easterly upper-level disturbances such as inverted troughs are the dominant driver of extreme precipitation. Due to the synoptic nature of RWB events, corresponding impacts and hazards extend beyond the Lake Mead watershed are relevant for the greater U.S. Southwest.


2018 ◽  
Author(s):  
Paulina Ordoñez ◽  
Raquel Nieto ◽  
Yolande L. Serra ◽  
Luis Gimeno ◽  
Pedro Ribera ◽  
...  

Abstract. This work examines the origin of atmospheric water vapor arriving to the North American Monsoon (NAM) region over a 34-yr period (1981–2014) by using a Lagrangian diagnosis method. This methodology computes budgets of evaporation minus precipitation by calculating changes in the specific humidity of thousands of air particles advected into the study area by the observed winds. During the NAM wet season, on average the recycling process is the main water vapor source, followed by the supply of moisture from the Gulf of California. However, the water vapor transport that generates synoptic-scale rainfall comes primarily from the Caribbean Sea, the Gulf of Mexico and terrestrial eastern Mexico. An additional moisture source over the southwestern US is also identified in association with synoptic rainfall events over the NAM region. A high (low) moisture supply from the Caribbean Sea and the Gulf of Mexico from 4 to 6 days before precipitation events is responsible for high (low) rainfall intensity on synoptic scales during the monsoon peak. Westward propagating mid to upper level inverted troughs (IVs) seem to favor these water vapor fluxes. A 200 % increase in the moisture flux from the Caribbean Sea is related to the occurrence of heavy precipitation in the NAM area, accompanied by a decrease in water vapor advection from the Gulf of California.


Ecohydrology ◽  
2008 ◽  
Vol 1 (3) ◽  
pp. 225-238 ◽  
Author(s):  
Enrique R. Vivoni ◽  
Alex J. Rinehart ◽  
Luis A. Méndez-Barroso ◽  
Carlos A. Aragón ◽  
Gautam Bisht ◽  
...  

2015 ◽  
Vol 15 (12) ◽  
pp. 6943-6958 ◽  
Author(s):  
E. Crosbie ◽  
J.-S. Youn ◽  
B. Balch ◽  
A. Wonaschütz ◽  
T. Shingler ◽  
...  

Abstract. A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012–2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm−3), highest in winter (430 cm−3) and have a secondary peak during the North American monsoon season (July to September; 372 cm−3). There is significant variability outside of seasonal patterns, with extreme concentrations (1 and 99 % levels) ranging from 56 to 1945 cm−3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82 % of the variance in CCN concentration. Changes in aerosol chemical composition are typically aligned with changes in size and aerosol number, such that hygroscopicity can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41 % (pre-monsoon) and 36 % (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, the complex interaction of meteorology, regional and local emissions and multi-phase chemistry during the North American monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Parameterized models typically exhibit improved predictive skill when there are strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol physicochemical processes, suggesting that similar findings could be possible in other locations with comparable climates and geography.


2012 ◽  
Vol 18 (4) ◽  
pp. 549-563 ◽  
Author(s):  
Vagner G. Ferreira ◽  
Zheng Gong ◽  
Samuel A. Andam-Akorful

GRACE satellite gravity data was used to estimate mass changes within the Volta River basin in West African for the period of January, 2005 to December, 2010. We also used the precipitation data from the Tropical Rainfall Measurement Mission (TRMM) to determine relative contributions source to the seasonal hydrological balance within the Volta River basin. We found out that the seasonal mass change tends to be detected by GRACE for periods from 1 month in the south to 4 months in the north of the basin after the rainfall events. The results suggested a significant gain in water storage in the basin at reference epoch 2007.5 and a dominant annual cycle for the period under consideration for both in the mass changes and rainfall time series. However, there was a low correlation between mass changes and rainfall implying that there must be other processes which cause mass changes without rainfall in the upstream of the Volta River basin.


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