Key drivers controlling stable isotope variations in daily precipitation of Costa Rica: Caribbean Sea versus Eastern Pacific Ocean moisture sources. (1st January 2016)

• Record Type: Journal Article
• Authors: Sánchez-Murillo, R.; Birkel, C.; Welsh, K.; Esquivel-Hernández, G.; Corrales-Salazar, J.; Boll, J.; Brooks, E.; Roupsard, O.; Sáenz-Rosales, O.; Katchan, I.; Arce-Mesén, R.; Soulsby, C.; Araguás-Araguás, L.J.
• Is Part Of: Quaternary science reviews. Volume 131:Part B(2016)
• Page Start: 250
• Page End: 261
• Publication Date: 2016-01-01
• Subjects: Costa Rica -- Stable isotopes -- Precipitation -- Air mass back trajectories -- Sounding profiles; δ2H deuterium isotope (‰) -- δ18O oxygen-18 isotope (‰) -- CAPE convection available potential energy (J/Kg) -- CAPEv convection available potential energy using virtual temperature (J/Kg) -- CIN convection inhibition (J/kg) -- CLLJ Caribbean low level jet -- CHOCO Colombian low level jet -- D-xs deuterium excess (‰) -- GNIP global network of isotopes in precipitation -- GWML global meteoric water line -- HYSPLIT hybrid single particle Lagrangian integrated trajectory model -- IAEA international atomic energy agency -- ITCZ intertropical convergence zone -- LCL lifted condensation level (m) -- LCLp lifted condensation level pressure (hPa) -- LCLt lifted condensation level temperature (°C) -- LFC level of free convection (m) -- LFCv level of free convection using virtual temperature (m) -- LMWL local meteoric water line -- MR mean layer mixing ratio -- MLR multiple linear regression -- P daily precipitation (mm) -- PW precipitable water (mm) -- RH mean daily relative humidity (%) -- T mean daily air temperature (°C) -- VSMOW vienna standard mean ocean water -- WMO world meteorological organization -- WS mean daily wind speed (m/s); Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2015.08.028
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: Costa Rica is located on the Central American Isthmus, which receives moisture inputs directly from the Caribbean Sea and the Eastern Pacific Ocean. This location includes unique mountainous and lowland microclimates, but only limited knowledge exists about the impact of relief and regional atmospheric circulation patterns on precipitation origin, transport, and isotopic composition. Therefore, the main scope of this project is to identify the key drivers controlling stable isotope variations in daily-scale precipitation of Costa Rica. The monitoring sites comprise three strategic locations across Costa Rica: Heredia (Central Valley), Turrialba (Caribbean slope), and Caño Seco (South Pacific slope). Sporadic dry season rain is mostly related to isolated enriched events ranging from −5.8‰ to −0.9‰ δ 18 O. By mid-May, the Intertropical Convergence Zone reaches Costa Rica resulting in a notable depletion in isotope ratios (up to −18.5‰ δ 18 O). HYSPLIT air mass back trajectories indicate the strong influence on the origin and transport of precipitation of three main moisture transport mechanisms, the Caribbean Low Level Jet, the Colombian Low Level Jet, and localized convection events. Multiple linear regression models constructed based on Random Forests of surface meteorological information and atmospheric sounding profiles suggest that lifted condensation level and surface relative humidity are the main factors controlling isotopic variations. These findings diverge from the recognized 'amount effect' in monthly composite samples across the tropics. Understanding of stable isotope dynamics in tropical precipitation can be used to a) enhance groundwater modeling efforts in ungauged basins where scarcity of long-term monitoring data drastically limit current and future water resources management, b) improve the re-construction of paleoclimatic records in the Central American land bridge, c) calibrate and validate regional circulation models. Highlights: Isotope variations are controlled by the condensation level and relative humidity. Rainfall amount plays a minor role on daily isotope values in tropical precipitation. Model trajectories indicate influence of the Caribbean and Colombian low level jets.