Characterizing South American Mesoscale Convective Complexes Using Isotope Hydrology Kyle J
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Western Kentucky University TopSCHOLAR® Masters Theses & Specialist Projects Graduate School Spring 2017 Characterizing South American Mesoscale Convective Complexes Using Isotope Hydrology Kyle J. Hogancamp Western Kentucky University, [email protected] Follow this and additional works at: http://digitalcommons.wku.edu/theses Part of the Climate Commons, Hydrology Commons, and the Other Oceanography and Atmospheric Sciences and Meteorology Commons Recommended Citation Hogancamp, Kyle J., "Characterizing South American Mesoscale Convective Complexes Using Isotope Hydrology" (2017). Masters Theses & Specialist Projects. Paper 1937. http://digitalcommons.wku.edu/theses/1937 This Thesis is brought to you for free and open access by TopSCHOLAR®. It has been accepted for inclusion in Masters Theses & Specialist Projects by an authorized administrator of TopSCHOLAR®. For more information, please contact [email protected]. CHARACTERIZING SOUTH AMERICAN MESOSCALE CONVECTIVE COMPLEXES USING ISOTOPE HYDROLOGY A Thesis Presented to the Faculty of the Department of Geography and Geology Western Kentucky University Bowling Green, Kentucky In Partial Fulfillment of the Requirements for the Degree Master of Geoscience By Kyle Jordan Hogancamp May 2017 TABLE OF CONTENTS 1. Introduction ..............................................................................................1 2. Literature Review.....................................................................................6 2.1 Climate .......................................................................................6 2.2 Isotope Geochemistry ..............................................................10 2.3 Isotope Hydroclimatology .......................................................16 2.4 Conclusion ...............................................................................24 3. Study Area .............................................................................................26 3.1 Justification for Study Area .....................................................26 3.2 Location ...................................................................................27 3.3 Study Area Climate ..................................................................29 4. Methodology ..........................................................................................34 4.1 Data Collection ........................................................................34 4.2 Data Analysis ...........................................................................36 5. Results and Discussion ..........................................................................39 5.1 Comparisons of δ2H and δ18O in Precipitation ........................39 5.2 Isotopic Trends.........................................................................48 5.3 MCC Event Characterization ...................................................74 5.4 Moisture Source Considerations ..............................................92 6. Conclusion .............................................................................................95 7. References ..............................................................................................98 iii List of Figures Figure 1.1 Global distribution map of MCCs ..............................................1 Figure 1.2 Outline of SSA MCC overlain with precipitation ......................2 Figure 3.1 Map of Brazil ............................................................................27 Figure 3.2 Map of Study Area ...................................................................28 Figure 3.3 Annual mean air temperature for Brazil ...................................30 Figure 3.4 Total annual rainfall in Brazil...................................................31 Figure 3.5 Köppen climate classification map of Brazil............................32 Figure 4.1 Work Flow ................................................................................34 Figure 4.2 Location of GNIP Sites in South America ...............................35 Figure 5.1 GNIP São Paulo LMWL and isotope values ............................41 Figure 5.2 Campo Grande LMWL and isotope values ..............................42 Figure 5.3 Porto Alegre LMWL and isotope values ..................................42 Figure 5.4 Rio de Janeiro LMWL and isotope values ...............................43 Figure 5.5 Summary of Hydrologic process influences ............................45 Figure 5.6 Seasonal variation of the ITCZ and SACZ ..............................49 Figure 5.7 São Paulo event d-excess by season .........................................50 Figure 5.8 Campo Grande monthly d-excess by season ............................51 Figure 5.9 Porto Alegre monthly d-excess by season ................................51 Figure 5.10 Rio de Janeiro monthly d-excess by season, 1966-1969 ........52 Figure 5.11 Rio de Janeiro monthly d-excess by season, 1973-1976 ........52 Figure 5.12 São Paulo event d-excess by ENSO phase .............................55 Figure 5.13 Campo Grande monthly d-excess by ENSO phase ................55 iv Figure 5.14 Porto Alegre monthly d-excess by ENSO phase ....................56 Figure 5.15 Rio de Janeiro monthly d-excess by ENSO phase ................56 Figure 5.16 Rio de Janeiro monthly d-excess by ENSO phase, 1973-1976 .................................................................................................57 Figure 5.17 Graph of d-excess influences..................................................59 Figure 5.18 São Paulo d-excess vs precipitation .......................................60 Figure 5.19 Campo Grande d-excess vs precipitation ...............................61 Figure 5.20 Porto Alegre d-excess vs precipitation ...................................61 Figure 5.21 Rio de Janeiro d-excess vs precipitation ................................62 Figure 5.22 São Paulo δ2H and precipitation .............................................63 Figure 5.23 São Paulo δ18O and precipitation ............................................64 Figure 5.24 Campo Grande monthly events ..............................................66 Figure 5.25 Porto Alegre monthly events, 1965-1970 ...............................67 Figure 5.26 Porto Alegre monthly events, 1972-1983 ...............................67 Figure 5.27 Rio de Janeiro monthly events, 1961-1969 ............................68 Figure 5.28 Rio de Janeiro monthly events, 1972-1976 ............................68 Figure 5.29 Rio de Janeiro monthly events, 1983-1985 ............................69 Figure 5.30 São Paulo Amount Effect Regression ....................................70 Figure 5.31 São Paulo GNIP El Niño Amount Effect ..............................71 Figure 5.32 São Paulo GNIP La Niña Amount Effect ...............................71 Figure 5.33 MCC rainfall contribution to total rainfall .............................73 Figure 5.34 São Paulo MCC LMWL Sample Period ................................74 Figure 5.35 São Paulo Non-MCC events LMWL .....................................75 Figure 5.36 São Paulo Amount Effect ......................................................75 v Figure 5.37 São Paulo MCC Amount Effect .............................................76 Figure 5.38 d-excess of Sao Paulo events ..................................................77 Figure 5.39 São Paulo d-excess vs precipitation .......................................78 Figure 5.40 São Paulo event δ18O and precipitation .................................79 Figure 5.41 São Paulo event δ18O vs. precipitation ..................................81 Figure 5.42 00:00 October 17, 1998, TRMM Map....................................82 Figure 5.43 03:00 October 17, 1998, TRMM Map....................................83 Figure 5.44 06:00 October 17, 1998, TRMM Map....................................84 Figure 5.45 09:00 October 17, 1998, TRMM Map....................................85 Figure 5.46 12:00 October 17, 1998, TRMM Map....................................86 Figure 5.47 15:00 October 17, 1998, TRMM Map....................................87 Figure 5.48 18:00 October 17, 1998, TRMM Map....................................88 Figure 5.49 21:00 October 17, 1998, TRMM Map....................................89 Figure 5.50 00:00 October 18, 1998, TRMM Map....................................90 Figure 5.51 Average δ18O of seawater .......................................................93 vi List of Tables Table 5.1 LMWL Values of GNIP Sites ....................................................43 Table 5.2 Hydrologic influences on δ2H and δ18O ....................................46 vii CHARACTERIZING SOUTH AMERICAN MESOSCALE CONVECTIVE COMPLEXES USING ISOTOPE HYDROLOGY Kyle Hogancamp May 2017 104 Pages Directed by: Jason Polk, Joshua Durkee, Xingang Fan Department of Geography and Geology Western Kentucky University Mesoscale convective complexes (MCCs) over subtropical South America contribute an average annual volume of precipitation equal to approximately seven km3 and occur with an average regularity in the region, with more than 30 per warm season. Isotopic characteristics of precipitation, such as δ2H and δ18O values, provide information that can be used to identify unique processes and sources related to precipitation events. The largest database of isotope characteristics of precipitation within the region is the Global Network of Isotopes in Precipitation (GNIP), which provides varying temporal resolution data from stations around the world, including subtropical