End‐Member Mixing Analysis as a Tool for the Detection of Major Storms in Lake Sediment Records

• Published in: Paleoceanography and paleoclimatology 2022-11, Vol.37 (11), p.n/a
• Main Authors: Patterson, R. Timothy, Nasser, Nawaf A., Reinhardt, Eduard G., Patterson, Calder W., Gregory, Braden R. B., Mazzella, Veronica, Roe, Helen M., Galloway, Jennifer M.
• Format: Article
• Language: English
• Subjects: Air masses; Analysis; Catchment area; Climatic zones; Coastal research; Coastal zone; Fluorescence; Grain size; Heavy rainfall; Hurricanes; Ice ages; Inland waters; Iron; Lake sediments; Lakes; Little Ice Age; Precipitation; Rain; Rainfall; Recognition; Runoff; Sediment; Storms; Trends; Tropical cyclone rainfall; Tropical cyclones; Weathering; Zirconium
• ISSN: 2572-4517; 2572-4525
• DOI: 10.1029/2022PA004510

Major Tropical Cyclone (TC) events cause extensive damage in coastal regions of the western North Atlantic Basin. The short instrumental record leaves significant gaps in understanding long‐term trends in TC recurrence and intensity, creating uncertainty about future storm trends. Analysis of an ∼520‐year core record from Harvey Lake, located >80 km from the Atlantic coast in southwestern New Brunswick, Canada was carried out using: (a) end‐member mixing analysis (EMMA) of lake sediment grain size data to identify storm‐linked sedimentological processes; and (2) ITRAX X‐ray fluorescence (XRF) derived element/ratios (Fe, Ti, Ca/Sr, Zr/Rb, K/Rb, and Br + Cl/Al) associated with precipitation, weathering, catchment runoff, and air masses. Three derived end members were correlated to heavy rainfall events (EM01), spring freshet (EM02), and TCs (EM03). CONISS analysis of the EMMA and XRF core data resulted in recognition of four unique climatic zones distinguished by distinct distributions of TC and rainfall/weathering/runoff/and air masses. Numerous, major (EM01) rainfall events and (EM03) TC events characterized the basal core record during the early Little Ice Age (LIAa; Zone 1) phase, terminating at ∼1645. A near cessation of heavy rainfall and TC events differentiated the subsequent colder LIAb (∼1645–1825; Zone 2) and subsequent Little Ice Age Transition (∼1825–1895; Zone 3). A resurgence of major rainfall and TC events occurred during recovery from the LIA starting in ∼1895 (Zone 4). EMMA provides a robust tool for recognition of TC and major rainfall events, and greatly expands the potential for paleo‐storm activity research well inland from coastal regions. Key Points Grain size End‐Member Mixing Analysis (EMMA) permits recognition of major storm and heavy rainfall events in an ∼500 years lake core record CONISS zonation of EMMA and ITRAX data from core delineated phases of the Little Ice Age (LIA) and transition to modern warm era Storm records and major rain events characterized LIAa, then nearly ceased before increasing dramatically during the modern warm era