Morphology of bistable 180° phase switches in 18.6‐year induced rainfall over the north‐eastern United States of America

Abstract

Abstract Using a novel data presentation technique, bistable 180° phase switches in 18.6‐year induced precipitation over the northeastern United States of America are re‐examined. It is found that bistable switching in 19‐year wavetrains occurred principally at epochs 1898–9, 1917.5, and 1954.7, although some occurred at mid‐epoch 1908–2, and at epochs 1936.1 and 1973.3 (epochs are dates of maximum in the luni‐solar 18.6‐year tide). The 180° phase switch at 1898.9 occurred along the northern Atlantic seaboard, and by epoch 1954.7 this invading ‘cell’ from the east blanketed virtually the entire region. O'Brien and Currie (1988) have provided a construct in mathematical physics which can explain how such sudden readjustments in the standing wave pattern for air pressure occur on subcontinental scales, and such adjustments are found in other climatic parameters such as air temperature and pressure. Results for seven tree‐ring chronologies in the region are also given, and are found to have serious inconsistencies both among themselves and also with respect to instrumental rain‐gauge data.