Extending the late 1963 to 1964 Mt Agung rescued searchlight aerosol profiles dataset, from early 1963 to 1976.

Here we present a set of aerosol turbidity profiles (ATP) and aerosol extinction profiles (AEP), observed with searchlight in New Mexico at 32ºN, digitized from plots in scientific articles. The ATP and AEP cover the periods February to June 1963 and September 1965 to May 1975, complementing a former dataset of 105 rescued individual AEP, corresponding to 36 days, between December 1963 and December 1964. Eleven AEPs were calculated (AEPc) from the ATP, and the corresponding stratospheric aerosol optical depth (sAOD) between 12 and 25 km were also derived. Estimates of digitization errors, the AEPc, and the sAOD were also calculated using information available in the literature. The combined set of rescued AEP reported here and the earlier rescued set of AEP from searchlight observations are the only AEP datasets covering the period between the 1963 Mt Agung and the 1974 Fuego eruptions at northern midlatitudes. Two relevant features identified in the AEP and the sAOD are described. The first, using AEPc from March and April 1963, identified what could be the date of arrival of the stratospheric aerosols from the Mt. Agung first eruption on March 17th, 1963. This fact challenges the accepted criteria that the arrival of the stratospheric aerosols from Mt Agung occurred in the northern hemisphere midlatitudes in the second half of 1963. The second feature shows two anomalous increases in the sAOD during a period that is supposed to correspond to the decay of the sAOD following the Mt. Agung eruption. They show our limited knowledge and understanding of the 1963 Mt Agung volcanic stratospheric aerosol transport. The work has been developed in the framework of the Stratospheric Sulfur and its Role in Climate (SSiRC) activity of the APARC.