Abstract
During the interval of 1818-1858, several curious decreases in the
number of sunspot observing days per year are noted in the observing
record of Samuel Heinrich Schwabe, the discoverer of the sunspot cycle,
and in the reconstructed record of Rudolf Wolf, the founder of the now
familiar relative sunspot number. These decreases appear to be nonrandom
in nature and often extended for 13 yr (or more). Comparison of these
decreases with equivalent annual mean temperature (both annual means and
4-yr moving averages). as recorded at Armagh Observatory (Northern
Ireland), indicates that the temperature during the years of decreased
number of observing days trended downward near the start of' each
decrease and upward (suggesting some sort of recovery) just before the
end of each decrease. The drop in equivalent annual mean temperature
associated with each decrease, as determined from the moving averages,
measured about 0.1-0.7 C. The decreases in number of observing days are
found to be closely related to the occurrences of large, cataclysmic
volcanic eruptions in the tropics or northern hemisphere. In particular,
the interval of increasing number of observing days at the beginning of
the record (i.e., 1818-1819) may be related to the improving
atmospheric conditions in Europe following the 1815 eruption of Tambora
(Indonesia; 8 deg. S), which previously, has been linked to "the year
without a summer" (in 1816) and which is the strongest eruption in
recent history, while the decreases associated with the years of 1824,
1837, and 1847 may, be linked, respectively, to the large, catacivsmic
volcanic eruptions of Galunggung (Indonesia; 7 deg. S) in 1822,
Cosiguina (Nicaragua) in 1835, and, perhaps, Hekla (Iceland; 64 deg. N)
in 1845. Surprisingly, the number of observing days per year, as
recorded specifically b), SchAabe (from Dessau, Germany), is found to be
linearly correlated against the yearly mean temperature at Armagh
Observatory (r = 0.5 at the 2 percent level of significance); thus.
years of fewer sunspot observing days in the historical record seem to
indicate years of probable cooler clime, while years (if many sunspot
observing days seem to indicate years of probable warmer clime (and Vice
versa). Presuming this relationship to be real, one infers that the
observed decrease in the number of observing days near 1830 (i.e.,
during "the lost record years" of 1825 to 1833) provides a strong
indication that temperatures at Armagh (and, perhaps, most of Europe, as
well) were correspondingly cooler. If true, then, the inferred cooling
may have resulted from the eruption of Kliuchevsoi(Russia; 56 deg. N) in
1829.
- Publication:
-
Technical Report, NASA/TP-1998-208592; M-889; NAS 1.60:208592
- Pub Date:
- August 1998
- Bibcode:
-
1998nasa.reptY....W
