Australia Bushfire Smoke Now Warming the Decrease Stratosphere?
From Dr. Roy Spencer’s Weblog
March 4th, 2020 by Roy W. Spencer, Ph. D.
Fig. 1. Bushfire smoke flowing eastward from SE Australia on January four, 2020 as seen from the Worldwide Area Station (NASA).
John Christy identified to me that our UAH decrease stratosphere (“LS”) temperature product which has peak sensitivity at about 17 km (70 hPa stress) has elevated within the final 2 months to its warmest worth for the reason that post-Pinatubo interval of warming (1991-93). This may be seen within the following plot of worldwide common anomalies.
Fig. 2. UAH Model 6 global-average decrease stratospheric (LS) temperature anomalies for January 1979 via February 2020.
At first I although we could be seeing warming from the mid-January eruption of Taal volcano within the Philippines, however even the far more huge mid-June 1991 eruption of Pinatubo didn’t present up within the LS temperatures till the month following the eruption, whereas we see proof of warming in Fig. 2 in the identical month because the Taal eruption.
NASA had beforehand reported that the smoke from the Australian bushfires had been detected in January as as excessive as 20-25 km, effectively into the stratosphere (see right here, right here, and right here). The measurements come from the CALIPSO spacecraft which has a lidar instrument able to correct altitude measurements of aerosols.
The mechanism for the warming of the decrease stratosphere by the smoke is a few mixture of direct photo voltaic heating of the smoke particles, and infrared (“greenhouse”) warming of the smoke layer, the latter being the mechanism that brought about the warming after the eruptions of El Chichon and Pinatubo. The aerosol layer could be very chilly, and it intercepts infrared radiation from under and so warms barely.
I’ll attempt to study the particular latitude band (30S-60S) being affected in additional element, together with temperature measurements from larger up (which we don’t produce official merchandise for). The issue is that there’s appreciable pure variation within the tropical and extra-tropical temperatures within the stratosphere which have a see-saw conduct on account of variations within the energy of the Brewer-Dobson circulation. Consequently, these stratospheric aerosol results on temperature have a tendency to point out up greatest in international or nearly-global averages (Fig. 2, above) the place such circulation induced adjustments common out.
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