Lower Tropospheric Temperature for 2017 is the second warmest in recent history

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Date Added: 
Thursday, January 4, 2018

 

Date from satellites shows that for the lower troposphere, 2017 was the second warmest recorded since satellite observations began in 1979. Last year, 2016, was the warmest ever recorded. The near-record warmth of 2017 is notable because an El Niño event did not occur in 2017. The other 3 warmest years, 1998, 2010, and 2016, were El Niño years. Except for 1998, all of the warmest years occur after 2000, providing clear evidence of global temperature increase in the troposphere.

Fig. 1. Annual mean, global (80S to 80N) temperature anomalies (difference from the long-term 1980-2009 average) for the lower troposphere (TLT).

Higher up, in the mid to upper troposphere, 2017 is edged out by 1998, a year with a large El Niño event. In the mid to upper troposphere, El Niño events result in larger temperature changes than in the lower troposphere because warming in at the surface in the tropics is amplified at higher altitude due to the moist adiabatic lapse rate. This pushed the annual mean for 1998 above 2017.

Fig. 2. Annual mean, global (80S to 80N) temperature anomalies (difference from the long-term 1980-2009 average) for the mid to upper troposphere (TTT). The data have been adjusted to reduce the effects of stratospheric cooling on measured temperatures.

For this work, we used the “Temperature Total Troposphere” (TTT) and “Temperature Lower Troposphere” (TLT) datasets for Remote Sensing Systems. TLT measures the temperature of a layer closer to the surface, extending from the surface to about 5 miles (about 8 km). TTT measures the temperature of a thick atmospheric layer, extending from the surface to about 8 miles (about 13 km) high, higher than TLT. Both these datasets have recently been updated. For more details see: Mears, C. A. and F. J. Wentz (2016). "Sensitivity of Satellite-Derived Tropospheric Temperature Trends to the Diurnal Cycle Adjustment." Journal of Climate 29: 3629-3646 and Mears, C. A., and F. J. Wentz (2017), A Satellite-Derived Lower-Tropospheric Atmospheric Temperature Dataset Using an Optimized Adjustment for Diurnal Effects, Journal of Climate, 30(19), 7695-7718. These papers are available online (open access)

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