TY - JOUR
T1 - Temperature trends in the tropical upper troposphere and lower stratosphere
T2 - Connections with sea surface temperatures and implications for water vapor and ozone
AU - Garfinkel, C. I.
AU - Waugh, D. W.
AU - Oman, L. D.
AU - Wang, L.
AU - Hurwitz, M. M.
PY - 2013/9/16
Y1 - 2013/9/16
N2 - Satellite observations and chemistry-climate model experiments are used to understand the zonal structure of tropical lower stratospheric temperature, water vapor, and ozone trends. The warming in the tropical upper troposphere over the past 30 years is strongest near the Indo-Pacific warm pool, while the warming trend in the western and central Pacific is much weaker. In the lower stratosphere, these trends are reversed: the historical cooling trend is strongest over the Indo-Pacific warm pool and is weakest in the western and central Pacific. These zonal variations are stronger than the zonal-mean response in boreal winter. Targeted experiments with a chemistry-climate model are used to demonstrate that sea surface temperature (hereafter SST) trends are driving the zonal asymmetry in upper tropospheric and lower stratospheric tropical temperature trends. Warming SSTs in the Indian Ocean and in the warm pool region have led to enhanced moist heating in the upper troposphere, and in turn to a Gill-like response that extends into the lower stratosphere. The anomalous circulation has led to zonal structure in the ozone and water vapor trends near the tropopause, and subsequently to less water vapor entering the stratosphere. The radiative impact of these changes in trace gases is smaller than the direct impact of the moist heating. Projected future SSTs appear to drive a temperature and water vapor response whose zonal structure is similar to the historical response. In the lower stratosphere, the changes in water vapor and temperature due to projected future SSTs are of similar strength to, though slightly weaker than, that due directly to projected future CO2, ozone, and methane. Key Points Zonal variations in TTL temperature trend are same magnitude as zonal mean trendSST trends have caused these zonal variationsThese zonal variations influence ozone and water vapor in UTLS
AB - Satellite observations and chemistry-climate model experiments are used to understand the zonal structure of tropical lower stratospheric temperature, water vapor, and ozone trends. The warming in the tropical upper troposphere over the past 30 years is strongest near the Indo-Pacific warm pool, while the warming trend in the western and central Pacific is much weaker. In the lower stratosphere, these trends are reversed: the historical cooling trend is strongest over the Indo-Pacific warm pool and is weakest in the western and central Pacific. These zonal variations are stronger than the zonal-mean response in boreal winter. Targeted experiments with a chemistry-climate model are used to demonstrate that sea surface temperature (hereafter SST) trends are driving the zonal asymmetry in upper tropospheric and lower stratospheric tropical temperature trends. Warming SSTs in the Indian Ocean and in the warm pool region have led to enhanced moist heating in the upper troposphere, and in turn to a Gill-like response that extends into the lower stratosphere. The anomalous circulation has led to zonal structure in the ozone and water vapor trends near the tropopause, and subsequently to less water vapor entering the stratosphere. The radiative impact of these changes in trace gases is smaller than the direct impact of the moist heating. Projected future SSTs appear to drive a temperature and water vapor response whose zonal structure is similar to the historical response. In the lower stratosphere, the changes in water vapor and temperature due to projected future SSTs are of similar strength to, though slightly weaker than, that due directly to projected future CO2, ozone, and methane. Key Points Zonal variations in TTL temperature trend are same magnitude as zonal mean trendSST trends have caused these zonal variationsThese zonal variations influence ozone and water vapor in UTLS
KW - SST trends
KW - TTL
KW - stratospheric ozone
KW - stratospheric temperature trends
KW - stratospheric water vapor
UR - http://www.scopus.com/inward/record.url?scp=84886066236&partnerID=8YFLogxK
U2 - 10.1002/jgrd.50772
DO - 10.1002/jgrd.50772
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AN - SCOPUS:84886066236
SN - 2169-897X
VL - 118
SP - 9658
EP - 9672
JO - Journal of Geophysical Research D: Atmospheres
JF - Journal of Geophysical Research D: Atmospheres
IS - 17
ER -
