التفاصيل البيبلوغرافية
| العنوان: |
Variability and trends in the PV-gradient dynamical tropopause. |
| المؤلفون: |
Turhal, Katharina, Plöger, Felix, Clemens, Jan, Birner, Thomas, Weyland, Franziska, Konopka, Paul, Hoor, Peter |
| المصدر: |
EGUsphere; 2/23/2024, p1-32, 32p |
| مصطلحات موضوعية: |
TROPOPAUSE, EL Nino, SOUTHERN oscillation, CLIMATOLOGY, STRATOSPHERE, ATMOSPHERIC temperature |
| مستخلص: |
The dynamical tropopause as a transport barrier between the tropical upper troposphere and extratropical lowermost stratosphere is characterized by steep gradients in potential vorticity (PV) along an isentropic surface. Hence, the latitudinal separation between the dynamical tropopause in the northern and southern hemispheres can be used as a metric of upper tropospheric width for assessing climate change impacts. Here, we obtain the PV gradient-based dynamical tropopause (PVG tropopause) from four meteorological satellite-era reanalyses (ERA5, ERA-Interim, JRA-55, MERRA-2) and investigate its climatology, variability and long-term trends ranging from 1980 to 2017. Our results show a distinct seasonal cycle with larger PV values and a poleward movement of the PVG tropopause in summer. The climatological tropopause PV values are substantially different between different reanalyses, but the tropopause latitude is similar. Significant inter-annual variability in the PVG tropopause latitude is related to El Niño Southern Oscillation (ENSO) and weaker variability also to the Quasi-Biennial Oscillation (QBO), and is consistently represented in reanalyses. In particular, El Niño causes equatorward shifts of the PVG tropopause, hence a decrease of upper tropospheric width. Long-term trends in the PVG tropopause over the period 1980–2017 exhibit a distinct vertical structure with poleward shifts below 340 K potential temperature, equatorward shifts between 340–370 K and poleward shifts between 370–380 K, implying an expansion of the troposphere at lower levels, a narrowing at upper levels and an expansion near the tropical tropopause. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
Complementary Index |
