The Response of Tropospheric Circulation to Perturbations in Lower-Stratospheric Temperature
نویسندگان
چکیده
A multiple regression analysis of the NCEP–NCAR reanalysis dataset shows a response to increased solar activity of a weakening and poleward shift of the subtropical jets. This signal is separable from other influences, such as those of El Niño–Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO), and is very similar to that seen in previous studies using global circulation models (GCMs) of the effects of an increase in solar spectral irradiance. The response to increased stratospheric (volcanic) aerosol is found in the data to be a weakening and equatorward shift of the jets. The GCM studies of the solar influence also showed an impact on tropospheric mean meridional circulation with a weakening and expansion of the tropical Hadley cells and a poleward shift of the Ferrel cells. To understand the mechanisms whereby the changes in solar irradiance affect tropospheric winds and circulation, experiments have been carried out with a simplified global circulation model. The results show that generic heating of the lower stratosphere tends to weaken the subtropical jets and the tropospheric mean meridional circulations. The positions of the jets, and the extent of the Hadley cells, respond to the distribution of the stratospheric heating, with low-latitude heating forcing them to move poleward, and high-latitude or latitudinally uniform heating forcing them equatorward. The patterns of response are similar to those that are found to be a result of the solar or volcanic influences, respectively, in the data analysis. This demonstrates that perturbations to the heat balance of the lower stratosphere, such as those brought about by solar or volcanic activity, can produce changes in the mean tropospheric circulation, even without any direct forcing below the tropopause.
منابع مشابه
Understanding the timescales of the tropospheric circulation response to abrupt CO2 forcing in the Southern Hemisphere: Seasonality and the role of the stratosphere
This study examines the time scales of the Southern Hemisphere (SH) tropospheric circulation response to increasing atmospheric CO2 concentrations in models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). In response to an abrupt quadrupling of atmospheric CO2, the midlatitude jet stream and poleward edge of the Hadley circulation shift poleward on the time scale of the risin...
متن کاملComment on ‘‘Tropospheric response to stratospheric perturbations in a relatively simple general circulation
متن کامل
On the Relation Between the Large-Scale Tropospheric Circulation and Air Quality in Tehran
The large-scale tropospheric circulation can play a controlling role in the accumulation and ventilation of air pollutants. It thus impacts air quality in large urban areas. This paper investigates the statistical relations between the dynamical indices related to circulation in the troposphere and visibility as a surrogate for air pollution in the urban area of Tehran for the climatological pe...
متن کاملStratospheric influence on the tropospheric circulation revealed by idealized ensemble forecasts
[1] The coupling between the stratosphere and troposphere following Stratospheric Sudden Warming (SSW) events is investigated in an idealized atmospheric General Circulation Model, with focus on the influence of stratosphericmemory on the troposphere. Ensemble forecasts are performed to confirm the role of the stratosphere in the observed equatorward shift of the tropospheric midlatitude jet fo...
متن کاملSolar Influences on Dynamical Coupling between the Stratosphere and Troposphere
We use a simplified atmospheric general circulation model (AGCM) to investigate the response of the lower atmosphere to thermal perturbations in the lower stratosphere. The results show that generic heating of the lower stratosphere tends to weaken the sub-tropical jets and the tropospheric mean meridional circulations. The positions of the jets, and the extent of the Hadley cells, respond to t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2005