Abstract
The tropical Pacific Walker circulation (PWC) is fundamentally important to global atmospheric circulation, and changes in it have a vital influence on the weather and climate systems. A novel three-pattern decomposition of a global atmospheric circulation (3P-DGAC) method, which can be used to investigate atmospheric circulations including the PWC, was proposed in our previous study. Therefore, the present study aims to examine the capability of this 3P-DGAC method to acquire interdecadal variations in the PWC and its connection to inhomogeneous air temperature changes in the period from 1961–2012. Our findings reveal that interdecadal variations in the PWC, i.e., weakening (strengthening) between the periods 1961–1974 and 1979–1997 (1979–1997 and 1999–2012), can be observed using the zonal stream function (ZSF) derived from the 3P-DGAC method. Enhancement of the PWC is also associated with the strengthening and weakening of zonal circulations in the tropical Indian Ocean (IOC) and Atlantic (AOC), respectively, and vice versa, implying a connection between these zonal overturning circulations in the tropics. The interdecadal variations in the zonal circulations correspond well to inhomogeneous air temperature changes, i.e., an enhancement of the PWC is associated with a warming (cooling) of the air temperature from 1000 to 300 hPa in the western (mid–eastern) Pacific Ocean and a cooling (warming) of the air temperature in the tropopause in the western (mid–eastern) Pacific Ocean. Furthermore, a novel index for the PWC intensity based on air temperature is defined, and the capability of the novel index in representing the PWC intensity is evaluated. This novel index is potentially important for the prediction of the PWC by using dynamic equations derived from the 3P-DGAC method.
Highlights
The tropical Pacific Walker circulation (PWC) is a thermally-direct circulation driven by convection over the warmer western Pacific and Maritime Continent and descending motion over the cooler eastern Pacific [1]
Intensity based on air temperature is defined, and the capability of the novel index in representing the PWC intensity is evaluated. This novel index is potentially important for the prediction of the PWC by using dynamic equations derived from the 3P-DGAC method
The PWC is a prominent and important component of global atmospheric circulation, since changes in it have a vital influence on precipitation and temperature patterns over tropical and subtropical regions; the PWC plays an important role in influencing the mean state and variability of global weather and climate systems [2,3,4,5,6,7]
Summary
The tropical Pacific Walker circulation (PWC) is a thermally-direct circulation driven by convection over the warmer western Pacific and Maritime Continent and descending motion over the cooler eastern Pacific [1]. In influencing factors of changes in the PWC intensity been widely investigated. Sohn et al [18] reported that the intensification of the PWC since 1979 is increased of the central Pacific. Pacific) in negative (resulting in an enhanced sea surface temperature (SST) gradient between the eastern and the late 1990s is one possible causeisofone the possible recent intensification the PWC [7,17,21,23,24]. Noted that the haseastward weakened andglobal shifted eastward with global warming suggested changes the air temperature aretemperature critical to PWC variations. Changes in sea pressure investigate the connections between interdecadal variations in the intensity and air temperature (SLP). It is important to investigate the connections between interdecadal variations in the gradient changes
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
