Long-term variations of the atmospheric thermobaric field as deduced from NCAR/NCEP Reanalysis data

摘要

Using the data from NCAR/NCEP Reanalysis we investigate long-term variations of thermobaric fields for the second half of the 20-th century. Middle and high latitudes are characterized by 10-20-year variations of meteorological characteristics. A most interesting feature of the global variations is the increase (starting in the 1960s) in pressure and surface air temperature in the tropics and subtropics of the northern and southern hemispheres (predominantly in the eastern hemisphere). In the circum-Antarctic depression the decrease in pressure is as significant. Conceivably the other atmospheric circulation variations might all be accounted for by these changes as well as by a gradual enhancement of the influence of the southern processes. The long-term variations in the tropics seem to be caused by the increased recurrence of El Nino events. The physical transport mechanism for disturbances to the region of Central Asia might be represented by the propagation of mixed Rossby-gravity waves; however, results of correlation analysis suggest much higher propagation velocities of disturbances.