Detection and analysis of rapid temperature changes over a large pole-centered spatial domain

Using the Microwave Sounding Unit (MSU) 20-year data set of lower tropospheric (T2LT) daily temperature anomalies, we have detected episodes of very rapid temperature change for a pole centered volume (PCV) of air representing approximately one fourth of the earth’s total atmosphere. Using a thresholding scheme, we have defined 22 cases where the average temperature of the volume increases or decreases by a degree K or more in a 10 day span. This represents a net anomalous flux of energy across the PCV boundaries on the order of 10¹⁵ Watts. Close agreement is noted between the temperature record in the MSU data set and with that of the National Center for Environmental Prediction (NCEP) reanalysis project.

In order to diagnose the cases of rapid temperature change, we have developed a daily energy budget for the PCV that includes storage of energy within the volume as well as relevant boundary fluxes. We use the NCEP reanalysis data set to calculate the flux and storage terms in the energy budget. We define pre, during, and post change periods of about 10 days each to see the time-evolution of the identified cases. Maps of both temperature and its rate of change are produced in order to investigate the spatial distribution of the observed rapid changes. By looking at the common features of the various cases we can make some general inferences concerning the mechanisms which take the climate system away from and back toward energy balance on short time scales.