Premium
Assessing trends in lower tropospheric heat content in the central United States using equivalent temperature
Author(s) -
Schoof J. T.,
Heern Z. A.,
Therrell M. D.,
Remo J. W. F.
Publication year - 2015
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.4175
Subject(s) - apparent temperature , environmental science , humidity , atmospheric sciences , climatology , equivalent temperature , latent heat , zonal and meridional , air temperature , water content , relative humidity , moisture , troposphere , heat index , heat wave , meteorology , climate change , geology , geography , oceanography , geotechnical engineering
ABSTRACT Isobaric equivalent temperature ( T E ) is the temperature that an air parcel would have if all associated water vapour were condensed and the resulting latent heat used to increase the temperature of the parcel. It is therefore an ideal metric for assessing changes in (1) total near‐surface heat content associated with both temperature and moisture content and (2) the joint behaviour of temperature and humidity, which is relevant to both lower atmospheric stability and human heat stress during extreme temperature events. We present results from an analysis of 50 years (1961–2010) of daily T E and its temperature and moisture components at seven stations in the central United States. The annual means of daily T Emax and T Emin increased at all stations during the period of analysis with the largest changes occurring in T Emin , largely as a result of increasing minimum air temperature. At western locations significant increases in the annual mean T Emax were also observed, resulting from a combination of increases in T max and humidity. Despite small summer ( JJA ) trends in maximum air temperature, summer T E trends were generally larger than their annual counterparts. The timing of the observed variations and the resulting spatial pattern are consistent with observed changes in meridional moisture flux associated with the Great Plains low‐level jet. Heat waves in the region were found to be characterized by increasing T Emin , primarily resulting from increases in minimum air temperature. At western stations, heat waves were also characterized by increasing T Emax as a result of positive trends in humidity. In most cases, equivalent temperature provides a perspective on local environmental change that differs from what is provided by consideration of temperature alone.