The effects of increasing humidity on heat transport by extratropical waves

Abstract

This study emphasizes the separate contributions of the warm and cold sectors of extratropical cyclones to poleward heat transport. Aquaplanet simulations are performed with an intermediate complexity climate model in which the response of the atmosphere to a range of values of saturation vapor pressure is assessed. These simulations reveal stronger poleward transport of latent heat in the warm sector as saturation vapor pressure is increased and an unexpected increase in poleward sensible heat transport in the cold sector. The latter results nearly equally from changes in the background stability of the atmosphere at low levels and changes in the temporal correlation between wind and temperature fields throughout the troposphere. Increased stability at low level reduces the likelihood that movement of cooler air over warmer water results in an absolutely unstable temperature profile, leading to less asymmetric damping of temperature and meridional velocity anomalies in cold and warm sectors.

Isca, v1.0: a framework for the global modelling of the atmospheres of Earth and other planets at varying levels of complexity

“…It includes various radiation schemes, including a grey scheme, as in Frierson et al (2006); a grey scheme with moisture feedback, similar to Byrne and O'Gorman (2013); a two-plus-one-band (two infrared, one solar) scheme with an infrared window, similar to Geen et al (2016); and a correlated-k multiband radiation scheme, the RRTM scheme described by Clough et al (2005) and used in the MiMA model of Jucker and Gerber (2017). The radiation may be dependent on the modelpredicted moisture levels or used with fixed optical depths in most of these schemes.…”

“…To provide an intermediate option between grey radiation and a more complete description of radiative transfer, a scheme with two infrared bands and one solar band, as described in Geen et al (2016), has been incorporated into our model with some adjustments. 2 The short-wave band (< 4 µm) treats all solar radiation and the two long-wave bands treat absorption in the infrared window region of the spectrum (8-14 µm) and in all other long-wave wavelengths (> 4 µm, non-window).…”

Isca, v1.0: A Framework for the Global Modelling of the Atmospheres of Earth and Other Planets at Varying Levels of Complexity

“…To provide an intermediate option between gray radiation and a more complete description of radiative transfer, the a scheme with two infra-red bands and one solar band, as described in Geen et al (2016), has been incorporated into our model with some adjustments.1 The shortwave band (< 4µm) treats all solar radiation and the two longwave bands treat absorption in the infra-red window region of the spectrum (8-14 µm), and in all other longwave wavelengths…”

“…Various radiation schemes, including a gray scheme, as in Frierson et al (2006); a gray scheme with moisture feedback, similar to Byrne and O'Gorman (2013); a two-plus-one-band (two infra-red, one solar) scheme with an infra-red window, similar to Geen et al (2016); and a full k-correlated multi-band radiation scheme, the 15 RRTM scheme described by Clough et al (2005) and used in the MiMA model of Jucker and Gerber (2017).…”

“…All bands were originally parameterized by fitting to data from SBDART for a range of atmospheric profiles. Differences from Geen et al (2016) are the addition of CO 2 absorption in each band, and changes to the functional form of the non-window optical depth formula. Although the original functional form was adequate with fixed sea surface temperatures, it was found to be unstable when coupled to a mixed layer ocean.…”