Reassessing the Effect of Cloud Type on Earth’s Energy Balance in the Age of Active Spaceborne Observations. Part II: Atmospheric Heating

Abstract

The role of clouds in modulating vertically integrated atmospheric heating is investigated using CloudSat’s multisensor radiative flux dataset. On the global mean, clouds are found to induce a net atmospheric heating of 0.07 ± 0.08 K day−1 that derives largely from 0.06 ± 0.07 K day−1 of enhanced shortwave absorption and a small, 0.01 ± 0.04 K day−1 reduction of longwave cooling. However, this small global average longwave effect results from the near cancellation of much larger regional warming by multilayered cloud systems in the tropics and cooling from stratocumulus clouds in subtropical oceans. Clouds are observed to warm the tropical atmosphere by 0.23 K day−1 and cool the polar atmosphere by −0.13 K day−1 enhancing required zonal heat redistribution by the meridional overturning circulation. Zonal asymmetries in the occurrence of multilayered clouds that are more frequent in the Northern Hemisphere and stratocumulus that occur more frequently over the southern oceans also leads to 3 times as much cloud heating in the Northern Hemisphere (0.1 K day−1) than the Southern Hemisphere (0.04 K day−1). These findings suggest that clouds very likely make the strongest contribution to the annual mean atmospheric energy imbalance between the hemispheres (2.0 ± 3.5 PW).

Joint cloud water path and rainwater path retrievals from airborne ORACLES observations

“…At the base of the cloud, uncertainties with any appreciable PIA contribution (i.e., > 0.01) result in uncertainties exceeding 1000 % or more. Clearly even successful retrievals in the first minute of this scene have rainfall rates near the upper limit of the range of algorithm applicability consistent with prior spaceborne radar rainfall retrievals (e.g., Haynes et al, 2009). Figure 6 also shows that the a priori constraint contributes heavily in heavier rainfall.…”

Reassessing the Effect of Cloud Type on Earth’s Energy Balance in the Age of Active Spaceborne Observations. Part I: Top of Atmosphere and Surface

“…This implies that, while cloud SW effects govern cloud impacts on total atmospheric heating, LW effects govern its redistribution. This result is explored in much greater detail in a companion paper (i.e., Part II of this paper, Hang et al 2019).…”

“…Finally, a summary and discussion will be given in section 4. A subsequent study (Hang et al 2019) will examine the implications of cloud type for radiative heating and cooling within the atmosphere.…”

FORUM: Unique Far-Infrared Satellite Observations to Better Understand How Earth Radiates Energy to Space

“…Understanding the cloud radiative effect (CRE) of high clouds has been the subject of numerous studies in recent decades. While there is no longer evidence that the global CRE of high clouds is warming (Hartmann et al 1992;Matus and L'Ecuyer 2017;Stephens 2005), the average value of this warming and its zonal and vertical distribution remains highly uncertain (Hang et al 2019;L'Ecuyer et al 2019;Oreopoulos et al 2016).…”