Reassessing the effect of cloud type on earth's energy balance in the age of active spaceborne observations. Part II: Atmospheric heating

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 ± 0.08K day21 that derives largely from 0.06 ± 0.07K day21 of enhanced shortwave absorption and a small, 0.0160.04K day21 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 0.23K day21 and cool the polar atmosphere by 20.13K day21 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 (0.1K day21) than the Southern Hemisphere (0.04K day21). 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).