Opposite phase changes of precipitation annual cycle over land and ocean
under global warming
The annual cycle of precipitation is a fundamental aspect of the global
water cycle. Climate warming induces amplitude enhancement and phase
delay in the zonal-mean tropical precipitation. Here, we report a
land-ocean contrast in the phase response of precipitation annual cycle,
with a delay over land and an advance over ocean as climate warms.
Although two-thirds of the Earth’s surface are covered by ocean, land
dominates the zonal-mean phase delay, attributable to an increase in the
effective atmospheric heat capacity. The phase advance over ocean is
associated with a precipitation shift from land to ocean during the peak
rainy season. This shift is well constrained by the energetic and
related to a land-ocean contrast in the amplitude change of surface
temperature annual cycle: seasonally different wind changes enhance this
amplitude over ocean, while increased effective atmospheric heat
capacity and surface cooling feedback reduce the amplitude over land.