ABSTRACT
This
study examines the relationship between precipitation and radiative
heating on intraseasonal time scales in the Tropics using collocated
top-of-atmosphere (TOA) and surface radiative flux measurements from
special field program data [Atmospheric Radiation Measurement (ARM)
Program and Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere
Response Experiment (TOGA COARE) experiments] as well as long-term TOA
flux data [from Earth Radiation Budget Experiment (ERBE) and Advanced
Very High Resolution Radiometer (AVHRR) satellite data]. All the
different datasets consistently show that the atmosphere-integrated
radiative heating is nearly in phase with the precipitation and
enhances the net condensation heating by about 10%–15%. The dominant
contribution to this radiative warming during wet periods is the
reduction of TOA outgoing longwave radiation (OLR), primarily by clouds
but with a small contribution by water vapor. This radiative heating is
reduced slightly by enhanced surface downwelling longwave radiation,
attributable to low cloud bases and reduced atmospheric shortwave
absorption attributable to shadowing by high cloud tops.
The
intraseasonal budget of TOA radiation, reflecting heating of the whole
ocean plus atmosphere column, is characterized by shortwave cloud
forcing anomalies that are substantially larger than the longwave cloud
forcing anomaly. This imbalance is in contrast with the near
cancellation between these two terms at the seasonal time scale.