Modulation Of Cloud And Radiation Heating By The Madden-Julian Oscillationand Kelvin Wave

Cloud radiative heating is an important component of diabatic heating, hence it is also an fundamental factor modulating the large-scale atmospheric circulation. It is crucial to accurately estimate cloud radiative heating profiles associated with MJO and Kelvin Waves (KW) to better understand these large-scale convective phenomena.This study used surface remote sensing data of cloud profiles from the DYNAMO and TWP-ICE instruments to quantify deviations of radiative heating deraived from the 1:30 and 13:30 sampling with that derived from the 24-hour sampling. The comparision was performed according to different phases of MJO and KW and the heating was computed by using Fu-liou radiative transfer model. It is found that under the "large-scale active convection" scenario the net heating was consistently over estimated if only using the two-time sampling. A constant parameter is then derived to account for the deviation of short wave heating due to zenith angle variations. A Gaussian fitting method was applied to reduce deviations of the long wave heating as well as that of the net heating. This convection-phase-based adjustment method was tested and found work well.The new method was applied to CloudSat and CALIPSO 1:30 and 13:30 observations. Radiative heating structures associated with MJO and KW were then investigated. It is found that the adjusted net radiative heating associated with active phases of both MJO and long-wave KW (wave numer<=4) were more "bottom heavy". The radiative heating associated with MJO is more "bottom heavy" than that associated with KW whose feature is dominated by waves with wave number>4. However, when the wave numer is less than 4 (ie. the spatial scale of its convection is comparable to that of MJO), the KW radiative heating structure is similar to that of MJO.