Given surface temperature and humidity, the model calculates the environmental temperature profile (and CAPE, buoyancy of convective updrafts), by conceptualizing the interactions between convective plumes and the environment.
Singh and O'Gorman 2013 formulated an elegant Zero-Buoyancy Plume Model (ZBM) which simplifies convective ensemble as a bulk entraining plume and predicts the environment temperature by considering it as zero-buoyant to the bulk plume.
Zhou and Xie 2019 dropped the zero-buoyancy assumption and formulated a Spectral Plume Model (SPM) based on the concept that the environmental temperature at a specific level equals to the temperature of the plume that reaches neutral buoyancy at this level. SPM remains analytical and uncovers an important term implicitly ignored in ZBM. SPM reproduces the C-shape temperature deviation, the increasing and upward-stretch with warming, as well as a smaller rate of increase in the extreme convective updraft compared with CAPE. Please see Research for more details.
(mjo.tar)
The MJO life cycle is categorized into eight MJO phases, which identifies different longitudinal locations of enhanced convection. Following the MJO Diagnostics Package provided by CLIVAR MJO Working Group, we compute the MJO-phase-composited fields in GCMs in the following five steps:
1) Subseasonal (20–100 day) bandpass-filtered anomalies are constructed by applying a 201-point Lanczos filter to unfiltered anomalies from the climatological daily mean.
2) First two leading EOFs of the MJO meridional pattern are generated from reanalysis using the equatorial-mean (10°N–10°S) subseasonal anomalies of 850-hPa zonal winds, 200-hPa zonal winds, and outgoing longwave radiation (OLR).
3) Real-time multivariable MJO (RMM) indices are computed for each model by projecting the simulated anomalous OLR and 250- and 850-hPa zonal winds onto the reanalysis EOFs. Projection onto the reanalysis EOFs allows for a consistent framework for comparison among the different models.
4) MJO phase is determined by tan−1(RMM2/RMM1), with each phase spanning 45o of the cycle.
5) Composites associated with the MJO phase are generated by considering days when the MJO amplitude is greater than 1.