Embedding a one-column ocean model in the Community Atmosphere Model 5.3 to improve Madden–Julian Oscillation simulation in boreal winter

Abstract. The effect of the air–sea interaction on Madden–Julian Oscillation (MJO) was investigated using one-column ocean model Snow–Ice–Thermocline (SIT 1.06) embedded in Community Atmosphere Model 5.3 (CAM5.3; hereafter CAM5–SIT v1.0). SIT with 41 vertical layers developed to simulate sea surface temperature (SST) and upper-ocean variations a high resolution that resolves cool skin diurnal warm layer upper oceanic gradient. A series 30-year sensitivity experiments were conducted which various configurations (e.g., coupled versus uncoupled, depth model, coupling domains, absence cycle) considered evaluate MJO simulation. Most exhibit higher fidelity than CAM5-alone experiment characterizing basic features such as spatiotemporal variability eastward propagation boreal winter. overall simulation performance benefits from (1) better resolving fine structure therefore results more realistic intraseasonal both SST atmospheric circulation (2) adequate thickness vertically gridded layer. demonstrate necessity tropical eastern Pacific addition Indian Ocean western Pacific. Coupling is essential south north Equator Enhanced could be obtained without considering cycle coupling.