Understanding and predicting the state of North Atlantic Oscillation (NAO) is key to forecasting weather in United Kingdom (UK). It has been shown that particular phases Madden–Julian (MJO) act as precursors either NAO+ or NAO? events. We assess ability UK Met Office coupled climate model (HadGEM3-GC3.1-MM) simulate these NAO responses at lead times 1–2 weeks show improvements are needed modell...

High-resolution simulations over a large tropical domain (;208S–208N, 428E–1808) using both explicit and parameterized convection are analyzed and compared to observations during a 10-day case study of an active Madden–Julian oscillation (MJO) event. The parameterized convection model simulations at both 40and 12-km grid spacing have a very weak MJO signal and little eastward propagation. A 4-k...

The Madden-Julian Oscillation (MJO) is the dominant component of tropical intraseasonal variability, and a theory explaining its structure and successful numerical simulation remains a major challenge. A successful model for the MJO should have a propagation speed of 4-7 m/s predicted by theory; a wavenumber-2 or -3 structure for the planetary-scale, low-frequency envelope with distinct active ...

This paper presents a new empirical model to simulate the Madden–Julian oscillation (MJO), which is the most prominent mode of tropical intraseasonal variability. Zonal wind components at 850 and 200 hPa from reanalysis (1948–2007) and outgoing longwave radiation from satellites (1979–2007) are used to identify MJOs and characterize their statistical properties. The temporal variability of the ...

The processes that lead to changes in the propagation and maintenance of the Madden-Julian Oscillation (MJO) as a response to increasing CO2 are examined by analyzing moist static energy budget of the MJO in a series of NASA GISS model simulations. It is found changes in MJO propagation is dominated by several key processes. Horizontal moisture advection, a key process for MJO propagation, is f...

Abstract The Madden‐Julian oscillation (MJO) significantly impacts North Atlantic hurricanes, with increased hurricane activity occurring when the MJO enhances convection over Africa and tropical Indian Ocean suppressed Pacific. Using data from 1905 to 2015, we find more cyclones (TCs) make landfall in continental United States convection. In addition, Western Pacific Hemisphere convection, TC ...

A kinetic energy budget for the Madden–Julian oscillation (MJO) is established in a three-scale framework. The three scales are the zonal mean, the MJO scale with wavenumbers 1–4, and the small scale with wavenumbers larger than 4. In the composite budget, the dominant balance at the MJO scale is between conversion from potential energy and work done by the pressure gradient force (PGF). This b...

Low-level barotropic dynamics may help to explain the modulation of eastern and western North Pacific tropical cyclones by the Madden–Julian oscillation (MJO) during Northern Hemisphere summer. The MJO is characterized by alternating periods of westerly and easterly 850-mb zonal wind anomalies across the tropical Pacific Ocean. When MJO 850-mb wind anomalies are westerly, small-scale, slow-movi...

In its default configuration, the Hadley Centre climate model (GA2.0) simulates roughly one-half the observed level of Madden–Julian oscillation activity, with MJO events often lasting fewer than 7 days. We use initialized, climate-resolution hindcasts to examine the sensitivity of the GA2.0 MJO to a range of changes in subgrid parametrizations and model configurations. All 22 changes are teste...

The large-scale vertical moist thermodynamic structure of the Madden–Julian oscillation (MJO) was documented using the first 2.5 yr (2002–05) of version 4 atmospheric specific humidity and temperature profiles from the Atmospheric Infrared Sounder (AIRS). In this study, this issue is further examined using currently available 7-yr version 5 AIRS data (2002–09) to test its dependence on the AIRS...