Abstract Two univariate indices of the Madden–Julian oscillation (MJO) based on outgoing longwave radiation (OLR) are developed to track convective component MJO while taking into account seasonal cycle. These compared with all-season Real-time Multivariate (RMM) index Wheeler and Hendon derived from a multivariate EOF circulation OLR. The gross features OLR composite MJOs similar regardless index, although RMM is characterized by stronger circulation. Diversity in amplitude phase individual...

Abstract Factors governing the strength and frequency of stratospheric ozone intrusions over Pacific‐North American region are considered for their role in modulating tropospheric on interannual timescales. The association between two major modes climate variability—the El Niño–Southern Oscillation (ENSO) Northern Annular Mode (NAM)—and amount contained tested context mechanisms that modulate stratosphere‐to‐troposphere transport (STT) ozone: (StratVarO 3 ) winter season buildup abundances...

Abstract Observational data are used to test the hypothesis that basic state modulates dispersion properties of convectively coupled equatorial waves (CCEWs). This is based on shallow water theory, which predicts zonal speed propagation such tropospheric modes altered by equivalent depth and flow. Localized space‐time spectra calculated investigate how CCEW spectral peaks vary across tropics they affected variations in wind observed geographically season. Doppler shifting barotropic flow...

Abstract This study examines the diurnal cycle of rainfall and cloudiness associated with Madden–Julian oscillation (MJO) using TRMM rate ISCCP multilevel cloud fraction data. There are statistically significant differences in amplitude phase between suppressed enhanced envelopes MJO convection. The middle–deep increases within convection, especially over ocean. However, generally smaller than daily mean values, so that its relative contribution to total or variance convection becomes...

Abstract The relationship between n = 0 mixed Rossby–gravity waves (MRGs) and eastward inertio-gravity (EIGs) from Matsuno’s shallow-water theory on an equatorial beta plane is studied using statistics of satellite brightness temperature Tb dynamical fields ERA-Interim data. Unlike other observed convectively coupled waves, which have spectral signals well separated into westward modes, there a continuum MRG–EIG power standing above the background that peaks near wavenumber 0. This also...

Despite decades of research on the role moist convective processes in large-scale tropical dynamics, forecast skill operational models is still deficient when compared to extratropics, even at short lead times. Here we compare and Northern Hemisphere (NH) for quantitative precipitation forecasts (QPFs) NCEP Global Forecast System (GFS) ECMWF Integrated (IFS) during January 2015–March 2016. Results reveal that, general, initial conditions are reasonably well estimated both systems, as...

Abstract Precipitation variability over the Maritime Continent is predominantly explained by its diurnal cycle and large-scale disturbances such as Madden–Julian oscillation (MJO) convectively coupled equatorial waves (CCEWs). To advance our understanding of their interactions physical processes, this study uses satellite data to examine changes in rainfall associated with MJO CCEWs Continent. We find that modulations passage any type disturbance are closely tied rain types land–sea...

Abstract Equatorial waves (EWs) are synoptic‐ to planetary‐scale propagating disturbances at low latitudes with periods from a few days several weeks. Here, this term includes Kelvin waves, equatorial Rossby mixed Rossby–gravity and inertio‐gravity which well described by linear wave theory, but it also other tropical such as easterly the intraseasonal Madden–Julian Oscillation more complex dynamics. EWs can couple deep convection, leading substantial modulation of clouds rainfall. amongst...

Abstract Mesoscale convective systems (MCSs) produce over 50% of tropical precipitation and account for the majority extreme rainfall flooding events. MCSs are considered building blocks larger‐scale convectively coupled equatorial waves (CCEWs). While CCEWs can provide favorable environments convection, how systematically impact organized convection thereby MCS characteristics is less clear. We examine this question by analyzing a global tracking data set. During active phase CCEWs,...

Abstract Variability of the Madden‐Julian Oscillation (MJO) inferred from tropical in‐situ observations during 1940–2023 is examined, and compared to that derived reanalyzes. MJO assessments are challenging because characterizing behavior outside satellite era suffers a lack detailed information about its observed state, remote signals often relies on climate models' typically poor representation. This study shows that, while soundings spatially temporally sparse, they still useful for...

A substantial amount of frictional dissipation in the atmosphere occurs microphysical shear zones surrounding falling precipitation. The rate is computed here from recently available satellite retrieval Tropical Rainfall Measurement Missions and found to average 1.8 watts per square meter between 30°S 30°N. geographical distribution precipitation-induced closely tied that precipitation but also reveals a stronger for continental convection than maritime convection. Because same magnitude as...

Abstract Realistically representing the multiscale interactions between moisture and tropical convection remains an ongoing challenge for weather prediction climate models. In this study, we revisit relationship precipitation column saturation fraction (CSF) by investigating their tendencies in CSF–precipitation space using satellite radar observations, as well reanalysis. A well-known, roughly exponential increase occurs CSF increases above a “critical point,” which acts attractor space....

Abstract Previous studies have shown that Madden‐Julian oscillation (MJO) convective activity increases when quasi‐biennial (QBO) easterlies appear in the lower stratosphere, and this relationship is seen only during boreal winter. However, physical mechanism behind not fully understood. Building upon previous literature on MJO‐QBO relationship, study first tests whether between QBO MJO extends to other modes of organized tropical convection. Our analysis shows does any significant with...

Abstract Recent theories of the dynamics Madden‐Julian Oscillation (MJO) have been building on its multiscale structure. While it is observed that much convection within MJO envelope related to higher frequency equatorial waves, not known what extent this organization systematic from one event another. For instance, interest know whether favors waves particular types and propagation direction, how variability changes seasonally. This work presents a wavenumber‐frequency spectral analysis...

Abstract Accurate dynamical forecasts of ocean variables in the California Current System (CCS) are essential decision support tools for advancing ecosystem‐based marine resource management. However, model and uncertainties present a significant challenge when attempting to incorporate these into formal decision‐making process. To provide guidance on reliability forecasts, previous studies have suggested that deterministic climate processes associated with atmospheric or oceanic...

Abstract The intrusion of lower-stratospheric extratropical potential vorticity into the tropical upper troposphere in weeks surrounding occurrence sudden stratospheric warmings (SSWs) is examined. analysis reveals that SSW-related PV intrusions are significantly stronger, penetrate more deeply tropics, and exhibit distinct geographic distributions compared to their climatological counterparts. While upper-tropospheric (UTLS) generally attributed synoptic-scale Rossby wave breaking, it found...

Abstract The fact that the Madden‐Julian Oscillation (MJO) is characterized by large‐scale patterns of enhanced tropical rainfall has been widely recognized for decades. However, precise nature any two‐way feedback between MJO and properties smaller‐scale organization makes up its convective envelope not well understood. Satellite estimates brightness temperature are used here as a proxy rainfall, variety diagnostics applied to determine degree which convection affected either locally or...

Abstract Rainfall over tropical South America is known to be modulated by convectively coupled Kelvin waves (CCKWs). In this work, the origin and dynamical features of American are revisited using satellite-observed brightness temperature, radiosonde, reanalysis datasets. Two main types CCKWs Amazon considered: with a Pacific precursor, precursor originating America. Amazonian CCKW’s associated preexisting convection in eastern account for about 35% total events. The cases precursors either...

Abstract The dynamics of convectively coupled gravity waves traveling over a precipitating region are analyzed in an idealized model for the large-scale atmospheric circulation. is composed shallow water system to advection equation moisture through convection term, utilizing quasi-equilibrium relaxation closure. Here authors investigate strict (SQE) infinitely short time. This framework applied study behavior disturbance propagating along narrow precipitation band, similar intertropical...

Abstract A number of studies suggest a two-way feedback between convectively coupled Kelvin waves (CCKWs) and the intertropical convergence zone (ITCZ). Viewed here as proxy for deep convection, analysis brightness temperature data reveals several aspects these interdependencies. wavenumber–frequency spectral is applied to satellite in order filter CCKWs. The ITCZ characterized by region low both location width are defined. phase speed CCKW determined using Radon transform method. Linear...

Abstract The organization of tropical convection is assessed through an object-based analysis satellite brightness temperature data Tb, a proxy for convective activity. involves the detection contiguous cloud regions (CCRs) in three-dimensional space latitude, longitude, and time where Tb falls below given threshold. A range thresholds considered only CCRs that satisfy minimum size constraint are retained analysis. Various statistical properties documented including their zonal speed...

Abstract There is a longstanding challenge in numerical weather and climate prediction to accurately model tropical wave variability, including convectively coupled equatorial waves (CCEWs) the Madden–Julian oscillation. For subseasonal prediction, European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS) has been shown be superior NOAA Global Forecast (GFS) simulating suggesting that ECMWF better at interaction between cumulus convection large-scale...

Abstract Convectively coupled equatorial waves (CCEWs) are modes of tropical variability that often seen as potentially beneficial for sub‐seasonal predictions. Quantifying this potential has been proven difficult in operational forecast systems because tends to be poorly represented such models. The European Center Medium‐Range Weather Forecasts (ECMWF) is a exception it shown have much improved representation the tropics. Here, ECMWF reforecasts used investigate predicted evolution CCEWs...