The Role of Low-Level Moisture Convergence and Ocean Latent Heat Fluxes in the Madden and Julian Oscillation: An Observational Analysis Using ISCCP Data and ECMWF Analyses

Jones, Charles; Weare, Bryan C.

doi:10.1175/1520-0442(1996)009<3086:trollm>2.0.co;2

Cited by 100 publications

(73 citation statements)

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“…This lead/lag relationship between the surface convergence and MJO deep convection ( Fig. 10.13 of Wang 2005) has been well documented by observational studies, such as Rui and Wang (1990), Hendon and Salby (1994), Zhang (1996), Jones and Weare (1996), Maloney and Hartmann (1998), Matthews (2000), Seo and Kim (2003), Sperber (2003), and Kiladis et al (2005). The surface frictional mass convergence associated with equatorial Kelvin waves should result in low-level moistening and warming ahead of the convection, while the surface frictional mass divergence associated with equatorial Rossby waves should result in low-level drying and cooling behind and under the convection.…”

Section: Summary and Discussionsupporting

confidence: 60%

“…Studies to date have made the most of the available, yet sparse, radiosonde data (e.g., Hendon and Liebmann 1990;Lin and Johnson 1996;KemballCook and Weare 2001;Kiladis et al 2005), the comprehensive, yet model-dependent, reanalysis products, such as the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis (Kalnay et al 1996) and the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (Gibson et al 1997; e.g., Rui and Wang 1990;Hendon and Salby 1994;Jones and Weare 1996;Maloney and Hartmann 1998;Sperber 2003;Seo and Kim 2003;Hsu and Lee 2005;Kiladis et al 2005), and in a few cases vertically resolving satellite data (e.g., Bantzer and Wallace 1996;Myers and Waliser 2003). In general these studies have characterized a number of important properties of the MJO.…”

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confidence: 99%

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Vertical Moist Thermodynamic Structure and Spatial–Temporal Evolution of the MJO in AIRS Observations

Tian

Waliser

Fetzer

et al. 2006

Journal of the Atmospheric Sciences

163

147

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The atmospheric moisture and temperature profiles from the Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit on the NASA Aqua mission, in combination with the precipitation from the Tropical Rainfall Measuring Mission (TRMM), are employed to study the vertical moist thermodynamic structure and spatial-temporal evolution of the Madden-Julian oscillation (MJO). The AIRS data indicate that, in the Indian Ocean and western Pacific, the temperature anomaly exhibits a trimodal vertical structure: a warm (cold) anomaly in the free troposphere (800-250 hPa) and a cold (warm) anomaly near the tropopause (above 250 hPa) and in the lower troposphere (below 800 hPa) associated with enhanced (suppressed) convection. The AIRS moisture anomaly also shows markedly different vertical structures as a function of longitude and the strength of convection anomaly. Most significantly, the AIRS data demonstrate that, over the Indian Ocean and western Pacific, the enhanced (suppressed) convection is generally preceded in both time and space by a low-level warm and moist (cold and dry) anomaly and followed by a low-level cold and dry (warm and moist) anomaly.The MJO vertical moist thermodynamic structure from the AIRS data is in general agreement, particularly in the free troposphere, with previous studies based on global reanalysis and limited radiosonde data. However, major differences in the lower-troposphere moisture and temperature structure between the AIRS observations and the NCEP reanalysis are found over the Indian and Pacific Oceans, where there are very few conventional data to constrain the reanalysis. Specifically, the anomalous lower-troposphere temperature structure is much less well defined in NCEP than in AIRS for the western Pacific, and even has the opposite sign anomalies compared to AIRS relative to the wet/dry phase of the MJO in the Indian Ocean. Moreover, there are well-defined eastward-tilting variations of moisture with height in AIRS over the central and eastern Pacific that are less well defined, and in some cases absent, in NCEP. In addition, the correlation between MJO-related midtropospheric water vapor anomalies and TRMM precipitation anomalies is considerably more robust in AIRS than in NCEP, especially over the Indian Ocean. Overall, the AIRS results are quite consistent with those predicted by the frictional Kelvin-Rossby wave/conditional instability of the second kind (CISK) theory for the MJO.

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Section: Summary and Discussionsupporting

confidence: 60%

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confidence: 99%

Vertical Moist Thermodynamic Structure and Spatial–Temporal Evolution of the MJO in AIRS Observations

Tian

Waliser

Fetzer

et al. 2006

Journal of the Atmospheric Sciences

163

147

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“…13g, h), thus inhibiting the formation of robust Pacific basin-wide overturning circulations. Present study reemphasizes the important role of enhanced boundary convergence ahead of MJO convection on its smooth eastward propagation (Wang and Li 1994;Hendon and Salby 1994;Jones and Weare 1996). It is expected that MJO convection in Indian Ocean will emanate a low sea level pressure tongue to its east as a Kelvin-wave response (e.g., the classic schematics of Madden and Julian 1972).…”

Section: Discussion and Concluding Remarksmentioning

confidence: 75%

Three different downstream fates of the boreal-summer MJOs on their passages over the Maritime Continent

Wang

Ren

et al. 2017

Clim Dyn

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phase. The convection of type-I and -III MJOs at eastern IO is able to generate positive boundary-layer moisture anomalies along with positive column-integrated moisture tendencies over the MC and western Pacific, thus allowing them to propagate eastward smoothly. On the other hand, the type-II MJO convection in eastern IO is associated with a very dry troposphere and negative column-integrated moisture tendency over western Pacific, which result in the rapid decay of convection over the MC. These results emphasize the important roles of robust Kelvin-wave responses and positive SST anomalies on the eastward propagation of boreal-summer MJOs over the MC through moistening the troposphere ahead of the convection.

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“…3) is primarily explained by wind variability. Other studies have also found LHFLX anomalies to be primarily wind driven (Jones and Weare 1996;Maloney and Esbensen 2007;AM08;Grodsky et al 2009;Yokoi et al 2014). Thermodynamic variability, on the other hand, largely opposes or damps the positive relationship between intraseasonal LHFLX anomalies and precipitation anomalies (i.e., Figs.…”

Section: Sensitivity Of Lhflx To Wind Vs Air-seamentioning

confidence: 83%

Analysis of MJO Wind-Flux Feedbacks in the Indian Ocean Using RAMA Buoy Observations

Dellaripa

Maloney

2015

Journal of the Meteorological Society of Japan

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Observations spanning 2004-2012 from two Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) buoys along the equator in the Indian Ocean are used in conjunction with Tropical Rainfall Measuring Mission (TRMM) to assess the relative importance of surface latent heat fluxes to intraseasonal convection. This work is motivated by previous observational and modeling studies that have suggested the importance of wind-induced surface fluxes to the dynamics of the Madden-Julian Oscillation (MJO).Intraseasonal variability is isolated in two ways: 1) 20-100-day bandpass filtering and 2) using the global real time multivariate MJO index. Linear regression shows latent heat flux anomalies to be between 4 % and 8 % of precipitation anomalies when the two variables are compared using similar Wm −2 energy units. From a moist static energy budget viewpoint, these results confirm the potential of wind-induced latent heat fluxes to aid destabilization of MJO convection. Results derived from using both simple intraseasonal filtering and global MJO indices indicate that precipitation leads latent heat flux on the order of a few days, indicating surface fluxes may be more important for maintenance of deep MJO convection in addition to helping set the MJO's propagation speed. Sensitivity tests using smoothed wind speed or thermodynamics (i.e., air temperature, relative humidity, and sea surface temperature) to compute latent heat flux show wind speed variability explains most of the latent heat flux variability on intraseasonal timescales. A similar conclusion is found via linearization of the latent heat flux formula. Additional analysis shows mesoscale and synoptic scale wind variability have negligible impact on intraseasonal latent heat flux anomalies.

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The Role of Low-Level Moisture Convergence and Ocean Latent Heat Fluxes in the Madden and Julian Oscillation: An Observational Analysis Using ISCCP Data and ECMWF Analyses

Cited by 100 publications

References 0 publications

Vertical Moist Thermodynamic Structure and Spatial–Temporal Evolution of the MJO in AIRS Observations

Vertical Moist Thermodynamic Structure and Spatial–Temporal Evolution of the MJO in AIRS Observations

Three different downstream fates of the boreal-summer MJOs on their passages over the Maritime Continent

Analysis of MJO Wind-Flux Feedbacks in the Indian Ocean Using RAMA Buoy Observations

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