Kinematic and Thermodynamic Characteristics of the Flow over the Western Pacific Warm Pool during TOGA COARE

Lin, Xin; Johnson, Richard H.

doi:10.1175/1520-0469(1996)053<0695:katcot>2.0.co;2

Cited by 243 publications

(249 citation statements)

References 0 publications

Supporting

Mentioning

204

Contrasting

Order By: Relevance

“…These observations reveal a central role of three cloud types above the boundary layer in the MJO: lower-middle troposphere congestus cloud decks that moisten and precondition the lower troposphere in the initial phase, followed by deep convection and a trailing wake of upper troposphere stratiform clouds (23,25). Observations also reveal the complex multiscale structure within the propagating largescale envelope of the MJO; the embedded smaller scale features include westward-propagating two-day waves, eastwardpropagating superclusters or convectively coupled Kelvin waves (26,27), and smaller-scale squall line clusters that typically propagate westward (2,25).…”

Section: T He Dominant Component Of Intraseasonal Variability In Thementioning

confidence: 90%

“…Analysis of observational data from TOGA-COARE (Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment) provides a revealing look into the multicloud and multiscale structure of convection in the Tropics (22) and, in particular, the MJO (23)(24)(25). These observations reveal a central role of three cloud types above the boundary layer in the MJO: lower-middle troposphere congestus cloud decks that moisten and precondition the lower troposphere in the initial phase, followed by deep convection and a trailing wake of upper troposphere stratiform clouds (23,25).…”

Section: T He Dominant Component Of Intraseasonal Variability In Thementioning

confidence: 99%

“…Observations also reveal the complex multiscale structure within the propagating largescale envelope of the MJO; the embedded smaller scale features include westward-propagating two-day waves, eastwardpropagating superclusters or convectively coupled Kelvin waves (26,27), and smaller-scale squall line clusters that typically propagate westward (2,25). The analysis of observations of the MJO (23,25,28) also reveals a complex vertical structure in the MJO envelope with a vertical tilt involving a low-level westerly onset region below easterlies, strong westerlies in the deep convective region, and strongest westerlies aloft in the lowermiddle troposphere in the stratiform region; there is also a leading vertical dipole potential temperature anomaly in the troposphere with warmer temperature anomalies above cooler temperature anomalies and leading low-level moistening.…”

Section: T He Dominant Component Of Intraseasonal Variability In Thementioning

confidence: 99%

“…The unstable wave has a westward, tilted vertical structure for heating, velocity, and temperature, with clear first and second baroclinic mode contributions and with low-level cooler potential temperature lead- ing and within the deep convection. All of these features are present in the MJO (7,23). Thus, the requirements from linear theory listed in Eq.…”

Section: Mjo Analog Waves: the Basic Examplementioning

confidence: 99%

See 3 more Smart Citations

Madden–Julian Oscillation analog and intraseasonal variability in a multicloud model above the equator

Majda

Stechmann

Khouider

2007

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

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 and inactive phases of deep convection; an intermittent turbulent chaotic multiscale structure within the planetary envelope involving embedded westward-and eastward-propagating deep convection events; and qualitative features of the low-frequency envelope from the observational record regarding, e.g., its zonal flow structure and heating. Here, such an MJO analog is produced by using the recent multicloud model of Khouider and Majda in an appropriate intraseasonal parameter regime for flows above the equator so that rotation is ignored. Key features of the multicloud model are (i) systematic low-level moisture convergence with retained conservation of vertically integrated moist static energy, and (ii) the use of three cumulus cloud types (congestus, stratiform, and deep convective) together with their differing vertical heating structures. Besides all of the above structure in the MJO analog waves, there are accurate predictions of the phase speed from linear theory and transitions from weak, regular MJO analog waves to strong, multiscale MJO analog waves as climatological parameters vary. With all of this structure in a simplified context, these models should be useful for MJO predictability studies in a fashion akin to the Lorenz 96 model for the midlatitude atmosphere.coherent planetary intraseasonal variability ͉ multiscale structure ͉ intermittency in convection ͉ nonlinear analog model T he dominant component of intraseasonal variability in theTropics is the 40-to 50-day tropical intraseasonal oscillation, often called the Madden-Julian Oscillation (MJO) after its discoverers (1). In the troposphere, the MJO is an equatorial planetary-scale wave envelope of complex multiscale convective processes that begins as a standing wave in the Indian Ocean and propagates across the western Pacific at a speed of Ϸ5 m⅐s Ϫ1 (2-5). The planetary-scale circulation anomalies associated with the MJO significantly affect monsoon development and intraseasonal predictability in midlatitudes and the development of the El Niño southern oscillation in the Pacific Ocean, which is one of the most important components of seasonal prediction (6, 7). Present-day computer general circulation models typically poorly represent the MJO (8, 9). One conjectured reason for the poor performance of general circulation models is the inadequate treatment across multiple spatial scales of the interaction of the hierarchy of organized structures that generate the MJO as their envelope.There have been a large number of theories attempting to explain the MJO through a specific linearized mechanism, such as evaporation-wind feedback (10, 11), boundary layer...

show abstract

Section: T He Dominant Component Of Intraseasonal Variability In Thementioning

confidence: 90%

Section: T He Dominant Component Of Intraseasonal Variability In Thementioning

confidence: 99%

Section: T He Dominant Component Of Intraseasonal Variability In Thementioning

confidence: 99%

Section: Mjo Analog Waves: the Basic Examplementioning

confidence: 99%

See 2 more Smart Citations

Madden–Julian Oscillation analog and intraseasonal variability in a multicloud model above the equator

Majda

Stechmann

Khouider

2007

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…In the control simulation the large-scale forcing is specified by a 39-day (December 5, 1992, to January 12, 1993) mean of the large-scale horizontal and vertical temperature and moisture advection over the Intensive Flux Array (IFA) of TOGA COARE [Lin and Johnson, 1996]. The domainaveraged horizontal velocities are constrained to follow the 39-day mean values, which is a simple way to represent the control of the cloud-scale properties by the large-scale dynamics ].…”

Section: Cloud-resolving Model and Experimental Designmentioning

confidence: 99%

Effects of sea surface temperature and large‐scale dynamics on the thermodynamic equilibrium state and convection over the tropical western Pacific

Wu¹,

Moncrieff²

1999

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract. The effects of sea surface temperature (SST) variations and large-scale dynamics on the cloud feedback and water vapor feedback are quantified using a finescale numerical model, or cloud-resolving model, in which the cloud-scale dynamics is explicitly treated instead of being parameterized as is necessary in a general circulation model. The SST variation has large impacts on the water vapor feedback and small impacts on the cloud feedback, radiation budget, and surface energy budget under a given large-scale dynamic state. As the SST gets warmer (increasing 2ø), the warm and moist equilibrium state of temperature and water vapor mixing ratio is obtained; the upper tropospheric relative humidity is enhanced; and the cloud amount and convective intensity are slightly reduced. The cooling (about 10 W m -2) at the surface due to the increase of surface evaporation is almost compensated by the warming at the surface due to the increase of surface shortwave flux, which results in a small increase of net surface heat flux. However, the change of large-scale dynamics has large effects on the cloud feedback, radiation budget, and surface energy budget and small effects on the water vapor feedback under a constant SST. An increased large-scale forcing slightly affects the equilibrium states of temperature and water vapor mixing ratio; the relative humidity is decreased above 10 km and increased below; and the cloud amount and convective intensity are enhanced. Both the variations of SST and large-scale dynamics are positively correlated with the surface precipitation.

show abstract

Diagnosing MJO hindcast biases in NCAR CAM3 using nudging during the DYNAMO field campaign

Subramanian

Zhang

2014

J. Geophys. Res. Atmos.

View full text Add to dashboard Cite

This study evaluates the Madden-Julian Oscillation (MJO) hindcast skill and investigates the hindcast biases in the dynamic and thermodynamic fields of the National Center for Atmospheric Research Community Atmosphere Model version 3. The analysis is based on the October 2011 MJO event observed during the Dynamics of the Madden-Julian Oscillation field campaign. The model captures the MJO initiation but, compared to the observations, the hindcast has a faster MJO phase speed, a dry relative humidity bias, a stronger zonal wind shear, and a weaker MJO peak amplitude. The MJO hindcast is then nudged toward the European Centre for Medium-Range Weather Forecast Reanalysis fields of temperature, specific humidity, horizontal winds, and surface pressure. The nudging tendencies highlight the model physics parameterization biases, such as not enough convective diabatic heating during the MJO initiation, not enough upper tropospheric stratiform condensation, and lower tropospheric reevaporation during the mature and decay phases and a strong zonal wind shear during the MJO evolution. To determine the role of temperature, specific humidity, and horizontal winds in the model physics parameterization errors, six additional nudging experiments are carried out, with either one or two of the fields allowed to evolve freely while the others are nudged. Results show that convection and precipitation increase when temperature or specific humidity are unconstrained and decrease when horizontal winds evolve freely or temperature alone is constrained to reanalysis. Budget analysis of moist static energy shows that the nudging tendency compensates for different process biases during different MJO phases. The diagnosis of such nudging tendencies provides a unique objective way to identify model physics biases, which usefully guides the model physics parameterization development.

show abstract

Kinematic and Thermodynamic Characteristics of the Flow over the Western Pacific Warm Pool during TOGA COARE

Cited by 243 publications

References 0 publications

Madden–Julian Oscillation analog and intraseasonal variability in a multicloud model above the equator

Madden–Julian Oscillation analog and intraseasonal variability in a multicloud model above the equator

Effects of sea surface temperature and large‐scale dynamics on the thermodynamic equilibrium state and convection over the tropical western Pacific

Diagnosing MJO hindcast biases in NCAR CAM3 using nudging during the DYNAMO field campaign

Contact Info

Product

Resources

About