Mixed layer modeling in the East Pacific warm pool during 2002

2011 ◽  
Vol 38 (11-12) ◽  
pp. 2559-2573 ◽  
Author(s):  
Luke P. Van Roekel ◽  
Eric D. Maloney
Keyword(s):  
Mixed Layer ◽  
Warm Pool ◽  
East Pacific ◽  
Pacific Warm Pool

scholarly journals On the Convective Coupling and Moisture Organization of East Pacific Easterly Waves

2015 ◽  
Vol 72 (10) ◽  
pp. 3850-3870 ◽  
Author(s):  
Adam V. Rydbeck ◽  
Eric D. Maloney
Keyword(s):  
Life Cycle ◽  
Zonal Wind ◽  
Wind Shear ◽  
Warm Pool ◽  
Moisture Gradient ◽  
Easterly Waves ◽  
East Pacific ◽  
Pacific Warm Pool ◽  
Meridional Winds ◽  
The Mean

Abstract Processes associated with the local amplification of easterly waves (EWs) in the east Pacific warm pool are explored. Developing EWs favor convection in the southwest and northeast quadrants of the disturbance. In nascent EWs, convection favors the southwest quadrant. As the EW life cycle progresses, convection in the northeast quadrant becomes increasingly prominent and southwest quadrant convection wanes. The EW moisture budget reveals that anomalous meridional winds acting on the mean meridional moisture gradient of the ITCZ produce moisture anomalies supportive of convection in the southwest quadrant early in the EW life cycle. As EWs mature, moisture anomalies on the poleward side of the EW begin to grow and are supported by the advection of anomalous moisture by the mean zonal wind. In the southwest and northeast portions of the wave, where convection anomalies are favored, lower-tropospheric vorticity is generated locally through vertical stretching that supports a horizontal tilt of the wave from the southwest to the northeast. EWs with such tilts are then able to draw energy via barotropic conversion from the background cyclonic zonal wind shear present in the east Pacific. Convection anomalies associated with EWs vary strongly with changes in the background intraseasonal state. EWs during westerly and neutral intraseasonal periods are associated with robust convection anomalies. Easterly intraseasonal periods are, at times, associated with very weak EW convection anomalies because of weaker moisture and diluted CAPE variations.

Subseasonal SST Variability in the Tropical Eastern North Pacific during Boreal Summer

2008 ◽  
Vol 21 (17) ◽  
pp. 4149-4167 ◽  
Author(s):  
Eric D. Maloney ◽  
Dudley B. Chelton ◽  
Steven K. Esbensen
Keyword(s):  
Costa Rica ◽  
Warm Pool ◽  
Boreal Summer ◽  
Sst Variability ◽  
East Pacific ◽  
Pacific Warm Pool ◽  
Northern Edge ◽  
Precipitation Anomalies ◽  
Sst Anomalies ◽  
Costa Rica Dome

Abstract Boreal summer intraseasonal (30–90-day time scale) sea surface temperature (SST) variability in the east Pacific warm pool is examined using Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) sea surface temperatures during 1998–2005. Intraseasonal SST variance maximizes at two locations in the warm pool: in the vicinity of 9°N, 92°W near the Costa Rica Dome and near the northern edge of the warm pool in the vicinity of 19°N, 108°W. Both locations exhibit a significant spectral peak at 50–60-day periods, time scales characteristic of the Madden–Julian oscillation (MJO). Complex empirical orthogonal function (CEOF) and spectra coherence analyses are used to show that boreal summer intraseasonal SST anomalies are coherent with precipitation anomalies across the east Pacific warm pool. Spatial variations of phase are modest across the warm pool, although evidence exists for the northward progression of intraseasonal SST and precipitation anomalies. Intraseasonal SSTs at the north edge of the warm pool lag those in the vicinity of the Costa Rica Dome by about 1 week. The MJO explains 30%–40% of the variance of intraseasonal SST anomalies in the east Pacific warm pool during boreal summer. Peak-to-peak SST variations of 0.8°–1.0°C occur during MJO events. SST is approximately in quadrature with MJO precipitation, with suppressed (enhanced) MJO precipitation anomalies leading positive (negative) SST anomalies by 7–10 days. Consistent with the CEOF and coherence analyses, MJO-related SST and precipitation anomalies near the Costa Rica Dome lead those at the northern edge of the warm pool by about 1 week.

scholarly journals Satellite and Buoy Observations of Boreal Summer Intraseasonal Variability in the Tropical Northeast Pacific

2007 ◽  
Vol 135 (1) ◽  
pp. 3-19 ◽  
Author(s):  
Eric D. Maloney ◽  
Steven K. Esbensen
Keyword(s):  
Heat Flux ◽  
Wind Speed ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Intraseasonal Variability ◽  
Warm Pool ◽  
East Pacific ◽  
Pacific Warm Pool ◽  
Westerly Flow ◽  
Trmm Precipitation

Abstract Tropical intraseasonal variability in the eastern North Pacific during June–September of 2000–03 is analyzed using satellite and buoy observations. Quick Scatterometer ocean vector winds and the Tropical Rainfall Measuring Mission (TRMM) precipitation indicate that periods of anomalous surface westerly flow over the east Pacific warm pool during a summertime intraseasonal oscillation (ISO) life cycle are generally associated with an enhancement of convection to the east of 120°W. An exception is a narrow band of suppressed precipitation along 8°N that is associated with negative column-integrated precipitable water anomalies and anticyclonic vorticity anomalies. Periods of surface easterly anomalies are generally associated with suppressed convection to the east of 120°W. Summertime wind jets in the Gulfs of Tehuantepec and Papagayo exhibit heightened activity during periods of ISO easterly anomalies and suppressed convection. Strong variations in east Pacific warm pool wind speed occur in association with the summertime ISO. Anomalous ISO westerly flow is generally accompanied by enhanced wind speed to the east of 120°W, while anomalous easterly flow is associated with suppressed wind speed. Intraseasonal vector wind anomalies added to the climatological flow account for the bulk of the wind speed enhancement in the warm pool during the westerly phase, while the easterly phase shows strong contributions to the negative wind speed anomaly from both intraseasonal vector wind anomalies and suppressed synoptic-scale eddy activity. An analysis using Tropical Atmosphere Ocean buoys and TRMM precipitation suggests that wind–evaporation feedback is important for supporting summertime intraseasonal convection over the east Pacific warm pool. A statistically significant correlation of 0.6 between intraseasonal latent heat flux and precipitation occurs at the 12°N, 95°W buoy. Correlations between precipitation and latent heat flux at the 10°N, 95°W and 8°N, 95°W buoys are positive (0.4), but not statistically significant. Intraseasonal latent heat flux anomalies at all buoys are primarily wind induced. Consistent with the suppressed convection there during the ISO westerly phase, a negative but not statistically significant correlation (−0.3) occurs between precipitation and latent heat flux at the 8°N, 110°W buoy.

scholarly journals Influence of the Madden–Julian Oscillation and Caribbean Low-Level Jet on East Pacific Easterly Wave Dynamics

2018 ◽  
Vol 75 (4) ◽  
pp. 1121-1141 ◽  
Author(s):  
Justin W. Whitaker ◽  
Eric D. Maloney
Keyword(s):  
Warm Pool ◽  
Central American ◽  
Madden Julian Oscillation ◽  
Easterly Waves ◽  
Low Level ◽  
East Pacific ◽  
Pacific Warm Pool ◽  
Low Level Jet ◽  
Favorable Conditions ◽  
Relationship Of

Abstract The east Pacific warm pool exhibits basic-state variability associated with the Madden–Julian oscillation (MJO) and Caribbean low-level jet (CLLJ), which affects the development of easterly waves (EWs). This study compares and contrasts composite changes in the background environment, eddy kinetic energy (EKE) budgets, and EW tracks during MJO and CLLJ events. While previous studies have shown that the MJO influences jet activity in the east Pacific, the influence of the MJO and CLLJ on the east Pacific and EWs is not synonymous. The CLLJ is a stronger modulator of the ITCZ than the MJO, while the MJO has a more expansive influence on the northeastern portion of the basin. Anomalous low-level westerly MJO and CLLJ periods are associated with favorable conditions for EW development paralleling the Central American coast, contrary to previous findings about the relationship of the CLLJ to EWs. Easterly MJO and CLLJ periods support enhanced ITCZ EW development, although the CLLJ is a greater modulator of EW tracks in this region, which is likely associated with stronger moisture and convection variations and their subsequent influence on the EKE budget. ITCZ EW growth during easterly MJO periods is more reliant on barotropic conversion than during strong CLLJ periods, when eddy available potential energy (EAPE)-to-EKE conversion associated with ITCZ convection is more important. Thus, the influence of these phenomena on east Pacific EWs should be considered distinct.

Equatorial Asymmetry of the East Pacific ITCZ: Observational Constraints on the Underlying Processes

2011 ◽  
Vol 24 (6) ◽  
pp. 1784-1800 ◽  
Author(s):  
Hirohiko Masunaga ◽  
Tristan S. L’Ecuyer
Keyword(s):  
Heat Flux ◽  
Mixed Layer ◽  
Seasonal Cycle ◽  
Heat Budget ◽  
Warm Pool ◽  
Surface Heat ◽  
Northeast Pacific ◽  
The North ◽  
Budget Analysis ◽  
East Pacific

Abstract The equatorial asymmetry of the east Pacific intertropical convergence zone (ITCZ) is explored on the basis of an ocean surface heat budget analysis carried out with a variety of satellite data products. The annual mean climatology of absorbed shortwave flux exhibits a pronounced meridional asymmetry due to a reduction of insolation by high clouds in the north ITCZ. Ocean mixed layer advection has the largest, if not exclusive, effect of counteracting this shortwave-exerted asymmetry. Other heat fluxes, in particular latent heat flux, predominate over the advective heat flux in magnitude but are secondary with respect to equatorial asymmetry. The asymmetry in advective heat flux stems from a warm pool off the Central American coast and, to a lesser extent, the North Equatorial Counter Current, neither of which exist in the Southern Hemisphere. The irregular continental geography presumably comes into play by generating a warm pool north of the equator and bringing cold waters to the south in the far eastern Pacific. In addition to the annual climatology, the north–south contrast in the seasonal cycle of surface heat flux is instrumental in sustaining the north ITCZ throughout the year. The northeast Pacific is exposed to a seasonal cycle that is considerably weaker than that in the southeast Pacific, arising from multiple causes including the finite eccentricity of the earth’s orbit and meridional gradient in mixed layer absorptivity. Simple experiments generating synthetic sea surface temperature (SST) illustrate that the muted seasonal cycle of heat flux forcing moderates the SST seasonal variability in the northeast Pacific and thus allows the north ITCZ to persist year round. Existing theories on the ITCZ asymmetry are briefly examined in light of the present findings.

scholarly journals Mechanisms for the Interannual Variability of SST in the East Pacific Warm Pool

2009 ◽  
Vol 22 (6) ◽  
pp. 1375-1392 ◽  
Author(s):  
Kristopher B. Karnauskas ◽  
Antonio J. Busalacchi
Keyword(s):  
Pacific Ocean ◽  
Interannual Variability ◽  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
Warm Pool ◽  
Equatorial Pacific ◽  
East Pacific ◽  
Pacific Warm Pool

Abstract In comparison with the western and equatorial Pacific Ocean, relatively little is known about the east Pacific warm pool (EPWP). Observations indicate that the interannual variability of sea surface temperature (SST) in the EPWP is highly correlated (0.95) with the El Niño–Southern Oscillation (ENSO). In this paper, an ocean general circulation model (OGCM) of the tropical Pacific Ocean and various atmospheric and oceanic observations are used to diagnose the physical processes governing the interannual variability of SST in the EPWP. Atmospheric forcings for the OGCM are derived purely from satellite observations between 1988 and 2004. Shortwave heating is identified as playing a dominant role in the interannual SST tendency of the EPWP. The high correlation between SST in the EPWP and eastern equatorial Pacific is therefore explained not by ocean processes, but by an atmospheric link. ENSO-driven equatorial SST anomalies modify the distribution of the overlying atmospheric vertical motions and therefore cloud cover and ultimately shortwave heating. During an El Niño event, for example, the ITCZ is equatorward displaced from its normal position over the EPWP, resulting in anomalously large shortwave heating over the EPWP. Analysis of poleward ocean heat transport and coastal Kelvin waves confirms that oceanic processes are not sufficient to explain the interannual variability of the EPWP.

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