Meridional Migration of Tropical Convergence Zones

Srinivasan, J.; Smith, George Van S.

doi:10.1175/1520-0450(1996)035<1189:mmotcz>2.0.co;2

Cited by 25 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Neelin and Held (1987), and Srinivasan and Smith (1996) have (Xie-Arkin, 1980± 1995, b Hack simulation (10 year), c MCA simulation (10 year), and d the 10 year mean difference between the summer mean Hack and MCA precipitation simulations (negative contours at À2, À4, À6 and À8 are shown dotted)…”

Section: Relationship Between Precipitable Water and Rainfallmentioning

confidence: 99%

Comparison of seasonal and intraseasonal variation of tropical climate in NCAR CCM2 GCM with two different cumulus schemes

Rajendran¹,

Nanjundiah²,

Srinivasan³

2002

Meteorology and Atmospheric Physics

Self Cite

View full text Add to dashboard Cite

The seasonal and intraseasonal variation of tropical climate in National Center for Atmospheric Research (NCAR) Community Climate Model Version 2 (CCM2) General Circulation Model (GCM) has been examined using two different cumulus parameterization schemes, the moist convective adjustment scheme of Manabe et al. (1965) and the mass-¯ux scheme of Hack (1994). Ten-year simulations have been undertaken with each of these schemes with SST prescribed according to the monthly mean climatology. The seasonal mean rainfall in the tropics simulated by the moist convective adjustment scheme (MCA) scheme was found to be more realistic than the mass-¯ux (Hack) scheme. The more realistic simulation by the MCA scheme was found to be on account of the fact that the mean moist static energy of the lower troposphere in the MCA scheme was closer to the observations than in the Hack scheme. In both the schemes, the precipitation in the tropics increases montonically with precipitable water vapour when the precipitable water vapour is above 40 mm. This is consistent with relationship between precipitation and precipitable water in the observations. The Hack scheme tends to simulate lower precipitation (for a given amount of precipitable water) when compared to observations. The MCA scheme simulates the eastward migration of convective systems along the equator quite well, although the speed of propagation is somewhat low. The poleward migration of convective systems in the Indian region is more realistically simulated by the MCA scheme than the Hack scheme. This is because the latitudinal gradient of the mean moist static energy in the MCA scheme is more realistic than in the Hack scheme. Over most of the tropics, simulation by the MCA scheme is more realistic on both seasonal and intraseasonal timescales.

show abstract

Section: Relationship Between Precipitable Water and Rainfallmentioning

confidence: 99%

Comparison of seasonal and intraseasonal variation of tropical climate in NCAR CCM2 GCM with two different cumulus schemes

Rajendran¹,

Nanjundiah²,

Srinivasan³

2002

Meteorology and Atmospheric Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…NPISOs comprise successive 30-40-day time-scale northward propagations of organized convection in summer over the Asia-west Pacific sector (Yasunari 1979;Sikka and Gadgil 1980;Srinivasan and Smith 1996). The time-latitude variation of 20-80-day band pass filtered (following Duchon 1979) TRMM 3B42 rainfall and TMI surface winds averaged over Indian longitudes (figure 7) shows the close relationship between propagating signals of active convection and the onset, active and break phases and withdrawal of monsoon.…”

Section: 2a Northward Propagating Intraseasonal Oscillations (Npiso)mentioning

confidence: 98%

The role of low-frequency intraseasonal oscillations in the anomalous Indian summer monsoon rainfall of 2002

2007

View full text Add to dashboard Cite

We analyze the dynamical features and responsible factors of the low-frequency intraseasonal time scales which influenced the nature of onset, intensity and duration of active/break phases and withdrawal of the monsoon during the anomalous Indian summer monsoon of 2002 -the most severe drought recorded in recent times. During that season, persistent warm sea surface temperature anomalies over the equatorial Indian Ocean played a significant role in modulating the strength of the monsoon Hadley circulation. This in turn affected the onset and intense break spells especially the long break during the peak monsoon month of July. Strong low-frequency intraseasonal modulations with significant impact on the onset and active/break phases occurred in 2002 which were manifested as a good association between low-frequency intraseasonal oscillations and the onset and active/break spells. Further, SST anomalies over the equatorial Indo-Pacific region on low-frequency intraseasonal time scales were found to affect the equatorial eastward and thereby off-equatorial northward propagations of enhanced convection over the Indian region. These propagations in turn modulated the active/break cycle deciding the consequent severity of the 2002 drought.

show abstract

“…During northern summer, the ITCZ is entirely in the northern hemisphere while during southern summer (northern winter) the ITCZ is located south of the equator. At the latitude of the Indian subcontinent (80 • E-82.5 • E), the seasonal migration of the ITCZ occurs between ∼ 5 • S and ∼ 20 • N (Srinivasan and Smith, 1996). The position of the ITCZ during the equinox seasons, on average, is centred approx.…”

Section: Seasonal Variation Of Momentum Flux Valuesmentioning

confidence: 99%

Seasonal variation of equatorial wave momentum fluxes at Gadanki (13.5° N, 79.2° E)

Sasi

Deepa

2001

Ann. Geophys.

View full text Add to dashboard Cite

Abstract.The vertical flux of the horizontal momentum associated with the equatorial Kelvin and Rossby-gravity waves are estimated from the winds measured by the Indian MST radar located at Gadanki (13.5 • N, 79.2 • E) during September 1995 to August 1996 in the tropospheric and lower stratospheric regions for all four seasons. The present study shows that momentum flux values are greater during equinox seasons than solstices, with values near the tropopause level being 16 × 10 −3 , 7.4 × 10 −3 , 27 × 10 −3 and 5.5 × 10 −3 m 2 s −2 for Kelvin waves and 5.5 × 10 −3 , 3.5 × 10 −3 , 6.7 × 10 −3 and 2.1 × 10 −3 m 2 s −2 for RG waves during autumnal equinox, winter, vernal equinox and summer seasons, respectively. Using these momentum flux values near the tropopause level, acceleration of the mean flow in the stratosphere up to a 29 km height were computed following Plumb (1984), by considering the wave-meanflow interaction and the deposition of the momentum through the radiative dissipation of the waves. A comparison of the estimated mean-flow acceleration in the stratosphere compares well, except at a few height levels, with the observed mean-flow accelerations in the stratosphere derived from the radiosonde data from a nearby station.

show abstract

Meridional Migration of Tropical Convergence Zones

Cited by 25 publications

References 0 publications

Comparison of seasonal and intraseasonal variation of tropical climate in NCAR CCM2 GCM with two different cumulus schemes

Comparison of seasonal and intraseasonal variation of tropical climate in NCAR CCM2 GCM with two different cumulus schemes

The role of low-frequency intraseasonal oscillations in the anomalous Indian summer monsoon rainfall of 2002

Seasonal variation of equatorial wave momentum fluxes at Gadanki (13.5° N, 79.2° E)

Contact Info

Product

Resources

About