Cloud-Top Height Variability Associated with Equatorial Kelvin Waves in the Tropical Tropopause Layer during the Mirai Indian Ocean cruise for the Study of the MJO-Convection Onset (MISMO) Campaign

Suzuki, Junko; Fujiwara, Masatomo; Hamada, Atsushi; Inai, Yoshihito; Yue, Jun; Shirooka, Ryuichi; Hasebe, Fumio; Takano, Toshiaki

doi:10.2151/sola.2010-025

Cited by 8 publications

(8 citation statements)

References 19 publications

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“…These results imply that the wave activities may change the water vapor and ozone budget in the TTL at time scales on the order of a week, as shown in recent observations by Fujiwara et al (2009) and Suzuki et al (2010b). Because of its quasi-conservative nature, ozone may be more suitable for detecting signals of turbulent mixing.…”

Section: Discussionsupporting

confidence: 59%

Water Vapor and Ozone Variations in the Tropical Tropopause Layer during the Central Equatorial Pacific Experiment Campaign

Koishi

Shiotani

2012

Journal of the Meteorological Society of Japan

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Water vapor and ozone profiles in the tropical tropopause layer (TTL) are investigated using measurements from balloon-borne frost-point hygrometers and ozone sensors during the Central Equatorial Pacific Experiment campaign. Variations in water vapor, ozone, and temperature are described during soundings taken over a period of two weeks and over a distance of approximately 2,700 km along the equator. These observations indicate that the first and latter halves of the campaign period are characterized as cold and warm phases near the cold point tropopause, respectively. Stationary and eastward-traveling components equally contributed to these temperature anomalies. During the transition between the two phases, the ozone increased around 350-400 K, with the maxima around the 360 K isentrope. The water vapor simultaneously increased and decreased around the 360-400 K and 350-360 K isentropes, respectively. Simultaneous increases in ozone and water vapor around 360-400 K with a reduction in the vertical gradients suggest the possibility of turbulent mixing associated with a large-scale wave structure. The enhancement of vertical shear of zonal wind during the transition between the two phases also supports this idea. The decrease in water vapor around the 350-360 K isentropes could be understood as a result of saturation on the isentropic surface. This study shows the importance of observing variations in isentropic coordinates, rather than altitude coordinates, around the TTL in order to make a quantitative argument concerning mixing and dehydration when a large-amplitude disturbance exists.

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Section: Discussionsupporting

confidence: 59%

Water Vapor and Ozone Variations in the Tropical Tropopause Layer during the Central Equatorial Pacific Experiment Campaign

Koishi

Shiotani

2012

Journal of the Meteorological Society of Japan

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“…The changes in tropospheric upwelling are driven by changes in convective activity, which are triggered by anomalously low temperatures near 100 hPa. Variations in tropopause temperatures associated with tropical waves are known to be capable of modulating equatorial convective activity (Zhou and Holton 2002;Suzuki et al 2010). A similar process could explain the impact of cooling in the equatorial stratosphere on the troposphere during SSW events.…”

Section: Discussionmentioning

confidence: 96%

A General Circulation Model Study of the Impact of a Stratospheric Sudden Warming Event on Tropical Convection

Kodera

Mukougawa

Kuroda³

2011

SOLA

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The impact of a Northern Hemisphere stratospheric sudden warming (SSW) event on tropical convection is investigated as an initial value problem using a general circulation model. The amplification of planetary waves that produced the simulated SSW was forced by introducing an anomalous field in the model initial conditions. The impact of this SSW event on the tropics was examined by comparing runs with and without the SSW. An increased stratospheric mean meridional circulation cools the tropical lower stratosphere when planetary waves propagate upward into the stratosphere, leading to enhanced convective activity in the equatorial Southern Hemisphere. This result is consistent with previous observational studies, and indicates that convective activity in the equatorial region is influenced by SSW events.

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“…An alternative method to diagnose convective penetration, such as that used by Suzuki et al (2010) employing cloud top height data by Hamada and Nishi (2010), is not used in the present analysis because the data set does not fully cover the SOWER campaign period and region.…”

Section: A2 Convective Penetrationmentioning

confidence: 99%

Dehydration in the tropical tropopause layer estimated from the water vapor match

et al. 2013

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We apply the match technique, whereby the same air mass is observed more than once and such cases are termed a "match", to study the dehydration process associated with horizontal advection in the tropical tropopause layer (TTL) over the western Pacific. The matches are obtained from profile data taken by the Soundings of Ozone and Water in the Equatorial Region (SOWER) campaign network observations using isentropic trajectories calculated from European Centre for Medium-Range Weather Forecasts (ECMWF) operational analyses. For the matches identified, extensive screening procedures are performed to verify the representativeness of the air parcel and the validity of the isentropic treatment, and to check for possible water injection by deep convection, consistency between the sonde data and analysis field referring to the ozone conservation. Among the matches that passed the screening tests, we identified some cases corresponding to the first quantitative value of dehydration associated with horizontal advection in the TTL. The statistical features of dehydration for the air parcels advected in the lower TTL are derived from the matches. The threshold of nucleation is estimated to be 146 ± 1% (1σ) in relative humidity with respect to ice (RH_ice), while dehydration seems to continue until RH_ice reaches about 75 ± 23% (1σ) in the altitude region from 350 to 360 K. The efficiency of dehydration expressed by the relaxation time required for the supersaturated air parcel to approach saturation is empirically determined from the matches. A relaxation time of approximately one hour reproduces the second water vapor observation reasonably well, given the first observed water vapor amount and the history of the saturation mixing ratio during advection in the lower TTL

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Cloud-Top Height Variability Associated with Equatorial Kelvin Waves in the Tropical Tropopause Layer during the Mirai Indian Ocean cruise for the Study of the MJO-Convection Onset (MISMO) Campaign

Cited by 8 publications

References 19 publications

Water Vapor and Ozone Variations in the Tropical Tropopause Layer during the Central Equatorial Pacific Experiment Campaign

Water Vapor and Ozone Variations in the Tropical Tropopause Layer during the Central Equatorial Pacific Experiment Campaign

A General Circulation Model Study of the Impact of a Stratospheric Sudden Warming Event on Tropical Convection

Dehydration in the tropical tropopause layer estimated from the water vapor match

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