Interannual variations of temperature and vertical motion at the tropical tropopause associated with ENSO

Hatsushika, Hiroaki; Yamazaki, Koji

doi:10.1029/2001gl012977

Cited by 27 publications

(28 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This hypothesis was generally accepted until Sherwood (2000) indicated that the vertical motion near the tropopause over the western Pacific is downward. This finding was supported in numerical simulations (Gettelman et al, 2000;Hatsushika and Yamazaki, 2001).…”

Section: Introductionsupporting

confidence: 73%

In situ observations of dehydrated air parcels advected horizontally in the Tropical Tropopause Layer of the western Pacific

et al. 2007

View full text Add to dashboard Cite

Abstract. Water vapor observations by chilled-mirror hygrometers were conducted at Bandung, Indonesia (6.90 • S, 107.60 • E) and Tarawa, Kiribati (1.35 • N, 172.91 • E) in December 2003 to examine the efficiency of dehydration during horizontal advection in the tropical tropopause layer (TTL). Trajectory analyses based on bundles of isentropic trajectories suggest that the modification of air parcels' identity due to irreversible mixing by the branching-out and merging-in of nearby trajectories is found to be an important factor, in addition to the routes air parcels follow, for interpreting the water vapor concentrations observed by chilled-mirror frostpoint hygrometers in the TTL. Clear correspondence between the observed water vapor concentration and the estimated temperature history of air parcels is found showing that drier air parcels were exposed to lower temperatures than were more humid ones during advection. Although the number of observations is quite limited, the water content in the observed air parcels on many occasions was more than that expected from the minimum saturation mixing ratio during horizontal advection prior to sonde observations.

show abstract

Section: Introductionsupporting

confidence: 73%

In situ observations of dehydrated air parcels advected horizontally in the Tropical Tropopause Layer of the western Pacific

et al. 2007

View full text Add to dashboard Cite

show abstract

“…However, Sherwood (2000) shows that the vertical motion near the tropopause over the western Pacific is downward. This finding is supported in a numerical simulation made by a general circulation model (Hatsushika and Yamazaki 2001).…”

Section: Introductionsupporting

confidence: 70%

Dynamical Properties of the Tropical Atmosphere Derived from Radiosonde Observations at San Cristobal and Singapore

Hasebe

Koyata

2004

Journal of the Meteorological Society of Japan

View full text Add to dashboard Cite

Operational radiosonde data at San Cristóbal (0.90 S, 89.62 W; eastern Pacific) are compared with those at Singapore (1.37 N, 103.98 E; western Pacific) intending to explore the differences in the dynamical properties of the tropopause region and in the activities of atmospheric waves between the eastern and the western tropical Pacific. The interannual variations in the meteorological parameters of the tropopause region are found to be almost synchronized between the two stations and do not show direct correspondence with the time evolution of El Niñ o. These evidences, as opposed to the general expectation of the strong influence of sea surface temperature variations on the tropopause properties, suggest that the tropospheric dynamical forcing is not a prevailing factor that drives the interannual variation of the tropical tropopause properties for these stations. The dynamical parameters of the tropopause region are affected by passages of vertically propagating atmospheric waves that characterize the time evolution of daily sounding data. The variations with the time scales of 15 to 20 days are identified as equatorial Kelvin waves of zonal wave number 1, which is consistent with the observed out-ofphase relationship between the two stations. The perturbations in the tropospheric temperature and wind are also brought about by those waves with the typical time scales of several days. These waves are more pronounced over San Cristóbal than in Singapore. As the convections are more active and reach higher altitude in the western than in the eastern Pacific, this evidence implies that the altitude rather than the strength of convection is more important in characterizing the daily fluctuations of the tropical troposphere. The differences between the two stations in the time evolution and magnitude of the quasibiennial oscillation in the equatorial stratosphere are found to be marginal, although occasional differences in the onset time and the magnitude of zonal wind acceleration could be pointed out.

show abstract

“…turn results in systematic changes to the tropical tropopause in this region, as shown by a diagnostic and modeling study by Gettelman et al [2001], while Hatsushika and Yamazaki [2001] demonstrated how the region of coldest (highest) tropopause moves with the convection maximum. Here we investigate how TST distributions over the Pacific are changed by ENSO.…”

Section: El Niñ O/southern Oscillationmentioning

confidence: 99%

A 15‐year climatology of stratosphere–troposphere exchange with a Lagrangian particle dispersion model 2. Mean climate and seasonal variability

et al. 2003

View full text Add to dashboard Cite

[1] A comprehensive climatology of stratosphere-troposphere exchange (STE), based on 15 years of ECMWF global atmospheric reanalysis data for the period 1979-1993, has been carried out with a specially tuned version of the Lagrangian particle dispersion model, FLEXPART. The typical amplitudes, timescales, seasonality, and spatial variability of STE revealed in the climatology are described. Mean distributions of STE air masses of various ages relate to aspects of the global circulation, while anomaly patterns, such as the North Atlantic Oscillation (NAO) and El Niño, influence STE variability. Characteristic differences are seen between shallow STE flows remaining within the tropopause region (TPR) and deep STE transports, which include cases of stratospheric air reaching the lower troposphere. Unlike for shallow STE events, such deep intrusions show a distinct winter maximum. This subsequently impacts on the seasonal cycle of stratospheric ozone in the troposphere, which thus depends on altitude but also on the decay timescale of ozone. A much broader view of STE than has previously been possible is enabled. The inherent scope of STE is far wider than a discussion of cross-tropopause fluxes alone. Indeed, more than 90% of all cross-tropopause flows return within 6 hours. It is thus crucial to distinguish between short-term STE, during which air parcels rapidly recross the tropopause, and deep and/or long-term STE, in which air parcels have subsequently long residence times away from their source.

show abstract

Interannual variations of temperature and vertical motion at the tropical tropopause associated with ENSO

Abstract: Abstract.Interannual

Cited by 27 publications

References 18 publications

In situ observations of dehydrated air parcels advected horizontally in the Tropical Tropopause Layer of the western Pacific

In situ observations of dehydrated air parcels advected horizontally in the Tropical Tropopause Layer of the western Pacific

Dynamical Properties of the Tropical Atmosphere Derived from Radiosonde Observations at San Cristobal and Singapore

A 15‐year climatology of stratosphere–troposphere exchange with a Lagrangian particle dispersion model 2. Mean climate and seasonal variability

Contact Info

Product

Resources

About