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

Hasebe, Fumio; Fujiwara, Masatomo; Nishi, Noriyuki; Shiotani, Masato; Vömel, H.; Oltmans, S. J.; Takashima, Hisahiro; Saraspriya, Slamet; Komala, Ninong; Inai, Yoshihito

doi:10.5194/acp-7-803-2007

Cited by 29 publications

(32 citation statements)

References 58 publications

(47 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To this end, we have been conducting the Soundings of Ozone and Water in the Equatorial Region (SOWER) project using radiosondes, ozonesondes, and chilled-mirror hygrometers in the western tropical Pacific (see Sect. 2; Hasebe et al, 2007, a companion paper: Hasebe et al, 2013). The data from SOWER campaigns, together with trajectory calculations, indicate that the dehydration associated with quasi-horizontal advection progresses on isentropes from 360 K to 380 K and that the threshold of homogeneous nucleation corresponding to approximately 1.6 times saturation proved to be consistent with the observations in the altitude region from the 360 to 365 K potential temperature surfaces (Hasebe et al, 2013).…”

Section: Y Inai Et Al: Water Vapor Matchsupporting

confidence: 57%

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

et al. 2013

Self Cite

View full text Add to dashboard Cite

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

show abstract

Section: Y Inai Et Al: Water Vapor Matchsupporting

confidence: 57%

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

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…Using forward trajectories, they were able to connect the mesoscale "mother clouds" to low number density NAT particle populations several days downstream. Lagrangian characterization of air parcels in order to quantify the efficiency of dehydration in the tropical tropopause layer (TTL) over the western Pacific was conducted as part of the Soundings of Ozone and Water in the Equatorial Region (SOWER) project using frost point hygrometers (Hasebe et al, 2007;Inai et al, 2013). The water vapor match determined from the SOWER network observations was chosen based on isentropic trajectories calculated from the ECMWF operational analysis data, fulfilling temperature and ozone mixing ratio criteria.…”

Section: "Match" Techniquementioning

confidence: 99%

Balloon-borne match measurements of midlatitude cirrus clouds

et al. 2014

View full text Add to dashboard Cite

Abstract.Observations of high supersaturations with respect to ice inside cirrus clouds with high ice water content (> 0.01 g kg −1 ) and high crystal number densities (> 1 cm −3 ) are challenging our understanding of cloud microphysics and of climate feedback processes in the upper troposphere. However, single measurements of a cloudy air mass provide only a snapshot from which the persistence of ice supersaturation cannot be judged. We introduce here the "cirrus match technique" to obtain information about the evolution of clouds and their saturation ratio. The aim of these coordinated balloon soundings is to analyze the same air mass twice. To this end the standard radiosonde equipment is complemented by a frost point hygrometer, "SnowWhite", and a particle backscatter detector, "COBALD" (Compact Optical Backscatter AerosoL Detector). Extensive trajectory calculations based on regional weather model COSMO (Consortium for Small-Scale Modeling) forecasts are performed for flight planning, and COSMO analyses are used as a basis for comprehensive microphysical box modeling (with grid scale of 2 and 7 km, respectively). Here we present the results of matching a cirrus cloud to within 2-15 km, realized on 8 June 2010 over Payerne, Switzerland, and a location 120 km downstream close to Zurich. A thick cirrus cloud was detected over both measurement sites. We show that in order to quantitatively reproduce the measured particle backscatter ratios, the smallscale temperature fluctuations not resolved by COSMO must be superimposed on the trajectories. The stochastic nature of the fluctuations is captured by ensemble calculations. Possibilities for further improvements in the agreement with the measured backscatter data are investigated by assuming a very slow mass accommodation of water on ice, the presence of heterogeneous ice nuclei, or a wide span of (spheroidal) particle shapes. However, the resulting improvements from these microphysical refinements are moderate and comparable in magnitude with changes caused by assuming different regimes of temperature fluctuations for clear-sky or cloudysky conditions, highlighting the importance of proper treatment of subscale fluctuations. The model yields good agreement with the measured backscatter over both sites and reproduces the measured saturation ratios with respect to ice over Payerne. Conversely, the 30 % in-cloud supersaturation measured in a massive 4 km thick cloud layer over Zurich cannot be reproduced, irrespective of the choice of meteorological or microphysical model parameters. The measured supersaturation can only be explained by either resorting to an unknown physical process, which prevents the ice particles from consuming the excess humidity, or -much more likely -by a measurement error, such as a contamination of the sensor housing of the SnowWhite hygrometer by a precipitation drop from a mixed-phase cloud just below the cirrus layer or from some very slight rain in the boundary layer. This uncertainty calls for in-flight checks or calibrations of hygrom...

show abstract

“…Eckhardt et al (2008) estimated the vertical profile of SO2 emissions from the eruption of Jebel at Tair by inversion method using an atmospheric transport model. Their estimation indicates that the 60% of the emission occurred above the lapse rate tropopause defined by WMO, but most of the estimated emission is lower than the CPT, or probably in the altitude range of tropical tropopause layer (TTL) (Hasebe et al 2007) taking account of the latitude of the volcano. The SSSCtransport to the stratosphere is consistent with the slow accent within TTL to the stratosphere following the anticyclonic motion indicated by Hatsushika and Yamazaki (2003).…”

Section: Discussion and Summarymentioning

confidence: 99%

Volcanic Clouds from the 2007 Eruption of Jebel at Tair (Yemen) Detected by Ground Based and Space Borne Lidar

Shibata

Kouketsu

2008

SOLA

View full text Add to dashboard Cite

Volcanic clouds from the eruption of Jebel at Tair (south-central Red Sea, Yemen) on 30th September 2007 were observed by ground based lidar at Nagoya, Japan, and also by the space borne lidar CALIOP. The cloud was found as a non-depolarized cloud layer in the upper troposphere by ground based Mie/Depolarization lidar. By tilted lidar observations from ground it was demonstrated that these clouds were not composed of ice particles. Clouds with similar characteristics were also observed by CALIOP. Some evidence confirmed their origin to be the said eruption. The estimated total mass of the cloud particles by lidar-observed data coincides with the estimated sulfuric acid oxidized from SO2 included in the volcanic cloud observed by Aura satellite. All of the clouds were observed at altitudes lower than the cold point tropopause for a week after the eruption. Since then parts of the clouds were observed in the stratosphere, indicating transport from the troposphere to the stratosphere.

show abstract

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

Cited by 29 publications

References 58 publications

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

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

Balloon-borne match measurements of midlatitude cirrus clouds

Volcanic Clouds from the 2007 Eruption of Jebel at Tair (Yemen) Detected by Ground Based and Space Borne Lidar

Contact Info

Product

Resources

About