Stratospheric influence on upper tropospheric tropical cirrus

Boehm, Matthew T.; Verlinde, Johannes

doi:10.1029/2000gl011678

Cited by 134 publications

(143 citation statements)

References 19 publications

(4 reference statements)

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“…There is now evidence from several studies (Boehm and Verlinde, 2000;Immler et al, 2008;Fujiwara et al, 2009;Virts et al, 2010;Flury et al, 2012) that there is a correlation between cold anomalies in the TTL and cirrus clouds. From recent studies on cirrus clouds in the TTL using the lidar in space onboard CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation), the vertical motions in the regions of cirrus cloud occurrence were estimated (Virts et al, 2010).…”

Section: Large-scale Dynamicsmentioning

confidence: 99%

Tropical tropopause ice clouds: a dynamic approach to the mystery of low crystal numbers

Spichtinger

Krämer²

2013

Atmos. Chem. Phys.

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Abstract. The occurrence of high, persistent ice supersaturation inside and outside cold cirrus in the tropical tropopause layer (TTL) remains an enigma that is intensely debated as the "ice supersaturation puzzle". However, it was recently confirmed that observed supersaturations are consistent with very low ice crystal concentrations, which is incompatible with the idea that homogeneous freezing is the major method of ice formation in the TTL. Thus, the tropical tropopause "ice supersaturation puzzle" has become an "ice nucleation puzzle". To explain the low ice crystal concentrations, a number of mainly heterogeneous freezing methods have been proposed. Here, we reproduce in situ measurements of frequencies of occurrence of ice crystal concentrations by extensive model simulations, driven by the special dynamic conditions in the TTL, namely the superposition of slow large-scale updraughts with high-frequency short waves. From the simulations, it follows that the full range of observed ice crystal concentrations can be explained when the model results are composed from scenarios with consecutive heterogeneous and homogeneous ice formation and scenarios with pure homogeneous ice formation occurring in very slow (< 1 cm s −1 ) and faster (> 1 cm s −1 ) largescale updraughts, respectively. This statistical analysis shows that about 80 % of TTL cirrus can be explained by "classical" homogeneous ice nucleation, while the remaining 20 % stem from heterogeneous and homogeneous freezing occurring within the same environment. The mechanism limiting ice crystal production via homogeneous freezing in an environment full of gravity waves is the shortness of the gravity waves, which stalls freezing events before a higher ice crystal concentration can be formed.

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Section: Large-scale Dynamicsmentioning

confidence: 99%

Tropical tropopause ice clouds: a dynamic approach to the mystery of low crystal numbers

Spichtinger

Krämer²

2013

Atmos. Chem. Phys.

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“…In contrast, the formation of in-situ cirrus can occur away from convection when a cold temperature anomaly causes the air to become saturated (or supersaturated). The cold anomaly may be caused by any number of mechanisms, such as gravity waves , Kelvin waves (Boehm and Verlinde, 2000), mid-latitude intrusions (Waugh and Polvani, 2000) and large scale uplift (Corti et al, 2006). On average, over the equatorial region, sub-visible cirrus clouds occur 30 % of the time (Mace et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Cirrus cloud-temperature interactions in the tropical tropopause layer: a case study

2011

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Abstract. Thin cirrus clouds in the Tropical Tropopause Layer (TTL) have important ramifications for radiative transfer, stratospheric humidity, and vertical transport. A horizontally extensive and vertically thin cirrus cloud in the TTL was detected by the Cloud Aerosol LIDAR and Infrared Pathfinder Satellite Observations (CALIPSO) on 27-29 January 2009 in the Tropical Eastern Pacific region, distant from any regions of deep convection. These observations indicate that the cloud is close to 3000 km in length along the CALIPSO orbit track. Measurements over this three day period indicate that the cloud event extended over a region from approximately 15 • S to 10 • N and 90 • W to 150 • W and may be one of the most extensive cirrus events ever observed. Coincident temperature observations from the Constellation of Observing Satellites for Meteorology, Ionosphere, and Climate (COSMIC) suggest that the cloud formed in-situ as a result of a cold anomaly arising from a midlatitude intrusion. The event appears to last for up to 2 days and the temperature observations do not show any indication of the expected infrared heating. It is hypothesized that the cloud could be maintained by either nucleation of numerous small ice crystals that don't sediment or by multiple localized ice nucleation events driven by temperature variability at scales smaller than the overall cloud field, producing small icecrystal sizes which have sufficiently long residence times (≈53 h) to maintain the cloud. It is possible that the residence times are augmented by vertical motion which could also act to offset the expected infrared heating. Further observations of similar events will be required in order to conclusively explain this curious cloud.

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“…The variability of TTL clouds depends on cloud microphysics , cloud dynamics (Boehm et al 1999), and large-scale dynamics (Fujiwara et al 2009). On synoptic to subseasonal time scales, equatorial Kelvin waves are one of the most influential disturbances in the TTL (Suzuki and Shiotani 2008;Suzuki et al 2010), significantly affecting the cirrus variability there (Boehm and Verlinde 2000;Immler et al 2008;Fujiwara et al 2009). …”

Section: Introductionmentioning

confidence: 99%

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

Fujiwara

Hamada

et al. 2010

SOLA

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Cloud-top height (CTH) variability in the tropical tropopause layer (TTL) in association with equatorial Kelvin waves is investigated using a new CTH dataset based on MTSAT-1R geostationary satellite measurements with a statistical look-up table constructed based on CloudSat measurements. We focus on a case in the tropical Indian Ocean during October−December 2006, when shipboard radiosonde, TTL water vapor, and 95-GHz cloud radar measurements were taken during the Mirai Indian Ocean cruise for the Study of the MJO-convection Onset (MISMO) field campaign. At 10−15 km, the satellite-based CTH data agree well with the radar echo top heights from shipboard radar reflectivity data. During the MISMO campaign, cloud frequency was suppressed in the warm phase of equatorial Kelvin waves propagating in the TTL. The suppressed-cloud region moves eastward to the western Pacific together with Kelvin waves. We found that changes in CTH occurrence frequency over the vessel in association with Kelvin waves are much greater than those associated with the diurnal cycle. It is expected that the phase of equatorial Kelvin waves is important for the intraseasonal variabilities of both the radiative budget of the tropical atmosphere and water vapor transport in the TTL.

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Stratospheric influence on upper tropospheric tropical cirrus

Cited by 134 publications

References 19 publications

Tropical tropopause ice clouds: a dynamic approach to the mystery of low crystal numbers

Tropical tropopause ice clouds: a dynamic approach to the mystery of low crystal numbers

Cirrus cloud-temperature interactions in the tropical tropopause layer: a case study

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

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