The impact of gravity waves and cloud nucleation threshold on stratospheric water and tropical tropospheric cloud fraction

Schoeberl, M. R.; Dessler, A. E.; Ye, Hao; Wang, Tao; Avery, Melody; Jensen, E. J.

doi:10.1002/2016ea000180

Cited by 19 publications

(55 citation statements)

References 42 publications

(63 reference statements)

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“…In fact, as Schoeberl et al . [] show, these waves play a more significant role in controlling tropical cirrus cloud fraction than in dehydration. Jensen et al .…”

Section: Resultsmentioning

confidence: 71%

“…[] and Schoeberl et al . []). The T ′ o values shown in Table are much smaller than observations reported in this paper.…”

Section: Resultsmentioning

confidence: 97%

“…This puts the cloud fraction higher than the range of CALIOP observations shown in Schoeberl et al . [] (Figures and ). Consistent with these results, Jensen et al .…”

Section: Summary and Discussionmentioning

confidence: 99%

“…[]. From our observations, Lagrangian models of stratospheric dehydration [ Schoeberl et al ., ; Ueyama et al ., ] are adding too little high‐frequency gravity wave energy. Putting Loon values into the Schoeberl et al .…”

Section: Summary and Discussionmentioning

confidence: 99%

“…Putting Loon values into the Schoeberl et al . [] model increases cirrus fraction by ~70% compared to model results with no gravity waves. This puts the cloud fraction higher than the range of CALIOP observations shown in Schoeberl et al .…”

Section: Summary and Discussionmentioning

confidence: 99%

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Gravity wave spectra in the lower stratosphere diagnosed from project loon balloon trajectories

et al. 2017

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Project Loon has been launching superpressure balloons since January 2013 to provide worldwide Internet coverage. These balloons typically fly between 18 and 21 km and provide measurements of winds and pressure fluctuations in the lower stratosphere. We divide 1560 Loon flights into 3405 two‐day segments for gravity wave analysis. We derive the kinetic energy spectrum from the horizontal balloon motion and estimate the temperature perturbation spectrum (proportional to the potential energy spectrum) from the pressure variations. We fit the temperature (and kinetic energy) data to the functional form T′2 = T′o2[ω/ωο)α, where ω is the wave frequency, ωο is daily frequency, T′o is the base temperature amplitude, and α is the spectral slope. Both the kinetic energy and temperature spectra show −1.9 ± 0.2 power‐law dependence in the intrinsic frequency window 3–50 cycles/day. The temperature spectrum slope is weakly anticorrelated with the base temperature amplitude. We also find that the wave base temperature distribution is highly skewed. The tropical modal temperature is 0.77 K. The highest amplitude waves occur over the mountainous regions, the tropics, and the high southern latitudes. Temperature amplitudes show little height variation over our 18–21 km domain. Our results are consistent with other limited superpressure balloon analyses. The modal temperature is higher than the temperature currently used in high‐frequency gravity wave parameterizations.

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“…In fact, as Schoeberl et al . [] show, these waves play a more significant role in controlling tropical cirrus cloud fraction than in dehydration. Jensen et al .…”

Section: Resultsmentioning

confidence: 71%

“…[] and Schoeberl et al . []). The T ′ o values shown in Table are much smaller than observations reported in this paper.…”

Section: Resultsmentioning

confidence: 97%

“…This puts the cloud fraction higher than the range of CALIOP observations shown in Schoeberl et al . [] (Figures and ). Consistent with these results, Jensen et al .…”

Section: Summary and Discussionmentioning

confidence: 99%

Section: Summary and Discussionmentioning

confidence: 99%

Section: Summary and Discussionmentioning

confidence: 99%

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Gravity wave spectra in the lower stratosphere diagnosed from project loon balloon trajectories

et al. 2017

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Convectively Driven Tropopause‐Level Cooling and Its Influences on Stratospheric Moisture

2018

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Characteristics of the tropopause‐level cooling associated with tropical deep convection are examined using CloudSat radar and Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS radio occultation measurements. Extreme deep convection is sampled based on the cloud top height (>17 km) from CloudSat, and colocated temperature profiles from COSMIC are composited around the deep convection. Response of moisture to the tropopause‐level cooling is also examined in the upper troposphere and lower stratosphere using microwave limb sounder measurements. The composite temperature shows an anomalous warming in the troposphere and a significant cooling near the tropopause (at 16–19 km) when deep convection occurs over the western Pacific, particularly during periods with active Madden‐Julian Oscillation (MJO). The composite of the tropopause cooling has a large horizontal scale (~6,000 km in longitude) with minimum temperature anomaly of ~ −2 K, and it lasts more than 2 weeks with support of mesoscale convective clusters embedded within the envelope of the MJO. The water vapor anomalies show strong correlation with the temperature anomalies (i.e., dry anomaly in the cold anomaly), showing that the convectively driven tropopause cooling actively dehydrate the lower stratosphere in the western Pacific region. The moisture is also affected by anomalous Matsuno‐Gill‐type circulation associated with the cold anomaly, in which dry air spreads over a wide range in the tropical tropopause layer (TTL). These results suggest that convectively driven tropopause cooling and associated transient circulation play an important role in the large‐scale dehydration process in the TTL.

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Modeling the TTL at Continental Scale for a Wet Season: An Evaluation of the BRAMS Mesoscale Model Using TRO‐Pico Campaign, and Measurements From Airborne and Spaceborne Sensors

et al. 2018

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In order to better understand the water vapor (WV) intrusion into the tropical stratosphere, a mesoscale simulation of the tropical tropopause layer using the BRAMS (Brazilian version of Regional Atmospheric Modeling System (RAMS)) model is evaluated for a wet season. This simulation with a horizontal grid point resolution of 20 km × 20 km cannot resolve the stratospheric overshooting convection (SOC). Its ability to reproduce other key parameters playing a role in the stratospheric WV abundance is investigated using the balloon‐borne TRO‐Pico campaign measurements, the upper‐air soundings over Brazil, and the satellite observations by Aura Microwave Limb Sounder, Microwave Humidity Sounder, and Geostationary Operational Environmental Satellite 12. The BRAMS exhibits a good ability in simulating temperature, cold‐point, WV variability around the tropopause. However, the simulation is typically observed to be warmer by ∼2.0°C and wetter by ∼0.4 ppmv at the hygropause, which can be partly affiliated with the grid boundary nudging of the model by European Centre for Medium‐Range Weather Forecasts operational analyses. The modeled cloud tops show a good correlation (maximum cross‐correlation of ∼0.7) with Geostationary Operational Environmental Satellite 12. Furthermore, the overshooting cells detected by Microwave Humidity Sounder are observed at the locations, where 75% of the modeled cloud tops are higher than 11 km. Finally, the modeled inertia‐gravity wave periodicity and wavelength are comparable with those deduced from the radio sounding measurements during TRO‐Pico campaign. The good behavior of BRAMS confirms the SOC contribution in the WV abundance, and variability is of lesser importance than the large‐scale processes. This simulation can be used as a reference run for upscaling the impact of SOC at a continental scale for future studies.

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The impact of gravity waves and cloud nucleation threshold on stratospheric water and tropical tropospheric cloud fraction

Cited by 19 publications

References 42 publications

Gravity wave spectra in the lower stratosphere diagnosed from project loon balloon trajectories

Gravity wave spectra in the lower stratosphere diagnosed from project loon balloon trajectories

Convectively Driven Tropopause‐Level Cooling and Its Influences on Stratospheric Moisture

Modeling the TTL at Continental Scale for a Wet Season: An Evaluation of the BRAMS Mesoscale Model Using TRO‐Pico Campaign, and Measurements From Airborne and Spaceborne Sensors

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