scholarly journals Mixing Layer Formation near the Tropopause Due to Gravity Wave–Critical Level Interactions in a Cloud-Resolving Model

2004 ◽  
Vol 61 (24) ◽  
pp. 3112-3124 ◽  
Author(s):  
Mohamed Moustaoui ◽  
Binson Joseph ◽  
Hector Teitelbaum
Keyword(s):  
Gravity Wave ◽  
Lower Stratosphere ◽  
Critical Level ◽  
Mixing Layer ◽  
Mixing Layers ◽  
Upper Troposphere ◽  
Cloud Resolving Model ◽  
Tropopause Region ◽  
Plausible Mechanism

Abstract A plausible mechanism for the formation of mixing layers in the lower stratosphere above regions of tropical convection is demonstrated numerically using high-resolution, two-dimensional (2D), anelastic, nonlinear, cloud-resolving simulations. One noteworthy point is that the mixing layer simulated in this study is free of anvil clouds and well above the cloud anvil top located in the upper troposphere. Hence, the present mechanism is complementary to the well-known process by which overshooting cloud turrets causes mixing within stratospheric anvil clouds. The paper is organized as a case study verifying the proposed mechanism using atmospheric soundings obtained during the Central Equatorial Pacific Experiment (CEPEX), when several such mixing layers, devoid of anvil clouds, had been observed. The basic dynamical ingredient of the present mechanism is (quasi stationary) gravity wave–critical level interactions, occurring in association with a reversal of stratospheric westerlies to easterlies below the tropopause region. The robustness of the results is shown through simulations at different resolutions. The insensitivity of the qualitative results to the details of the subgrid scheme is also evinced through further simulations with and without subgrid mixing terms. From Lagrangian reconstruction of (passive) ozone fields, it is shown that the mixing layer is formed kinematically through advection by the resolved-scale (nonlinear) velocity field.

scholarly journals A Case Study of Mass Transport during the East-West Oscillation of the Asian Summer Monsoon Anticyclone

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Jiali Luo ◽  
Jiayao Song ◽  
Hongying Tian ◽  
Lei Liu ◽  
Xinlei Liang
Keyword(s):  
Lower Stratosphere ◽  
Asian Summer Monsoon ◽  
Chemical Transport ◽  
Upward Motion ◽  
High Concentration ◽  
Upper Troposphere ◽  
Asian Summer ◽  
Mode Tm ◽  
East West

We use ERA-Interim reanalysis, MLS observations, and a trajectory model to examine the chemical transport and tracers distribution in the Upper Troposphere and Lower Stratosphere (UTLS) associated with an east-west oscillation case of the anticyclone in 2016. The results show that the spatial distribution of water vapor (H2O) was more consistent with the location of the anticyclone than carbon monoxide (CO) at 100 hPa, and an independent relative high concentration center was only found in H2O field. At 215 hPa, although the anticyclone center also migrated from the Tibetan Mode (TM) to the Iranian Mode (IM), the relative high concentration centers of both tracers were always colocated with regions where upward motion was strong in the UTLS. When the anticyclone migrated from the TM, air within the anticyclone over Tibetan Plateau may transport both westward and eastward but was always within the UTLS. The relative high concentration of tropospheric tracers within the anticyclone in the IM was from the east and transported by the westward propagation of the anticyclone rather than being lifted from surface directly. Air within the relative high geopotential height centers over Western Pacific was partly from the main anticyclone and partly from lower levels.

Internal gravity wave selection in the upper troposphere and lower stratosphere observed by the MU radar: Preliminary results

1989 ◽  
Vol 130 (2-3) ◽  
pp. 481-495 ◽  
Author(s):  
Manabu D. Yamanaka ◽  
Shoichiro Fukao ◽  
Hiromasa Matsumoto ◽  
Toru Sato ◽  
Toshitaka Tsuda ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Lower Stratosphere ◽  
Internal Gravity Wave ◽  
Upper Troposphere ◽  
Preliminary Results ◽  
Mu Radar

Water vapour in the Upper Troposphere and Lower Stratosphere (UTLS): A new vertically resolved dataset from limb and nadir satellite observations

2020 ◽  
Author(s):  
Hao Ye ◽  
Michaela Hegglin ◽  
Martina Krämer ◽  
Christian Rolf ◽  
Alexandra Laeng ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Vapour ◽  
Radiative Forcing ◽  
Lower Stratosphere ◽  
Climate Model ◽  
Chemical Properties ◽  
Upper Troposphere ◽  
Data Record ◽  
Tropopause Region ◽  
Quality Water

<p>Water vapour in the upper troposphere and lower stratosphere (UTLS) has a significant impact both on the radiative and chemical properties of the atmosphere. Reliable water vapour observations are essential for the evaluation of the accuracy of UTLS water vapour from model simulations, and thereafter of the contribution to the global radiative forcing and climate change. Limb-viewing and nadir satellites provide high quality water vapour observations above the lower stratosphere and below the upper troposphere, respectively, but show large uncertainties in the tropopause region.<span>  </span>Within the ESA Water Vapour Climate Change Initiative, we have developed a new scheme to optimally estimate water vapour profiles in the UTLS and in particular across the tropopause, by merging observations from a set of limb and nadir satellites from 2010 to 2014. The new data record of vertically resolved water vapour is validated against the aircraft in-situ water vapour observations from the JULIA database and frostpoint hydrometer records from WAVAS. Furthermore, the new data record is used to evaluate the UTLS water vapour distribution and interannual variations from chemistry-climate model (CCM) simulations and the ERA-5 reanalysis.</p>

scholarly journals When does new particle formation not occur in the upper troposphere?

2007 ◽  
Vol 7 (5) ◽  
pp. 14209-14232 ◽  
Author(s):  
D. R. Benson ◽  
L.-H. Young ◽  
S.-H. Lee ◽  
T. L. Campos ◽  
D. C. Rogers ◽  
...  
Keyword(s):  
Case Studies ◽  
Surface Area ◽  
Lower Stratosphere ◽  
Vertical Motion ◽  
Particle Formation ◽  
New Particle Formation ◽  
Upper Troposphere ◽  
Surface Areas ◽  
Total Particle ◽  
Tropopause Region

Abstract. Recent aircraft studies showed that new particle formation is very active in the free troposphere and lower stratosphere. And, these observations lead to a new question: when does new particle formation not occur? Here, we provide case studies to show how convection and surface area affect new particle formation in the upper troposphere, using the measured aerosol size distributions during the NSF/NCAR GV Progressive Science Missions in December 2005. There were ten research flights, including three days of nighttime experiments, at latitudes from 18 to 52° N and altitudes up to 14 km. About 78% of the total samples showed the new particle formation feature with number concentrations of particles with diameters from 4 to 9 nm, 670±1270 cm−3, and the total particle number concentrations with diameters from 4 to 2000 nm, 920±1470 cm−3. Our case studies show that new particle formation was closely associated with convection and low surface areas of preexisting aerosol particles (<4 μm² cm−3). On the other hand, for the cases where no new particle formation events were observed, air masses usually did not experience a vertical motion and air often originated from either the upper troposphere or lower stratosphere where precursor concentrations are relatively low; in addition, it was also a general trend that non-event cases also had higher surface areas (~16 μm² cm−3). These observations are consistent with other observations during the Progressive Science Missions (Young et al., 2007). Because of the lower temperatures in this region (T<250 K), nucleation is thermodynamically favorable; but because of low aerosol precursor concentrations, nucleation is sensitive to aerosol precursor concentration and surface area. Under such conditions, convection (which brings higher concentrations of aerosol precursors and water vapor to higher altitudes) and low surface area play critical roles on whether new particle formation takes place or not. Latitude dependence of new particles also shows higher particle concentrations in the midlatitude tropopause region than in the subtropics, consistent with Hermann et al. (2003).

scholarly journals On the Development of Above-Anvil Cirrus Plumes in Extratropical Convection

2017 ◽  
Vol 74 (5) ◽  
pp. 1617-1633 ◽  
Author(s):  
Cameron R. Homeyer ◽  
Joel D. McAuliffe ◽  
Kristopher M. Bedka
Keyword(s):  
Gravity Wave ◽  
Wave Breaking ◽  
Lower Stratosphere ◽  
Atmospheric Conditions ◽  
Upper Troposphere ◽  
Using Data ◽  
The Stability ◽  
Anvil Cirrus ◽  
Cloud Material ◽  
Relative Wind

Abstract Expansive cirrus clouds present above the anvils of extratropical convection have been observed in satellite and aircraft-based imagery for several decades. Despite knowledge of their occurrence, the precise mechanisms and atmospheric conditions leading to their formation and maintenance are not entirely known. Here, the formation of these cirrus “plumes” is examined using a combination of satellite imagery, four-dimensional ground-based radar observations, assimilated atmospheric states from a state-of-the-art reanalysis, and idealized numerical simulations with explicitly resolved convection. Using data from 20 recent events (2013–present), it is found that convective cores of storms with above-anvil cirrus plumes reach altitudes 1–6 km above the tropopause. Thus, it is likely that these clouds represent the injection of cloud material into the lower stratosphere. Comparison of storms with above-anvil cirrus plumes and observed tropopause-penetrating convection without plumes reveals an association with large vector differences between the motion of a storm and the environmental wind in the upper troposphere and lower stratosphere (UTLS), suggesting that gravity wave breaking and/or stretching of the tropopause-penetrating cloud are/is more prevalent in plume-producing storms. A weak relationship is found between plume occurrence and the stability of the lower stratosphere (or tropopause structure), and no relationship is found with the duration of stratospheric penetration or stratospheric humidity. Idealized model simulations of tropopause-penetrating convection with small and large magnitudes of storm-relative wind in the UTLS are found to reproduce the observationally established storm-relative wind relationship and show that frequent gravity wave breaking is the primary mechanism responsible for plume formation.

scholarly journals A case study of gravity wave dissipation in the polar MLT region using sodium LIDAR and radar data

2014 ◽  
Vol 32 (10) ◽  
pp. 1195-1205 ◽  
Author(s):  
T. Takahashi ◽  
S. Nozawa ◽  
M. Tsutsumi ◽  
C. Hall ◽  
S. Suzuki ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Critical Level ◽  
Maximum Amplitude ◽  
Radar Data ◽  
Radar Echo ◽  
The Difference ◽  
Using Data ◽  
Mlt Region ◽  
Mf Radar

Abstract. This paper is primarily concerned with an event observed from 16:30 to 24:30 UT on 29 October 2010 during a very geomagnetically quiet interval (Kp &amp;leq; 1). The sodium LIDAR observations conducted at Tromsø, Norway (69.6° N, 19.2° E) captured a clearly discernible gravity wave (GW) signature. Derived vertical and horizontal wavelengths, maximum amplitude, apparent and intrinsic period, and horizontal phase velocity were about ~ 11.9 km, ~ 1.38 × 103 km, ~ 15 K, 4 h, ~ 7.7 h, and ~ 96 m s−1, respectively, between a height of 80 and 95 km. Of particular interest is a temporal development of the uppermost altitude that the GW reached. The GW disappeared around 95 km height between 16:30 and 21:00 UT, while after 21:00 UT the GW appeared to propagate to higher altitudes (above 100 km). We have evaluated three mechanisms (critical-level filtering, convective and dynamic instabilities) for dissipations using data obtained by the sodium LIDAR and a meteor radar. It is found that critical-level filtering did not occur, and the convective and dynamic instabilities occurred on some occasions. MF radar echo power showed significant enhancements between 18:30 and 21:00 UT, and an overturning feature of the sodium mixing ratio was observed between 18:30 and 21:20 UT above about 95 km. From these results, we have concluded that the GW was dissipated by wave breaking and instabilities before 21:00 UT. We have also investigated the difference of the background atmosphere for the two intervals and would suggest that a probable cause of the change in the GW propagation was due to the difference in the temperature gradient of the background atmosphere above 94 km.

Internal Gravity Wave Selection in the Upper Troposphere and Lower Stratosphere Observed by the MU Radar: Preliminary Results

1989 ◽  
pp. 481-495 ◽  
Author(s):  
Manabu D. Yamanaka ◽  
Shoichiro Fukao ◽  
Hiromasa Matsumoto ◽  
Toru Sato ◽  
Toshitaka Tsuda ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Lower Stratosphere ◽  
Internal Gravity Wave ◽  
Upper Troposphere ◽  
Preliminary Results ◽  
Mu Radar

scholarly journals Horizontal variations of gravity wave activities in the lower stratosphere over Japan: A case study in the Baiu season 1991

1999 ◽  
Vol 51 (2) ◽  
pp. 107-113 ◽  
Author(s):  
Shin-Ya Ogino ◽  
Manabu D. Yamanaka ◽  
Yoshiaki Shibagaki ◽  
Toyoshi Shimomai ◽  
Shoichiro Fukao
Keyword(s):  
Gravity Wave ◽  
Lower Stratosphere ◽  
Horizontal Variations
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