scholarly journals Formation of ice supersaturation by mesoscale gravity waves

2005 ◽  
Vol 5 (1) ◽  
pp. 67-100 ◽  
Author(s):  
P. Spichtinger ◽  
K. Gierens ◽  
A. Dörnbrack
Keyword(s):  
Gravity Waves ◽  
Internal Gravity Waves ◽  
Specific Humidity ◽  
Cirrus Cloud ◽  
Weather Forecasts ◽  
Medium Range ◽  
Formation And Evolution ◽  
The Baltic ◽  
Wave Induced ◽  
Mesoscale Simulations

Abstract. We investigate the formation and evolution of an ice-supersaturated region (ISSR) that was detected by means of an operational radiosonde sounding launched from the meteorological station of Lindenberg on 21 March 2000, 00:00 UTC. The supersaturated layer was 5 situated below the local tropopause, between 320 and 408 hPa altitude. Our investigation uses satellite imagery (METEOSAT, AVHRR) and analyses of the European Centre for Medium-Range Weather Forecasts (ECMWF). Mesoscale simulations reveal that the ISSR was formed by a temporary vertical uplift of upper tropospheric air parcels by 20 to 40 hPa in 1 to 2 h. This resulted in a significant local increase of the 10 specific humidity by the moisture transport from below. The ascent was triggered by the superposition of two internal gravity waves, a mountain wave induced by flow past the Erzgebirge and Riesengebirge south of Lindenberg, and an inertial gravity wave excited by the anticyclonically curved jet stream over the Baltic Sea. The wave-induced ISSR was rather thick with a depth of about 2 km. The wave-induced upward motion 15 causing the supersaturation also triggered the formation of a cirrus cloud. METEOSAT imagery shows that the cirrus cloud got optically thick within two hours. During this period another longer lasting thin but extended cirrus existed just beneath the tropopause. The wave-induced ISSR disappeared after about half a day in accordance with the decaying wave activity.

scholarly journals Formation of ice supersaturation by mesoscale gravity waves

2005 ◽  
Vol 5 (5) ◽  
pp. 1243-1255 ◽  
Author(s):  
P. Spichtinger ◽  
K. Gierens ◽  
A. Dörnbrack
Keyword(s):  
Gravity Waves ◽  
Internal Gravity Waves ◽  
Specific Humidity ◽  
Cirrus Cloud ◽  
Weather Forecasts ◽  
Formation And Evolution ◽  
The Baltic ◽  
Wave Induced ◽  
Mesoscale Simulations ◽  
Very High

Abstract. We investigate the formation and evolution of an ice-supersaturated region (ISSR) that was detected by means of an operational radiosonde sounding launched from the meteorological station of Lindenberg on 21 March 2000, 00:00 UTC. The supersaturated layer was situated below the local tropopause, between 320 and 408 hPa altitude. Our investigation uses satellite imagery from METEOSAT and the Advanced Very High Resolution Radiometer (AVHRR) and analyses of the European Centre for Medium-Range Weather Forecasts (ECMWF). Mesoscale simulations reveal that the ISSR was formed by a temporary vertical uplift of upper tropospheric air parcels by 20 to 40 hPa in 1 to 2 h. This resulted in a significant local increase of the specific humidity by the moisture transport from below. The ascent was triggered by the superposition of two internal gravity waves, a mountain wave induced by flow past the Erzgebirge and Riesengebirge south of Lindenberg, and an inertial gravity wave excited by the anti-cyclonically curved jet stream over the Baltic Sea. The wave-induced ISSR was rather thick with a depth of about 2 km. The wave-induced upward motion causing the supersaturation also triggered the formation of a cirrus cloud. METEOSAT imagery shows that the cirrus cloud got optically thick within two hours. During this period another longer lasting thin but extended cirrus existed just beneath the tropopause. The wave-induced ISSR disappeared after about half a day in accordance with the decaying wave activity.

scholarly journals Characteristics of Tropical Easterly Wave Pouches during Tropical Cyclone Formation

2014 ◽  
Vol 142 (2) ◽  
pp. 626-633 ◽  
Author(s):  
Zhuo Wang ◽  
Isaac Hankes
Keyword(s):  
Potential Temperature ◽  
Specific Humidity ◽  
Easterly Waves ◽  
Weather Forecasts ◽  
Warm Core ◽  
Easterly Wave ◽  
Equivalent Potential ◽  
Medium Range ◽  
Vertically Aligned ◽  
Climate Prediction Center

Abstract The pregenesis evolution of wave pouches was examined for 164 named tropical cyclones that originated from zonally propagating tropical easterly waves over the Atlantic during July–October 1989–2010 using the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) and the Climate Prediction Center (CPC) morphing technique (CMORPH) precipitation. East of 60°W, most wave pouches (~80%) form at 700 hPa first, often extending down to 850 or 925 hPa off the coast of West Africa. By contrast, the majority of the wave pouches (~68%) over the west Atlantic (west of 60°W) form at 850 or 925 hPa first. Wave pouches become more vertically aligned approaching genesis. It was also found that vorticity at 925 hPa intensifies faster than that at 600 hPa. A warm-core structure forms at the meso-β scale near the pouch center prior to genesis but is less well defined at the meso-α pouch scale. The evolution of precipitation and the low-level convergence suggests that convection begins to organize near the pouch center about 1 day prior to genesis, along with the rapid intensification of vorticity in the inner pouch region. The composites derived from ERA-Interim show that the inner pouch region has higher specific humidity and equivalent potential temperature, especially in the middle troposphere within 1 day prior to genesis.

scholarly journals On the Prediction of Stratospheric Balloon Trajectories: Improving Winds with Mesoscale Simulations

2016 ◽  
Vol 33 (8) ◽  
pp. 1629-1647 ◽  
Author(s):  
Valérian Jewtoukoff ◽  
Riwal Plougonven ◽  
Albert Hertzog ◽  
Chris Snyder ◽  
Glen Romine
Keyword(s):  
Wrf Model ◽  
Weather Forecasts ◽  
Phase Errors ◽  
Forecasting Error ◽  
Operational Forecasts ◽  
Safety Compliance ◽  
Medium Range ◽  
Stratospheric Balloon ◽  
Touchdown Point ◽  
Mesoscale Simulations

AbstractSafety compliance issues for operational studies of the atmosphere with balloons require quantifying risks associated with descent and developing strategies to reduce the uncertainties at the location of the touchdown point. Trajectory forecasts are typically computed from weather forecasts produced by an operational center, for example, the European Centre for Medium-Range Weather Forecasts. This study uses past experiments to investigate strategies for improving these forecasts. Trajectories for open stratospheric balloon (OSB) short-term flights are computed using mesoscale simulations with the Weather and Research Forecasting (WRF) Model initialized with ECMWF operational forecasts and are assimilated with radio soundings using the Data Assimilation Research Testbed (DART) ensemble Kalman filter, for three case studies during the Strapolété 2009 campaign in Sweden. The results are very variable: in one case, the error in the final simulated position is reduced by 90% relative to the forecast using the ECMWF winds, while in another case the forecast is hardly improved. Nonetheless, they reveal the main source of forecasting error: during the ceiling phase, errors due to unresolved inertia–gravity waves accumulate as the balloon continuously experiences one phase of a wave for a few hours, whereas they essentially average out during the ascent and descent phases, when the balloon rapidly samples through whole wave packets. This sensitivity to wind during the ceiling phase raises issues regarding the feasibility of such forecasts and the observations that would be needed. The ensemble spread is also analyzed, and it is noted that the initial ensemble perturbations should probably be improved in the future for better forecasts.

scholarly journals Wave Activity Events and the Variability of the Stratospheric Polar Vortex

2014 ◽  
Vol 27 (20) ◽  
pp. 7796-7806 ◽  
Author(s):  
Abraham Solomon
Keyword(s):  
Polar Vortex ◽  
Wave Activity ◽  
Stratospheric Polar Vortex ◽  
Weather Forecasts ◽  
Planetary Scale ◽  
Intraseasonal Variations ◽  
Medium Range ◽  
Polar Stratosphere ◽  
Hemisphere Winter ◽  
Wave Induced

Abstract During Northern Hemisphere winter, polar stratospheric winds and temperatures exhibit significant variability that is due to the vertical propagation of planetary-scale waves. The most dramatic intraseasonal variations in temperature are associated with sudden stratospheric warmings (SSWs), which are wave-breaking events that occur approximately every other year. This paper will introduce the concept of wave activity events (WAEs), which are periods of enhanced pseudomomentum density in the polar stratosphere that occur every year. It will be demonstrated that all SSWs are associated with WAEs; furthermore, minor warmings and many final warmings in the polar spring are also WAEs, and therefore a better understanding of these more frequent wave events can provide additional insights into stratospheric wave-induced variability. Employing the Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) for 1979–2011, 119 WAEs are identified and their life cycle is compared with that of the 23 SSWs observed during this period.

Model of the internal gravity waves excited by lithospheric greenhouse effect gases

2001 ◽  
Vol 7 (2s) ◽  
pp. 26-33 ◽  
Author(s):  
O.E. Gotynyan ◽  
◽  
V.N. Ivchenko ◽  
Yu.G. Rapoport ◽  
◽  
...  
Keyword(s):  
Gravity Waves ◽  
Greenhouse Effect ◽  
Internal Gravity Waves

scholarly journals Shear-induced breaking of internal gravity waves

2021 ◽  
Vol 921 ◽  
Author(s):  
Christopher J. Howland ◽  
John R. Taylor ◽  
C.P. Caulfield
Keyword(s):  
Gravity Waves ◽  
Internal Gravity Waves

Abstract

scholarly journals Rolls of the internal gravity waves in the Earth's atmosphere

2014 ◽  
Vol 32 (2) ◽  
pp. 181-186 ◽  
Author(s):  
O. Onishchenko ◽  
O. Pokhotelov ◽  
W. Horton ◽  
A. Smolyakov ◽  
T. Kaladze ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Gravity Waves ◽  
Closed System ◽  
Wind Shear ◽  
Internal Gravity Waves ◽  
Temperature Gradients ◽  
System Of Equations ◽  
Vertical Temperature ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere

Abstract. The effect of the wind shear on the roll structures of nonlinear internal gravity waves (IGWs) in the Earth's atmosphere with the finite vertical temperature gradients is investigated. A closed system of equations is derived for the nonlinear dynamics of the IGWs in the presence of temperature gradients and sheared wind. The solution in the form of rolls has been obtained. The new condition for the existence of such structures was found by taking into account the roll spatial scale, the horizontal speed and wind shear parameters. We have shown that the roll structures can exist in a dynamically unstable atmosphere.

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