scholarly journals Organization of Dust Storms and Synoptic Scale Transport of Dust by Kelvin Waves

2019 ◽  
Author(s):  
Ashok Kumar Pokharel ◽  
Michael L. Kaplan
Keyword(s):  
Dust Storm ◽  
Large Scale ◽  
Kelvin Waves ◽  
Dust Storms ◽  
Cold Pool ◽  
Kelvin Wave ◽  
Synoptic Scale ◽  
Dust Transport ◽  
Horizontal Length ◽  
Bodele Depression

Abstract. Based on the large scale transport of dust driven by the winds parallel to the mountains in the Harmattan, Saudi Arabian, and Bodélé Depression dust storms cases, a detailed study of the generation of Kelvin Waves and its possible role in organizing these dust storms and large scale dust transport was accomplished. For this study, observational and numerical model analyses were done in an in depth manner. For this, MERRA reanalysis datasets, WRF simulated high resolution variables, MODIS/Aqua and Terra images, EUMETSAT images, NAAPS aerosol modelling plots, and MERRA-2 dust scattering AOD modelling plots, surface observations, and rawinsonde soundings were analyzed for each of these three case studies. We found there were meso-β scale (horizontal length scale of 20–200 km) adjustment processes resulting in Kelvin waves only in the Harmattan and the Bodélé Depression cases. The Kelvin wave preceded a cold pool accompanying the air behind the large scale cold front instrumental in the major dust storm. We find that this Kelvin wave organized the major dust storm in a narrow zone parallel to the mountains before it expanded upscale (meso-α to synoptic).

scholarly journals Organization of dust storms and synoptic-scale transport of dust by Kelvin waves

2019 ◽  
Vol 10 (4) ◽  
pp. 651-666 ◽  
Author(s):  
Ashok Kumar Pokharel ◽  
Michael L. Kaplan
Keyword(s):  
Dust Storm ◽  
Large Scale ◽  
Reanalysis Data ◽  
Kelvin Waves ◽  
Dust Storms ◽  
Cold Pool ◽  
Kelvin Wave ◽  
Dust Transport ◽  
Aerosol Modeling ◽  
Bodele Depression

Abstract. Based on the large-scale transport of dust driven by the winds parallel to the mountains in the Harmattan, Saudi Arabian, and Bodélé Depression dust storm cases, a detailed study of the generation of Kelvin waves and its possible role in organizing these dust storms and large-scale dust transport was accomplished. For this study, observational and numerical model analyses were done in an in depth manner. For this, MERRA reanalysis data sets; WRF-simulated high-resolution variables; MODIS Aqua and Terra images; EUMETSAT images; NAAPS aerosol modeling plots; and MERRA-2 dust scattering aerosol optical depth (AOD) modeling plots, surface observations, and rawinsonde soundings were analyzed for each of these three case studies. We found that there were meso-β-scale (horizontal length scale of 20–200 km) adjustment processes resulting in Kelvin waves only in the Harmattan and the Bodélé Depression cases. The Kelvin wave preceded a cold pool accompanying the air behind the large-scale cold front instrumental in the major dust storm. We find that this Kelvin wave organized the major dust storm in a narrow zone parallel to the mountains before it expanded upscale (meso-α to synoptic).

scholarly journals Convectively Coupled Kelvin Waves: From Linear Theory to Global Models

2015 ◽  
Vol 73 (1) ◽  
pp. 407-428 ◽  
Author(s):  
Michael J. Herman ◽  
Zeljka Fuchs ◽  
David J. Raymond ◽  
Peter Bechtold
Keyword(s):  
Composite Structures ◽  
Large Scale ◽  
Kelvin Waves ◽  
Radiosonde Data ◽  
3D Analysis ◽  
Kelvin Wave ◽  
Scale Characteristics ◽  
Precipitation Anomalies ◽  
Convective Inhibition ◽  
Ecmwf Model

Abstract The authors analyze composite structures of tropical convectively coupled Kelvin waves (CCKWs) in terms of the theory of Raymond and Fuchs using radiosonde data, 3D analysis and reanalysis model output, and annual integrations with the ECMWF model on the full planet and on an aquaplanet. Precipitation anomalies are estimated using the NOAA interpolated OLR and TRMM 3B42 datasets, as well as using model OLR and rainfall diagnostics. Derived variables from these datasets are used to examine assumptions of the theory. Large-scale characteristics of wave phenomena are robust in all datasets and models where Kelvin wave variance is large. Indices from the theory representing column moisture and convective inhibition are also robust. The results suggest that the CCKW is highly dependent on convective inhibition, while column moisture does not play an important role.

Dust storm episodes at the aerodromes in the Asian part of Russia

2021 ◽  
Vol 2 ◽  
pp. 20-42
Author(s):  
A.R. Ivanova ◽  
◽  
E.N. Skriptunova ◽  
N.I. Komasko ◽  
A.A. Zavialova ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Dust Storm ◽  
Trajectory Analysis ◽  
Dust Storms ◽  
Strong Wind ◽  
Dust Transport ◽  
Air Masses ◽  
Classical Definition ◽  
Dust Events ◽  
Definition Of

Dust storm episodes at the aerodromes in the Asian part of Russia / Ivanova A.R., Skriptunova E.N., Komasko N.I., Zavialova A.A.// Hydrometeorological Research and Forecasting, 2021, no. 2 (380), pp. 20-42. According to 2001-2020 METAR data, episodes of dust storms at 26 international aerodromes in the Asian Russia causing poor visibility are studied. The conditions for issuing reports on dust storms, their correspondence to the definition of a dust storm are discussed. It was found that out of 337 reports describing dust transport by strong wind, only 7 episodes registered at the aerodromes of Irkutsk, Abakan, Omsk, and Blagoveshchensk corresponded to the classical definition. The others detected at 15 of 26 aerodromes may be defined as “dust events” – the episodes of dust transfer causing the nonessential visibility reduction. The seasonal variation in such episodes and its connection with changes in visibility are studied. The characteristics of dusty air masses and the direction of their advection are given. Keywords: dust storm, dust events, aerodromes of Asian Russia, seasonal variation, trajectory analysis

scholarly journals An Observational Overview of Dusty Deep Convection in Martian Dust Storms

2019 ◽  
Vol 76 (11) ◽  
pp. 3299-3326 ◽  
Author(s):  
Nicholas G. Heavens ◽  
David M. Kass ◽  
James H. Shirley ◽  
Sylvain Piqueux ◽  
Bruce A. Cantor
Keyword(s):  
Dust Storm ◽  
Large Scale ◽  
Middle Atmosphere ◽  
Deep Convection ◽  
High Surface ◽  
Dust Storms ◽  
Radiative Heating ◽  
Storm Activity ◽  
Mesoscale Circulations ◽  
Convective Structures

Abstract Deep convection, as used in meteorology, refers to the rapid ascent of air parcels in Earth’s troposphere driven by the buoyancy generated by phase change in water. Deep convection undergirds some of Earth’s most important and violent weather phenomena and is responsible for many aspects of the observed distribution of energy, momentum, and constituents (particularly water) in Earth’s atmosphere. Deep convection driven by buoyancy generated by the radiative heating of atmospheric dust may be similarly important in the atmosphere of Mars but lacks a systematic description. Here we propose a comprehensive framework for this phenomenon of dusty deep convection (DDC) that is supported by energetic calculations and observations of the vertical dust distribution and exemplary dusty deep convective structures within local, regional, and global dust storm activity. In this framework, DDC is distinct from a spectrum of weaker dusty convective activity because DDC originates from preexisting or concurrently forming mesoscale circulations that generate high surface dust fluxes, oppose large-scale horizontal advective–diffusive processes, and are thus able to maintain higher dust concentrations than typically simulated. DDC takes two distinctive forms. Mesoscale circulations that form near Mars’s highest volcanoes in dust storms of all scales can transport dust to the base of the upper atmosphere in as little as 2 h. In the second distinctive form, mesoscale circulations at low elevations within regional and global dust storm activity generate freely convecting streamers of dust that are sheared into the middle atmosphere over the diurnal cycle.

scholarly journals Tropical temperature variability and Kelvin-wave activity in the UTLS from GPS RO measurements

2017 ◽  
Vol 17 (2) ◽  
pp. 793-806 ◽  
Author(s):  
Barbara Scherllin-Pirscher ◽  
William J. Randel ◽  
Joowan Kim
Keyword(s):  
Large Scale ◽  
Deep Convection ◽  
Wave Activity ◽  
Kelvin Waves ◽  
Temperature Variability ◽  
Stationary Waves ◽  
Kelvin Wave ◽  
Quasi Biennial Oscillation ◽  
Tropical Tropopause ◽  
Tropopause Region

Abstract. Tropical temperature variability over 10–30 km and associated Kelvin-wave activity are investigated using GPS radio occultation (RO) data from January 2002 to December 2014. RO data are a powerful tool for quantifying tropical temperature oscillations with short vertical wavelengths due to their high vertical resolution and high accuracy and precision. Gridded temperatures from GPS RO show the strongest variability in the tropical tropopause region (on average 3 K2). Large-scale zonal variability is dominated by transient sub-seasonal waves (2 K2), and about half of sub-seasonal variance is explained by eastward-traveling Kelvin waves with periods of 4 to 30 days (1 K2). Quasi-stationary waves associated with the annual cycle and interannual variability contribute about a third (1 K2) to total resolved zonal variance. Sub-seasonal waves, including Kelvin waves, are highly transient in time. Above 20 km, Kelvin waves are strongly modulated by the quasi-biennial oscillation (QBO) in stratospheric zonal winds, with enhanced wave activity during the westerly shear phase of the QBO. In the tropical tropopause region, however, peaks of Kelvin-wave activity are irregularly distributed in time. Several peaks coincide with maxima of zonal variance in tropospheric deep convection, but other episodes are not evidently related. Further investigations of convective forcing and atmospheric background conditions are needed to better understand variability near the tropopause.

scholarly journals Synoptic-Scale Structure and the Character of Coastally Trapped Wind Reversals

2007 ◽  
Vol 135 (1) ◽  
pp. 60-81 ◽  
Author(s):  
Wendell A. Nuss
Keyword(s):  
Kelvin Waves ◽  
Direct Link ◽  
Kelvin Wave ◽  
Synoptic Scale ◽  
Coastal Dynamics ◽  
Synoptic Forcing ◽  
Different Types ◽  
Scale Characteristics ◽  
Offshore Flow ◽  
The U.S

Abstract Coastally trapped wind reversals that occur along the U.S. West Coast have been described in numerous other studies. The synoptic-scale environment and the forcing of a coastally trapped Kelvin wave are highly linked in the development of these wind reversals. However, not all wind reversals appear to behave like propagating Kelvin waves and the analysis of coastal buoy observations for three years indicates that different types of disturbances occur. Both propagating disturbances and nonpropagating disturbances occur with similar frequencies. While the synoptic-scale characteristics associated with propagating and nonpropagating wind reversals are sometimes rather subtle, several distinct differences occur that suggest a direct link between the coastal dynamics and the synoptic-scale forcing. Synoptic forcing characterized by persistent low-level offshore flow favors the development of propagating disturbances, while weak, nonsustained offshore flow characterizes nonpropagating disturbances. These differences support the idea that propagating events represent a favorable interaction between the synoptic-scale forcing and the excitation and propagation of Kelvin waves, whereas nonpropagating events either represent a less favorable interaction or are simply trapped ageostrophic flow due to the synoptic scale without a Kelvin wave response. These dynamic differences imply different stratus behavior, which is important to forecasters.

scholarly journals Synoptic-Scale Flow and Valley Cold Pool Evolution in the Western United States

2009 ◽  
Vol 24 (6) ◽  
pp. 1625-1643 ◽  
Author(s):  
Heather Dawn Reeves ◽  
David J. Stensrud
Keyword(s):  
United States ◽  
Large Scale ◽  
Numerical Models ◽  
Western United States ◽  
Cold Pool ◽  
Synoptic Scale ◽  
Temperature Changes ◽  
Cold Pools ◽  
Upper Level ◽  
Forecast Problem

Abstract Valley cold pools (VCPs), which are trapped, cold layers of air at the bottoms of basins or valleys, pose a significant problem for forecasters because they can lead to several forms of difficult-to-forecast and hazardous weather such as fog, freezing rain, or poor air quality. Numerical models have historically failed to routinely provide accurate guidance on the formation and demise of VCPs, making the forecast problem more challenging. In some case studies of persistent wintertime VCPs, there is a connection between the movement of upper-level waves and the timing of VCP formation and decay. Herein, a 3-yr climatology of persistent wintertime VCPs for five valleys and basins in the western United States is performed to see how often VCP formation and decay coincides with synoptic-scale (∼200–2000 km) wave motions. Valley cold pools are found to form most frequently as an upper-level ridge approaches the western United States and in response to strong midlevel warming. The VCPs usually last as long as the ridge is over the area and usually only end when a trough, and its associated midlevel cooling, move over the western United States. In fact, VCP strength appears to be almost entirely dictated by midlevel temperature changes, which suggests large-scale forcing is dominant for this type of VCP most of the time.

A complete Martian year of atmospheric observations with InSight instruments

2021 ◽  
Author(s):  
Aymeric Spiga ◽  
Don Banfield ◽  
Claire Newman ◽  
Naomi Murdoch ◽  
Ralph Lorenz ◽  
...  
Keyword(s):  
Seasonal Variability ◽  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Dust Storms ◽  
Global Climate Models ◽  
Synoptic Scale ◽  
Atmospheric Variability ◽  
Atmospheric Observations ◽  
Convective Vortices

<p>On the first hundreds of sols in which the InSight lander operated on the surface of Mars, its instrumentation has proven to be particularly suitable to unveil and understand atmospheric variability at all temporal scales, from the synoptic scale (baroclinic waves) to the sub-hour scale (gravity waves, bores) down to the turbulent scale (vortices, gusts, infrasounds). Recently, the InSight lander achieved a complete Martian year of observations of the atmosphere of Mars -- allowing for the seasonal variability of the Martian atmosphere and its phenomena at all scales to be monitored almost continuously, including during several large dust storms episodes. In this presentation, based on this Martian year of InSight observations, we will review the annual CO2 sublimation / condensation cycle, the variability of large-scale meteorology, the statistics of a year of wind observations -- and insightful comparisons with global climate models, the strong seasonal variability of gravity wave and turbulent activity, including a burst of activity of convective vortices in Mars' southern summer. We will also discuss how the atmosphere influences seismic and magnetic signals captured by InSight -- and the search for Martian infrasound.</p>

scholarly journals Tropical temperature variability and Kelvin wave activity in the UTLS from GPS RO measurements

2016 ◽  
Author(s):  
Barbara Scherllin-Pirscher ◽  
William J. Randel ◽  
Joowan Kim
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Wave Activity ◽  
Kelvin Waves ◽  
Temperature Variability ◽  
Kelvin Wave ◽  
Quasi Biennial Oscillation ◽  
Tropical Tropopause ◽  
Tropopause Region ◽  
High Frequency Waves

Abstract. Tropical temperature variability over 10–30 km and associated Kelvin wave activity is investigated using GPS radio occultation (RO) data from January 2002 to December 2014. RO data are a powerful tool to quantify tropical temperature oscillations with short vertical wavelengths due to their high vertical resolution and high accuracy and precision. Gridded temperatures from GPS RO show strongest variability in the tropical tropopause region (on average 3 K2). Large-scale zonal variability is dominated by transient high-frequency waves (2 K2) and about half of high-frequency variance is explained by eastward traveling Kelvin waves with periods of 7 to 30 days (1 K2). Quasi-stationary waves associated with the annual cycle and inter-annual variability contribute about a third (1 K2) to total resolved zonal variance. High-frequency waves, including Kelvin waves, are highly transient in time. Above 20 km, Kelvin waves are strongly modulated by the quasi-biennial oscillation (QBO) in stratospheric zonal winds, with enhanced wave activity during the westerly shear phase of the QBO. In the tropical tropopause region, however, peaks of Kelvin wave activity are irregularly distributed in time. Several peaks coincide with maxima of zonal variance in tropospheric deep convection, but other episodes are not evidently related. Further investigations of convective forcing and atmospheric background conditions are needed to better understand variability near the tropopause.

scholarly journals New insights into the vertical structure of the September 2015 dust storm employing 8 ceilometers over Israel

2017 ◽  
Author(s):  
Leenes Uzan ◽  
Smadar Egert ◽  
Pinhas Alpert
Keyword(s):  
Dust Storm ◽  
Vertical Structure ◽  
Additional Data ◽  
Meteorological Data ◽  
Dust Storms ◽  
Synoptic Scale ◽  
Forecast Models ◽  
Formation And Evolution ◽  
Ground Coverage ◽  
Regional Forecast

Abstract. On September 7th 2015, an unprecedented dust storm approached the East Mediterranean (EM) basin. The storm origin was in the Iran, Iraq, Syria and the Turkey border. The Israeli meteorological service considered the storm as exceptional due to its extent of over 6 days, occurrence time in early September and concentrations reaching values 100 times the normal. Previous studies examined the formation and evolution of the dust storm synoptic scale and explained why aerosol models often failed to simulate it. This study concentrates on spatial and vertical meso-scale dust spreading over Israel based on several remote sensing instruments including eight micro light detection and ranging (LIDAR) ceilometers. The ceilometers high resolution attenuated backscatter profiles (every 10 m and 15 s) reveal the downward motion of elevated dust plume as it penetrated Israel, ground coverage and gradual dispersion. The additional data of spectral radiometers and ground particulate matter under 10 micro-meter aero-diameter (PM10) as well as meteorological data made it possible to verify the dust properties and the differences between its ground deposition and elevated dispersion. Further investigations of dust storms in the EM by the ceilometer array will help improve the regional forecast models.

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