scholarly journals Identifying convective transport of carbon monoxide by comparing remotely sensed observations from TES with cloud modeling simulations

2008 ◽  
Vol 8 (6) ◽  
pp. 19201-19247 ◽  
Author(s):  
J. J. Halland ◽  
H. E. Fuelberg ◽  
K. E. Pickering ◽  
M. Luo
Keyword(s):  
Carbon Monoxide ◽  
Convective Transport ◽  
Vertical Transport ◽  
Squall Line ◽  
Free Atmosphere ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Retrieval Scheme ◽  
Cloud Modeling ◽  
The Impact

Abstract. Understanding the mechanisms that transport pollutants from the surface to the free atmosphere is important for determining the atmosphere's chemical composition. This study quantifies the vertical transport of tropospheric carbon monoxide (CO) by deep mesoscale convective systems and assesses the ability of the satellite-borne Tropospheric Emission Spectrometer (TES) to detect the resulting enhanced CO in the upper atmosphere. A squall line that is similar to one occurring during NASA's INTEX-B mission is simulated using a typical environmental wind shear profile and the 2-D Goddard Cumulus Ensemble model. The simulation provides post-convection CO profiles. The structure of the simulated squall line is examined, and its vertical transport of CO is quantified. Then, TES' ability to resolve the convectively modified CO distribution is documented using a "clear-sky" retrieval scheme. Results show that the simulated squall line transports the greatest mass of CO in the upper levels, with a value of 96 t upward and 67 t downward at 300 hPa. Maximum updraft speed is found to be unimportant in determining the net CO flux transported by a storm, but is important in determining the altitude to which the storm transports the boundary layer CO. Results indicate that TES has sufficient sensitivity to resolve convectively lofted CO, as long as the retrieval scene is cloud-free. TES swaths located immediately downwind of squall lines have the greatest chance of sensing convective transport because the impact of clouds on retrieval quality becomes less. A note of caution is to always analyze TES-derived CO data (or data from any satellite sensor) together with the retrieval averaging kernel diagonals or other parameters describing the information content of the retrieval.

scholarly journals Identifying convective transport of carbon monoxide by comparing remotely sensed observations from TES with cloud modeling simulations

2009 ◽  
Vol 9 (13) ◽  
pp. 4279-4294 ◽  
Author(s):  
J. J. Halland ◽  
H. E. Fuelberg ◽  
K. E. Pickering ◽  
M. Luo
Keyword(s):  
Carbon Monoxide ◽  
Convective Transport ◽  
Vertical Transport ◽  
Squall Line ◽  
Free Atmosphere ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Retrieval Scheme ◽  
Cloud Modeling ◽  
The Impact

Abstract. Understanding the mechanisms that transport pollutants from the surface to the free atmosphere is important for determining the atmosphere's chemical composition. This study quantifies the vertical transport of tropospheric carbon monoxide (CO) by deep mesoscale convective systems and assesses the ability of the satellite-borne Tropospheric Emission Spectrometer (TES) to detect the resulting enhanced CO in the upper atmosphere. A squall line that is similar to one occurring during NASA's INTEX-B mission is simulated using a typical environmental wind shear profile and the 2-D Goddard Cumulus Ensemble model. The simulation provides post-convection CO profiles. The structure of the simulated squall line is examined, and its vertical transport of CO is quantified. Then, TES' ability to resolve the convectively modified CO distribution is documented using a "clear-sky" retrieval scheme. Results show that the simulated squall line transports the greatest mass of CO in the upper levels, with a value of 96 t upward and 67 t downward at 300 hPa. Results indicate that TES has sufficient sensitivity to resolve convectively lofted CO, as long as the retrieval scene is cloud-free. TES swaths located immediately downwind of squall lines have the greatest chance of sensing convective transport because the impact of clouds on retrieval quality becomes less. A note of caution is to always analyze TES-derived CO data (or data from any satellite sensor) together with the retrieval averaging kernels that describe the information content of the retrieval.

scholarly journals The role of horizontal model resolution in assessing the transport of CO in a middle latitude cyclone using WRF-Chem

2014 ◽  
Vol 14 (2) ◽  
pp. 609-627 ◽  
Author(s):  
C. A. Klich ◽  
H. E. Fuelberg
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Deep Convection ◽  
Middle Latitude ◽  
Convective Transport ◽  
Vertical Transport ◽  
Squall Line ◽  
Grid Spacing ◽  
Chemical Transport Model ◽  
Hysplit Model

Abstract. We use the Weather Research and Forecasting with Chemistry (WRF-Chem) online chemical transport model to simulate a middle latitude cyclone in East Asia at three different horizontal resolutions (45, 15, and 5 km grid spacing). The cyclone contains a typical warm conveyor belt (WCB) with an embedded squall line that passes through an area having large surface concentrations (> 400 ppbv) of carbon monoxide (CO). Model output from WRF-Chem is used to compare differences between the large-scale CO vertical transport by the WCB (the 45 km simulation) with the smaller-scale transport due to its convection (the 5 km simulation). Forward trajectories are calculated from WRF-Chem output using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. At 45 km grid spacing, the WCB exhibits gradual ascent, lofting surface CO to 6–7 km. Upon reaching the warm front, the WCB and associated CO ascend more rapidly and later turn eastward over the Pacific Ocean. Convective transport at 5 km resolution with explicitly resolved convection occurs much more rapidly, with surface CO lofted to altitudes greater than 10 km in 1 h or less. We also compute CO vertical mass fluxes over specified areas and times to compare differences in transport due to the different grid spacings. Upward CO flux exceeds 110 000 t h−1 in the domain with explicit convection when the squall line is at peak intensity, while fluxes from the two coarser resolutions are an order of magnitude smaller. Specific areas of interest within the 5 km domain are defined to compare the magnitude of convective transport to that within the entire 5 km region. Although convection encompasses only a small portion of the 5 km domain, it is responsible for ~40% of the upward CO transport. We also examine the vertical transport due to a short wave trough and its associated area of convection, not related to the cyclone, that lofts CO to the upper troposphere. Results indicate that fine-scale resolution with explicitly resolved convection is important when assessing the vertical transport of surface emissions in areas of deep convection.

A Wave-Relative Framework Analysis of AEW–MCS Interactions Leading to Tropical Cyclogenesis

2020 ◽  
Vol 148 (11) ◽  
pp. 4657-4671
Author(s):  
Kelly M. Núñez Ocasio ◽  
Jenni L. Evans ◽  
George S. Young
Keyword(s):  
West Africa ◽  
Thermodynamic Characteristics ◽  
Convective Cloud ◽  
Type Systems ◽  
Squall Line ◽  
Tropical Cyclogenesis ◽  
Framework Analysis ◽  
Convective Systems ◽  
Cloud Clusters ◽  
Mesoscale Convective

AbstractAn African easterly wave (AEW) and associated mesoscale convective systems (MCSs) dataset has been created and used to evaluate the propagation of MCSs, AEWs, and, especially, the propagation of MCSs relative to the AEW with which they are associated (i.e., wave-relative framework). The thermodynamic characteristics of AEW–MCS systems are also analyzed. The analysis is done for both AEW–MCS systems that develop into tropical cyclones and those that do not to quantify significant differences. It is shown that developing AEWs over West Africa are associated with a larger number of convective cloud clusters (CCCs; squall-line-type systems) than nondeveloping AEWs. The MCSs of developing AEWs propagate at the same speed of the AEW trough in addition to being in phase with the trough, whereas convection associated with nondeveloping AEWs over West Africa moves faster than the trough and is positioned south of it. These differences become important for the intensification of the AEW vortex as this slower-moving convection (i.e., moving at the same speed of the AEW trough) spends more time supplying moisture and latent heat to the AEW vortex, supporting its further intensification. An analysis of the rainfall rate (MCS intensity), MCS area, and latent heating rate contribution reveals that there are statistically significant differences between developing AEWs and nondeveloping AEWs, especially over West Africa where the fraction of extremely large MCS areas associated with developing AEWs is larger than for nondeveloping AEWs.

A new parameterization of the accretion of cloud water by snow and its evaluation through simulations of mesoscale convective systems

2020 ◽  
Author(s):  
Han-Gyul Jin ◽  
Jong-Jin Baik
Keyword(s):  
Mesoscale Convective System ◽  
Cloud Droplet ◽  
Spherical Shape ◽  
Heavy Precipitation ◽  
Cloud Water ◽  
Squall Line ◽  
Convective System ◽  
Cloud Droplets ◽  
Convective Systems ◽  
Mesoscale Convective

<p>A new parameterization of the accretion of cloud water by snow for use in bulk microphysics schemes is derived by analytically solving the stochastic collection equation (SCE), where the theoretical collision efficiency for individual snowflake–cloud droplet pairs is applied. The snowflake shape is assumed to be nonspherical with the mass- and area-size relations suggested by an observational study. The performance of the new parameterization is compared to two parameterizations based on the continuous collection equation, one with the spherical shape assumption for snowflakes (SPH-CON), and the other with the nonspherical shape assumption employed in the new parameterization (NSP-CON). In box model simulations, only the new parameterization reproduces a relatively slow decrease in the cloud droplet number concentration which is predicted by the direct SCE solver. This results from considering the preferential collection of cloud droplets depending on their sizes in the new parameterization based on the SCE. In idealized squall-line simulations using a cloud-resolving model, the new parameterization predicts heavier precipitation in the convective core region compared to SPH-CON, and a broader area of the trailing stratiform rain compared to NSP-CON due to the horizontal advection of greater amount of snow in the upper layer. In the real-case simulations of a line-shaped mesoscale convective system that passed over the central Korean Peninsula, the new parameterization predicts higher frequencies of light precipitation rates and lower frequencies of heavy precipitation rates. The relatively large amount of upper-level snow in the new parameterization contributes to a broadening of the area with significant snow water path.</p>

scholarly journals Mesoscale Convection and Bimodal Cyclogenesis over the Bay of Bengal

2015 ◽  
Vol 143 (9) ◽  
pp. 3495-3517 ◽  
Author(s):  
Nasreen Akter
Keyword(s):  
Bay Of Bengal ◽  
Deep Convection ◽  
Leading Edge ◽  
Vertical Shear ◽  
Squall Line ◽  
Convergence Zone ◽  
Low Level ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Long Time

Abstract Mesoscale convective systems (MCSs) are an essential component of cyclogenesis, and their structure and characteristics determine the intensity and severity of associated cyclones. Case studies were performed by simulating tropical cyclones that formed during the pre- and postmonsoon periods in 2007 and 2010 over the Bay of Bengal (BoB). The pre- (post) monsoon environment was characterized by the coupling of northwesterly (southwesterly) wind to the early advance southwesterly (northeasterly) monsoonal wind in the BoB. The surges of low-level warm southwesterlies with clockwise-rotating vertical shear in the premonsoon period and moderately cool northeasterlies with anticlockwise-rotating vertical shear in the postmonsoon period transported moisture and triggered MCSs within preexisting disturbances near the monsoon trough over the BoB. Mature MCSs associated with bimodal cyclone formations were quasi linear, and they featured leading-edge deep convection and a trailing stratiform precipitation region, which was very narrow in the postmonsoon cases. In the premonsoon cases, the MCSs became severe bow echoes when intense and moist southwesterlies were imposed along the dryline convergence zone in the northern and northwestern BoB. However, the development formed a nonsevere and nonorganized linear system when the convergence zone was farther south of the dryline. In the postmonsoon cases, cyclogenesis was favored by squall-line MCSs with a north–south orientation over the BoB. All convective systems moved quickly, persisted for a long time, and contained suitable environments for developing low-level cyclonic mesovortices at their leading edges, which played an additional role in forming mesoscale convective vortices during cyclogenesis in the BoB.

scholarly journals The Impact of Low-Level Moisture Errors on Model Forecasts of an MCS Observed during PECAN

2017 ◽  
Vol 145 (9) ◽  
pp. 3599-3624 ◽  
Author(s):  
John M. Peters ◽  
Erik R. Nielsen ◽  
Matthew D. Parker ◽  
Stacey M. Hitchcock ◽  
Russ S. Schumacher
Keyword(s):  
Convective Available Potential Energy ◽  
Mesoscale Convective System ◽  
Squall Line ◽  
Convective System ◽  
Low Level ◽  
Eastern Flank ◽  
Western Flank ◽  
Mesoscale Convective ◽  
Outflow Boundary ◽  
The Impact

This article investigates errors in forecasts of the environment near an elevated mesoscale convective system (MCS) in Iowa on 24–25 June 2015 during the Plains Elevated Convection at Night (PECAN) field campaign. The eastern flank of this MCS produced an outflow boundary (OFB) and moved southeastward along this OFB as a squall line. The western flank of the MCS remained quasi stationary approximately 100 km north of the system’s OFB and produced localized flooding. A total of 16 radiosondes were launched near the MCS’s eastern flank and 4 were launched near the MCS’s western flank. Convective available potential energy (CAPE) increased and convective inhibition (CIN) decreased substantially in observations during the 4 h prior to the arrival of the squall line. In contrast, the model analyses and forecasts substantially underpredicted CAPE and overpredicted CIN owing to their underrepresentation of moisture. Numerical simulations that placed the MCS at varying distances too far to the northeast were analyzed. MCS displacement error was strongly correlated with models’ underrepresentation of low-level moisture and their associated overrepresentation of the vertical distance between a parcel’s initial height and its level of free convection ([Formula: see text], which is correlated with CIN). The overpredicted [Formula: see text] in models resulted in air parcels requiring unrealistically far northeastward travel in a region of gradual meso- α-scale lift before these parcels initiated convection. These results suggest that erroneous MCS predictions by NWP models may sometimes result from poorly analyzed low-level moisture fields.

scholarly journals Use of a Rain Gauge Network to Infer the Influence of Environmental Factors on the Propagation of Quasi-Linear Convective Systems in West Africa

2007 ◽  
Vol 22 (5) ◽  
pp. 1016-1030 ◽  
Author(s):  
Jon M. Schrage ◽  
Andreas H. Fink
Keyword(s):  
Environmental Factors ◽  
Propagation Rate ◽  
Rain Gauge ◽  
West African ◽  
Squall Line ◽  
Propagation Characteristics ◽  
Convective Systems ◽  
Squall Lines ◽  
Radiosonde Station ◽  
The Impact

Abstract The West African squall line is a key quasi-linear storm system that brings much of the precipitation observed in the data-poor Sudanian climate zone. Squall lines propagate at a wide range of speeds and headings, but the lack of operational radar stations in the region makes quantifying the propagation of the squall lines difficult. A new method of estimating the propagation rate and heading for squall lines is proposed. Based on measurements of the time of onset of precipitation (OOP) at a network of rain gauge stations, an estimate of the propagation characteristics of the squall line can be inferred. By combining estimates of propagation rate with upper-air observations gathered at a nearby radiosonde station, the impact of various environmental factors on the propagation characteristics of West African squall lines is inferred. Results suggest that the propagation speed for West African squall lines is related to the conditions at midtropospheric levels, where dry air and an enhanced easterly flow favor faster propagation. Northerly anomalies at these levels are also associated with faster propagation. When applied to West African squall lines, the correlations between these environmental factors and the speed of propagation are significantly higher than those of methods developed for mesoscale convective systems in other parts of the world.

scholarly journals Macrophysical, Microphysical, and Radiative Properties of Tropical Mesoscale Convective Systems over Their Life Cycle

2016 ◽  
Vol 29 (9) ◽  
pp. 3353-3371 ◽  
Author(s):  
Dominique Bouniol ◽  
Rémy Roca ◽  
Thomas Fiolleau ◽  
D. Emmanuel Poan
Keyword(s):  
Life Cycle ◽  
Large Scale ◽  
Radiative Heating ◽  
Radiative Properties ◽  
Mesoscale Convective Systems ◽  
Cloud Base ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Polar Orbiting Satellite ◽  
The Impact

Abstract Mesoscale convective systems (MCSs) are important drivers of the atmospheric large-scale circulation through their associated diabatic heating profile. Taking advantage of recent tracking techniques, this study investigates the evolution of macrophysical, microphysical, and radiative properties over the MCS life cycle by merging geostationary and polar-orbiting satellite data. These observations are performed in three major convective areas: continental West Africa, the adjacent Atlantic Ocean, and the open Indian Ocean. MCS properties are also investigated according to internal subregions (convective, stratiform, and nonprecipitating anvil). Continental MCSs show a specific life cycle, with more intense convection at the beginning. Larger and denser hydrometeors are thus found at higher altitudes, as well as up to the cirriform subregion. Oceanic MCSs have more constant reflectivity values, suggesting a less intense convective updraft, but more persistent intensity. A layer of small crystals is found in all subregions, but with a depth that varies according to the MCS subregion and life cycle. Radiative properties are also examined. It appears that the evolution of large and dense hydrometeors tends to control the evolution of the cloud albedo and the outgoing longwave radiation. The impact of dense hydrometeors, detrained from the convective towers, is also seen in the radiative heating profiles, in particular in the shortwave domain. A dipole of cooling near the cloud top and heating near the cloud base is found in the longwave; this cooling intensifies near the end of the life cycle.

scholarly journals Evaluation of UTLS carbon monoxide simulations in GMI and GEOS-Chem chemical transport models using Aura MLS observations

2016 ◽  
Vol 16 (9) ◽  
pp. 5641-5663 ◽  
Author(s):  
Lei Huang ◽  
Jonathan H. Jiang ◽  
Lee T. Murray ◽  
Megan R. Damon ◽  
Hui Su ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Chemical Transport ◽  
Temporal Variations ◽  
Vertical Transport ◽  
Spatial Distributions ◽  
Transport Models ◽  
Chemical Transport Models ◽  
The Tropics ◽  
The Impact ◽  
Co Concentrations

Abstract. This study evaluates the distribution and variation of carbon monoxide (CO) in the upper troposphere and lower stratosphere (UTLS) during 2004–2012 as simulated by two chemical transport models, using the latest version of Aura Microwave Limb Sounder (MLS) observations. The simulated spatial distributions, temporal variations and vertical transport of CO in the UTLS region are compared with those observed by MLS. We also investigate the impact of surface emissions and deep convection on CO concentrations in the UTLS over different regions, using both model simulations and MLS observations. Global Modeling Initiative (GMI) and GEOS-Chem simulations of UTLS CO both show similar spatial distributions to observations. The global mean CO values simulated by both models agree with MLS observations at 215 and 147 hPa, but are significantly underestimated by more than 40 % at 100 hPa. In addition, the models underestimate the peak CO values by up to 70 % at 100 hPa, 60 % at 147 hPa and 40 % at 215 hPa, with GEOS-Chem generally simulating more CO at 100 hPa and less CO at 215 hPa than GMI. The seasonal distributions of CO simulated by both models are in better agreement with MLS in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH), with disagreements between model and observations over enhanced CO regions such as southern Africa. The simulated vertical transport of CO shows better agreement with MLS in the tropics and the SH subtropics than the NH subtropics. We also examine regional variations in the relationships among surface CO emission, convection and UTLS CO concentrations. The two models exhibit emission–convection–CO relationships similar to those observed by MLS over the tropics and some regions with enhanced UTLS CO.

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