scholarly journals A revised dry deposition scheme for land–atmosphere exchange of trace gases in ECHAM/MESSy v2.54

2021 ◽  
Vol 14 (1) ◽  
pp. 495-519
Author(s):  
Tamara Emmerichs ◽  
Astrid Kerkweg ◽  
Huug Ouwersloot ◽  
Silvano Fares ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Tropospheric Ozone ◽  
General Circulation ◽  
Process Model ◽  
Trace Gases ◽  
Stomatal Closure ◽  
Circulation Model ◽  
Ground Level ◽  
Global Models ◽  
Ground Level Ozone

Abstract. Dry deposition to vegetation is a major sink of ground-level ozone and is responsible for about 20 % of the total tropospheric ozone loss. Its parameterization in atmospheric chemistry models represents a significant source of uncertainty for the global tropospheric ozone budget and might account for the mismatch with observations. The model used in this study, the Modular Earth Submodel System version 2 (MESSy2) linked to the fifth-generation European Centre Hamburg general circulation model (ECHAM5) as an atmospheric circulation model (EMAC), is no exception. Like many global models, EMAC employs a “resistance in series” scheme with the major surface deposition via plant stomata which is hardly sensitive to meteorology, depending only on solar radiation. Unlike many global models, however, EMAC uses a simplified high resistance for non-stomatal deposition which makes this pathway negligible in the model. However, several studies have shown this process to be comparable in magnitude to the stomatal uptake, especially during the night over moist surfaces. Hence, we present here a revised dry deposition in EMAC including meteorological adjustment factors for stomatal closure and an explicit cuticular pathway. These modifications for the three stomatal stress functions have been included in the newly developed MESSy VERTEX submodel, i.e. a process model describing the vertical exchange in the atmospheric boundary layer, which will be evaluated for the first time here. The scheme is limited by a small number of different surface types and generalized parameters. The MESSy submodel describing the dry deposition of trace gases and aerosols (DDEP) has been revised accordingly. The comparison of the simulation results with measurement data at four sites shows that the new scheme enables a more realistic representation of dry deposition. However, the representation is strongly limited by the local meteorology. In total, the changes increase the dry deposition velocity of ozone up to a factor of 2 globally, whereby the highest impact arises from the inclusion of cuticular uptake, especially over moist surfaces. This corresponds to a 6 % increase of global annual dry deposition loss of ozone resulting globally in a slight decrease of ground-level ozone but a regional decrease of up to 25 %. The change of ozone dry deposition is also reasoned by the altered loss of ozone precursors. Thus, the revision of the process parameterization as documented here has, among others, the potential to significantly reduce the overestimation of tropospheric ozone in global models.

scholarly journals A revised dry deposition scheme for land-atmosphere exchange of trace gases in ECHAM/MESSy v2.54

2020 ◽  
Author(s):  
Tamara Emmerichs ◽  
Astrid Kerkweg ◽  
Huug Ouwersloot ◽  
Silvano Fares ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Tropospheric Ozone ◽  
Process Model ◽  
Trace Gases ◽  
Stomatal Closure ◽  
Deposition Velocity ◽  
Measurement Data ◽  
Ground Level ◽  
Global Models ◽  
Ground Level Ozone

Abstract. Dry deposition to vegetation is a major sink of ground-level ozone and is responsible for about 20 % of the total tropospheric ozone loss. Its parametrisation in atmospheric chemistry models represent a significant source of uncertainty for the global tropospheric ozone budget and might account for the mismatch with observations. The model used in this study, the Modular Earth Submodel System (MESSy2) linked to ECHAM5 as an atmospheric circulation model (EMAC), is no exception. Like many global models, EMAC employs a “resistance in series” scheme with the major surface deposition via plant stomata which is hardly sensitive to meteorology, depending only on solar radiation. Unlike many global models, however, EMAC uses a simplified high resistance for non-stomatal deposition which makes this pathway negligible in the model. However, several studies have shown this process to be comparable in magnitude to the stomatal uptake, especially during the night over moist surfaces. Hence, we present here a revised dry deposition in EMAC. The default dry deposition scheme has been extended with adjustment factors to predict stomatal responses to temperature and vapour pressure deficit. Furthermore, an explicit formulation of the non-stomatal deposition to the leaf surface (cuticle) dependent on humidity has been implemented based on established schemes. Finally, the soil moisture availability function for plants has been revised to be consistent with the simple hydrological model available in EMAC. This revision was necessary in order to avoid unrealistic stomatal closure where the model shows a strong soil dry bias, e.g. in the Amazon basin in the dry season. These modifications for the three stomatal stress functions have been included in the newly developed MESSy submodel VERTEX, i.e. a process model describing the vertical exchange in the atmospheric boundary layer, which will be evaluated for the first time here. The MESSy submodel describing the dry deposition of trace gases and aerosols (DDEP) has been revised accordingly. The comparison of the simulation results with measurement data at four sites shows that the new scheme enables a more realistic representation of dry deposition. However, the representation is strongly limited by the local meteorology. In total, the changes increase the dry deposition velocity of ozone up to a factor of 2 globally, whereby the highest impact arises from the inclusion of cuticular uptake, especially over moist surfaces. This corresponds to a 6 % increase of global annual dry deposition loss of ozone resulting globally in a slight decrease of ground-level ozone but a regional decrease of up to 25 %. Thus, the revision of the process parameterisation as documented here has the potential to significantly reduce the overestimation of tropospheric ozone in global models.

Surface ozone and land-atmosphere coupling

2020 ◽  
Author(s):  
Tamara Emmerichs ◽  
Huug Ouwersloot ◽  
Astrid Kerkweg ◽  
Silvano Fares ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Tropospheric Ozone ◽  
Amazon Basin ◽  
Surface Ozone ◽  
Stomatal Closure ◽  
Circulation Model ◽  
Vapour Pressure Deficit ◽  
Air Pollutant ◽  
Global Models

<p>Surface ozone is a harmful air pollutant, heavily influenced by chemical production and loss processes. Dry deposition to vegetation is a relevant loss process responsible for 20 % of the total tropospheric ozone loss. Its parametrization in atmospheric chemistry models represents a major source of uncertainty for the global tropospheric ozone budget and might account for the mismatch with observations. The model used in this study, the Modular Earth Submodel System (MESSy2) linked to ECHAM5 as atmospheric circulation model (EMAC) is no exception. Like many global models, EMAC employs a “resistances in series” scheme with the major surface deposition via plant stomata which is hardly sensitive to meteorology depending only on solar radiation. Unlike many global models, however, EMAC uses a simplified high resistance for non-stomatal deposition which makes this pathway negligible.                             </p><p>Hence, a revision of the dry deposition scheme of EMAC is desirable. The scheme has been extended with empirical adjustment factors to predict stomatal responses to temperature and vapour pressure deficit. Furthermore, an explicit formulation of humidity depending non-stomatal deposition at the leaf surface (cuticle) has been implemented based on established schemes. Next, the soil moisture availability function for plants has been critically reviewed and modified in order to avoid a stomatal closure where the model shows a strong soil dry bias, e.g. Amazon basin in dry season.</p><p>The last part of the presentation will show comparisons of dry deposition velocities and fluxes comparing simulations with data obtained from four experimental sites where ozone deposition is measured with micrometeorological techniques. The impacts of the changes on daily and seasonal patterns of ozone dry deposition will be discussed with a highlight on surface ozone, global distribution and budget.</p>

scholarly journals Preindustrial-to-present-day radiative forcing by tropospheric ozone from improved simulations with the GISS chemistry-climate GCM

2003 ◽  
Vol 3 (5) ◽  
pp. 1675-1702 ◽  
Author(s):  
D. T. Shindell ◽  
G. Faluvegi ◽  
N. Bell
Keyword(s):  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Tropospheric Chemistry ◽  
True Value ◽  
Tropopause Region ◽  
Dynamics Simulations ◽  
Goddard Institute

Abstract. Improved estimates of the radiative forcing from tropospheric ozone increases since the preindustrial have been calculated with the tropospheric chemistry model used at the Goddard Institute for Space Studies (GISS) within the GISS general circulation model (GCM). The chemistry in this model has been expanded to include simplified representations of peroxyacetylnitrates and non-methane hydrocarbons in addition to background NOx-HOx-Ox-CO-CH4 chemistry. The GCM has improved resolution and physics in the boundary layer, improved resolution near the tropopause, and now contains a full representation of stratospheric dynamics. Simulations of present-day conditions show that this coupled chemistry-climate model is better able to reproduce observed tropospheric ozone, especially in the tropopause region, which is critical to climate forcing. Comparison with preindustrial simulations gives a global annual average radiative forcing due to tropospheric ozone increases of 0.30 W/m2 with standard assumptions for preindustrial emissions. Locally, the forcing reaches more than 0.8 W/m2 in parts of the northern subtropics during spring and summer, and is more than 0.6 W/m2 through nearly all the Northern subtropics and mid-latitudes during summer. An alternative preindustrial simulation with soil NOx emissions reduced by two-thirds and emissions of isoprene, paraffins and alkenes from vegetation increased by 50% gives a forcing of 0.33 W/m2. Given the large uncertainties in preindustrial ozone amounts, the true value may lie well outside this range.

scholarly journals Development of the global atmospheric chemistry general circulation model BCC-GEOS-Chem v1.0: model description and evaluation

2020 ◽  
Vol 13 (9) ◽  
pp. 3817-3838
Author(s):  
Xiao Lu ◽  
Lin Zhang ◽  
Tongwen Wu ◽  
Michael S. Long ◽  
Jun Wang ◽  
...  
Keyword(s):  
General Circulation Model ◽  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
General Circulation ◽  
Climate Models ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Circulation Model ◽  
Satellite Observations ◽  
Model Description

Abstract. Chemistry plays an indispensable role in investigations of the atmosphere; however, many climate models either ignore or greatly simplify atmospheric chemistry, limiting both their accuracy and their scope. We present the development and evaluation of the online global atmospheric chemical model BCC-GEOS-Chem v1.0, coupling the GEOS-Chem chemical transport model (CTM) as an atmospheric chemistry component in the Beijing Climate Center atmospheric general circulation model (BCC-AGCM). The GEOS-Chem atmospheric chemistry component includes detailed tropospheric HOx–NOx–volatile organic compounds–ozone–bromine–aerosol chemistry and online dry and wet deposition schemes. We then demonstrate the new capabilities of BCC-GEOS-Chem v1.0 relative to the base BCC-AGCM model through a 3-year (2012–2014) simulation with anthropogenic emissions from the Community Emissions Data System (CEDS) used in the Coupled Model Intercomparison Project Phase 6 (CMIP6). The model captures well the spatial distributions and seasonal variations in tropospheric ozone, with seasonal mean biases of 0.4–2.2 ppbv at 700–400 hPa compared to satellite observations and within 10 ppbv at the surface to 500 hPa compared to global ozonesonde observations. The model has larger high-ozone biases over the tropics which we attribute to an overestimate of ozone chemical production. It underestimates ozone in the upper troposphere which is likely due either to the use of a simplified stratospheric ozone scheme or to biases in estimated stratosphere–troposphere exchange dynamics. The model diagnoses the global tropospheric ozone burden, OH concentration, and methane chemical lifetime to be 336 Tg, 1.16×106 molecule cm−3, and 8.3 years, respectively, which is consistent with recent multimodel assessments. The spatiotemporal distributions of NO2, CO, SO2, CH2O, and aerosol optical depth are generally in agreement with satellite observations. The development of BCC-GEOS-Chem v1.0 represents an important step for the development of fully coupled earth system models (ESMs) in China.

scholarly journals Quantitative Sensitivity Analysis of Physical Parameterizations for Cases of Deep Convection in the NASA GEOS-5

2016 ◽  
Vol 29 (2) ◽  
pp. 455-479 ◽  
Author(s):  
Derek J. Posselt ◽  
Bruce Fryxell ◽  
Andrea Molod ◽  
Brian Williams
Keyword(s):  
General Circulation ◽  
Process Model ◽  
Large Scale ◽  
Climate Models ◽  
Deep Convection ◽  
Input Parameter ◽  
Circulation Model ◽  
Parameter Sensitivity ◽  
Global Climate Models ◽  
Simulation Code

Abstract Parameterization of processes that occur on length scales too small to resolve on a computational grid is a major source of uncertainty in global climate models. This study investigates the relative importance of a number of parameters used in the Goddard Earth Observing System Model, version 5 (GEOS-5), atmospheric general circulation model, focusing on cloud, convection, and boundary layer parameterizations. Latin hypercube sampling is used to generate a few hundred sets of 19 candidate physics parameters, which are subsequently used to generate ensembles of single-column model realizations of cloud content, precipitation, and radiative fluxes for four different field campaigns. A Gaussian process model is then used to create a computationally inexpensive emulator for the simulation code that can be used to determine a measure of relative parameter sensitivity by sampling the response surface for a very large number of input parameter sets. Parameter sensitivities are computed for different geographic locations and seasons to determine whether the intrinsic sensitivity of the model parameterizations changes with season and location. The results indicate the same subset of parameters collectively control the model output across all experiments, independent of changes in the environment. These are the threshold relative humidity for cloud formation, the ice fall speeds, convective and large-scale autoconversion, deep convection relaxation time scale, maximum convective updraft diameter, and minimum ice effective radius. However, there are differences in the degree of parameter sensitivity between continental and tropical convective cases, as well as systematic changes in the degree of parameter influence and parameter–parameter interaction.

scholarly journals Spatial-Temporal Variability of Small Gas Impurities over Lake Baikal during the Forest Fires in the Summer of 2019

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 20
Author(s):  
Galina Zhamsueva ◽  
Alexander Zayakhanov ◽  
Vadim Tcydypov ◽  
Ayuna Dementeva ◽  
Tumen Balzhanov
Keyword(s):  
Lake Baikal ◽  
Forest Fires ◽  
Boreal Forests ◽  
Trace Gases ◽  
Experimental Studies ◽  
Ground Level ◽  
Global Scale ◽  
Water Area ◽  
Ground Level Ozone ◽  
Comprehensive Study

Lake Baikal—a unique ecosystem on a global scale—is undoubtedly of great interest for a comprehensive study of its ecosystem. In recent years, one of the most significant sources of atmospheric pollution in the Baikal region was the emission of smoke aerosol and trace gases from forest fires, the number of which is increasing in the region. The transport and accumulation of aerosol and small gas impurities over water area of Lake Baikal is observed every summer due to forest fires occurring in the boreal forests of Siberia. The atmosphere above the lake covers a huge area (31,500 km2) and is still a little-studied object. This article presents the results of experimental studies of ground-level ozone, sulfur dioxide, and nitrogen oxides in the atmosphere over Lake Baikal, carried out on a research vessel during the boreal forest fires in Siberia in the summer of 2019.

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