scholarly journals Which processes drive observed variations of HCHO columns over India?

2018 ◽  
Vol 18 (7) ◽  
pp. 4549-4566 ◽  
Author(s):  
Luke Surl ◽  
Paul I. Palmer ◽  
Gonzalo González Abad
Keyword(s):  
Atmospheric Chemistry ◽  
Seasonal Cycle ◽  
Transport Model ◽  
Monsoon Season ◽  
Gangetic Plain ◽  
Model Calculations ◽  
Propene Oxidation ◽  
Meridional Gradient ◽  
Northeastern India ◽  
Continental Scale

Abstract. We interpret HCHO column variations observed by the Ozone Monitoring Instrument (OMI), aboard the NASA Aura satellite, over India during 2014 using the GEOS-Chem atmospheric chemistry and transport model. We use a nested version of the model with a horizontal resolution of approximately 25 km. HCHO columns are related to local emissions of volatile organic compounds (VOCs) with a spatial smearing that increases with the VOC lifetime. Over India, HCHO has biogenic, pyrogenic, and anthropogenic VOC sources. Using a 0-D photochemistry model, we find that isoprene has the largest molar yield of HCHO which is typically realized within a few hours. We also find that forested regions that neighbour major urban conurbations are exposed to high levels of nitrogen oxides. This results in depleted hydroxyl radical concentrations and a delay in the production of HCHO from isoprene oxidation. We find that propene is the only anthropogenic VOC emitted in major Indian cities that produces HCHO at a comparable (but slower) rate to isoprene. The GEOS-Chem model reproduces the broad-scale annual mean HCHO column distribution observed by OMI (r = 0.6), which is dominated by a distinctive meridional gradient in the northern half of the country, and by localized regions of high columns that coincide with forests. Major discrepancies are noted over the Indo-Gangetic Plain (IGP) and Delhi. We find that the model has more skill at reproducing observations during winter (JF) and pre-monsoon (MAM) months with Pearson correlations r > 0.5 but with a positive model bias of  ≃ 1×1015 molec cm−2. During the monsoon season (JJAS) we reproduce only a diffuse version of the observed meridional gradient (r = 0.4). We find that on a continental scale most of the HCHO column seasonal cycle is explained by monthly variations in surface temperature (r = 0.9), suggesting a role for biogenic VOCs, in agreement with the 0-D and GEOS-Chem model calculations. We also find that the seasonal cycle during 2014 is not significantly different from the 2008 to 2015 mean seasonal variation. There are two main loci for biomass burning (the states of Punjab and Haryana, and northeastern India), which we find makes a significant contribution (up to 1×1015 molec cm−2) to observed HCHO columns only during March and April over northeastern India. The slow production of HCHO from propene oxidation results in a smeared hotspot over Delhi that we resolve only on an annual mean timescale by using a temporal oversampling method. Using a linear regression model to relate GEOS-Chem isoprene emissions to HCHO columns we infer seasonal isoprene emissions over two key forest regions from the OMI HCHO column data. We find that the a posteriori emissions are typically lower than the a priori emissions, with a much stronger reduction of emissions during the monsoon season. We find that this reduction in emissions during monsoon months coincides with a large drop in satellite observations of leaf phenology that recovers in post monsoon months. This may signal a forest-scale response to monsoon conditions.

scholarly journals Which processes drive observed variations of HCHO columns over India?

2017 ◽  
Author(s):  
Luke Surl ◽  
Paul I. Palmer ◽  
Gonzalo González Abad
Keyword(s):  
Atmospheric Chemistry ◽  
Seasonal Cycle ◽  
Transport Model ◽  
Monsoon Season ◽  
Gangetic Plain ◽  
Model Calculations ◽  
Propene Oxidation ◽  
Meridional Gradient ◽  
Northeastern India ◽  
Continental Scale

Abstract. We interpret HCHO column variations observed by the Ozone Monitoring Instrument (OMI), aboard the NASA Aura satellite, over India during 2014 using the GEOS-Chem atmospheric chemistry and transport model. We use a nested version of the model with a spatial resolution of approximately 25 km. HCHO columns are related to local emissions of volatile organic compounds (VOCs) with a spatial smearing that increases with the VOC lifetime. Over India, HCHO has biogenic, pyrogenic, and anthropogenic VOC sources. Using a 0-D photochemistry model, we find that isoprene has the largest molar yield of HCHO that is typically realized within a few hours. We find that forested regions that neighbours major urban conurbations are exposed to high levels of nitrogen oxides. This results in depleted hydroxyl radical concentrations and a delay in the production of HCHO from isoprene oxidation. We find that propene is the only anthropogenic VOC emitted in major Indian cities that produces HCHO at a comparable (slower) rate to isoprene. The GEOS-Chem model reproduces the broadscale annual mean HCHO column distribution observed by OMI (r = 0.6), which is dominated by a distinctive meridional gradient in the northern half of the country, and by localized regions of high columns that coincide with forests. Major discrepancies are over the Indo-Gangetic Plain and Delhi. We find that the model has more skill at reproducing observations during winter (JF) and pre-monsoon (MAM) months with Pearson correlations r > 0.5 but with a positive model bias of 1 × 1015 molec/cm2. During the monsoon season (JJAS) we reproduce only a diffuse version of the observed meridional gradient (r = 0.4). Generally, we find that on a continental scale most of the seasonal cycle is explained by monthly variations in surface temperature (r = 0.9), suggesting a strong role for biogenic VOCs, in agreement with the 0-D and GEOS-Chem model calculations. We also find that the seasonal cycle during 2014 is not significantly different from the 2008–2015 mean seasonal variation but there are large year to year variations. There are two main loci for biomass burning (states of Punjab and Haryana, and northeastern India), which we find only contributes a significant contribution (up to 1 × 1015 molec/cm2) to observed HCHO columns during March to April over northeastern India. The slow production of HCHO from propene oxidation results in a smeared hotspot over Delhi that we resolve only on an annual mean timescale by using a temporal oversampling method. Using a linear regression model to relate GEOS-Chem isoprene emissions to HCHO columns we infer seasonal isoprene emissions over two key forest regions from the OMI HCHO column data. We find that the a posteriori emissions are typically lower than the a priori emissions, with a much stronger reduction of emissions during the monsoon season. We find that this reduction in emissions during monsoon months coincides with a large drop in satellite observations of leaf phenology that recovers in post monsoon months. This may signal a forest-scale response to monsoon conditions.

scholarly journals Frontiers in air quality modelling

2014 ◽  
Vol 7 (1) ◽  
pp. 203-210 ◽  
Author(s):  
A. Colette ◽  
B. Bessagnet ◽  
F. Meleux ◽  
E. Terrenoire ◽  
L. Rouïl
Keyword(s):  
Air Pollution ◽  
Atmospheric Chemistry ◽  
Urban Areas ◽  
High Performance ◽  
Transport Model ◽  
Atomic Energy Commission ◽  
Computing System ◽  
Mitigation Strategies ◽  
Continental Scale ◽  
Computing Center

Abstract. The first pan-European kilometre-scale atmospheric chemistry simulation is introduced. The continental-scale air pollution episode of January 2009 is modelled with the CHIMERE offline chemistry transport model with a massive grid of 2 million horizontal points, performed on 2000 CPU of a high-performance computing system hosted by the Research and Technology Computing Center at the French Alternative Energies and Atomic Energy Commission (CCRT/CEA). Besides the technical challenge, we find that model biases are significantly reduced, especially over urban areas. The high-resolution grid also allows revisiting of the contribution of individual city plumes to the European burden of pollution, providing new insights to target the appropriate geographical level of action when designing air pollution mitigation strategies.

scholarly journals Role of emission sources and atmospheric sink on the seasonal cycle of CH<sub>4</sub> and δ<sup>13</sup>-CH<sub>4</sub>: analysis based on the atmospheric chemistry transport model TM5

2021 ◽  
Author(s):  
Vilma Kangasaho ◽  
Aki Tsuruta ◽  
Leif Backman ◽  
Pyry Mäkinen ◽  
Sander Houweling ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Seasonal Cycle ◽  
Oil And Gas ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Seasonal Cycles ◽  
Enteric Fermentation ◽  
Niwot Ridge ◽  
Straight Lines ◽  
Spatially Varying

Abstract. This study investigates the contribution of different CH4 sources to the seasonal cycle of 𝛿13C during years 2000–2012 using the TM5 atmospheric transport model. The seasonal cycles of anthropogenic emissions from two versions of the EDGAR inventories, v4.3.2 and v5.0 are examined. Those includes emissions from Enteric Fermentation and Manure Management (EFMM), rice cultivation and residential sources. Those from wetlands obtained from LPX-Bern v1.4 are also examined in addition to other sources such as fires and ocean sources. We use spatially varying isotopic source signatures for EFMM, coal, oil and gas, wetlands, fires and geological emission and for other sources a global uniform value. We analysed the results as zonal means for 30° latitudinal bands. Seasonal cycles of 𝛿13C are found to be an inverse of CH4 cycles in general, with a peak-to-peak amplitude of 0.07–0.26 ‰. However, due to emissions, the phase ellipses do not form straight lines, and the anti-correlations between CH4 and 𝛿13C are weaker (−0.35 to −0.91) in north of 30° S. We found that wetland emissions are the dominant driver in the 𝛿13C seasonal cycle in the Northern Hemisphere and Tropics, such that the timing of 𝛿13C seasonal minimum is shifted by ∼90 days in 60° N–90° N from the end of the year to the beginning of the year when seasonality of wetland emissions is removed. The results also showed that in the Southern Hemisphere Tropics, emissions from fires contribute to the enrichment of 𝛿13C in July–October. In addition, we also compared the results against observations from the South Pole, Antarctica, Alert, Nunavut, Canada and Niwot Ridge, Colorado, USA. In light of this research, comparison to the observation showed that the seasonal cycle of EFMM emissions in EDGAR v5.0 inventory is more realistic than in v4.3.2. In addition, the comparison at Alert showed that modelled 𝛿13C amplitude was approximately half of the observations, mainly because the model could not reproduce the strong depletion in autumn. This indicates that CH4 emission magnitude and seasonal cycle of wetlands may need to be revised. Results from Niwot Ridge indicate that in addition to biogenic emissions, the proportion of biogenic to fossil based emissions may need to be revised.

scholarly journals Increasing boreal wetland emissions inferred from reductions in atmospheric CH<sub>4</sub> seasonal cycle

2016 ◽  
Author(s):  
J. M. Barlow ◽  
P. I. Palmer ◽  
L. M. Bruhwiler
Keyword(s):  
Significant Role ◽  
Atmospheric Chemistry ◽  
Seasonal Cycle ◽  
Fossil Fuel ◽  
Transport Model ◽  
High Northern Latitude ◽  
Northern Latitude ◽  
The Past ◽  
Boreal Wetland ◽  
Fossil Fuel Emissions

Abstract. Observed variations of the atmospheric greenhouse gas methane (CH4) over the past two decades remain the subject of debate. These variations reflect changes in emission, uptake, and atmospheric chemistry and transport. We isolate changes in the seasonal cycle of atmospheric CH4 using a wavelet transform. We report a previously undocumented persistent decrease in the peak-to-peak amplitude of the seasonal cycle of atmospheric CH4 at six out of seven high northern latitude sites over the past two to three decades. The observed amplitude changes are statistically significant for sites at Barrow, Alaska and Ocean Station M, Norway, which we find are the most sensitive of our sites to high northern latitude wetland emissions. We find using a series of numerical experiments using the TM5 atmospheric chemistry transport model that increasing wetland emissions and/or decreasing fossil fuel emissions can explain these observed changes, but no significant role for trends in meteorology and tropical wetlands. We also find no evidence in past studies to support a significant role for variations in the hydroxyl radical sink of atmospheric CH4. Using the TM5 model we find that changes in fossil fuel emissions of CH4, described by a conservative state-of-the-science bottom-up emission inventory, are not sufficient to reconcile observed changes in atmospheric CH4 at these sites. The remainder of the observed trend in amplitude, by process of elimination, must be due to an increase in high northern latitude wetland emissions, corresponding to an annual increase of at least 0.7 %/yr (equivalent to 5 Tg CH4/yr over 30 years).

scholarly journals New approach to evaluate satellite derived XCO<sub>2</sub> over oceans by integrating ship and aircraft observations

2020 ◽  
Author(s):  
Astrid Müller ◽  
Hiroshi Tanimoto ◽  
Takafumi Sugita ◽  
Toshinobu Machida ◽  
Shin-ichiro Nakaoka ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Satellite Observations ◽  
Reference Dataset ◽  
Model Calculations ◽  
New Approach ◽  
Mixing Ratios ◽  
In Situ Data

Abstract. Satellite observations provide spatially-resolved global estimates of column-averaged mixing ratios of CO2 (XCO2) over the Earth's surface. The accuracy of these datasets can be validated against reliable standards in some areas, but other areas remain inaccessible. To date, limited reference data over oceans hinders successful uncertainty quantification or bias correction efforts, and precludes reliable conclusions about changes in the carbon cycle in some regions. Here, we propose a new approach to analyze and evaluate seasonal, interannual and latitudinal variations of XCO2 over oceans by integrating cargo-ship (SOOP, Ship Of Opportunity) and commercial aircraft (CONTRAIL, Comprehensive Observation Network for Trace gases by Airliner) observations with the aid of state-of-the art atmospheric chemistry-transport model calculations. The consistency of the in situ based column-averaged CO2 dataset (in situ XCO2) with satellite estimates was analyzed over the Western Pacific between 2014 and 2017, and its utility as reference dataset evaluated. Our results demonstrate that the new dataset accurately captures seasonal and interannual variations of CO2. Retrievals of XCO2 over the ocean from GOSAT (Greenhouse gases observing satellite: NIES v02.75, National Institute for Environmental Studies; ACOS v7.3, Atmospheric CO2 Observation from Space) and OCO-2 (Orbiting Carbon Observatory, v9r) observations show a negative bias of about 1 parts per million (ppm) in northern midlatitudes, which was attributed to measurement uncertainties of the satellite observations. The NIES retrieval had higher consistency with in situ XCO2 at midlatitudes as compared to the other retrievals. At low latitudes, it shows many fewer valid data and high scatter, such that ACOS and OCO-2 appear to provide a better representation of the carbon cycle. At different times, the seasonal cycles of all three retrievals show positive phase shifts of one month relative to the in situ data. The study indicates that even if the retrievals complement each other, remaining uncertainties limit the accurate interpretation of spatiotemporal changes in CO2 fluxes. A continuous long-term XCO2 dataset with wide latitudinal coverage based on the new approach has a great potential as a robust reference dataset for XCO2 and can help to better understand changes in the carbon cycle in response to climate change using satellite observations.

Investigation of global atmospheric carbonyl sulphide between 2004 and 2018: an observational and modelling study

2020 ◽  
Author(s):  
Michael P. Cartwright ◽  
Jeremy J. Harrison ◽  
David P. Moore ◽  
John J. Remedios ◽  
Martyn P. Chipperfield ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Atmospheric Carbon Dioxide ◽  
Transport Model ◽  
Carbonyl Sulfide ◽  
Global Scale ◽  
Chemical Transport Model ◽  
Sources And Sinks ◽  
Continental Scale ◽  
Retrieval Scheme ◽  
The Relationship

&lt;p&gt;The challenge in quantifying the sources and sinks of atmospheric carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) is that the CO&lt;sub&gt;2&lt;/sub&gt; taken up by plants during photosynthesis cannot be distinguished from the CO&lt;sub&gt;2&lt;/sub&gt; released by plants and micro-organisms during respiration. It has been shown that carbonyl sulfide (OCS), the sulphur-containing analogue of CO&lt;sub&gt;2&lt;/sub&gt;, can be used as a proxy for photosynthesis. The relationship between the vegetative flux of OCS and CO&lt;sub&gt;2&lt;/sub&gt; has been quantified for various species of plants and ecosystems, the results of which have been used in observing the relationship on a continental scale. The aim of this project is to both quantify the location and magnitude of the sources and sinks of atmospheric OCS, and to use these data to infer photosynthetic uptake of CO&lt;sub&gt;2&lt;/sub&gt; by vegetation on a global scale.&lt;/p&gt;&lt;p&gt;A tracer version of the 3-dimensional chemical transport model TOMCAT has been adapted to include eleven different sources and sinks of OCS, including direct and indirect oceanic emissions, vegetative uptake and stratospheric photolysis. The modelled OCS (TOMCAT-OCS) distribution between 2004 and 2018 has been co-located spatially and temporally to OCS profiles measured by the Atmospheric Chemistry Experiment (ACE-FTS) over the 5 &amp;#8211; 30 km altitude, showing generally good agreement. Furthermore, surface TOMCAT-OCS has been compared to OCS measurements made at twelve NOAA-ESRL sites, across both hemispheres, showing that the model captures the seasonal cycle at the surface.&lt;/p&gt;&lt;p&gt;There have been several calls in recent years for a new satellite product of atmospheric OCS, which this project aims to satisfy. Work is ongoing to retrieve OCS total columns from measurements taken by the Infrared Atmospheric Sounding Interferometer (IASI) instruments on-board the MetOp satellites. The University of Leicester IASI Retrieval Scheme (ULIRS) has been adapted to retrieve OCS columns globally. Various case studies for different geographic regions and time periods will be presented and compared to other satellite observations.&lt;/p&gt;

Anthropogenic water depletion in the Indo-Gangetic Plain

2020 ◽  
Author(s):  
Bingshi Liu ◽  
Xiancai Zou ◽  
Jiancheng Li
Keyword(s):  
Global Climate ◽  
Monsoon Season ◽  
Supply And Demand ◽  
Gangetic Plain ◽  
Water Depletion ◽  
Continental Scale ◽  
Glacier Meltwater ◽  
Terrestrial Water ◽  
Indo Gangetic Plain ◽  
Precipitation And Temperature

&lt;p&gt;The Indo-Gangetic Plain, feeding more than 9 billion people, are facing serious water scarcity due to expanding populations and development in agriculture and industry. Rainfall concentrated in monsoon season, about 70% of precipitation falls between June and September, causes the imbalance between water supply and demand. A large amount of groundwater is extracted for irrigation during dry season, causes the groundwater to decline. Increasing glacier meltwater under the ongoing warming of global climate from upstream high mountainous also modulates the variation of terrestrial water storage (TWS) in this region. Thus, estimating and evaluating anthropogenic water depletion are beneficial to water resources protection and management in the Indo-Gangetic Plain.&lt;/p&gt;&lt;p&gt;Here, we propose a method to remove the influence of climate variability and obtain human-driven TWS variability. Atmosphere-driven TWS variability is estimated by a relationship between change in TWS (GRACE data) and precipitation and temperature, which has been confirmed that these two variables (precipitation and temperature) already explain a substantial fraction of continental-scale run off dynamics in previous studies. Glacier melting recharge from upstream high mountainous is calculated by the proportion with the temperature.&lt;/p&gt;&lt;p&gt;Results show that the rate of anthropogenic depletion of water in Indus Plain increased from -5.5 km&lt;sup&gt;3&lt;/sup&gt;/yr to -25.0 km&lt;sup&gt;3&lt;/sup&gt;/yr during 2003 - 2011 due to the deficient precipitation, and remained stable from 2011 to 2016 at the rate of ~-26.0 km&lt;sup&gt;3&lt;/sup&gt;/yr with increasing precipitation and enhancing glacier meltwater recharge. The rate of anthropogenic depletion of water in Ganges Plain (including the Brahmaputra River) slowed from -37.7 km&lt;sup&gt;3&lt;/sup&gt;/yr to -12.0 km&lt;sup&gt;3&lt;/sup&gt;/yr during 2003 -2011due to the increased glacier meltwater recharge, which reduced the pressure of irrigation water in northwest of the Plain. However, with the increasing temperature since 2014, The rate of anthropogenic depletion of water increased to -20.0 km&lt;sup&gt;3&lt;/sup&gt;/yr in 2016.&lt;/p&gt;

scholarly journals New approach to evaluate satellite-derived XCO<sub>2</sub> over oceans by integrating ship and aircraft observations

2021 ◽  
Vol 21 (10) ◽  
pp. 8255-8271
Author(s):  
Astrid Müller ◽  
Hiroshi Tanimoto ◽  
Takafumi Sugita ◽  
Toshinobu Machida ◽  
Shin-ichiro Nakaoka ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Satellite Observations ◽  
Reference Dataset ◽  
Commercial Aircraft ◽  
Model Calculations ◽  
New Approach ◽  
Mixing Ratios ◽  
Spatially Resolved

Abstract. Satellite observations provide spatially resolved global estimates of column-averaged mixing ratios of CO2 (XCO2) over the Earth's surface. The accuracy of these datasets can be validated against reliable standards in some areas, but other areas remain inaccessible. To date, limited reference data over oceans hinder successful uncertainty quantification or bias correction efforts and preclude reliable conclusions about changes in the carbon cycle in some regions. Here, we propose a new approach to analyze and evaluate seasonal, interannual, and latitudinal variations of XCO2 over oceans by integrating cargo-ship (Ship Of Opportunity – SOOP) and commercial aircraft (Comprehensive Observation Network for Trace gases by Airliner – CONTRAIL) observations with the aid of state-of-the art atmospheric chemistry-transport model calculations. The consistency of the “observation-based column-averaged CO2” dataset (obs. XCO2) with satellite estimates was analyzed over the western Pacific between 2014 and 2017, and its utility as a reference dataset evaluated. Our results demonstrate that the new dataset accurately captures seasonal and interannual variations of CO2. Retrievals of XCO2 over the ocean from GOSAT (Greenhouse Gases Observing Satellite: National Institute for Environmental Studies – NIES v02.75; Atmospheric CO2 Observation from Space – ACOS v7.3) and OCO-2 (Orbiting Carbon Observatory, v9r) observations show a negative bias of about 1 part per million (ppm) in northern midlatitudes, which was attributed to measurement uncertainties of the satellite observations. The NIES retrieval had higher consistency with obs. XCO2 at midlatitudes as compared to the other retrievals. At low latitudes, it shows many fewer valid data and high scatter, such that ACOS and OCO-2 appear to provide a better representation of the carbon cycle. At different times, the seasonal cycles of all three retrievals show positive phase shifts of 1 month relative to the observation-based data. The study indicates that even if the retrievals complement each other, remaining uncertainties limit the accurate interpretation of spatiotemporal changes in CO2 fluxes. A continuous long-term XCO2 dataset with wide latitudinal coverage based on the new approach has great potential as a robust reference dataset for XCO2 and can help to better understand changes in the carbon cycle in response to climate change using satellite observations.

scholarly journals Frontiers in air quality modelling

2013 ◽  
Vol 6 (3) ◽  
pp. 4189-4205
Author(s):  
A. Colette ◽  
B. Bessagnet ◽  
F. Meleux ◽  
L. Rouïl
Keyword(s):  
Air Pollution ◽  
Atmospheric Chemistry ◽  
Urban Areas ◽  
High Performance ◽  
Transport Model ◽  
Control Strategies ◽  
Atomic Energy Commission ◽  
Computing System ◽  
Air Pollution Control ◽  
Continental Scale

Abstract. The first pan-European kilometre-scale atmospheric chemistry simulation is introduced. The continental-scale air pollution episode of January 2009 is modelled with the CHIMERE offline chemistry-transport model with a massive grid of 2 million horizontal points, performed on 2000 CPU of a high performance computing system hosted by the Research and Technology Computing Center at the French Alternative Energies and Atomic Energy Commission (CCRT/CEA). Besides the technical challenge, we find that model biases are significantly reduced, especially over urban areas. The high resolution grid also allows revisiting the contribution of individual city plumes to the European burden of pollution, providing new insights for designing air pollution control strategies.

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