scholarly journals Stratospheric influence on the seasonal cycle of nitrous oxide in the troposphere as deduced from aircraft observations and model simulations

2010 ◽  
Vol 115 (D20) ◽  
Author(s):  
Kentaro Ishijima ◽  
Prabir K. Patra ◽  
Masayuki Takigawa ◽  
Toshinobu Machida ◽  
Hidekazu Matsueda ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Seasonal Cycle ◽  
Model Simulations ◽  
Aircraft Observations

scholarly journals Interannual fluctuations in the seasonal cycle of nitrous oxide and chlorofluorocarbons due to the Brewer-Dobson circulation

2013 ◽  
Vol 118 (19) ◽  
pp. 10,694-10,706 ◽  
Author(s):  
P. G. Simmonds ◽  
A. J. Manning ◽  
M. Athanassiadou ◽  
A. A. Scaife ◽  
R. G. Derwent ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Seasonal Cycle ◽  
Interannual Fluctuations

scholarly journals Global reconstruction reduces the uncertainty of oceanic nitrous oxide emissions and reveals a vigorous seasonal cycle

2020 ◽  
Vol 117 (22) ◽  
pp. 11954-11960 ◽  
Author(s):  
Simon Yang ◽  
Bonnie X. Chang ◽  
Mark J. Warner ◽  
Thomas S. Weber ◽  
Annie M. Bourbonnais ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Seasonal Cycle ◽  
Coastal Upwelling ◽  
Learning Algorithm ◽  
Southern Oscillation ◽  
Latitudinal Gradients ◽  
Nitrous Oxide Emissions ◽  
Boreal Summer ◽  
Intergovernmental Panel ◽  
Tropical Ocean

Assessment of the global budget of the greenhouse gas nitrous oxide (N2O) is limited by poor knowledge of the oceanicN2O flux to the atmosphere, of which the magnitude, spatial distribution, and temporal variability remain highly uncertain. Here, we reconstruct climatologicalN2O emissions from the ocean by training a supervised learning algorithm with over 158,000N2O measurements from the surface ocean—the largest synthesis to date. The reconstruction captures observed latitudinal gradients and coastal hot spots ofN2O flux and reveals a vigorous global seasonal cycle. We estimate an annual meanN2O flux of 4.2 ± 1.0 Tg N⋅y−1, 64% of which occurs in the tropics, and 20% in coastal upwelling systems that occupy less than 3% of the ocean area. ThisN2O flux ranges from a low of 3.3 ± 1.3 Tg N⋅y−1in the boreal spring to a high of 5.5 ± 2.0 Tg N⋅y−1in the boreal summer. Much of the seasonal variations in globalN2O emissions can be traced to seasonal upwelling in the tropical ocean and winter mixing in the Southern Ocean. The dominant contribution to seasonality by productive, low-oxygen tropical upwelling systems (>75%) suggests a sensitivity of the globalN2O flux to El Niño–Southern Oscillation and anthropogenic stratification of the low latitude ocean. This ocean flux estimate is consistent with the range adopted by the Intergovernmental Panel on Climate Change, but reduces its uncertainty by more than fivefold, enabling more precise determination of other terms in the atmosphericN2O budget.

scholarly journals Impacts of updated spectroscopy on thermal infrared retrievals of methane evaluated with HIPPO data

2014 ◽  
Vol 7 (9) ◽  
pp. 10059-10107
Author(s):  
M. J. Alvarado ◽  
V. H. Payne ◽  
K. E. Cady-Pereira ◽  
J. D. Hegarty ◽  
S. S. Kulawik ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Trace Gases ◽  
Thermal Infrared ◽  
Trace Gas ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectroscopic Parameters ◽  
Mixing Ratios ◽  
Aircraft Observations ◽  
The Impact

Abstract. Errors in the spectroscopic parameters used in the forward radiative transfer model can introduce altitude-, spatially-, and temporally-dependent biases in trace gas retrievals. For well-mixed trace gases such as methane, where the variability of tropospheric mixing ratios is relatively small, reducing such biases is particularly important. We use aircraft observations from all five missions of the HIAPER Pole-to-Pole Observations (HIPPO) of the Carbon Cycle and Greenhouse Gases Study to evaluate the impact of updates to spectroscopic parameters for methane (CH4), water vapor (H2O), and nitrous oxide (N2O) on thermal infrared retrievals of methane from the NASA Aura Tropospheric Emission Spectrometer (TES). We find that updates to the spectroscopic parameters for CH4 result in a substantially smaller mean bias in the retrieved CH4 when compared with HIPPO observations. After an N2O-based correction, the bias in TES methane upper tropospheric representative values for measurements between 50° S and 50° N decreases from 56.9 to 25.7 ppbv, while the bias in the lower tropospheric representative value increases only slightly (from 27.3 to 28.4 ppbv). For retrievals with less than 1.6 DOFS, the bias is reduced from 26.8 to 4.8 ppbv. We also find that updates to the spectroscopic parameters for N2O reduce the errors in the retrieved N2O profile.

scholarly journals Storm-Track Activity in IPCC AR4/CMIP3 Model Simulations

2013 ◽  
Vol 26 (1) ◽  
pp. 246-260 ◽  
Author(s):  
Edmund K. M. Chang ◽  
Yanjuan Guo ◽  
Xiaoming Xia ◽  
Minghua Zheng
Keyword(s):  
Seasonal Cycle ◽  
Storm Track ◽  
Coupled Model ◽  
Storm Tracks ◽  
Intergovernmental Panel ◽  
Cmip3 Model ◽  
Model Simulations ◽  
Storm Track Activity ◽  
Highly Correlated ◽  
Ipcc Ar4

Abstract The climatological storm-track activity simulated by 17 Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4)/phase 3 of the Coupled Model Intercomparison Project (CMIP3) models is compared to that in the interim ECMWF Re-Analysis (ERA-Interim). Nearly half of the models show significant biases in storm-track amplitude: four models simulate storm tracks that are either significantly (>20%) too strong or too weak in both hemispheres, while four other models have interhemispheric storm-track ratios that are biased by over 10%. Consistent with previous studies, storm-track amplitude is found to be negatively correlated with grid spacing. The interhemispheric ratio of storm-track activity is highly correlated with the interhemispheric ratio of mean available potential energy, and this ratio is biased in some model simulations due to biases in the midlatitude temperature gradients. In terms of geographical pattern, the storm tracks in most CMIP3 models exhibit an equatorward bias in both hemispheres. For the seasonal cycle, most models can capture the equatorward migration and strengthening of the storm tracks during the cool season, but some models exhibit biases in the amplitude of the seasonal cycle. Possible implications of model biases in storm-track climatology have been investigated. For both hemispheres, models with weak storm tracks tend to have larger percentage changes in storm-track amplitudes over the seasonal cycle. Under global warming, for the NH, models with weak storm tracks tend to project larger percentage changes in storm-track amplitude whereas, for the SH, models with large equatorward biases in storm-track latitude tend to project larger poleward shifts. Preliminary results suggest that CMIP5 model projections also share these behaviors.

Emission of groundwater-derived nitrous oxide into the atmosphere: model simulations based on a 15N field experiment

2010 ◽  
Vol 62 (2) ◽  
pp. 216-225 ◽  
Author(s):  
J. Böttcher ◽  
D. Weymann ◽  
R. Well ◽  
C. Von Der Heide ◽  
A. Schwen ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Field Experiment ◽  
Model Simulations ◽  
15N Field Experiment ◽  
Atmosphere Model

scholarly journals Comparison of Global Datasets of Sodium Densities in the Mesosphere and Lower Thermosphere from GOMOS, SCIAMACHY and OSIRIS Measurements and WACCM Model Simulations from 2008 to 2012

2017 ◽  
Author(s):  
Martin P. Langowski ◽  
Christian von Savigny ◽  
John P. Burrows ◽  
Didier Fussen ◽  
Erin C. M. Dawkins ◽  
...  
Keyword(s):  
Seasonal Cycle ◽  
Lower Thermosphere ◽  
Temporal Variations ◽  
Equatorial Region ◽  
Local Times ◽  
Vertical Column ◽  
Model Simulations ◽  
Mesosphere And Lower Thermosphere ◽  
Summer Minimum ◽  
Global Datasets

Abstract. During the last decade, multiple limb sounding satellites have measured the global sodium (Na) number densities in the mesosphere and lower thermosphere (MLT).Datasets are now available from GOMOS, SCIAMACHY (both on Envisat) and OSIRIS/Odin. Furthermore, global model simulations of the Na layer in the MLT simulated with WACCM-Na are available. In this paper, we compare these global datasets. Globally, there is an agreement in the observed and simulated monthly average of Na vertical column densities that were compared with each other. They show a clear seasonal cycle with a summer minimum most pronounced at the poles. They also show signs of a semi-annual oscillation in the equatorial region. The vertical column densities vary between 0.5 × 109 cm−2 to 7 × 109 cm−2 near the poles and between 3 × 109 cm−2 to 4 × 109 cm−2 at the equator. The phase of the seasonal cycle and semi-annual oscillation shows small differences between the different instruments. The full width at half maximum of the profiles is 10 to 16 km for most latitudes, but significantly smaller in the polar summer. The centroid altitudes of the measured sodium profiles range from 89 to 95 km, while the model shows on average 2 to 4 km lower centroid altitudes. This coincides with a 3 km lower mesopause altitude in the WACCM simulations compared to measurements, which may be the reason for the low centroid altitudes. Despite this global 2 to 4 km shift, the model captures latitudinal and temporal variations. The variation of the WACCM dataset during the year at different latitudes is similar to the one of the measurements. Furthermore, the differences between the measured profiles with different instruments and therefore different local times are also present in the model simulated profiles. This capturing of latitutinal and temporal variations is also found for the vertical column densities and profile widths.

scholarly journals An intercomparison of total column-averaged nitrous oxide between ground-based FTIR TCCON and NDACC measurements at seven sites and comparisons with the GEOS-Chem model

2019 ◽  
Vol 12 (2) ◽  
pp. 1393-1408 ◽  
Author(s):  
Minqiang Zhou ◽  
Bavo Langerock ◽  
Kelley C. Wells ◽  
Dylan B. Millet ◽  
Corinne Vigouroux ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Southern Hemisphere ◽  
Near Infrared ◽  
A Priori ◽  
Polar Vortex ◽  
Inversion Method ◽  
Seasonal Cycles ◽  
A Posteriori ◽  
Model Simulations ◽  
N2o Fluxes

Abstract. Nitrous oxide (N2O) is an important greenhouse gas and it can also generate nitric oxide, which depletes ozone in the stratosphere. It is a common target species of ground-based Fourier transform infrared (FTIR) near-infrared (TCCON) and mid-infrared (NDACC) measurements. Both TCCON and NDACC networks provide a long-term global distribution of atmospheric N2O mole fraction. In this study, the dry-air column-averaged mole fractions of N2O (XN2O) from the TCCON and NDACC measurements are compared against each other at seven sites around the world (Ny-Ålesund, Sodankylä, Bremen, Izaña, Réunion, Wollongong, Lauder) in the time period of 2007–2017. The mean differences in XN2O between TCCON and NDACC (NDACC–TCCON) at these sites are between −3.32 and 1.37 ppb (−1.1 %–0.5 %) with standard deviations between 1.69 and 5.01 ppb (0.5 %–1.6 %), which are within the uncertainties of the two datasets. The NDACC N2O retrieval has good sensitivity throughout the troposphere and stratosphere, while the TCCON retrieval underestimates a deviation from the a priori in the troposphere and overestimates it in the stratosphere. As a result, the TCCON XN2O measurement is strongly affected by its a priori profile. Trends and seasonal cycles of XN2O are derived from the TCCON and NDACC measurements and the nearby surface flask sample measurements and compared with the results from GEOS-Chem model a priori and a posteriori simulations. The trends and seasonal cycles from FTIR measurement at Ny-Ålesund and Sodankylä are strongly affected by the polar winter and the polar vortex. The a posteriori N2O fluxes in the model are optimized based on surface N2O measurements with a 4D-Var inversion method. The XN2O trends from the GEOS-Chem a posteriori simulation (0.97±0.02 (1σ) ppb yr−1) are close to those from the NDACC (0.93±0.04 ppb yr−1) and the surface flask sample measurements (0.93±0.02 ppb yr−1). The XN2O trend from the TCCON measurements is slightly lower (0.81±0.04 ppb yr−1) due to the underestimation of the trend in TCCON a priori simulation. The XN2O trends from the GEOS-Chem a priori simulation are about 1.25 ppb yr−1, and our study confirms that the N2O fluxes from the a priori inventories are overestimated. The seasonal cycles of XN2O from the FTIR measurements and the model simulations are close to each other in the Northern Hemisphere with a maximum in August–October and a minimum in February–April. However, in the Southern Hemisphere, the modeled XN2O values show a minimum in February–April while the FTIR XN2O retrievals show different patterns. By comparing the partial column-averaged N2O from the model and NDACC for three vertical ranges (surface–8, 8–17, 17–50 km), we find that the discrepancy in the XN2O seasonal cycle between the model simulations and the FTIR measurements in the Southern Hemisphere is mainly due to their stratospheric differences.

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