English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Nitrous oxide (N2O) is an important greenhouse gas and it can alsogenerate nitric oxide, which depletes ozone in the stratosphere. It is acommon target species of ground-based Fourier transform infrared (FTIR) near-infrared (TCCON) andmid-infrared (NDACC) measurements. Both TCCON and NDACC networks provide along-term global distribution of atmospheric N2O mole fraction. In thisstudy, the dry-air column-averaged mole fractions of N2O (XN2O) fromthe TCCON and NDACC measurements are compared against each other at sevensites around the world (Ny-Alesund, Sodankyla, Bremen, Izana,Reunion, Wollongong, Lauder) in the time period of 2007–2017. The meandifferences in XN2O between TCCON and NDACC (NDACC–TCCON) at thesesites are between −3.32 and 1.37 ppb (−1.1 %–0.5 %) with standarddeviations between 1.69 and 5.01 ppb (0.5 %–1.6 %), which are within theuncertainties of the two datasets. The NDACC N2O retrieval has goodsensitivity throughout the troposphere and stratosphere, while the TCCONretrieval underestimates a deviation from the a priori in the troposphere andoverestimates it in the stratosphere. As a result, the TCCON XN2Omeasurement is strongly affected by its a priori profile. Trends and seasonal cycles of XN2O are derived from the TCCON and NDACCmeasurements and the nearby surface flask sample measurements and comparedwith the results from GEOS-Chem model a priori and a posteriori simulations.The trends and seasonal cycles from FTIR measurement at Ny-Alesund andSodankyla are strongly affected by the polar winter and the polar vortex.The a posteriori N2O fluxes in the model are optimized based on surfaceN2O measurements with a 4D-Var inversion method. The XN2O trendsfrom 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) andthe surface flask sample measurements (0.93±0.02 ppb yr−1). TheXN2O 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. TheXN2O trends from the GEOS-Chem a priori simulation are about 1.25 ppb yr−1, and our study confirms that theN2O fluxes from the a prioriinventories are overestimated. The seasonal cycles of XN2O from theFTIR measurements and the model simulations are close to each other in theNorthern Hemisphere with a maximum in August–October and a minimum inFebruary–April. However, in the Southern Hemisphere, the modeled XN2Ovalues show a minimum in February–April while the FTIR XN2O retrievals showdifferent patterns. By comparing the partial column-averaged N2O from themodel and NDACC for three vertical ranges (surface–8, 8–17, 17–50 km), wefind that the discrepancy in the XN2O seasonal cycle between the modelsimulations and the FTIR measurements in the Southern Hemisphere is mainlydue to their stratospheric differences.

atmospheric measurement techniques

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