MICS-Asia III: Multi-model comparison of reactive Nitrogen deposition over China

Abstract

Abstract. Atmospheric nitrogen deposition in China has attracted huge public attention in recently years due to the increasing anthropogenic emission of reactive nitrogen (Nr) and its impacts on the terrestrial and aquatic ecosystems. However, limited long-term and multi-site measurements have restrained the understanding on the mechanism of the Nr deposition as well as the chemical transport model (CTM) improvement. In this study, the performance of the simulated wet and dry deposition for different Nr species, i.e., particulate NO3− and NH4+, gaseous NOx, HNO3 and NH3, have been conducted using the framework of Model Inter-Comparison Study for Asia (MICS-Asia) phase III. Nine Models, including 5 WRF-CAMQ models, 2 self-developed regional models, a global model and a RAMS-CMAQ model, have been selected for the comparison. For wet depositions, observation data from 83 measurement sites of EANET, CREN, CAUDN, NADMN and DEE of China have been collected and normalized to compare with model results. In general, most models showed the consistent spatial and temporal variation of both oxidized N (Nox) and reduced N (Nrd) wet depositions in China with the NME around at 50 %, which is lower than the value of 70 % based on EANET observation over Asia. Both the ratio of wet or dry deposition to the total inorganic N deposition (TIN) and the ratios of TIN to their emissions have shown the consistent results with the NNDMN estimations. The performance of ensemble results (ENM) was further assessed with the measurement from satellite. In different regions of China, the results showed that the simulated Nox wet deposition was overestimated in North East China (NE) but underestimated in south of China (SE+SW), while the Nrd wet deposition was underpredicted in all regions by all models. The deposition of Nox have large uncertainties than the Nrd especially in North China (NC), indicating chemical reaction process is one of the most importance factors that affecting the model performance. Compared to Critical load (CL) value, the Nr deposition in NC, SE and SW reached or exceeded the reported CL value and exerted serious ecological impacts. The control of Nrd in NC and SW and Nox in SE would be effective to mitigate the TIN deposition in these regions. More interestingly, the Nr deposition in Tibet plateau with the high ratio of TIN/emission (~3.0), indicating a significant import from outside should be focused in the future due to its climatical influence to the sensitive ecosystem in whole China.

MICS-Asia III: overview of model intercomparison and evaluation of acid deposition over Asia

“…For this deposition analysis, seven of the nine models (M1, M2, M4, M5, M6, M11, and M12) were configured with the same domain and meteorological conditions driven by the WRF. The WRF is configured as follows: longwave radiation is computed with the rapid radiative transfer model (Mlawer et al, 1997), shortwave radiation with the Goddard scheme (Chou and Suarez, 1994;Matsui et al, 2018), microphysics with Lin's scheme (Chen and Sun, 2002), cumulus physics with the Grell 3D ensemble scheme (Grell, 1993;Grell and Devenyi, 2002), the planetary boundary layer with the Yonsei University scheme (YSU) (Hong et al, 2006), the surface layer with the revised fifth-generation Penn State/NCAR Mesoscale Model (MM5) (Jiménez et al, 2012), and land surface with the unified Noah model (Tewari et al, 2004). The WRF also includes the urban canopy model (Chen et al, 2011).…”

“…In summary, for the wet deposition of N, all models except M5 and M11 underestimated this parameter; however, the relationship between the wet deposition of N and the atmospheric concentration of N was not obvious, and this point was different from this relationship for S. Because the correlation coefficient for the model performance of the wet deposition of N is lower than that for S, future studies should focus on N and related species in greater detail. Our future companion paper will attempt a detailed analysis of N using an intensive observation network over China (Ge et al, 2020).…”

“…The available observations in China have been limited over the past decades; however, there are extensive observations to capture them. A detailed model intercomparison over China based on the available observations will be reported in work following our companion paper (Ge et al, 2020). Additionally, we limited the evaluation to wet deposition, due to the difficulty of measuring dry deposition, and relied on the model performance to determine atmospheric concentrations.…”

Supplementary material to "Comparison of three aerosol representations of NHM-Chem (v1.0) for the simulations of air quality and climate-relevant variables"

“…Many of the schemes are similar or almost equivalent to those implemented in widely used regional community models, such as CMAQ (Byun and Schere, 2006;Wong et al, 2012) and WRF-Chem (Grell et al, 2005;Chapman et al, 2009), as seen from the result of a multi-CTM intercomparison study (Li et al, 2019;Chen et al, 2019;Itahashi et al, 2020;Kong et al, 2020;Tan et al, 2020;Ge et al, 2020): NHM-Chem behaved similarly to the other models, including CMAQ and WRF-Chem. The advantage of the current model is not considerable, except for the detailed fog deposition and belowcloud scavenging parameterizations.…”

Comparison of three aerosol representations of NHM-Chem (v1.0) for the simulations of air quality and climate-relevant variables

“…S1-1). The offline NHM-Chem with WRF was used for a multi-CTM intercomparison study in Asia Chen et al, 2019;Itahashi et al, 2020;Kong et al, 2020;Tan et al, 2020;Ge et al, 2020) and a multimeteorological model study of the Fukushima nuclear accident (Kajino et al, 2019b). The offline model with SCALE was used for a multi-CTM intercomparison study for the Fukushima nuclear accident and that with ASUCA is currently being used by JMA to produce an operational forecast for photochemical smog bulletins (http://www.jma.go.jp/jma/kishou/know/kurashi/smog.html; last access: 18 June 2020, in Japanese).…”