The roughness length for heat zT was evaluated over an urban canopy, using the measured sensible heat flux and radiometric temperature. To overcome thermal heterogeneity in the urban area, the measured radiometric temperature was transformed into the equivalent temperature of an upward longwave radiation flux. The equivalent temperature was found to provide an effective parameterization of the radiometric temperature. The daytime average of the resulting ln(zT/z0) was 10, where z0 is the aerodynamic roughness length. This result generally agrees with previous studies; however, the anthropogenic heat is a large uncertainty, which could cause an error at least 240% in zT.

Roughness length for heat over an urban canopy

Process analysis of ozone formation under different weather conditions over the Kanto region of Japan using the MM5/CMAQ modelling system

To understand the effect of the NH3 emissions from vehicles, the NH4+ bulk deposition and concentrations of gaseous NH3 and particulate NH4+ were measured at two sites in Saitama prefecture, Japan, one at the roadside of an arterial road (Kounosu), and the other in an agricultural area (Kisai). We observed that the NH4+ bulk deposition and NH3 concentration were significantly increased in Kounosu; the effect of NH3 emissions from vehicles was confirmed. NOx was a primary pollutant mainly emitted by vehicle exhaust in the vicinity of arterial roads, and the relationship between NOx and sum of gaseous NH3 and particulate NH4+ (T-NH4+) was examined. The [T-NH4+/NOx] ratios in Kounosu ranged from 0.08 to 0.23 (average 0.15), and in Kisai they ranged from 0.16 to 0.67 (average 0.39). In Kounosu, the effect of vehicle exhaust was great, but seasonal variation was small. The contribution ratio of NH3 from vehicle emissions increased at low temperatures, while that from the non-vehicle emissions increased at high temperatures.

Comparison of Ammonium Deposition Flux at Roadside and at an Agricultural Area for Long-Term Monitoring: Emission of Ammonia from Vehicles

We evaluated the performance of the newly developed atmospheric mesoscale model, WRF, for the simulation of urban-scale weather in the Tokyo metropolitan area during a high photochemical Oxidant event. The simulation clearly shows that WRF represents the spatial distribution of surface air temperature during the daytime, although the model temperature is lower than the observations in the late afternoon to evening in the urban area. The wind system can be well reproduced in WRF. Simulated convergence zone moves toward the inland areas located to the northwest of the coastal area during the three hours. These results are consistent with the observations of temperature and Photochemical Oxidant, indicating that WRF has enough potential to predict the ongoing Oxidant concentration.

https://www.jstage.jst.go.jp/article/jsmeb/49/1/49_1_72/_pdf

Numerical Simulation of Local Weather for a High Photochemical Oxidant Event Using the WRF Model

Despite ozone precursor emission reduction efforts in most polluted areas worldwide, photochemical ozone remains among the most concerning air pollutants in some regions, possibly because of spatial heterogeneity of ozone sensitivity to individual precursors. However, regional differences in ozone sensitivity to volatile organic compounds (VOCs), a major precursor, have not been quantitatively shown. Therefore, this study estimated the spatial variations in the efficacy of VOC emission reductions to mitigate photochemical ozone concentrations and population exposure (as related to ozone-related health problems) over Japan, and to inform policy makers pursuing effective ozone reduction strategies in polluted regions. Using air quality simulations, we found that the abovementioned efficacy differed substantially, up to 10-fold, among 20 × 20-km areas in which VOCs had been reduced. Using the above-calculated spatial distribution of the efficacy and data on emission source locations of several industries, upstream industries (e.g., petroleum and coal products) showed greater reduction efficacies than downstream industries (e.g., plastic products). By comparing the calculated ozone sensitivity to VOCs with the ozone–NOx–VOC sensitivity derived from space-based observations of the HCHO/NO2 column ratio from the Ozone Monitoring Instrument, the general spatial trends in ozone sensitivity to VOC emission reductions were verified qualitatively. Thus, regional countermeasures should be considered rather than the existing uniform nationwide measures in Japan. Moreover, to prioritize VOC emission reductions by industry, considering the reactivity or ozone formation potential of each emitted VOC exclusively, as is currently done, is insufficient, the emission locations of each industry should also be considered.

Modeling study on the spatial variation of the sensitivity of photochemical ozone concentrations and population exposure to VOC emission reductions in Japan

関東平野における初冬季の高濃度SPM汚 染を対象として,SPMを 構成する一次粒子および二 次粒子前駆ガス成分を対象 とした発生源モデルを構築 した。元素状炭素粒子および有機炭素成分の 主要排出源の一つとして,実 走行状態の自動車群からの排出係数を自動車専用道路における観測か ら推定した。清掃工場および産業廃棄物処理場からの塩化水素発生量を,各 施設の排ガス中濃度お よび排ガス量の調査結果ら求め,排 ガス濃度が報告されていない場合は排ガス処理装置種別に一定 値を与えた。アンモニアについては,家 畜 ・肥料使用,排 煙脱硝装置,ガ ソリン車,人 体,お よび 下水処理からの発生量を推定した。窒素酸化物,二 酸化硫黄,お よび非メタン炭化水素の発生源モ デルについては,過 去の調査事例をもとに整備 ・拡充する形で作成した。設定領域からは,面 積に してほぼ匹敵する広さを持つSouth Coast Air Basin領 域(ロ スアンゼルス周辺領域)の4倍 の元 素状炭素の排出量が推計され,ま た1984年 時の英国全土からのHC1排 出量の約80%の 排出が見. 込まれるなど,関 東地方からのSPM原 因物質の排出量が極めて大きなものであると推計された。 アンモニアの発生量については,発 生源データの不確定性から,推 計値には大きな誤差が含まれる 可能性がある。

https://www.jstage.jst.go.jp/article/taiki1995/37/5/37_5_302/_pdf

Modeling of Suspended Particulate Matter during Early-winter Severe Pollution Episodes (I)

Feasibility of a Method Simulating Long-term Average Concentration of Pollutants Based on a Mesoscale Meteorological Model : (I) Classification of Weather Patterns and Application to NOx in the Kanto Plain

https://www.jstage.jst.go.jp/article/jawe1982/1998/75/1998_75_61/_pdf

Motoo Suzuki

Papers

Modeling of Suspended Particulate Matter during Early-winter Severe Pollution Episodes (I)

Feasibility of a Method Simulating Long-term Average Concentration of Pollutants Based on a Mesoscale Meteorological Model : (I) Classification of Weather Patterns and Application to NOx in the Kanto Plain

Numerical analysis of the severe air pollution episode of Ox and NO2 with a prediction model including photochemical reactions

Inter-Comparison of the Local Circulation Models : Sea Breeze Case