Pandora 관측 방법 및 복원 알고리즘에 따른 대류권 NO2 수직컬럼밀도 비교 연구

다국어 초록 (Multilingual Abstract)

In this study, the consistency of tropospheric nitrogen dioxide vertical column density (NO2 TropoVCD) depending on the different measurement methods (DS and MAX-DOAS) from Pandora 54 in Seoul, Korea, was investigated. The NO2 TropoVCD from both measurement methods converged within a narrow range (R=0.96), but the slope of the best-fit line was slightly higher than 1, indicating that a higher NO2 from direct sun, which is reliable, than MAX-DOAS mode. According to the dependence of the difference in measurement azimuth angles between the two modes, a tendency for the MAX-DOAS/DS ratio was decreased as it approached zero (the solar zenith angle decreased). The MAX-DOAS/DS ratio was linearly increased as the solar zenith angle increased (R = 0.93). To understand the difference in measured zenith angle depending on methods, we investigated the NO2 vertical distribution retrieved from the MAX-DOAS method. The MAX-DOAS/DS ratio near sunrise (eastward) and sunset (westward), when the NO2 vertical gradient is pronounced, is close to 1. However, when the NO2 concentration vertical gradient is gradual around noon, the NO2 TropoVCD ratio is less than 1, suggesting that the influence of the NO2 concentration vertical gradient is not significant. Finally, to investigate the effect of aerosols, we examined the variation in MAX-DOAS/DS ratio depending on aerosol optical depth (AOD) measured by AERONET at the same location. Similar to changes in solar zenith angle, the MAX-DOAS/DS ratio increased as AOD increased. This AOD-dependent difference is considered to be more pronounced in MAX-DOAS methods that consider changes in climatological aerosols (O2-O2) compared to direct sun mode which estimates relatively accurate AOD.
In addition, MAX-DOAS measurements from Pandora 164 in Seosan, Korea, were used to compare NO2 TropoVCD and vertical profiles retrieved by the PGNMAX, JM1, and JM1new algorithms. PGNMAX, a geometry calculation based NASA real-time algorithm, was evaluated against the OEM-based JM1 and the improved JM1new algorithms. JM1new showed a smaller positive bias (∼11%) than JM1 (∼14%) relative to PGNMAX and produced surface concentrations closer to in-situ measurements. Although both JM1 and JM1new underestimated in-situ NO2 (R = 0.59), JM1new exhibited a higher regression slope (0.50) than JM1 (0.34), indicating reduced underestimation. Vertical profile comparisons showed that JM1new produced more surface-concentrated NO2, while PGNMAX tended to yield more vertically diffused structures. Comparisons with aircraft observations from the GMAP-2020 campaign demonstrated that JM1new most accurately reproduced real atmospheric vertical profiles. Across all research flights, normalized mean biases were −50.9% for PGNMAX, −34.3% for JM1new, and −42.8% for JM1, confirming that JM1new provided the most realistic NO2 vertical profiles among the three algorithms.
Overall, this study provides new insights into the discrepancy and underlying causes between Pandora DS and MAX-DOAS measurements and quantitatively characterizes algorithm-dependent differences in MAX-DOAS NO2 products. By evaluating uncertainties relative to in-situ and aircraft observations, the findings highlight important considerations for use of PGN data. Moreover, the improved vertical profile accuracy demonstrated by JM1new suggests potential for enhancing satellite NO2 validation and contributing to future refinement of satellite retrieval algorithms.

목차 (Table of Contents)

• 1. 서론 1
• 1.1. 연구배경 1
• 1.2. 연구목적 및 내용 7
• 2. 연구 방법 9
• 2.1. 연구 지점 및 기간 9
• 2.2. GMAP-2020 캠페인 14
• 2.3. Pandora 16
• 2.4. Japanese MAX-DOAS 복원 알고리즘 22
• 3. 연구결과 26
• 3.1. Pandora 관측 방법에 따른 서울 NO2 TropoVCD 비교 26
• 3.1.1. NO2 TropoVCD의 월변화 26
• 3.1.2. 관측 방법에 따른 NO2 TropoVCD 간의 상관관계 31
• 3.1.3. 방위각 차이에 따른 NO2 TropoVCD의 비율 변화 34
• 3.1.4. 태양의 천정각 구간별 NO2 TropoVCD의 비율 변화 37
• 3.1.5. NO2 연직분포 및 에어로졸의 영향 40
• 3.2. Pandora MAX-DOAS 복원 알고리즘 간 NO2 TropoVCD 비교 46
• 3.2.1. JM1, JM1new PGNMAX 알고리즘 간 NO2 TropoVCD 및 지표농도 비교 46
• 3.2.2. JM1new 및 PGNMAX 복원 NO2 TropoVCD의 시간적 변화 52
• 3.2.3. JM1new 및 PGNMAX 복원 연직분포 계절별 일변화 55
• 3.2.4. GMAP-2020 캠페인 기간 동안 NO2 연직분포 비교 59
• 4. 결론 67
• 5. 참고문헌 74
• Abstract 94