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The HCHO concentrations measured at the major International ports in the subcontinent. Measurements from six satellite instruments and their average (AVG) are shown. Fig. 2 shows the location of the seaports.

The HCHO concentrations measured at the major International ports in the subcontinent. Measurements from six satellite instruments and their average (AVG) are shown. Fig. 2 shows the location of the seaports.

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Article
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Atmospheric formaldehyde (HCHO) has significant adverse health effects at higher concentrations. It is an unstable and inflammable organic compound, and is an index for atmospheric pollution. Although the ambient HCHO is due to methane oxidation, the localised enhancement in HCHO is mostly from the emissions of non-methane volatile organic compound...

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... is, the high temperature and sunlight enhance the emissions and oxidation of NMVOCs such as isoprene owing to the photochemistry in summer (MAM) months. In India, the highest concentrations of HCHO are observed in the months of March, April and May (this can be slightly different with respect to data and period of analyses, as demonstrated in Fig. S4 for the combined data used here and for the SCIAMACHY data), which can be attributed to biomass burning, whereas the high levels in September and October can be related to biogenic emissions ( Fu et al., 2007 ). Higher quantities of HCHO in the regions with extensive vegetation and biomass burning indicate that biogenic emissions are ...
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... illustrated in Fig. 4 , the inter-annual analysis indicates a steady increase in HCHO concentration over India from 2005 to 2009. However, 2006, 2009 and 2011-13) in the northeast India, however, can be attributed to forest fire events in these areas ( Chauhan and Singh, 2021 ;Kuttippurath et al., 2020 ). Similar results are found in a multiyear analysis of ...
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... also looked at the time series of measurements at Indian seaports, international seaports, cities and specific geographic regions (Fig. S2). For instance, Fig. 4 shows the temporal evolution of HCHO measured by different satellites over the international seaports around India; Dhaka, Colombo, Kqaukpyu, Karachi and Chattogram. We have consid- ered the international seaports around India here, as the high concentrations of HCHO at these regions might affect HCHO over India through atmospheric ...

Citations

... As OMI provides long-term measurements of HCHO, the OMI HCHO product has been extensively employed in atmospheric studies. This data set has been a useful resource for estimating variations and trends in atmospheric HCHO levels and identifying emission sources (Kuttippurath et al., 2022;Surl et al., 2018;, quantifying isoprene emissions (Kaiser et al., 2018;Marais et al., 2012Marais et al., , 2014H. Wang et al., 2021), estimating surface HCHO concentrations to evaluate potential health risks , and studying the ozone sensitivity of different regions worldwide (Duncan et al., 2010;Jin & Holloway, 2015;Jin et al., 2017;D. ...
Article
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This study presents the ozone monitoring instrument (OMI) Collection 4 formaldehyde (HCHO) retrieval developed with the Smithsonian Astrophysical Observatory's (SAO) Making Earth System Data Records for Use in Research Environments (MEaSUREs) algorithm. The retrieval algorithm updates and makes improvements to the NASA operational OMI HCHO (OMI Collection 3 HCHO) algorithm, and has been transitioned to use OMI Collection 4 Level‐1B radiances. This paper describes the updated retrieval algorithm and compares Collection 3 and Collection 4 data products. The OMI Collection 4 HCHO exhibits remarkably improved stability over time in comparison to the OMI Collection 3 HCHO product, with better precision and the elimination of artificial trends present in the Collection 3 during the later years of the mission. We validate the OMI Collection 4 HCHO data product using Fourier‐Transform Infrared (FTIR) ground‐based HCHO measurements. The climatological monthly averaged OMI Collection 4 HCHO vertical column densities (VCDs) agree well with the FTIR VCDs, with a correlation coefficient of 0.83, root‐mean‐square error (RMSE) of 2.98×1015 2.98×10152.98\times 1{0}^{15} molecules cm−2 cm2{\text{cm}}^{-2}, regression slope of 0.79, and intercept of 8.21×1014 8.21×10148.21\times 1{0}^{14} molecules cm−2 cm2{\text{cm}}^{-2}. Additionally, we compare the monthly averaged OMI Collection 4 HCHO VCDs to OMPS Suomi NPP, OMPS NOAA‐20, and TROPOMI HCHO VCDs in overlapping years for 12 geographic regions. This comparison demonstrates high correlation coefficients of 0.98 (OMPS Suomi NPP), 0.97 (OMPS NOAA‐20), and 0.90 (TROPOMI).
... Specifically, Georgoulias et al. (2019) provided a 295 satellite-based analysis of NO₂ trends from 1996 to 2017, which supports the long-term consistency of our observations, albeit with minor discrepancies in the examined time periods. For a nuanced understanding of HCHO trends, both regional studies (Fan et al., 2023;Kuttippurath et al., 2022) and global perspectives (De Smedt et al., 2008;De Smedt et al., 2015) are instrumental. ...
... India, with its unique climate and emissions profile, exhibits a large area in the quasi-NOx-limited range (3.5-4.5). India's hot and humid climate contributes to elevated BVOC and HCHO emissions (Kuttippurath et al., 2022), reducing NOx lifetime and accumulation, which tends to be more NOxlimited. We observe an urban-rural transition from VOC-limited to NOx-limited in megacity clusters, with the periphery zones showing the initial shift toward NOx-limited, progressing inward. ...
Preprint
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Ground-level ozone (O3) formation in urban areas is nonlinearly dependent on the relatively availability of its precursors: oxides of nitrogen (NOx) and volatile organic compounds (VOCs). To mitigate O3 pollution, a crucial question is to identify the O3 formation regime (NOx-limited or VOC-limited). Here we leverage ground-based O3 observations alongside space-based observations of O3 precursors, namely NO2 and formaldehyde (HCHO), to study the long-term shifts in O3 chemical regimes across global source regions. We first derive the regime threshold values for satellite-derived HCHO/NO2 ratio by examining its relationship with the O3 weekend effect. We find that a regime transition from VOC-limited to NOx-limited occurs around 3.5 for HCHO/NO2 with regional variations. By integrating data from four satellite instruments, including GOME, SCIAMACHY, OMI, and TROPOMI, we build a 27-year (1996–2022) satellite HCHO/NO2 record, from which we assess the long-term trends in O3 production regimes. A discernible global trend towards NOx-limited regimes is evident, particularly in developed regions such as North America, Europe, and Japan, with emerging trends in developing countries like China and India over the past two decades. This shift is supported by both increasing HCHO/NO2 ratios and a diminishing O3 weekend effect. Yet, urban areas still hover in the VOC-limited and transitional regime on the basis of annual averages. Our findings stress the importance of adaptive emission control strategies to mitigate O3 pollution.
... HCHO levels are shrinking over Tokyo, New York, and other cities of developed countries (De Smedt et al., 2010), but it is increasing over India and China (De Smedt et al., 2010;Mahajan et al., 2015;Shen et al., 2019;Sun et al., 2021). Several studies have reported HCHO to be an important measure of air quality (De Smedt et al., 2010;Kuttippurath et al., 2022;Li et al., 2021;Millet et al., 2008;Shen et al., 2019). ...
... CO in turn facilitates HCHO formation through its reaction with hydroxyl radicals because the oxidation of CO with hydroxyl radical generates additional hydroxyl radicals from subsequent reactions (R11). These hydroxyl radicals react with methane and NMVOCs (R5, R6) to produce De Smedt et al., 2010;Kuttippurath et al., 2022;Mahajan et al., 2015;Seinfeld & Pandis, 1998). This dual pathway illustrates the intricate association between HCHO and CO in atmospheric chemistry. ...
... Their work also revealed that the spatial distributions of HCHO and CHOCHO obtained from OMI, GOME-2A, and SCIAMACHY were similar but OMI retrievals generally showed higher column values compared to GOME-2A and SCIAMACHY due to differences in resolution and the sampling of different air masses resulting from distinct overpass times. Kuttippurath et al. (2022) examined 20 years of HCHO trends (1997-2020) over India and reported peak levels in the Indo-Gangetic Plains, southern, and eastern India, associating these with biomass burning and vegetation. Their work also highlighted elevated HCHO over ports and mining areas. ...
Article
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This study investigates the spatio-temporal distribution of formaldehyde (HCHO) over the mainland Southeast Asian region (including Northeast India) from 2019 to 2022 using TROPOMI satellite data. HCHO is a key atmospheric trace gas which is influenced by both natural processes and anthropogenic activities. We analyze HCHO levels in relation to atmospheric species including carbon monoxide (CO), nitrogen dioxide (NO2), and environmental factors such as land surface temperature (LST), precipitation (PPT), fire radiative power (FRP), and enhanced vegetation index (EVI). Peak levels of HCHO are particularly observed in March and April, which coincide with the dry and warm seasons and reflect seasonal variability arising from both fluctuating emission sources and regional climate patterns. Correlation analyses reveal significant associations between HCHO and CO (r = 0.727), followed by HCHO and NO2 (r = 0.577) and HCHO and LST (r = 0.539). Conversely, a negative correlation with PPT (r = − 0.233) is observed as HCHO decreases with increased precipitation due to washout. The negative correlation with EVI (r = − 0.319) is unexpected since biogenic emissions are significant contributors to HCHO. This outcome likely results from the confounding effect of precipitation. A robust multiple regression model incorporating these variables is developed which is able to explain 61.8% of the variance in HCHO. It enhances predictive capabilities facilitating the estimation of HCHO distribution and supporting air quality management efforts in the region. This research contributes to understanding the complex interactions of HCHO with atmospheric chemistry and climate variability in Southeast Asia. Insights gained from this study are crucial for informing environmental policies aimed at reducing air pollution and protecting public health in rapidly developing regions.
... Bi-hierarchical balanced incomplete block (BiHBIB) designs more popularly known as nested balanced incomplete block (NBIB) designs, eliminate two sources of hierarchical variation present in the experimental material. Several researchers addressed the problem of finding optimal ME design using NBIB designs, group divisible designs, circular designs, etc. [12][13][14][15] . ...
... We observed a significant surge in CO and HCHO concentration over northern parts of Uttar Pradesh and Bihar during April 2024 caused by forest fires in Uttarakhand and subsequent transport by prevailing wind conditions. Although HCHO has a short atmospheric lifetime varying from several minutes to a few hours 12 , it can still be detected from a satellite due to prolonged emissions from fire events and wind-driven transport. ...
Article
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Forest fires in the Western Himalaya region pose significant environmental and health challenges. The present communication examines the impact of these fires on air quality, focusing on elevated levels of carbon monoxide, formaldehyde and aerosols. Utilizing satellite inputs and chemistry transport models such as Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT), the study traces pollutant dispersion and concentration. The findings highlight high concentration and extended lifetime of trace gases, with implications for public health and long-term environmental effects.
... Figure 4 shows the global maps of HCHO total column trends derived from OMI, the prior M2GMI, and the posterior M2GMI. The widespread upward trends in HCHO over India are evident due to a lack of effective efforts to cut emissions related to VOCs (e.g., De Kuttippurath et al., 2022;Bauwens et al., 2022). We observe HCHO columns going up in the northwestern US and over oil sands in Canada, possibly due to increased evergreen needleleaf forests and an increase in crude oil production , respectively. ...
Article
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The tropospheric hydroxyl (TOH) radical is a key player in regulating oxidation of various compounds in Earth's atmosphere. Despite its pivotal role, the spatiotemporal distributions of OH are poorly constrained. Past modeling studies suggest that the main drivers of OH, including NO2, tropospheric ozone (TO3), and H2O(v), have increased TOH globally. However, these findings often offer a global average and may not include more recent changes in diverse compounds emitted on various spatiotemporal scales. Here, we aim to deepen our understanding of global TOH trends for more recent years (2005–2019) at 1×1°. To achieve this, we use satellite observations of HCHO and NO2 to constrain simulated TOH using a technique based on a Bayesian data fusion method, alongside a machine learning module named the Efficient CH4-CO-OH (ECCOH) configuration, which is integrated into NASA's Goddard Earth Observing System (GEOS) global model. This innovative module helps efficiently predict the convoluted response of TOH to its drivers and proxies in a statistical way. Aura Ozone Monitoring Instrument (OMI) NO2 observations suggest that the simulation has high biases for biomass burning activities in Africa and eastern Europe, resulting in a regional overestimation of up to 20 % in TOH. OMI HCHO primarily impacts the oceans, where TOH linearly correlates with this proxy. Five key parameters, i.e., TO3, H2O(v), NO2, HCHO, and stratospheric ozone, can collectively explain 65 % of the variance in TOH trends. The overall trend of TOH influenced by NO2 remains positive, but it varies greatly because of the differences in the signs of anthropogenic emissions. Over the oceans, TOH trends are primarily positive in the Northern Hemisphere, resulting from the upward trends in HCHO, TO3, and H2O(v). Using the present framework, we can tap the power of satellites to quickly gain a deeper understanding of simulated TOH trends and biases.
... The Indo-Gangetic Plain (IGP) stretches from Eastern Pakistan to Bangladesh and is a major agricultural region in India (Kuttippurath et al., 2022). Thus, averaging the HCHO columns over a diverse landscape can lead to less-prominent seasonality. ...
... The observed and modeled amplitudes of the HCHO seasonal cycle are 40 %. Both datasets show enhanced HCHO levels during spring, consistent with high isoprene concentrations (Fig. S4) Biogenic emissions are the main driver of the HCHO levels in east India; however, emissions from mines are also potential sources of NO x and VOCs (Kuttippurath et al., 2022). ...
Article
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Formaldehyde (HCHO), a precursor to tropospheric ozone, is an important tracer of volatile organic compounds (VOCs) in the atmosphere. Two years (2019–2020) of HCHO simulations obtained from the global chemistry transport model CHASER at a horizontal resolution of 2.8° × 2.8° have been evaluated using the Tropospheric Monitoring Instrument (TROPOMI) and multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations. In situ measurements from the Atmospheric Tomography Mission (ATom) in 2018 were used to evaluate the HCHO simulations for 2018. CHASER reproduced the TROPOMI-observed global HCHO spatial distribution with a spatial correlation (r) of 0.93 and a negative bias of 7 %. The model showed a good capability to reproduce the observed magnitude of the HCHO seasonality in different regions, including the background conditions. The discrepancies between the model and satellite in the Asian regions were related mainly to the underestimated and missing anthropogenic emission inventories. The maximum difference between two HCHO simulations based on two different nitrogen oxide (NOx) emission inventories was 20 %. TROPOMI's finer spatial resolution than that of the Ozone Monitoring Instrument (OMI) sensor reduced the global model–satellite root-mean-square error (RMSE) by 20 %. The OMI- and TROPOMI-observed seasonal variations in HCHO abundances were consistent. The simulated seasonality showed better agreement with TROPOMI in most regions. The simulated HCHO and isoprene profiles correlated strongly (R=0.81) with the ATom observations. However, CHASER overestimated HCHO mixing ratios over dense vegetation areas in South America and the remote Pacific region (background condition), mainly within the planetary boundary layer (< 2 km). The simulated seasonal variations in the HCHO columns showed good agreement (R>0.70) with the MAX-DOAS observations and agreed within the 1σ standard deviation of the observed values. However, the temporal correlation (R∼0.40) was moderate on a daily scale. CHASER underestimated the HCHO levels at all sites, and the peak occurrences in the observed and simulated HCHO seasonality differed. The coarseness of the model's resolution could potentially lead to such discrepancies. Sensitivity studies showed that anthropogenic emissions were the highest contributor (up to ∼ 35 %) to the wintertime regional HCHO levels.
... 89 HCHO has adverse health effects at higher concentration from direct exposure, and due to its catalytic effects in the formation of atmospheric sulphate, which is a key component of particulate matter (PM). 90,91 HCOOH is an organic acid present in the atmosphere, which has an impact on the precipitation chemistry and acidity of the rain water. [92][93][94] It is also a greenhouse gas which affects the radiative balance of the atmosphere by the direct absorption of the solar radiation or by the scattering of radiation by generated secondary organic aerosol (SOA). ...
Article
The reactions of the simplest Criegee intermediate (CH2OO) with n-butyraldehyde (nBD) and isobutyraldehyde (iBD) were studied at 253–318 K and (50 ± 2) torr, using Cavity Ring-down spectroscopy (CRDS). The rate coefficients obtained at room temperature were (2.63 ± 0.14) × 10−12 and (2.20 ± 0.21) × 10−12 cm3 molecule−1 s−1 for nBD and iBD, respectively. Both the reactions show negative temperature-dependency, following equations, knBD(T = 253–318 K) = (11.51 ± 4.33) × 10−14 × exp{(918.1 ± 107.2)/T} and kiBD(T = 253–318 K) = (6.23 ± 2.29) × 10−14 × exp{(1051.4 ± 105.2)/T} cm3 molecule−1 s−1. High-pressure limit rate coefficients were determined from theoretical calculations at the CCSD(T)-F12/cc-pVTZ-F12//B3LYP/6-311+G(2df, 2p) level of theory, with <40% deviation from the experimental results at room temperature and above. The kinetic simulations were performed using a master equation solver to predict the temperature-dependency of the rate coefficients at the experimental pressure, as well as to predict the contribution of individual pathways. The major products predicted from the theoretical calculations were formaldehyde and formic acid, along with butyric acid from nBD and isobutyric acid from iBD reactions.
... As per the IHME evalutions, it was linked to 365,000 premature deaths worldwide due to chronic obstructive pulmonary disease (COPD) in 2016 alone and has been increasing from 2014 onwards (Izadi, 2018). The formation of ozone near the surface is driven by a number of complex reactions of precursors with transport on all scales (Travis et al., 2016;Joshi et al., 2023;Kuttippurath et al., 2022). As each city has its unique pollution sources and challenges, tailored interventions are devised globally to address local air pollution issues effectively (Han et al., 2022;Chen et al., 2021;Liu et al., 2022). ...
... HCHO is considered a proxy for VOCs, as it is produced directly by the oxidation of VOCs (Gopikrishnan & Kuttippurath, 2021). Kuttippurath et al. (2022) investigated the sources and long-term trends in HCHO using different satellite measurements and reported positive trends of 0.3-0.5×10 15 molec cm − 2 yr − 1 in India during the period 2005-2020. ...
Article
There is a significant increase in ozone at the surface and troposphere due to growing population, industrialization and urbanization. The initiation of National Clean Air Programme (NCAP) in 2019 marked a turning point in addressing air pollution in Indian cities. The Central Pollution Control Board (CPCB) ground-based measurements show a reduction in number of days with continuous exposure to 8 h surface ozone (MDA-8) exceeding 100 ppb since the implementation of NCAP. For instance, cities such as Visakhapatnam and Tirupati reported zero days of MDA-8 ozone surpassing 100 ppb in 2022. Also, a substantial reduction is observed in the frequency of MDA-8 ozone exceeding the 100 ppb threshold at other stations. The NO2 and PM2.5 measurements from CPCB show a decreasing trend at most stations, whereas satellite-based HCHO and NO2 measurements show negative (0–0.004 mol m−2 month−1) and positive (0–0.02 m−2 month−1) trends, respectively, during the period of 2019–2022. Therefore, although the implementation of NCAP is oriented towards reducing PM10 concentrations, it is also proven to be effective in curbing ozone pollution in most cities of India. This study, therefore, suggests to continue the efforts of NCAP and to implement tailored regulations for reducing ozone pollution in cities with high pollution.
... Kuttippurath et al believed that HCHO was of great harm to human body. They used remote sensing satellite to measure HCHO column concentration in India and found that in the lockdown period of COVID-19, the increase of HCHO concentration in atmosphere was related to pyrogen and biological sources besides anthropogenic sources [5]. Bai et al estimated the emission fluxes of isoprene and BVOCs in subtropical plantation based on HCHO data measured by satellites and the quantitative relationship between BVOCs-HCHO [6]. ...
Article
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In recent years, with the acceleration of industrialization and the expansion of urban scale, air pollution including formaldehyde (HCHO) becomes more and more serious. In order to study HCHO pollution in the Yangtze River Economic Belt (YEB), the temporal and spatial evolution of atmospheric HCHO and its influencing factors were analyzed by using the Ozone Monitoring Instrument (OMI) during 2012-2021. The results showed that the concentration of YEB HCHO column was unevenly distributed, with high values concentrated in Anhui, Jiangsu, Yunnan and Hubei provinces. During the past 10 years, the concentration of YEB HCHO column varied between 10.28 and 17.19×1015molec/cm2, and the lowest concentration of HCHO column was 13.16×1015molec/cm2 in 2015. However, it reached the peak value in 2018 (14.93×1015molec/cm2). In natural sources, normalized vegetation index (NDVI) and leaf area index (LAI) had greater influence on YEB HCHO, and the correlation was -0.91~0.97 and -0.9~0.95, respectively. The positive correlation area between HCHO and Mean annual temperature (MAT) reached 93%. The contribution of high-intensity human activity areas to HCHO cannot be underestimated. Industrial and civil sources have great influence on HCHO. In addition, the potential source of HCHO in Shanghai is affected by local emission sources, trans-regional potential sources, northwest air mass and ocean airflow.