Pinhua Xie

Chinese Academy of Sciences | CAS · Anhui Institute of Optics and Fine Mechanics

The Yangze River Delta (YRD) in China encountered with prolonged ozone pollution in September 2020, which had significant impacts on the respiratory, dermatological, and visual health of local residents. To accurately elucidate the limitations of oxidation processes in the chemical-complex atmosphere, a full suite of radical measurements (OH, HO2,...

Significant amounts of nitrous acid (HONO) released from soil affect the tropospheric atmosphere, as a major precursor of hydroxyl radical. However, the scarcity of soil–atmosphere HONO exchange flux has constrained the comprehension of emission processes and reactive nitrogen budget. Herein, we performed measurements of HONO and NOx fluxes over pa...

This study explores a gas measurement method based on Fabry-Perot (F-P) angle-dependent correlated spectroscopy, which achieves highly sensitive and selective gas measurements by adjusting the angle to match the F-P interference peak with the gas absorption peak. Methane (CH4) is the chosen target gas, and an F-P etalon is designed with parameters...

Passive differential optical absorption spectroscopy (DOAS) is widely used to monitor the three-dimensional distribution of atmospheric pollutants. However, the observational and retrieval accuracy of this technique is significantly influenced by the precise wavelength calibration of solar spectra. Current calibration methods face challenges in aut...

Comprehensive observations of hydroxyl (OH) and hydroperoxy (HO2) radicals were conducted in October 2019 at a coastal continental site in the Pearl River Delta (YMK site, 22.55∘ N, 114.60∘ E). The daily maximum OH and HO2 concentrations were (4.7–9.5) × 106 and (4.2–8.1) × 108 cm-3, respectively. The synchronized air mass transport from the northe...

In the Multi-Axis Differential Absorption Spectroscopy (MAX-DOAS) trace gas and aerosol profile inversion algorithm, the vertical resolution and the observation information obtained through a series of continuous observations with multiple elevation angles (EAs) can affect the accuracy of an aerosol profile, thus further affecting the results of th...

Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO2) retrieved from sun-synchronous satellite instruments have provided abundant NO2 data for environmental studies, but such data are limited by retrieval uncertainties and insufficient temporal sampling (e.g., once a day). The Geostationary Environment Monitoring Spectrometer (GEM...

Air pollutants represent an environmental and health risk, and the methods for their effective assessment are of the greatest importance. The MAX-DOAS method is a reliable retrieval algorithm, enabling a vertical gas profile analysis. However, the current MAX-DOAS retrieval algorithm heavily relies on the a priori profile, limiting its accuracy. To...

Comprehensive observations of hydroxyl (OH) and hydroperoxy (HO2) radicals were conducted in October 2019 at a coastal continental site in the Pearl River Delta (YMK site, 22.55° N, 114.60° E). The average daily maximum OH and HO2 concentrations were (4.7–9.5) × 106 cm−3 and (4.2–8.1) × 108 cm−3, respectively. The synchronized air mass transport fr...

Formaldehyde (HCHO) is a tracer of volatile organic compounds (VOCs), and its concentration has gradually decreased with the reduction in VOC emissions in recent years, which puts forward higher requirements for the detection of trace HCHO. Therefore, a quantum cascade laser (QCL) with a central excitation wavelength of 5.68 μm was applied to detec...

Nitrogen dioxide (NO2) is a major air pollutant. Tropospheric NO2 vertical column densities (VCDs) retrieved from sun-synchronous satellite instruments have provided abundant NO2 data for environmental studies, but such data are limited by insufficient temporal sampling (e.g., once a day). The Geostationary Environment Monitoring Spectrometer (GEMS...

This paper investigates a method for measuring SO2 concentration using Fabry–Perot interferometer correlation spectroscopy. In this method, the experimental system is designed as a separated beam, with the beam entering the F–P cavity at two incidence angles simultaneously to match the peak and valley positions of the SO2 absorption cross-section....

NO3, NO2, O3, and relevant parameters were measured at a rural site on the North China Plain during June 2014. During the campaign, the average concentrations of NO3 and N2O5 were 4.8 ± 3.3 pptv and 30.5 ± 35.4 pptv, respectively. The average NO3 production rate was 1.03 ± 0.48 ppbvh−1, and the steady-state lifetimes of NO3 and N2O5 were 26 s and 1...

To explore the impact of open straw burning on air quality in the Yangtze River Delta (YRD) and surrounding areas, three key cities in the YRD, namely Hefei, Nanjing, and Shanghai, were selected to observe changes in aerosol characteristics. Based on Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations from May to June 20...

Dinitrogen pentoxide (N2O5) plays an important role in nighttime chemistry. A field campaign was conducted to measure N2O5 by cavity ring-down spectroscopy method from November 13 to December 3, 2016, in an urban site in Beijing. During the campaign, there were only 4 days that N2O5 concentrations were above the detection limit due to high NO emiss...

Atmospheric oxidation is a driving force of complex air pollution, and accurate hydroxyl radical (OH) measurement is helpful in investigating the radical-cored photooxidation mechanism in the troposphere. A self-developed laser-induced fluorescence instrument by the Anhui Institute of Optics Fine Mechanics, Chinese Academy of Sciences (AIOFM-LIF),...

Nach herkömmlicher Auffassung sind Feinstaubpartikel in der Atmosphäre eine wichtige Senke für OH‐Radikale. Im Gegensatz dazu zeigen Xiao Cheng Zeng, Joseph S. Francisco, Hong He et al. in ihrer Zuschrift (DOI: 10.1002/ange.202201638), dass Wasser und O2 auf der Oberfläche von kohlenstoffhaltigem Ruß reagieren und bei Bestrahlung gasförmige OH‐Radi...

A conventional view is that particulate matter (PM) in the atmosphere is a major sink of OH radicals. By contrary, Xiao Cheng Zeng, Joseph S. Francisco, Hong He et al. demonstrate in their Communication (DOI: 10.1002/anie.202201638) that water and O2 react on carbonaceous soot surface and give rise to gaseous OH radicals under irradiation. This new...

OH radicals in the air maintain the oxidizing power of the troposphere. A conventional view is that particulate matter (PM) in the atmosphere is a major sink of OH radicals, thereby lowering the oxidizing power of atmosphere in the event of high‐level PM. By contrary, our joint experimental/theoretical study reveals a new mechanism for the generati...

OH radicals in the air maintain the oxidizing power of the troposphere. A conventional view is that particulate matter (PM) in the atmosphere is a major sink of OH radicals, thereby lowering the oxidizing power of atmosphere in the event of high‐level PM. By contrary, our joint experimental/theoretical study reveals a new mechanism for the generati...

Abrupt air pollution accidents can endanger people's health and destroy the local ecological environment. The appropriate emergency response can minimize the harmful effects of accidents and protect people's lives and property. This paper provides an overview of the key emergency response technologies for abrupt air pollution accidents around the g...

Comprehensive observations of the nocturnal atmospheric oxidation of NO3 and N2O5 were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy (CRDS) from 27 May to 24 June, 2019. High concentrations of NO3 precursors were observed, and the nocturnal production rate of NO3 was determined to be 1.7 ± 1.2 ppbv/hr. How...

To investigate nitrous acid (HONO) levels and potential HONO sources above crop rotation fields. The HONO fluxes were measured by the aerodynamic gradient (AG) method from 14 December 2019 to 2 January 2020 over an agricultural field in the Huaihe River Basin. The ambient HONO levels were measured at two different heights (0.15 and 1.5 m), showing...

The research on the mechanism of combined air pollution in the Yangtze–Huaihe region, which is characterized by unique meteorological and geographical conditions and pollution emission characteristics, is still insufficient. We performed an experiment on key pollutants and an ozone formation study in Hefei, which is a pivotal city in the Yangtze–Hu...

Accurate monitoring of the atmospheric environment and its evolution are important for understanding the sources, chemical mechanisms, and transport processes of air pollution and carbon emissions in China, and for regulatory and control purposes. This study gives an overview of atmospheric environment monitoring technology and equipment in China a...

Because nitrous acid (HONO) photolysis is a key source of hydroxyl (OH) radicals, identifying the atmospheric sources of HONO is essential to enhance the understanding of atmospheric chemistry processes and improve the accuracy of simulation models. We performed seasonal field observations of HONO in a coastal city of southeastern China, along with...

Haze and dust pollution have a significant impact on human production, life, and health. In order to understand the pollution process, the study of these two pollution characteristics is important. In this study, a one-year observation was carried out at the Beijing Southern Suburb Observatory using the MAX-DOAS instrument, and the pollution charac...

A continuous wintertime observation of ambient OH and HO2 radicals was first carried out in Shanghai, in 2019. This effort coincided with the second China International Import Expo (CIIE), during which strict emission controls were implemented in Shanghai, resulting in an average PM2.5 concentration of less than 35 μg/m³. The self-developed instrum...

Multi‐AXis Differential Optical Absorption Spectroscopy (MAX‐DOAS) observations were carried out from March 1, 2019 to February 29, 2020 in Qingdao, China, on the coast of the Yellow Sea (120.67°E, 36.35°N). Atmospheric parameters retrieved from the MAX‐DOAS instrument included vertical profiles of aerosol extinction, gaseous aerosol precursors (NO...

Because nitrous acid (HONO) photolysis is a key source of hydroxyl (OH) radicals, identifying the atmospheric sources of HONO is essential to enhance the understanding of atmospheric chemistry processes and improve the accuracy of simulation models. We performed seasonal field observations of HONO in a coastal city of southeastern China, along with...

Atmospheric aerosols have effects on atmospheric radiation assessments, global climate change, local air quality and visibility. In particular, aerosols are more likely transformed and accumulated in winter. In this paper, we used the Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument to study the characteristics of aeros...

Ground-based Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) is a state-of-the-art remote sensing technique for deriving vertical profiles of trace gases and aerosols. However, MAX-DOAS profile inversions under aerosol pollution scenarios are challenging because of the complex radiative transfer and limited information content of...

NO3 radicals can clean the atmospheric primary contaminants during the night. However, it can also effect the formation of secondary organic aerosol (SOA) and nitrate, which may worsen air quality. We report field observations of NO3 radicals with a home-made long path differential optical absorption spectroscopy (LP-DOAS) at a rural site in the po...

The smog chamber experimental systems, which have been widely used in laboratory simulation for studying atmospheric processes, are comprehensively reviewed in this paper. The components, development history, main research topics, and main achievements of smog chambers are introduced. The typical smog chambers in the world, including their volumes,...

Water vapor transport affects regional precipitation and climate change. The measurement of precipitable water (PW) and water vapor flux (WVF) is of great importance for the study of precipitation and water vapor transport. This study presented a new method of computing PW and estimating WVF using the water vapor vertical column density (VCD) and p...

Although the government of Nanjing implemented the more stringent atmospheric control measures during the second half of 2019, compared with the same period in 2018, the air pollution has increased unexpectedly, such as the O3 pollution and the acid rain. In this study, therefore, we performed observations of the vertical structures of the precurso...

This paper studied the method for converting the aerosol extinction to the mass concentration of particulate matter (PM) and obtained the spatio-temporal distribution and transportation of aerosol, nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) based on multi-axis differential optical absorption spectroscopy (MAX-DOAS) observ...

Ground-based Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) is a state of the art remote sensing technique for deriving vertical profiles of trace gases and aerosols. However, MAX-DOAS profile inversions under aerosol pollution scenarios are challenging because of the complex radiative transfer and limited information content of...

This study reports on the first continuous measurements of ambient OH and HO2 radicals at a suburban site in Chengdu, Southwest China, which were collected during 2019 as part of a comprehensive field campaign ‘CompreHensive field experiment to explOre the photochemical Ozone formation mechaniSm in summEr - 2019 (CHOOSE-2019)’. The mean concentrati...

The second Cabauw Intercomparison of Nitrogen Dioxide measuring Instruments (CINDI-2) took place in Cabauw (the Netherlands) in September 2016 with the aim of assessing the consistency of multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of tropospheric species (NO2, HCHO, O3, HONO, CHOCHO and O4). This was achieved th...

An instrument to detect atmospheric HO2 radicals using fluorescence assay by gas expansion (FAGE) technique has been developed. HO2 is measured by reaction with NO to form OH and subsequent detection of OH by laser-induced fluorescence at low pressure. The system performance has been improved by optimizing the expansion distance and pressure, the i...

We present an improved incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) system based on an iterative retrieval algorithm for the simultaneous detection of atmospheric nitrous acid (HONO) and nitrogen dioxide (NO2). The conventional IBBCEAS retrieval algorithm depends on the absolute change in the light intensity, which require...

Mobile differential optical absorption spectroscopy (mobile DOAS) has become an important tool for the quantification of emission sources, including point sources (e.g., individual power plants) and area emitters (e.g., entire cities). In this study, we focused on the error budget of mobile DOAS measurements from point sources, and we also offered...

We present the inter-comparison of delta slant column densities (SCDs) and vertical profiles of nitrous acid (HONO) derived from measurements of different multi-axis differential optical absorption spectroscopy (MAX-DOAS) instruments and using different inversion algorithms during the Second Cabauw Inter-comparison campaign for Nitrogen Dioxide mea...

We present the inter-comparison of delta slant column densities (SCDs) and vertical profiles of nitrous acid (HONO) derived from measurements of different multi-axis differential optical absorption spectroscopy (MAX-DOAS) instruments and using different inversion algorithms during the Second Cabauw Inter-comparison campaign for Nitrogen Dioxide mea...

Because nitrous acid (HONO) photolysis is a key source of hydroxyl (OH) radicals, identifying the atmospheric sources of HONO is essential to enhance the understanding of atmospheric chemistry processes and improve the accuracy of simulation models. We performed seasonal field observations of HONO in a coastal city of southeastern China, along with...

We present a new product with explicit aerosol corrections, POMINO-TROPOMI, for tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs) over East Asia, based on the newly launched TROPOspheric Monitoring Instrument with an unprecedented high horizontal resolution. Compared to the official TM5-MP-DOMINO (OFFLINE) product, POMINO-TROPOMI...

NOX (NOX = NO + NO2) emissions measurements in Beijing are of great significance because they can aid in understanding how NOX pollution develops in mega-cities throughout China. However, NOX emissions in mega-cities are difficult to measure due to changes in wind patterns and moving sources on roads during measurement. To obtain good spatial cover...

We present an improved incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) system based on iterative retrieval algorithm for simultaneous detection of atmospheric nitrous acid (HONO) and nitrogen dioxide (NO2). The conventional IBBCEAS retrieval algorithm depends on the absolute change of light intensity, which requires high stab...

An automated dynamic chamber system was first developed to simultaneously measure the HONO flux and NOx flux. The new dynamic chamber system was applied to field observation, and the HONO and NOX exchange flux of farmland in the Huaihe River Basin was obtained for the first time. The performance of the dynamic chamber system was verified in the fie...

The nitrate radical (NO3) and dinitrogen pentoxide (N2O5) play an important role in the nocturnal atmosphere chemistry. Observations of NO3 radicals and N2O5 were performed in a semirural ground site at Tai'Zhou in polluted southern China using cavity ring down spectroscopy (CRDS) from 23 May to 15 June 2018. The observed NO3 and N2O5 concentration...