scholarly journals Observation of slant column NO<sub>2</sub> using the super-zoom mode of AURA-OMI

2011 ◽  
Vol 4 (9) ◽  
pp. 1929-1935 ◽  
Author(s):  
L. C. Valin ◽  
A. R. Russell ◽  
E. J. Bucsela ◽  
J. P. Veefkind ◽  
R. C. Cohen
Keyword(s):  
United Arab Emirates ◽  
Random Noise ◽  
Point Sources ◽  
Optical Absorption Spectroscopy ◽  
Ozone Monitoring Instrument ◽  
Spatial Response ◽  
Individual Detector ◽  
Instrumental Precision ◽  
Good Agreement ◽  
Ground Calibration

Abstract. We retrieve slant column NO2 from the super-zoom mode of the Ozone Monitoring Instrument (OMI) to explore its utility for understanding NOx emissions and variability. Slant column NO2 is operationally retrieved from OMI (Boersma et al., 2007; Bucsela et al., 2006) with a nadir footprint of 13 × 24 km2, the result of averaging eight detector elements on board the instrument. For 85 orbits in late 2004, OMI reported observations from individual "super-zoom" detector elements (spaced at 13 × 3 km2 at nadir). We assess the spatial response of these individual detector elements in-flight and determine an upper-bound on spatial resolution of 9 km, in good agreement with on-ground calibration (7 km FWHM). We determine the precision of the super-zoom mode to be 2.1 × 1015 molecules cm−2, approximately a factor of √8 lower than an identical retrieval at operational scale as expected if random noise dominates the uncertainty. We retrieve slant column NO2 over the Satpura power plant in India; Seoul, South Korea; Dubai, United Arab Emirates; and a set of large point sources on the Rihand Reservoir in India using differential optical absorption spectroscopy (DOAS). Over these sources, the super-zoom mode of OMI observes variation in slant column NO2 of up to 30 × the instrumental precision within one operational footprint.

scholarly journals Observation of slant column NO<sub>2</sub> using the super-zoom mode of AURA-OMI

2011 ◽  
Vol 4 (2) ◽  
pp. 1989-2005 ◽  
Author(s):  
L. C. Valin ◽  
A. R. Russell ◽  
E. J. Bucsela ◽  
J. P. Veefkind ◽  
R. C. Cohen
Keyword(s):  
United Arab Emirates ◽  
Spatial Resolution ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
Optical Absorption Spectroscopy ◽  
Ozone Monitoring Instrument ◽  
Spatial Response ◽  
Close Proximity ◽  
Individual Detector ◽  
Good Agreement

Abstract. We retrieve slant column NO2 from the super-zoom mode of the Ozone Monitoring Instrument (OMI) to explore its utility for understanding NOx emissions and removal. Slant column NO2 is operationally retrieved from OMI at 13 × 24 km2, a nadir footprint resulting from the on-board average of eight detector elements. For 85 orbits in late 2004, OMI reported observations from individual "super-zoom" detector elements (spaced at 13 × 3 km2 at nadir). We assess the spatial response of these individual detector elements in-flight and determine an upper-bound on spatial resolution of 9 km, in good agreement with on-ground calibration (7 km FWHM). We retrieve slant column NO2 from these super-zoom observations over Sarni, India (19 November), Seoul, South Korea (21 November), Dubai, United Arab Emirates (21 November) and the Rihand Reservoir in India (23 November) using differential optical absorption spectroscopy. Comparison of super-zoom and operational-scale retrievals highlights the capacity of the super-zoom mode to distinguish NOx sources in close proximity. The 1-σ signal to noise ratio (SNR) for these retrievals is as high as 25 and is greater than 5 over the observed enhancements indicating that instrumental noise is not the limitation to obtaining high spatial resolution NO2 maps. We show that these high resolution observations provide constraints on NO2 gradients providing a direct measure of the NOx lifetime in the near field of large plumes.

scholarly journals Seasonal variation of tropospheric bromine monoxide over the Rann of Kutch salt marsh seen from space

2016 ◽  
Vol 16 (20) ◽  
pp. 13015-13034 ◽  
Author(s):  
Christoph Hörmann ◽  
Holger Sihler ◽  
Steffen Beirle ◽  
Marloes Penning de Vries ◽  
Ulrich Platt ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Monsoon Season ◽  
Point Sources ◽  
Optical Absorption Spectroscopy ◽  
Polar Regions ◽  
Ambient Conditions ◽  
Ozone Monitoring Instrument ◽  
Vertical Column ◽  
Monitoring Instrument ◽  
Ozone Monitoring

Abstract. The Rann of Kutch (India and Pakistan) is one of the largest salt deserts in the world. Being a so-called "seasonal salt marsh", it is regularly flooded during the Indian summer monsoon. We present 10 years of bromine monoxide (BrO) satellite observations by the Ozone Monitoring Instrument (OMI) over the Great and Little Rann of Kutch. OMI spectra were analysed using Differential Optical Absorption Spectroscopy (DOAS) and revealed recurring high BrO vertical column densities (VCDs) of up to 1.4  ×  1014 molec cm−2 during April/May, but no significantly enhanced column densities during the monsoon season (June–September). In the following winter months, the BrO VCDs are again slightly enhanced while the salty surface dries up. We investigate a possible correlation of enhanced reactive bromine concentrations with different meteorological parameters and find a strong relationship between incident UV radiation and the total BrO abundance. In contrast, the second Global Ozone Monitoring Instrument (GOME-2) shows about 4 times lower BrO VCDs over the Rann of Kutch than found by OMI and no clear seasonal cycle is observed. One reason for this finding might be the earlier local overpass time of GOME-2 compared to OMI (around 09:30 vs. 13:30 LT), as the ambient conditions significantly differ for both satellite instruments at the time of the measurements. Further possible reasons are discussed and mainly attributed to instrumental issues. OMI additionally confirms the presence of enhanced BrO concentrations over the Dead Sea valley (Israel/Jordan), as suggested by former ground-based observations. The measurements indicate that the Rann of Kutch salt marsh is probably one of the strongest natural point sources of reactive bromine compounds outside the polar regions and is therefore supposed to have a significant impact on local and regional ozone chemistry.

scholarly journals Discrete-wavelength DOAS NO<sub>2</sub> slant column retrievals from OMI and TROPOMI

2019 ◽  
Author(s):  
Cristina Ruiz Villena ◽  
Jasdeep S. Anand ◽  
Roland J. Leigh ◽  
Paul S. Monks ◽  
Claire E. Parfitt ◽  
...  
Keyword(s):  
Spatial Information ◽  
Optical Filters ◽  
Point Sources ◽  
Optical Absorption Spectroscopy ◽  
Emission Point ◽  
The World ◽  
Simple Implementation ◽  
Level 2 ◽  
Selection Of ◽  
Good Agreement

Abstract. The use of satellite NO2 data for air quality studies is increasingly revealing the need for observations with higher spatial and temporal resolution. The study of the NO2 diurnal cycle, global sub-urban scale observations, and identification of emission point sources are some examples of important applications not possible at the resolution provided by current instruments. One way to achieve increased spatial resolution is to reduce the spectral information needed for the retrieval, allowing both dimensions of conventional 2-D detectors to be used to record spatial information. In this work we investigate the use of ten discrete wavelengths with the well-established Differential Optical Absorption Spectroscopy (DOAS) technique for NO2 slant column density (SCD) retrievals. To test the concept we use a selection of individual OMI and TROPOMI Level 1B swaths from various regions around the world which contain a mixture of clean and heavily polluted areas. To discretise the data we simulate a set of Gaussian optical filters centred at various key wavelengths of the NO2 absorption cross section. We perform SCD retrievals of the discrete data using a simple implementation of the DOAS algorithm and compare the results with the corresponding Level 2 SCD products, namely QA4ECV for OMI and the operational TROPOMI product. For OMI the overall results from our discrete-wavelength retrieval are in very good agreement with the Level 2 data (mean difference

scholarly journals Primary Evaluation of the GCOM-C Aerosol Products at 380 nm Using Ground-Based Sky Radiometer Observations

2020 ◽  
Vol 12 (16) ◽  
pp. 2661
Author(s):  
Hossain Mohammed Syedul Hoque ◽  
Hitoshi Irie ◽  
Alessandro Damiani ◽  
Masahiro Momoi
Keyword(s):  
Dry Season ◽  
Diurnal Variations ◽  
Mean Bias Error ◽  
Optical Absorption Spectroscopy ◽  
Bias Error ◽  
Ozone Monitoring Instrument ◽  
Rural Sites ◽  
Primary Evaluation ◽  
Absorbing Aerosols ◽  
Good Agreement

The Global Change Observation Mission-Climate (GCOM-C) is currently the only satellite sensor providing aerosol optical thickness (AOT) in the ultraviolet (UV) region during the morning overpass time. The observations in the UV region are important to detect the presence of absorbing aerosols in the atmosphere. The recently available GCOM-C dataset of AOT at 380 nm for January to September 2019 were evaluated using ground-based SKYNET sky radiometer measurements at Chiba, Japan (35.62° N, 140.10° E) and Phimai, central Thailand (15.18° N, 102.56° E), representing urban and rural sites, respectively. AOT retrieved from sky radiometer observations in Chiba and Phimai was compared with coincident AERONET and multi-axis differential optical absorption spectroscopy (MAX-DOAS) AOT values, respectively. Under clear sky conditions, the datasets showed good agreement. The sky radiometer and GCOM-C AOT values showed a positive correlation (R) of ~0.73 for both sites, and agreement between the datasets was mostly within ±0.2 (the number of coincident points at both sites was less than 50 for the coincidence criterion of ≤30 km). At Chiba, greater differences in the AOT values were primarily related to cloud screening in the datasets. The mean bias error (MBE) (GCOM-C – sky radiometer) for the Chiba site was −0.02 for a coincidence criterion of ≤10 km. For a similar coincidence criterion, the MBE values were higher for observations at the Phimai site. This difference was potentially related to the strong influence of biomass burning during the dry season (Jan–Apr). The diurnal variations in AOT, inferred from the combination of GCOM-C and ozone monitoring instrument (OMI) observations, showed good agreement with the sky radiometer data, despite the differences in the absolute AOT values. Over Phimai, the AOT diurnal variations from the satellite and sky radiometer observations were different, likely due to the large differences in the AOT values during the dry season.

scholarly journals Seasonal variation of tropospheric bromine monoxide over the Rann of Kutch salt marsh seen from space

2016 ◽  
Author(s):  
C. Hörmann ◽  
H. Sihler ◽  
S. Beirle ◽  
M. J. M. Penning de Vries ◽  
U. Platt ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Monsoon Season ◽  
Strong Relationship ◽  
Point Sources ◽  
Optical Absorption Spectroscopy ◽  
Polar Regions ◽  
Ambient Conditions ◽  
Ozone Monitoring Instrument ◽  
Monitoring Instrument ◽  
Ozone Monitoring

Abstract. The Rann of Kutch (India/Pakistan) is one of the largest salt deserts in the world. Being a so-called 'seasonal salt marsh', it is regularly flooded during the Indian Summer Monsoon. We present 10 years of bromine monoxide (BrO) satellite observations by the Ozone Monitoring Instrument (OMI) over the Great and Little Rann of Kutch. OMI spectra were analysed using Differential Optical Absorption Spectroscopy (DOAS) and revealed recurring high BrO VCDs up to 1.4 × 1014 molec/cm2 during April/May, but no significantly enhanced column densities during the monsoon season (June–September). In the following winter months, the BrO VCDs are again slightly enhanced while the salty surface dries up. We investigate a possible correlation of enhanced reactive bromine concentrations with different meteorological parameters and find a strong relationship between incident UV radiation and the total BrO abundance. In contrast, the second Global Ozone Monitoring Instrument (GOME-2) shows about four times lower BrO VCDs over the Rann of Kutch than found by OMI and no clear seasonal cycle is observed. One reason for this finding might be the earlier local overpass time of GOME-2 compared to OMI (around 9:30 vs. 13:30 LT), as the ambient conditions significantly differ for both satellite instruments at the time of the measurements. Further possible reasons are discussed and mainly attributed to instrumental issues. OMI additionally confirms the presence of enhanced BrO concentrations over the Dead Sea valley (Israel/Jordan), as suggested by former ground-based observations. The measurements indicate that the Rann of Kutch salt marsh is probably one of the strongest natural point sources of reactive bromine compounds outside the polar regions and is therefore supposed to have an significant impact on local and regional ozone chemistry.

scholarly journals Tropospheric NO<sub>2</sub> column densities deduced from zenith-sky DOAS measurements in Shanghai, China, and their application to satellite validation

2009 ◽  
Vol 9 (11) ◽  
pp. 3641-3662 ◽  
Author(s):  
D. Chen ◽  
B. Zhou ◽  
S. Beirle ◽  
L. M. Chen ◽  
T. Wagner
Keyword(s):  
Satellite Data ◽  
Urban Site ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Error Sources ◽  
Satellite Validation ◽  
Tropospheric No2 ◽  
Realistic Information ◽  
Good Agreement

Abstract. Zenith-sky scattered sunlight observations using differential optical absorption spectroscopy (DOAS) technique were carried out in Shanghai, China (31.3° N, 121.5° E) since December 2006. At this polluted urban site, the measurements provided NO2 total columns in the daytime. Here, we present a new method to extract time series of tropospheric vertical column densities (VCDs) of NO2 from these observations. The derived tropospheric NO2 VCDs are important quantities for the estimation of emissions and for the validation of satellite observations. Our method makes use of assumptions on the relative NO2 height profiles and the diurnal variation of stratospheric NO2 VCDs. The main error sources arise from the uncertainties in the estimated stratospheric slant column densities (SCDs) and the determination of tropospheric NO2 air mass factor (AMF). For a polluted site like Shanghai, the accuracy of our method is conservatively estimated to be <25% for solar zenith angle (SZA) lower than 70°. From simultaneously performed long-path DOAS measurements, the NO2 surface concentrations at the same site were observed and the corresponding tropospheric NO2 VCDs were estimated using the assumed seasonal NO2 profiles in the planetary boundary layer (PBL). By making a comparison between the tropospheric NO2 VCDs from zenith-sky and long-path DOAS measurements, it is found that the former provides more realistic information about total tropospheric pollution than the latter, so it's more suitable for satellite data validation. A comparison between the tropospheric NO2 VCDs from ground-based zenith-sky measurements and SCIAMACHY was also made. Satellite validation for a strongly polluted area is highly needed, but exhibits also a great challenge. Our comparison shows good agreement, considering in particular the different spatial resolutions between the two measurements. Remaining systematic deviations are most probably related to the uncertainties of satellite data caused by the assumptions on aerosol properties as well as the layer heights of aerosols and NO2.

scholarly journals MAX-DOAS observations of the total atmospheric water vapour column and comparison with independent observations

2013 ◽  
Vol 6 (1) ◽  
pp. 131-149 ◽  
Author(s):  
T. Wagner ◽  
M. O. Andreae ◽  
S. Beirle ◽  
S. Dörner ◽  
K. Mies ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Water Vapour ◽  
Satellite Observations ◽  
Shielding Effect ◽  
Optical Absorption Spectroscopy ◽  
Atmospheric Water ◽  
Near Surface ◽  
Atmospheric Water Vapour ◽  
Independent Observations ◽  
Good Agreement

Abstract. We developed an algorithm for the retrieval of the atmospheric water vapour column from Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations in the yellow and red spectral range. The retrieval is based on the so-called geometric approximation and does not depend on explicit a priori information for individual observations, extensive radiative transfer simulations, or the construction of large look-up tables. Disturbances of the radiative transfer due to aerosols and clouds are simply corrected using the simultaneously measured absorptions of the oxygen dimer, O4. We applied our algorithm to MAX-DOAS observations made at the Max Planck Institute for Chemistry in Mainz, Germany, from March to August 2011, and compared the results to independent observations. Good agreement with Aerosol Robotic Network (AERONET) and European Centre for Medium-Range Weather Forecasting (ECMWF) H2O vertical column densities (VCDs) is found, while the agreement with satellite observations is less good, most probably caused by the shielding effect of clouds for the satellite observations. Good agreement is also found with near-surface in situ observations, and it was possible to derive average daily H2O scale heights (between 1.5 km and 3 km). MAX-DOAS measurements use cheap and simple instrumentation and can be run automatically. One important advantage of our algorithm is that the H2O VCD can be retrieved even under cloudy conditions (except clouds with very high optical thickness).

scholarly journals Description of a formaldehyde retrieval algorithm for the Geostationary Environment Monitoring Spectrometer (GEMS)

2019 ◽  
Vol 12 (7) ◽  
pp. 3551-3571 ◽  
Author(s):  
Hyeong-Ahn Kwon ◽  
Rokjin J. Park ◽  
Gonzalo González Abad ◽  
Kelly Chance ◽  
Thomas P. Kurosu ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Cross Sections ◽  
Correlation Coefficients ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Environment Monitoring ◽  
Ozone Monitoring Instrument ◽  
Nonlinear Fitting ◽  
Regression Slopes

Abstract. We describe a formaldehyde (HCHO) retrieval algorithm for the Geostationary Environment Monitoring Spectrometer (GEMS) that will be launched by the Korean Ministry of Environment in 2019. The algorithm comprises three steps: preprocesses, radiance fitting, and postprocesses. The preprocesses include a wavelength calibration, as well as interpolation and convolution of absorption cross sections; radiance fitting is conducted using a nonlinear fitting method referred to as basic optical absorption spectroscopy (BOAS); and postprocesses include air mass factor calculations and bias corrections. In this study, several sensitivity tests are conducted to examine the retrieval uncertainties using the GEMS HCHO algorithm. We evaluate the algorithm with the Ozone Monitoring Instrument (OMI) Level 1B irradiance/radiance data by comparing our retrieved HCHO column densities with OMI HCHO products of the Smithsonian Astrophysical Observatory (OMHCHO) and of the Quality Assurance for Essential Climate Variables project (OMI QA4ECV). Results show that OMI HCHO slant columns retrieved using the GEMS algorithm are in good agreement with OMHCHO, with correlation coefficients of 0.77–0.91 and regression slopes of 0.94–1.04 for March, June, September, and December 2005. Spatial distributions of HCHO slant columns from the GEMS algorithm are consistent with the OMI QA4ECV products, but relatively poorer correlation coefficients of 0.52–0.76 are found compared to those against the OMHCHO products. Also, we compare the satellite results with ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations. OMI GEMS HCHO vertical columns are 9 %–25 % lower than those of MAX-DOAS at Haute-Provence Observatory (OHP) in France, Bremen in Germany, and Xianghe in China. We find that the OMI GEMS retrievals have less bias than the OMHCHO and OMI QA4ECV products at OHP and Bremen in comparison with MAX-DOAS.

scholarly journals A wide field-of-view imaging DOAS instrument for two-dimensional trace gas mapping from aircraft

2015 ◽  
Vol 8 (12) ◽  
pp. 5113-5131 ◽  
Author(s):  
A. Schönhardt ◽  
P. Altube ◽  
K. Gerilowski ◽  
S. Krautwurst ◽  
J. Hartmann ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Point Sources ◽  
West Germany ◽  
Field Of View ◽  
Trace Gas ◽  
Optical Absorption Spectroscopy ◽  
Small Scale ◽  
Wide Field ◽  
Flight Altitude ◽  
Good Imaging

Abstract. The Airborne imaging differential optical absorption spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP) has been developed for the purpose of trace gas measurements and pollution mapping. The instrument has been characterized and successfully operated from aircraft. Nitrogen dioxide (NO2) columns were retrieved from the AirMAP observations. A major benefit of the push-broom imaging instrument is the spatially continuous, gap-free measurement sequence independent of flight altitude, a valuable characteristic for mapping purposes. This is made possible by the use of a charge coupled device (CCD) frame-transfer detector. A broad field of view across track of around 48° is achieved with wide-angle entrance optics. This leads to a swath width of about the same size as the flight altitude. The use of fibre coupled light intake optics with sorted light fibres allows flexible instrument positioning within the aircraft and retains the very good imaging capabilities. The measurements yield ground spatial resolutions below 100 m depending on flight altitude. The number of viewing directions is chosen from a maximum of 35 individual viewing directions (lines of sight, LOS) represented by 35 individual fibres. The selection is adapted to each situation by averaging according to signal-to-noise or spatial resolution requirements. Observations at 30 m spatial resolution are obtained when flying at 1000 m altitude and making use of all 35 viewing directions. This makes the instrument a suitable tool for mapping trace gas point sources and small-scale variability. The position and aircraft attitude are taken into account for accurate spatial mapping using the Attitude and Heading Reference System of the aircraft. A first demonstration mission using AirMAP was undertaken in June 2011. AirMAP was operated on the AWI Polar-5 aircraft in the framework of the AIRMETH-2011 campaign. During a flight above a medium-sized coal-fired power plant in north-west Germany, AirMAP clearly detected the emission plume downwind from the exhaust stack, with NO2 vertical columns around 2 × 1016 molecules cm−2 in the plume centre. NOx emissions estimated from the AirMAP observations are consistent with reports in the European Pollutant Release and Transfer Register. Strong spatial gradients and variability in NO2 amounts across and along flight direction are observed, and small-scale enhancements of NO2 above a motorway are detected.

scholarly journals Anthropogenic and volcanic point source SO<sub>2</sub> emissions derived from TROPOMI onboard Sentinel 5 Precursor: first results

2020 ◽  
Author(s):  
Vitali Fioletov ◽  
Chris A. McLinden ◽  
Debora Griffin ◽  
Nicolas Theys ◽  
Diego G. Loyola ◽  
...  
Keyword(s):  
Absolute Magnitude ◽  
Point Sources ◽  
Ozone Monitoring Instrument ◽  
So2 Emissions ◽  
Large Area ◽  
Vertical Column ◽  
Very High Spatial Resolution ◽  
First Results ◽  
Vertical Column Density ◽  
Very High

Abstract. The paper introduces the first TROPOMI-based sulfur dioxide (SO2) emissions estimates for point sources. A total of about 500 continuously emitting point sources releasing from about 10 kT y−1 to more than 2000 kT y−1 of SO2 per year, previously identified from Ozone Monitoring Instrument (OMI) observations, were analysed using TROPOMI measurements for one full year, from April 2018 to March 2019. The annual emissions from these sources were estimated and compared to similar estimates from OMI and Ozone Mapping Profiling Suite (OMPS) measurements. Note that emissions from many of these 500 sources declined significantly since 2005 making their quantification more challenging. We were able to identify 278 sources where annual emissions are significant and can be reliably estimated from TROPOMI. The standard deviations of TROPOMI vertical column density data, about 1 Dobson Unit (DU, where 1 DU = 2.69 × 1016 molecules/cm2) over tropics and 1.5 DU over high latitudes, are larger than those of OMI (0.6–1 DU) and OMPS (0.3–0.4 DU). Due to its very high spatial resolution, TROPOMI produces 12–20 times more observations over a certain area than OMI and 96 times more than OMPS. Despite higher uncertainties of individual TROPOMI observations, TROPOMI data averaged over a large area have roughly two-three times lower uncertainties compared to OMI and OMPS data. Similarly, TROPOMI annual emissions can be estimated with uncertainties that are 1.5–2 times lower than the uncertainties of annual emissions estimates from OMI. While there are area biases in TROPOMI data over some regions that have to be removed for emission calculations, the absolute magnitude of these are modest, typically within ±0.25 DU, it can be comparable to SO2 values over large sources.

Sign in / Sign up

Export Citation Format

Share Document