scholarly journals High-resolution NO<sub>2</sub> remote sensing from the Airborne Prism EXperiment (APEX) imaging spectrometer

2012 ◽  
Vol 5 (9) ◽  
pp. 2211-2225 ◽  
Author(s):  
C. Popp ◽  
D. Brunner ◽  
A. Damm ◽  
M. Van Roozendael ◽  
C. Fayt ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Air Quality ◽  
Spatial Resolution ◽  
In Situ Measurements ◽  
High Signal ◽  
Waste Incinerator ◽  
Imaging Spectrometer ◽  
Airborne Measurements ◽  
Spectrometer Data

Abstract. We present and evaluate the retrieval of high spatial resolution maps of NO2 vertical column densities (VCD) from the Airborne Prism EXperiment (APEX) imaging spectrometer. APEX is a novel instrument providing airborne measurements of unique spectral and spatial resolution and coverage as well as high signal stability. In this study, we use spectrometer data acquired over Zurich, Switzerland, in the morning and late afternoon during a flight campaign on a cloud-free summer day in June 2010. NO2 VCD are derived with a two-step approach usually applied to satellite NO2 retrievals, i.e. a DOAS analysis followed by air mass factor calculations based on radiative transfer computations. Our analysis demonstrates that APEX is clearly sensitive to NO2 VCD above typical European tropospheric background abundances (>1 × 1015 molec cm−2). The two-dimensional maps of NO2 VCD reveal a very convincing spatial distribution with strong gradients around major NOx sources (e.g. Zurich airport, waste incinerator, motorways) and low NO2 in remote areas. The morning overflights resulted in generally higher NO2 VCD and a more distinct pattern than the afternoon overflights which can be attributed to the meteorological conditions prevailing during that day with stronger winds and hence larger dilution in the afternoon. The remotely sensed NO2 VCD are also in reasonably good agreement with ground-based in-situ measurements from air quality networks considering the limitations of comparing column integrals with point measurements. Airborne NO2 remote sensing using APEX will be valuable to detect NO2 emission sources, to provide input for NO2 emission modelling, and to establish links between in-situ measurements, air quality models, and satellite NO2 products.

scholarly journals High resolution NO<sub>2</sub> remote sensing from the Airborne Prism EXperiment (APEX) imaging spectrometer

2012 ◽  
Vol 5 (2) ◽  
pp. 2449-2486 ◽  
Author(s):  
C. Popp ◽  
D. Brunner ◽  
A. Damm ◽  
M. Van Roozendael ◽  
C. Fayt ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Air Quality ◽  
Spatial Resolution ◽  
In Situ Measurements ◽  
High Signal ◽  
Waste Incinerator ◽  
Imaging Spectrometer ◽  
Airborne Measurements ◽  
Spectrometer Data

Abstract. We present and evaluate the retrieval of high spatial resolution maps of NO2 vertical column densities (VCD) from the Airborne Prism EXperiment (APEX) imaging spectrometer. APEX is a novel instrument providing airborne measurements of unique spectral and spatial resolution and coverage as well as high signal stability. In this study, we use spectrometer data acquired over Zurich, Switzerland, in the morning and late afternoon during a flight campaign on a cloud-free summer day in June 2010. NO2 VCD are derived with a two-step approach usually applied to satellite NO2 retrievals, i.e. a DOAS analysis followed by air mass factor calculations based on radiative transfer computations. Our analysis demonstrates that APEX is clearly sensitive to NO2 VCD above typical European tropospheric background abundances (>1 × 1015 molec cm−2). The two-dimensional maps of NO2 VCD reveal a very plausible spatial distribution with strong gradients around major NOx sources (e.g. Zurich airport, waste incinerator, motorways) and low NO2 in remote areas. The morning overflights resulted in generally higher NO2 VCD and a more distinct pattern than the afternoon overflights which can be attributed to the meteorological conditions prevailing during that day (development of the boundary layer and increased wind speed in the afternoon) as well as to photochemical loss of NO2. The remotely sensed NO2 VCD are also highly correlated with ground-based in-situ measurements from local and national air quality networks (R=0.73). Airborne NO2 remote sensing using APEX will be valuable to detect NO2 emission sources, to provide input for NO2 emission modeling, and to establish links between in-situ measurements, air quality models, and satellite NO2 products.

scholarly journals Application of infrared remote sensing to constrain in-situ estimates of ice crystal particle size during SPartICus

2011 ◽  
Vol 4 (3) ◽  
pp. 3055-3081
Author(s):  
S. J. Cooper ◽  
T. J. Garrett
Keyword(s):  
Remote Sensing ◽  
In Situ Measurements ◽  
Ice Crystals ◽  
Cirrus Cloud ◽  
Atmospheric Conditions ◽  
Airborne Measurements ◽  
Remote Sensing Technique ◽  
Infrared Remote Sensing ◽  
Retrieval Scheme

Abstract. In a prior paper (Cooper and Garrett, 2010), an infrared remote sensing technique was developed that quantifies the effective radius re of ice crystals in cirrus clouds. By accounting for a broad range of expected inversion uncertainties, this retrieval scheme isolates those radiometric signatures that can only occur if the cirrus has nominally "small" values of re below 20 μm. The method is applicable only for specific cloud and atmospheric conditions. However, it can be particularly useful in constraining in-situ estimates of cirrus cloud re obtained from aircraft. Recent studies suggest that airborne measurements may be compromised by the shattering of ice crystals on airborne instrument inlets, so robust, independent confirmation of these measurements is needed. Here, we expand the Cooper and Garrett (2010) retrieval scheme to identify ice clouds that are likely to have "large" values of re greater than 20 μm. Using MODIS observations, we then compare assessments of cirrus cloud re with in-situ measurements obtained during three test cases from the 2010 SpartICus campaign. In general, there is good agreement between retrievals and in-situ measurements for a "small" and "large" crystal case. For a more ambiguously "small" re case, the 2D-S cloud probe indicates values of re that are slightly larger than expected from infrared retrievals, possibly indicating a slight bias in the 2D-S results towards large particles. There is no evidence to support that an FSSP-100 with unmodified inlets produces measurements of re in cirrus that are strongly biased low, as has been claimed.

scholarly journals Using remote sensing to enhance modelling of fine sediment dynamics in the Dutch coastal zone

2013 ◽  
Vol 16 (2) ◽  
pp. 458-476 ◽  
Author(s):  
A. M. Y. Kamel ◽  
G. Y. El Serafy ◽  
B. Bhattacharya ◽  
T. van Kessel ◽  
D. P. Solomatine
Keyword(s):  
Remote Sensing ◽  
Temporal Distribution ◽  
Fine Sediment ◽  
In Situ Measurements ◽  
Sediment Dynamics ◽  
Model Parameters ◽  
Imaging Spectrometer ◽  
Suspended Particulate ◽  
Medium Resolution

Modelling fine sediment dynamics, including transport, deposition and re-suspension, is very complex. This led to studies that validate the modelled suspended particulate matter (SPM) based on in-situ measurements. While in-situ measurements are often sparse in time and space, satellite measurements provide us with higher spatial and temporal resolution. This information can be used to validate and enhance the model's capability of predicting the spatial and temporal distribution of SPM. In this paper, the SPM retrieved from the MEdium Resolution Imaging Spectrometer (MERIS) on board European Space Agency's ENVISAT spacecraft is used to carry out a thorough calibration and validation of the SPM description provided by the Delft3DWAQ model of the Southern North Sea for the year 2007. In an uncertainty analysis framework, the key model parameters affecting the SPM distributions were first identified in predefined physical regions. The sensitivity of the model to slight changes in those parameters is tested and the spatial and temporal errors compared to remote sensing images were identified and a new set of parameters has been suggested and further subjected to uncertainty to define prediction intervals of the SPM distribution at a number of locations. The so-called adapted model has been validated against independent data and has shown a decrease in errors, particularly along the Dutch coast.

scholarly journals Application of infrared remote sensing to constrain in-situ estimates of ice crystal particle size during SPartICus

2011 ◽  
Vol 4 (8) ◽  
pp. 1593-1602 ◽  
Author(s):  
S. J. Cooper ◽  
T. J. Garrett
Keyword(s):  
Remote Sensing ◽  
In Situ Measurements ◽  
Ice Crystals ◽  
Test Cases ◽  
Cirrus Cloud ◽  
Atmospheric Conditions ◽  
Airborne Measurements ◽  
Infrared Remote Sensing ◽  
Retrieval Scheme

Abstract. In a prior paper (Cooper and Garrett, 2010), an infrared remote sensing technique was developed that quantifies the effective radius re of ice crystals in cirrus clouds. By accounting for a broad range of expected inversion uncertainties, this retrieval scheme isolates those radiometric signatures that can only occur if the cirrus has nominally "small" values of re below 20 μm. The method is applicable only for specific cloud and atmospheric conditions. However, it can be particularly useful in constraining in-situ estimates of cirrus cloud re obtained from aircraft. Recent studies suggest that airborne measurements may be compromised by the shattering of ice crystals on airborne instrument inlets, so robust, independent confirmation of these measurements is needed. Here, we expand the Cooper and Garrett (2010) retrieval scheme to identify ice clouds that are likely to have "large" values of re greater than 20 μm. Using MODIS observations, we then compare assessments of cirrus cloud re with in-situ measurements obtained during three test cases from the 2010 SPartICus campaign. In general, there is good agreement between retrievals and in-situ measurements for a "small" and "large" crystal case. For a more ambiguously "small" re case, the 2D-S cloud probe indicates values of re that are slightly larger than expected from infrared retrievals, possibly indicating a slight bias in the 2D-S results towards large particles. For our test cases, there is no evidence to suggest that an FSSP-100 with unmodified inlets produces measurements of re in cirrus that are strongly biased low.

Particulate matter variability in Kathmandu based on in-situ measurements, remote sensing, and reanalysis data

2021 ◽  
pp. 105623
Author(s):  
Stefan Becker ◽  
Ramesh Prasad Sapkota ◽  
Binod Pokharel ◽  
Loknath Adhikari ◽  
Rudra Prasad Pokhrel ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Particulate Matter ◽  
Reanalysis Data ◽  
In Situ Measurements

scholarly journals Aerosol optical and microphysical retrievals from a hybrid multiwavelength lidar data set – DISCOVER-AQ 2011

2014 ◽  
Vol 7 (9) ◽  
pp. 3095-3112 ◽  
Author(s):  
P. Sawamura ◽  
D. Müller ◽  
R. M. Hoff ◽  
C. A. Hostetler ◽  
R. A. Ferrare ◽  
...  
Keyword(s):  
Remote Sensing ◽  
In Situ Measurements ◽  
Index Of Refraction ◽  
High Spectral Resolution ◽  
Lidar Data ◽  
Data Set ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
Multiwavelength Lidar

Abstract. Retrievals of aerosol microphysical properties (effective radius, volume and surface-area concentrations) and aerosol optical properties (complex index of refraction and single-scattering albedo) were obtained from a hybrid multiwavelength lidar data set for the first time. In July 2011, in the Baltimore–Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne (in situ and remote sensing) and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar data set combines ground-based elastic backscatter lidar measurements at 355 nm with airborne High-Spectral-Resolution Lidar (HSRL) measurements at 532 nm and elastic backscatter lidar measurements at 1064 nm that were obtained less than 5 km apart from each other. This was the first study in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in situ measurements for 11 cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor in such discrepancies.

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