scholarly journals The Spectral Nature of Earth’s Reflected Radiation: Measurement and Science Applications

2021 ◽  
Vol 2 ◽  
Author(s):  
Graeme Stephens ◽  
Olga Kalashnikova ◽  
Jake J. Gristey ◽  
Peter Pilewskie ◽  
David R. Thompson ◽  
...  
Keyword(s):  
Cloud Droplet ◽  
Radiation Measurement ◽  
Spectral Measurements ◽  
Research Topics ◽  
Radiative Fluxes ◽  
Radiative Process ◽  
Vertical Profiling ◽  
Shallow Clouds ◽  
Shortwave Infrared ◽  
Total Column

This paper introduces the aerosol, clouds, convection and precipitation (ACCP) program that is currently in the process of defining a number of measurement objectives for NASA that are to be implemented toward the end of the current decade. Since a (solar) visible-shortwave infrared (VSWIR) spectrometer is being considered as part of the ACCP architecture, illustrations of the different ways these measurements will contribute to this program and how these measurements can be expected to advance the science objectives of ACCP are highlighted. These contributions range from 1) constraining cloud radiative process and related estimates of radiative fluxes, 2) scene discrimination, 3) providing aerosol and cloud optical properties, and 4) providing other enhanced information such as the phase of water in clouds, and total column water vapor. The spectral measurements also offer new capabilities that will further enhance the ACCP science such as the discrimination of dust aerosol and the potential for the vertical profiling cloud droplet size in shallow clouds. The areas where the maturity of approaches is lacking is also highlighted as a way of emphasizing research topics to be a focus in the coming years.

scholarly journals Distinct aerosol effects on cloud-to-ground lightning in the plateau and basin regions of Sichuan, Southwest China

2020 ◽  
Vol 20 (21) ◽  
pp. 13379-13397
Author(s):  
Pengguo Zhao ◽  
Zhanqing Li ◽  
Hui Xiao ◽  
Fang Wu ◽  
Youtong Zheng ◽  
...  
Keyword(s):  
Cloud Droplet ◽  
Lightning Activity ◽  
Freezing Process ◽  
Plateau Region ◽  
Freezing Level ◽  
Aerosol Loading ◽  
Cloud To Ground Lightning ◽  
Basin Region ◽  
Total Column ◽  
Cg Lightning

Abstract. The joint effects of aerosol, thermodynamic, and cloud-related factors on cloud-to-ground lightning in Sichuan were investigated by a comprehensive analysis of ground-based measurements made from 2005 to 2017 in combination with reanalysis data. Data include aerosol optical depth, cloud-to-ground (CG) lightning density, convective available potential energy (CAPE), mid-level relative humidity, lower- to mid-tropospheric vertical wind shear, cloud-base height, total column liquid water (TCLW), and total column ice water (TCIW). Results show that CG lightning density and aerosols are positively correlated in the plateau region and negatively correlated in the basin region. Sulfate aerosols are found to be more strongly associated with lightning than total aerosols, so this study focuses on the role of sulfate aerosols in lightning activity. In the plateau region, the lower aerosol concentration stimulates lightning activity through microphysical effects. Increasing the aerosol loading decreases the cloud droplet size, reducing the cloud droplet collision–coalescence efficiency and inhibiting the warm-rain process. More small cloud droplets are transported above the freezing level to participate in the freezing process, forming more ice particles and releasing more latent heat during the freezing process. Thus, an increase in the aerosol loading increases CAPE, TCLW, and TCIW, stimulating CG lightning in the plateau region. In the basin region, by contrast, the higher concentration of aerosols inhibits lightning activity through the radiative effect. An increase in the aerosol loading reduces the amount of solar radiation reaching the ground, thereby lowering the CAPE. The intensity of convection decreases, resulting in less supercooled water being transported to the freezing level and fewer ice particles forming, thereby increasing the total liquid water content. Thus, an increase in the aerosol loading suppresses the intensity of convective activity and CG lightning in the basin region.

scholarly journals Carbon monoxide total column retrievals from TROPOMI shortwave infrared measurements

2016 ◽  
Vol 9 (10) ◽  
pp. 4955-4975 ◽  
Author(s):  
Jochen Landgraf ◽  
Joost aan de Brugh ◽  
Remco Scheepmaker ◽  
Tobias Borsdorff ◽  
Haili Hu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Carbon Monoxide ◽  
Transport Model ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Atmospheric Scattering ◽  
Clear Sky ◽  
Infrared Measurements ◽  
Shortwave Infrared ◽  
Total Column

Abstract. The Tropospheric Monitoring Instrument (TROPOMI) spectrometer is the single payload of the Copernicus Sentinel 5 Precursor (S5P) mission. It measures Earth radiance spectra in the shortwave infrared spectral range around 2.3 µm with a dedicated instrument module. These measurements provide carbon monoxide (CO) total column densities over land, which for clear sky conditions are highly sensitive to the tropospheric boundary layer. For cloudy atmospheres over land and ocean, the column sensitivity changes according to the light path through the atmosphere. In this study, we present the physics-based operational S5P algorithm to infer atmospheric CO columns satisfying the envisaged accuracy ( <  15 %) and precision ( <  10 %) both for clear sky and cloudy observations with low cloud height. Here, methane absorption in the 2.3 µm range is combined with methane abundances from a global chemical transport model to infer information on atmospheric scattering. For efficient processing, we deploy a linearized two-stream radiative transfer model as forward model and a profile scaling approach to adjust the CO abundance in the inversion. Based on generic measurement ensembles, including clear sky and cloudy observations, we estimated the CO retrieval precision to be  ≤  11 % for surface albedo  ≥  0.03 and solar zenith angle  ≤  70°. CO biases of  ≤  3 % are introduced by inaccuracies in the methane a priori knowledge. For strongly enhanced CO concentrations in the tropospheric boundary layer and for cloudy conditions, CO errors in the order of 8 % can be introduced by the retrieval of cloud parameters of our algorithm. Moreover, we estimated the effect of a distorted spectral instrument response due to the inhomogeneous illumination of the instrument entrance slit in the flight direction to be  <  2 % with pseudo-random characteristics when averaging over space and time. Finally, the CO data exploitation is demonstrated for a TROPOMI orbit of simulated shortwave infrared measurements. Overall, the study demonstrates that for an instrument that performs in compliance with the pre-flight specifications, the CO product will meet the required product performance well.

scholarly journals FIELD SPECTROSCOPY FOR VEGETATION EVALUATION ALONG THE NUTRIENT AND ELEVATION GRADIENT ABOVE THE TREE LINE IN THE KRKONOŠE MOUNTAINS NATIONAL PARK

2016 ◽  
Vol XLI-B6 ◽  
pp. 211-214
Author(s):  
L. Červená ◽  
L. Kupková ◽  
R. Suchá
Keyword(s):  
Plant Cover ◽  
Elevation Gradient ◽  
Vegetation Indices ◽  
Infrared Region ◽  
Spectral Measurements ◽  
Vegetation Height ◽  
Vegetation Water Content ◽  
Red Edge ◽  
Vegetation Water ◽  
Shortwave Infrared

This paper examines the relations between vegetation spectra measured in the field along the nutrient and elevation gradient in the most valuable parts of The Krkonoše Mountains tundra and selected parameters describing vegetation state and condition (fAPAR, plant cover and average vegetation height). The main goal was to find relations and indices based on spectral measurements that could be used for vegetation evaluation and classification in practice and management. The vegetation parameters and spectral properties were also compared for two datasets – one acquired in July and second in August 2015. The best correlations were obtained for plant cover (R<sup>2</sup> above 0.8 for July dataset and above 0.7 for August dataset) and two types of indices – using the wavelengths of red edge, e.g. OSAVI or mND705, and indices for vegetation water content estimates using the wavelengths in shortwave infrared region of the spectra in combination with wavelengths above 800 nm, e. g. NDII. The worst results were found for fAPAR with maximal values of R<sup>2</sup> just above 0.4 with the indices using the wavelengths around 700 nm. For vegetation height the results differ between July and August data – R<sup>2</sup> around 0.62 in July and only 0.47 in August for vegetation indices using the wavelengths of visible and red edge regions.

An 11 year record of GOSAT XCO2 measurements from NASA's ACOS version 9 retrieval algorithms: comparisons to models, TCCON, and OCO-2

2021 ◽  
Author(s):  
Thomas Taylor ◽  
Christopher O'Dell ◽  
Annmarie Eldering ◽  
David Crisp ◽  
Michael Gunson ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Total Carbon ◽  
High Spectral Resolution ◽  
Absorption Bands ◽  
Software Suite ◽  
Aggregated Data ◽  
Observation Network ◽  
Shortwave Infrared ◽  
Total Column

&lt;p&gt;The GOSAT TANSO-FTS sensor has been collecting high spectral resolution measurements of reflected solar radiation in the Oxygen A-band (0.76 microns) and two shortwave-infrared carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) absorption bands (1.6 and 2.0 microns) since April, 2009. The measured radiances allow for estimates of the total column carbon dioxide (XCO&lt;sub&gt;2&lt;/sub&gt;) via retrieval inversion. An eleven year long record of XCO&lt;sub&gt;2&amp;#160;&lt;/sub&gt;retrieved via NASA&amp;#8217;s Atmospheric Carbon Observations from Space (ACOS) build 9 software suite is analyzed and discussed. The v9 XCO&lt;sub&gt;2&amp;#160;&lt;/sub&gt;data has been publicly available on the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) since the spring of 2020.&lt;/p&gt;&lt;p&gt;The ACOS GOSAT v9 XCO&lt;sub&gt;2 &amp;#160;&lt;/sub&gt;is evaluated against CO&lt;sub&gt;2&amp;#160;&lt;/sub&gt;flux inversion models, observations from the Total Carbon Column Observation Network (TCCON), as well as against collocated measurements from NASA&amp;#8217;s OCO-2 satellite. The results indicate a product that agrees with OCO-2 and models within approximately 0.25 ppm with less than 1 ppm standard deviation (&amp;#963;). Agreement with TCCON is within approximately 0.1 ppm with approximately 1 ppm &amp;#963; for daily overpass mean aggregated data. The ACOS GOSAT v9 XCO&lt;sub&gt;2&amp;#160;&lt;/sub&gt;product will allow CO&lt;sub&gt;2&amp;#160;&lt;/sub&gt;flux inversion modelers and terrestrial ecologists to address questions about long term (decadal) carbon cycle dynamics related to net and gross carbon fluxes.&lt;/p&gt;

scholarly journals A new WRF-Chem treatment for studying regional-scale impacts of cloud processes on aerosol and trace gases in parameterized cumuli

2015 ◽  
Vol 8 (2) ◽  
pp. 409-429 ◽  
Author(s):  
L. K. Berg ◽  
M. Shrivastava ◽  
R. C. Easter ◽  
J. D. Fast ◽  
E. G. Chapman ◽  
...  
Keyword(s):  
Deep Convection ◽  
Trace Gases ◽  
Regional Scale ◽  
Cloud Droplet ◽  
Convective Cloud ◽  
Cumulus Parameterization ◽  
Sulfate Production ◽  
Shallow Clouds ◽  
The Impact ◽  
Wet Removal

Abstract. A new treatment of cloud effects on aerosol and trace gases within parameterized shallow and deep convection, and aerosol effects on cloud droplet number, has been implemented in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) version 3.2.1 that can be used to better understand the aerosol life cycle over regional to synoptic scales. The modifications to the model include treatment of the cloud droplet number mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convective cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. These changes have been implemented in both the WRF-Chem chemistry packages as well as the Kain–Fritsch (KF) cumulus parameterization that has been modified to better represent shallow convective clouds. Testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS). The simulation results are used to investigate the impact of cloud–aerosol interactions on regional-scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column-integrated BC can be as large as −50% when cloud–aerosol interactions are considered (due largely to wet removal), or as large as +40% for sulfate under non-precipitating conditions due to sulfate production in the parameterized clouds. The modifications to WRF-Chem are found to account for changes in the cloud droplet number concentration (CDNC) and changes in the chemical composition of cloud droplet residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to the latest version of WRF-Chem, and it is anticipated that they will be included in a future public release of WRF-Chem.

scholarly journals Distinct aerosol effects on cloud-to-ground lightning in the plateau and basin regions of Sichuan, Southwest China

2020 ◽  
Author(s):  
Pengguo Zhao ◽  
Zhanqing Li ◽  
Hui Xiao ◽  
Fang Wu ◽  
Youtong Zheng ◽  
...  
Keyword(s):  
Cloud Droplet ◽  
Lightning Activity ◽  
Freezing Process ◽  
Plateau Region ◽  
Freezing Level ◽  
Aerosol Loading ◽  
Cloud To Ground Lightning ◽  
Basin Region ◽  
Total Column ◽  
Cg Lightning

Abstract. The joint effects of aerosol, thermodynamic, and cloud-related factors on cloud-to-ground lightning in Sichuan were investigated by a comprehensive analysis of ground measurements made from 2005 to 2017 in combination with reanalysis data. Data include aerosol optical depth, cloud-to-ground (CG) lightning density, convective available potential energy (CAPE), mid-level relative humidity, lower- to mid-tropospheric vertical wind shear, cloud-base height, total column liquid water (TCLW), and total column ice water (TCIW). Results show that CG lightning density and aerosols are positively correlated in the plateau region and negatively correlated in the basin region. Sulfate aerosols are found to be more strongly associated with lightning than total aerosols, so this study focuses on the role of sulfate aerosols in lightning activity. In the plateau region, the lower aerosol concentration stimulates lightning activity through microphysical effects. Increasing the aerosol loading reduces the cloud droplet size, reducing the cloud droplet collision-coalescence efficiency and inhibiting the warm-rain process. More small cloud droplets are transported above the freezing level to participate in the freezing process, forming more ice particles and releasing more latent heat during the freezing process. Thus, an increase in aerosol loading increases CAPE, TCLW, and TCIW, stimulating CG lightning in the plateau region. In the basin region, by contrast, the higher concentration of aerosols inhibits lightning activity through the radiative effect. An increase in aerosol loading reduces the amount of solar radiation reaching the ground, thereby lowering CAPE. The intensity of convection decreases, resulting in less supercooled water transported to the freezing level and fewer ice particles forming, thus increasing the total liquid water content. Therefore, an increase in aerosol loading suppresses the intensity of convective activity and CG lightning in the basin region.

scholarly journals Impact of Molecular Spectroscopy on Carbon Monoxide Abundances from TROPOMI

2020 ◽  
Vol 12 (21) ◽  
pp. 3486
Author(s):  
Philipp Hochstaffl ◽  
Franz Schreier ◽  
Manfred Birk ◽  
Georg Wagner ◽  
Dietrich G. Feist ◽  
...  
Keyword(s):  
Molecular Spectroscopy ◽  
Atmospheric Composition ◽  
Spectral Fitting ◽  
Spectroscopic Information ◽  
Retrieval Errors ◽  
The Difference ◽  
Shortwave Infrared ◽  
The Impact ◽  
Total Column

The impact of SEOM–IAS (Scientific Exploitation of Operational Missions–Improved Atmospheric Spectroscopy) spectroscopic information on CO columns from TROPOMI (Tropospheric Monitoring Instrument) shortwave infrared (SWIR) observations was examined. HITRAN 2016 (High Resolution Transmission) and GEISA 2015 (Gestion et Etude des Informations Spectroscopiques Atmosphériques 2015) were used as a reference upon which the spectral fitting residuals, retrieval errors and inferred quantities were assessed. It was found that SEOM–IAS significantly improves the quality of the CO retrieval by reducing the residuals to TROPOMI observations. The magnitude of the impact is dependent on the climatological region and spectroscopic reference used. The difference in the CO columns was found to be rather small, although discrepancies reveal, for selected scenes, in particular, for observations with elevated molecular concentrations. A brief comparison to Total Column Carbon Observing Network (TCCON) and Network for the Detection of Atmospheric Composition Change (NDACC) also demonstrated that both spectroscopies cause similar columns; however, the smaller retrieval errors in the SEOM with Speed-Dependent Rautian and line-Mixing (SDRM) inferred CO turned out to be beneficial in the comparison of post-processed mole fractions with ground-based references.

scholarly journals A new WRF-Chem treatment for studying regional scale impacts of cloud-aerosol interactions in parameterized cumuli

2014 ◽  
Vol 7 (2) ◽  
pp. 2651-2704 ◽  
Author(s):  
L. K. Berg ◽  
M. Shrivastava ◽  
R. C. Easter ◽  
J. D. Fast ◽  
E. G. Chapman ◽  
...  
Keyword(s):  
Deep Convection ◽  
Regional Scale ◽  
Cloud Droplet ◽  
Convective Cloud ◽  
Cumulus Parameterization ◽  
Cloud Drop ◽  
Sulfate Production ◽  
Shallow Clouds ◽  
The Impact ◽  
Wet Removal

Abstract. A new treatment of cloud-aerosol interactions within parameterized shallow and deep convection has been implemented in WRF-Chem that can be used to better understand the aerosol lifecycle over regional to synoptic scales. The modifications to the model to represent cloud-aerosol interactions include treatment of the cloud droplet number mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convective cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. These changes have been implemented in both the WRF-Chem chemistry packages as well as the Kain–Fritsch cumulus parameterization that has been modified to better represent shallow convective clouds. Preliminary testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS) as well as a high-resolution simulation that does not include parameterized convection. The simulation results are used to investigate the impact of cloud-aerosol interactions on regional scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column integrated BC can be as large as −50% when cloud-aerosol interactions are considered (due largely to wet removal), or as large as +40% for sulfate in non-precipitating conditions due to the sulfate production in the parameterized clouds. The modifications to WRF-Chem version 3.2.1 are found to account for changes in the cloud drop number concentration (CDNC) and changes in the chemical composition of cloud-drop residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to WRF-Chem version 3.5, and it is anticipated that they will be included in a future public release of WRF-Chem.

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