scholarly journals RETRIEVAL OF AEROSOL MICROPHYSICAL PROPERTIES BASED ON THE OPTIMAL ESTIMATION METHOD: INFORMATION CONTENT ANALYSIS FOR SATELLITE POLARIMETRIC REMOTE SENSING MEASUREMENTS

2018 ◽  
Vol XLII-3 ◽  
pp. 533-537 ◽  
Author(s):  
W. Z. Hou ◽  
Z. Q. Li ◽  
F. X. Zheng ◽  
L. L. Qie
Keyword(s):  
Content Analysis ◽  
Information Content ◽  
Estimation Method ◽  
Soil Surface ◽  
Optimal Estimation ◽  
Bare Soil ◽  
Transfer Model ◽  
Surface Reflectance ◽  
Microphysical Properties ◽  
Single Viewing

This paper evaluates the information content for the retrieval of key aerosol microphysical and surface properties for multispectral single-viewing satellite polarimetric measurements cantered at 410, 443, 555, 670, 865, 1610 and 2250 nm over bright land. To conduct the information content analysis, the synthetic data are simulated by the Unified Linearized Vector Radiative Transfer Model (UNLVTM) with the intensity and polarization together over bare soil surface for various scenarios. Following the optimal estimation theory, a principal component analysis method is employed to reconstruct the multispectral surface reflectance from 410 nm to 2250 nm, and then integrated with a linear one-parametric BPDF model to represent the contribution of polarized surface reflectance, thus further to decouple the surface-atmosphere contribution from the TOA measurements. Focusing on two different aerosol models with the aerosol optical depth equal to 0.8 at 550 nm, the total DFS and DFS component of each retrieval aerosol and surface parameter are analysed. The DFS results show that the key aerosol microphysical properties, such as the fine- and coarse-mode columnar volume concentration, the effective radius and the real part of complex refractive index at 550 nm, could be well retrieved with the surface parameters simultaneously over bare soil surface type. The findings of this study can provide the guidance to the inversion algorithm development over bright surface land by taking full use of the single-viewing satellite polarimetric measurements.

scholarly journals All-sky Information Content Analysis for Novel Passive Microwave Instruments in the Range from 23.8 GHz up to 874.4 GHz

2017 ◽  
Author(s):  
Verena Grützun ◽  
Stefan A. Buehler ◽  
Lukas Kluft ◽  
Jana Mendrok ◽  
Manfred Brath ◽  
...  
Keyword(s):  
Content Analysis ◽  
Information Content ◽  
Atmospheric Composition ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Submillimeter Wavelength ◽  
Great Ability ◽  
Microphysical Properties ◽  
Spatial Coverage ◽  
Cloud Ice

Abstract. We perform an all-sky information content analysis for channels in the millimeter/submillimeter wavelength with 24 channels in the region from 23.8 up to 874.4 GHz. Our set of channels corresponds to the instruments ISMAR and MARSS, which are available on the British FAAM research aircraft, and it is complemented by two precipitation channels at low frequencies from Deimos. The channels also cover ICI, which will be part of the MetOp-SG mission. We use simulated atmospheres from the ICON model as basis for the study and quantify the information content with the reduction of degrees of freedom (ΔDOF). The required Jacobians are calculated with the radiative transfer model ARTS. Specifically we focus on the dependence of the information content on the atmospheric composition. In general we find a high information content for the frozen hydrometeors, which mainly comes from the higher channels beyond 183.31 GHz (on average 4.99 for cloud ice and 4.84 for snow). Profile retrievals may be possible for the mass densities and some information about the microphysical properties, especially for cloud ice, can be gained. The information about the liquid hydrometeors comes from the lower channels and is comparably low (2.36 for liquid cloud water and 1.81 for rain). There is little information about the profile or the microphysical properties. The Jacobians for a specific cloud hydrometeor strongly depend on the atmospheric composition. Especially for the liquid hydrometeors they even change sign in some cases. However, the information content is robust. For liquid hydrometeors it slightly decreases in the presence of any frozen hydrometeor, for the frozen hydrometeors it slightly decreases in the presence of the respective other frozen hydrometeor. The overall results with regard to the frozen hydrometeors in principle also hold for the ICI sensor. This points to its great ability to observe ice clouds from space on a global scale with a good spatial coverage in unprecedented detail.

scholarly journals Industrial Plume Properties Retrieved by Optimal Estimation Using Combined Hyperspectral and Sentinel-2 Data

2021 ◽  
Vol 13 (10) ◽  
pp. 1865
Author(s):  
Gabriel Calassou ◽  
Pierre-Yves Foucher ◽  
Jean-François Léon
Keyword(s):  
Matched Filter ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Model Parameters ◽  
Surface Reflectance ◽  
Sequential Method ◽  
Modal Radius ◽  
Sentinel 2

Stack emissions from the industrial sector are a subject of concern for air quality. However, the characterization of the stack emission plume properties from in situ observations remains a challenging task. This paper focuses on the characterization of the aerosol properties of a steel plant stack plume through the use of hyperspectral (HS) airborne remote sensing imagery. We propose a new method, based on the combination of HS airborne acquisition and surface reflectance imagery derived from the Sentinel-2 Multi-Spectral Instrument (MSI). The proposed method detects the plume footprint and estimates the surface reflectance under the plume, the aerosol optical thickness (AOT), and the modal radius of the plume. Hyperspectral surface reflectances are estimated using the coupled non-negative matrix factorization (CNMF) method combining HS and MSI data. The CNMF reduces the error associated with estimating the surface reflectance below the plume, particularly for heterogeneous classes. The AOT and modal radius are retrieved using an optimal estimation method (OEM), based on the forward model and allowing for uncertainties in the observations and in the model parameters. The a priori state vector is provided by a sequential method using the root mean square error (RMSE) metric, which outperforms the previously used cluster tuned matched filter (CTMF). The OEM degrees of freedom are then analysed, in order to refine the mask plume and to enhance the quality of the retrieval. The retrieved mean radii of aerosol particles in the plume is 0.125 μμm, with an uncertainty of 0.05 μμm. These results are close to the ultra-fine mode (modal radius around 0.1 μμm) observed from in situ measurements within metallurgical plant plumes from previous studies. The retrieved AOT values vary between 0.07 (near the source point) and 0.01, with uncertainties of 0.005 for the darkest surfaces and above 0.010 for the brightest surfaces.

scholarly journals Inter-comparison of MAX-DOAS measurements of tropospheric HONO slant column densities and vertical profiles during the CINDI-2 Campaign

2020 ◽  
Author(s):  
Yang Wang ◽  
Arnoud Apituley ◽  
Alkiviadis Bais ◽  
Steffen Beirle ◽  
Nuria Benavent ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Early Morning ◽  
Radiative Transfer Model ◽  
Measuring Instruments ◽  
Transfer Model ◽  
Vertical Profiles ◽  
Near Surface ◽  
Profile Inversion

Abstract. We present the inter-comparison of delta slant column densities (SCDs) and vertical profiles of nitrous acid (HONO) derived from measurements of different MAX-DOAS instruments and using different inversion algorithms during the Second Cabauw Inter-comparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2), in September 2016, at Cabauw, The Netherlands (51.97° N, 4.93° E). Systematic discrepancies of HONO delta SCDs are observed in the range of ±0.3 × 1015 molecules cm−2, which is half of the typical random discrepancy of 0.6 × 1015 molecules cm−2. For a typical high HONO delta SCD of 2 × 1015 molecules cm−2, the relative systematic and random discrepancies are about 15 % and 30 %, respectively. The inter-comparison of HONO profiles shows that both systematic and random discrepancies of HONO VCDs and near-surface volume mixing ratios (VMRs) are mostly in the range of ~ ±0.5 × 1015 molecules cm−2 and ~ ±0.1 ppb (typically ~ 20 %). Further we find that the discrepancies of the retrieved HONO profiles are dominated by discrepancies of the HONO delta SCDs. The profile retrievals only contribute to the discrepancies of the HONO profiles by ~ 5 %. However, some data sets with substantial larger discrepancies than the typical values indicate that inappropriate implementations of profile inversion algorithms and configurations of radiative transfer models in the profile retrievals can also be an important uncertainty source. In addition, estimations of measurement uncertainties of HONO dSCDs, which can significantly impact profile retrievals using the optimal estimation method, need to consider not only DOAS fit errors, but also atmospheric variability, especially for an instrument with a DOAS fit error lower than ~ 3 × 1015 molecules cm−2. The MAX-DOAS results during the CINDI-2 campaign indicate that the peak HONO levels (e.g. near-surface VMRs of ~ 0.4 ppb) often appeared in the early morning and below 0.2 km. The near-surface VMRs retrieved from the MAX-DOAS observations are compared with those measured using a co-located long-path DOAS instrument. The systematic differences are smaller than 0.15 ppb and 0.07 ppb during early morning and around noon, respectively. Since true HONO values at high altitudes are not known in the absence of real measurements, in order to evaluate the abilities of profile inversion algorithms to respond to different HONO profile shapes, we performed sensitivity studies using synthetic HONO delta SCDs simulated by a radiative transfer model with assumed HONO profiles. The tests indicate that the profile inversion algorithms based on the optimal estimation method with proper configurations can well reproduce the different HONO profile shapes. Therefore we conclude that the feature of HONO accumulated near the surface derived from MAX-DOAS measurements are expected to well represent the ambient HONO profiles.

scholarly journals H<sub>2</sub><sup>16</sup>O and HDO measurements with IASI/MetOp

2009 ◽  
Vol 9 (2) ◽  
pp. 9267-9290 ◽  
Author(s):  
H. Herbin ◽  
D. Hurtmans ◽  
C. Clerbaux ◽  
L. Clarisse ◽  
P.-F. Coheur
Keyword(s):  
Water Vapour ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Temporal Variations ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Inversion Procedure ◽  
Spatio Temporal ◽  
The Vertical Distribution

Abstract. In this paper we analyze distributions of water vapour isotopologues in the troposphere using infrared spectra recorded by the Infrared Atmospheric Sounding Interferometer (IASI), which operates onboard the Metop satellite in nadir geometry. The simultaneous uncorrelated retrieval of H216O and HDO was performed on radiance measurements using a line-by-line radiative transfer model and an inversion procedure based on the Optimal Estimation Method (OEM). The characterizations of the retrieved products in terms of vertical sensitivity and error budgets show that IASI measurements contain up to 6 independent pieces of information on the vertical distribution of H216O and up to 3.5 for HDO from the surface up to the upper troposphere (0–20 km). The H216O retrieved profiles are in good agreement with local sonde measurements at different latitudes during different times of the year. Our results demonstrate the ability of the IASI instrument to monitor atmospheric isotopologic water vapour distributions with unprecedented sensitivity. As a case study, we analyse concentration distributions and spatio-temporal variations of H216O and HDO during the October 2007 Krosa super-typhoon over South-East Asia and show with this example the IASI potential to capture variations in the HDO/H216O isotopologic ratio values over space and time.

scholarly journals Vertical profile of tropospheric ozone derived from synergetic retrieval using three different wavelength ranges, UV, IR, and microwave: sensitivity study for satellite observation

2018 ◽  
Vol 11 (3) ◽  
pp. 1653-1668 ◽  
Author(s):  
Tomohiro O. Sato ◽  
Takao M. Sato ◽  
Hideo Sagawa ◽  
Katsuyuki Noguchi ◽  
Naoko Saitoh ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Tropospheric Ozone ◽  
Vertical Profile ◽  
Reduction Rate ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Sensitivity Study ◽  
Maximum Sensitivity ◽  
Radiative Transfer Model ◽  
Transfer Model

Abstract. We performed a feasibility study of constraining the vertical profile of the tropospheric ozone by using a synergetic retrieval method on multiple spectra, i.e., ultraviolet (UV), thermal infrared (TIR), and microwave (MW) ranges, measured from space. This work provides, for the first time, a quantitative evaluation of the retrieval sensitivity of the tropospheric ozone by adding the MW measurement to the UV and TIR measurements. Two observation points in East Asia (one in an urban area and one in an ocean area) and two observation times (one during summer and one during winter) were assumed. Geometry of line of sight was nadir down-looking for the UV and TIR measurements, and limb sounding for the MW measurement. The retrieval sensitivities of the ozone profiles in the upper troposphere (UT), middle troposphere (MT), and lowermost troposphere (LMT) were estimated using the degree of freedom for signal (DFS), the pressure of maximum sensitivity, reduction rate of error from the a priori error, and the averaging kernel matrix, derived based on the optimal estimation method. The measurement noise levels were assumed to be the same as those for currently available instruments. The weighting functions for the UV, TIR, and MW ranges were calculated using the SCIATRAN radiative transfer model, the Line-By-Line Radiative Transfer Model (LBLRTM), and the Advanced Model for Atmospheric Terahertz Radiation Analysis and Simulation (AMATERASU), respectively. The DFS value was increased by approximately 96, 23, and 30 % by adding the MW measurements to the combination of UV and TIR measurements in the UT, MT, and LMT regions, respectively. The MW measurement increased the DFS value of the LMT ozone; nevertheless, the MW measurement alone has no sensitivity to the LMT ozone. The pressure of maximum sensitivity value for the LMT ozone was also increased by adding the MW measurement. These findings indicate that better information on LMT ozone can be obtained by adding constraints on the UT and MT ozone from the MW measurement. The results of this study are applicable to the upcoming air-quality monitoring missions, APOLLO, GMAP-Asia, and uvSCOPE.

scholarly journals All-sky information content analysis for novel passive microwave instruments in the range from 23.8 to 874.4 GHz

2018 ◽  
Vol 11 (7) ◽  
pp. 4217-4237 ◽  
Author(s):  
Verena Grützun ◽  
Stefan A. Buehler ◽  
Lukas Kluft ◽  
Jana Mendrok ◽  
Manfred Brath ◽  
...  
Keyword(s):  
Content Analysis ◽  
Information Content ◽  
Degrees Of Freedom ◽  
Atmospheric Composition ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Low Frequencies ◽  
Great Ability ◽  
Spatial Coverage ◽  
Cloud Ice

Abstract. We perform an all-sky information content analysis for channels in the millimetre and sub-millimetre wavelength with 24 channels in the region from 23.8 to 874.4 GHz. The employed set of channels corresponds to the instruments ISMAR and MARSS, which are available on the British FAAM research aircraft, and it is complemented by two precipitation channels at low frequencies from Deimos. The channels also cover ICI, which will be part of the MetOp-SG mission. We use simulated atmospheres from the ICON model as basis for the study and quantify the information content with the reduction of degrees of freedom (ΔDOF). The required Jacobians are calculated with the radiative transfer model ARTS. Specifically we focus on the dependence of the information content on the atmospheric composition. In general we find a high information content for the frozen hydrometeors, which mainly comes from the higher frequency channels beyond 183.31 GHz (on average 3.10 for cloud ice and 2.57 for snow). Considerable information about the microphysical properties, especially for cloud ice, can be gained. The information content about the liquid hydrometeors comes from the lower frequency channels. It is 1.69 for liquid cloud water and 1.08 for rain using the full set of channels. The Jacobians for a specific cloud hydrometeor strongly depend on the atmospheric composition. Especially for the liquid hydrometeors the Jacobians even change sign in some cases. However, the information content is robust across different atmospheric compositions. For liquid hydrometeors the information content decreases in the presence of any frozen hydrometeor, for the frozen hydrometeors it decreases slightly in the presence of the respective other frozen hydrometeor. Due to the lack of channels below 183 GHz liquid hydrometeors are hardly seen by ICI. However, the overall results with regard to the frozen hydrometeors also hold for the ICI sensor. This points to ICI's great ability to observe ice clouds from space on a global scale with a good spatial coverage in unprecedented detail.

scholarly journals Global distributions of water vapour isotopologues retrieved from IMG/ADEOS data

2007 ◽  
Vol 7 (14) ◽  
pp. 3957-3968 ◽  
Author(s):  
H. Herbin ◽  
D. Hurtmans ◽  
S. Turquety ◽  
C. Wespes ◽  
B. Barret ◽  
...  
Keyword(s):  
Water Vapour ◽  
Experimental Studies ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Temporal Variations ◽  
Global Scale ◽  
Radiative Transfer Model ◽  
Small Scale ◽  
Transfer Model ◽  
Water Isotopologues

Abstract. The isotopologic composition of water vapour in the atmosphere provides valuable information on many climate, chemical and dynamical processes. The accurate measurements of the water isotopologues by remote-sensing techniques remains a challenge, due to the large spatial and temporal variations. Simultaneous profile retrievals of the main water isotopologues (i.e. H216O, H218O and HDO) and their ratios are presented here for the first time, along their retrieved global distributions. The results are obtained by exploiting the high resolution infrared spectra recorded by the Interferometric Monitor for Greenhouse gases (IMG) instrument, which has operated in the nadir geometry onboard the ADEOS satellite between 1996 and 1997. The retrievals are performed on cloud-free radiances, measured during ten days of April 1997, considering two atmospheric windows (1205–1228 cm−1; 2004–2032 cm−1) and using a line-by-line radiative transfer model and an inversion procedure based on the Optimal Estimation Method (OEM). Characterizations in terms of vertical sensitivity and error budget are provided. We show that a relatively high vertical resolution is achieved for H216O (~4–5 km), and that the retrieved profiles are in fair agreement with local sonde measurements, at different latitudes. The retrieved global distributions of H216O, H218O, HDO and their ratios are presented and found to be consistent with previous experimental studies and models. The Ocean-Continent difference, the latitudinal and vertical dependence of the water vapour amount and the isotopologic depletion are notably well reproduced. Others trends, possibly related to small-scale variations in the vertical profiles are also discussed. Despite the difficulties encountered for computing accurately the isotopologic ratios, our results demonstrate the ability of infrared nadir sounding for monitoring atmospheric isotopologic water vapour distributions on a global scale.

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