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Light-absorbing black carbon (BC) aerosols strongly affect Earth's radiation budget and climate. This paper presents satellite retrieval of BC over India based on observations from the Cloud and Aerosol Imager-2 (CAI-2) on board the Greenhouse gases Observing Satellite-2 (GOSAT-2). To evaluate and validate the satellite retrievals, near-surface BC mass concentrations measured across the Aerosol Radiative Forcing over India NETwork (ARFINET) of aerosol observatories are used. Then the findings are extended to elucidate global BC features. The analysis reveals that this satellite retrieval clearly demonstrates the regional and seasonal features of BC over the Indian region, similarly to those recorded by surface observations. Validation and closure studies between the two datasets show RMSE < 1 and absolute difference below 2 µg m−3 for > 60 % of simultaneous observations, exhibiting good associations for December, January, and February (R of approximately 0.73) and March, April, and May (R approx. 0.76). Over the hotspot regions of India, satellite retrievals show a soot volume fraction of approx. 5 %, columnar single-scattering albedo of approx. 0.8, and BC column optical depth of approx. 0.1 during times of the highest BC loading, which are comparable to other in situ and satellite measurements. In terms of global spatiotemporal variation, satellite retrievals show higher BC occurring mostly in areas where biomass burning is intense. Overall, this study highlights the effectiveness of satellite retrieval of BC, which can be used effectively for the regular monitoring of BC loading attributable to vehicular, industrial, or biomass burning activities.

Global monitoring of isotopic composition of water vapor in the atmosphere provides information regarding atmospheric hydgrological cycle in the Earth’s climate system. The observed HDO to H2O ratio (δD) in atmospheric water vapor gives information on origin and history of air masses in the atmosphere.In this study we present a method, software tool and some results on δD ratio retrieval from spectra, measured simultaneously in the thermal (TIR) and short wave infrared (SWIR) spectral ranges. The TANSO-FTS high spectral resolution spectrometer on board GOSAT-2 satellite is unique to perform simultaneous measurements in TIR and SWIR spectral bands. A method of simultaneous using of these both bands can improve vertical resolution of δD retrieved profile.We applied conventional optimal estimation method to solve inverse problem. The output data of atmospheric general circulation model ECHAM5-wiso were used as a statistical ensemble of HDO and H2O a priori profiles. The averaging kernels, a posteriori covariance matrices and degrees of freedom are calculated. The retrieval algorithm is implemented using original FIRE-ARMS software and VLIDORT radiation transfer model.This study is supported by the Russian Science Foundation grant No. 18-11-00024.

A novel, practical observation system for measuring tropospheric carbon dioxide (CO2) concentrations using a non-dispersive infrared analyzer carried by a small helium-filled balloon (CO2 sonde) has been developed for the first time. Vertical profiles of atmospheric CO2 can be measured with a 240–400 m altitude resolution through regular onboard calibrations using two different CO2 standard gases. The standard deviations (1σ) of the measured mole fractions in the laboratory experiments using a vacuum chamber at a temperature of 298 K were approximately 0.6 ppm at 1010 hPa and 1.2 ppm at 250 hPa. Two CO2 vertical profile data obtained using the CO2 sondes, which were launched on 31 January and 3 February 2011 at Moriya, were compared with the chartered aircraft data on the same days and the commercial aircraft data obtained by the Comprehensive Observation Network for TRace gases by Airliner (COTRAIL) program on the same day (31 January) and 1 d before (2 February). The difference between the CO2 sonde data and these four sets of in situ aircraft data (over the range of each balloon altitude ±100 m) up to the altitude of 7 km was 0.6±1.2 ppm (average ±1σ). In field experiments, the CO2 sonde detected an increase in CO2 concentration in an urban area and a decrease in a forested area near the surface. The CO2 sonde was shown to be a useful instrument for observing and monitoring the vertical profiles of CO2 concentration in the troposphere.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2016-04-27, 資料番号: PA1710018000

A four-dimensional variational method (4D-Var) is a popular technique for source/sink inversions of atmospheric constituents, but it is not without problems. Using an icosahedral grid transport model and the 4D-Var method, a new atmospheric greenhouse gas (GHG) inversion system has been developed. The system combines offline forward and adjoint models with a quasi-Newton optimization scheme. The new approach is then used to conduct identical twin experiments to investigate optimal system settings for an atmospheric CO2 inversion problem, and to demonstrate the validity of the new inversion system. In this paper, the inversion problem is simplified by assuming the prior flux errors to be reasonably well known and by designing the prior error correlations with a simple function as a first step. It is found that a system of forward and adjoint models with smaller model errors but with nonlinearity has comparable optimization performance to that of another system that conserves linearity with an exact adjoint relationship. Furthermore, the effectiveness of the prior error correlations is demonstrated, as the global error is reduced by about 15 % by adding prior error correlations that are simply designed when 65 weekly flask sampling observations at ground-based stations are used. With the optimal setting, the new inversion system successfully reproduces the spatiotemporal variations of the surface fluxes, from regional (such as biomass burning) to global scales. The optimization algorithm introduced in the new system does not require decomposition of a matrix that establishes the correlation among the prior flux errors. This enables us to design the prior error covariance matrix more freely.

Site environments and instrumental characteristics of carbon dioxide (CO2) measurements operated by local governments in the Kanto Plain, the center of which is Tokyo were summarized for this study. The observation sites were classified into environments of three types: urban, suburban, and woodland. Based on a few decades of accumulated hourly data, the diurnal and seasonal variations of CO2 concentrations were analyzed as a composite of anomalies from annual means recorded for each site. In urban areas, the highest concentrations appear before midnight in winter. The second peak corresponds to the morning rush hour and strengthening of the inversion layer. Suburban areas can be characterized as having the highest concentration before dawn and the lowest concentration during the daytime in summer in association with the activation of respiration and photosynthesis of vegetation. In these areas, concentration peaks also appear during the morning rush hour. Woodland areas show background features, with the highest concentration in early spring: higher than the global background by about 5 ppmv.

Column-averaged concentrations of carbon dioxide (XCO_2) and methane (XCH_4) were retrieved from spectra observed by the Greenhouse gases Observing SATellite (GOSAT) using the so-called Photon path length Probability Density Function-Simultaneous (PPDF-S) retrieval method, which explains cloud/aerosol effects in terms of light path modification. The PPDF-S data, as well as the standard products for General Users (GU) of XCO_2 and XCH_4 retrieved using the full physics (FP) method, were validated through comparison with Total Carbon Column Observing Network (TCCON) data. Results show that bias and its standard deviation of XCO_2 over the land are 0.73 and 1.83 ppm for the PPDF-S data, and −0.32 and 2.16 ppm for GU products. For XCH_4, they are 1.4 and 14.1 ppb, and −1.9 and 12.5 ppb, respectively. Although the magnitude relations between XCO_2 and XCH_4 retrieved by the PPDF-S and GU products are identical over the land, they differ over the ocean. This fact emphasizes the importance of additional validation data over the ocean. Results also show that 68% of FP data that were screened out through an Aerosol Optical Thickness (AOT) test passed all screening tests for the PPDF-S method, implying the applicability of the PPDF-S method to denser aerosol conditions.