Clear-sky closure studies of lower tropospheric aerosol and water vapor during ACE-2 using airborne sunphotometer, airborne in-situ, space-borne, and ground-based measurements

AbstractThis paper presents a study on long-term surface solar radiation (SSR) changes over China under clear- and all-sky conditions and analyzes the causes of the “dimming” and “brightening.” To eliminate the nonclimatic signals in the historical records, the daily SSR dataset was first homogenized using quantile-matching (QM) adjustment. The results reveal rapid dimming before 2000 not only under all-sky conditions, but also under clear-sky conditions, at a decline rate of −9.7 ± 0.4 W m−2 decade−1 (1958–99). This is slightly stronger than that under all-sky conditions at −7.4 ± 0.4 W m−2 decade−1, since the clear-sky dimming stopped 15 years later. A rapid “wettening” of about 40-Pa surface water vapor pressure (SWVP) from 1985 to 2000 was found over China. It contributed 2.2% to the SSR decline under clear-sky conditions during the whole dimming period (1958–99). Therefore, water vapor cannot be the main cause of the long-term dimming in China. After a stable decade (1999–2008), an intensive brightening appeared under the clear-sky conditions at a rate of 10.6 ± 2.0 W m−2 decade−1, whereas a much weaker brightening (−0.8 ± 3.1 W m−2 decade−1) has been observed under all-sky conditions between 2008 and 2016. The remarkable divergence between clear- and all-sky trends in recent decades indicates that the clouds played two opposite roles in the SSR changes during the past 30 years, by compensating for the declining SSR under the cloud-free conditions in 1985–99 and by counteracting the increasing SSR under cloud-free conditions in 2008–16. Aerosols remain as the main cause of dimming and brightening over China in the last 60 years, although the clouds counteract the effects of aerosols after 2000.

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In-situ NiO nanostructure growth during heating in water vapor atmosphere

Microscopy and Microanalysis ◽

10.1017/s1431927621007595 ◽

2021 ◽

Vol 27 (S1) ◽

pp. 2102-2103

Author(s):

Boyi Qu ◽

Klaus van Benthem

Keyword(s):

Water Vapor ◽

Water Vapor Atmosphere

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In situ FTIR studies of CO oxidation over Fe-free and Fe-promoted PtY catalysts: Effect of water vapor addition

Journal of Molecular Catalysis A Chemical ◽

10.1016/j.molcata.2011.05.008 ◽

2011 ◽

Vol 344 (1-2) ◽

pp. 111-121 ◽

Cited By ~ 9

Author(s):

Zeinhom M. El-Bahy ◽

Ahmed I. Hanafy ◽

Mohamed M. Ibrahim ◽

Masakazu Anpo

Keyword(s):

Water Vapor ◽

Co Oxidation ◽

In Situ Ftir ◽

Effect Of Water ◽

Ftir Studies

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The global 3-D distribution of tropospheric aerosols as characterized by CALIOP

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-3345-2013 ◽

2013 ◽

Vol 13 (6) ◽

pp. 3345-3361 ◽

Cited By ~ 255

Author(s):

D. M. Winker ◽

J. L. Tackett ◽

B. J. Getzewich ◽

Z. Liu ◽

M. A. Vaughan ◽

...

Keyword(s):

Lower Troposphere ◽

Aerosol Extinction ◽

Transport Pathways ◽

3 Dimensional ◽

Clear Sky ◽

Tropospheric Aerosol ◽

Vertical Distributions ◽

Dimensional Distribution ◽

Level 3 ◽

Sky Conditions

Abstract. The CALIOP lidar, carried on the CALIPSO satellite, has been acquiring global atmospheric profiles since June 2006. This dataset now offers the opportunity to characterize the global 3-D distribution of aerosol as well as seasonal and interannual variations, and confront aerosol models with observations in a way that has not been possible before. With that goal in mind, a monthly global gridded dataset of daytime and nighttime aerosol extinction profiles has been constructed, available as a Level 3 aerosol product. Averaged aerosol profiles for cloud-free and all-sky conditions are reported separately. This 6-yr dataset characterizes the global 3-dimensional distribution of tropospheric aerosol. Vertical distributions are seen to vary with season, as both source strengths and transport mechanisms vary. In most regions, clear-sky and all-sky mean aerosol profiles are found to be quite similar, implying a lack of correlation between high semi-transparent cloud and aerosol in the lower troposphere. An initial evaluation of the accuracy of the aerosol extinction profiles is presented. Detection limitations and the representivity of aerosol profiles in the upper troposphere are of particular concern. While results are preliminary, we present evidence that the monthly-mean CALIOP aerosol profiles provide quantitative characterization of elevated aerosol layers in major transport pathways. Aerosol extinction in the free troposphere in clean conditions, where the true aerosol extinction is typically 0.001 km−1 or less, is generally underestimated, however. The work described here forms an initial global 3-D aerosol climatology which we plan to extend and improve over time.

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Combining airborne in situ and ground-based lidar measurements for attribution of aerosol layers

10.5194/acp-2017-1085 ◽

2018 ◽

Author(s):

Anna Nikandrova ◽

Ksenia Tabakova ◽

Antti Manninen ◽

Riikka Väänänen ◽

Tuukka Petäjä ◽

...

Keyword(s):

Boundary Layer ◽

Size Distribution ◽

Aerosol Size Distribution ◽

Long Range Transport ◽

Back Trajectories ◽

Clear Sky ◽

Temporal And Spatial Variability ◽

Range Transport ◽

Temporal And Spatial

Abstract. Understanding the distribution of aerosol layers is important for determining long range transport and aerosol radiative forcing. In this study we combine airborne in situ measurements of aerosol with data obtained by a ground-based High Spectral Resolution Lidar (HSRL) and radiosonde profiles to investigate the temporal and vertical variability of aerosol properties in the lower troposphere. The HSRL was deployed in Hyytiälä, Southern Finland, from January to September 2014 as a part of the US DoE ARM (Atmospheric Radiation Measurement) mobile facility during the BAECC (Biogenic Aerosols – Effects on Cloud and Climate) Campaign. Two flight campaigns took place in April and August 2014 with instruments measuring the aerosol size distribution from 10 nm to 10 µm at altitudes up to 3800 m. Two case studies from the flight campaigns, when several aerosol layers were identified, were selected for further investigation: one clear sky case, and one partly cloudy case. During the clear sky case, turbulent mixing ensured low temporal and spatial variability in the measured aerosol size distribution in the boundary layer whereas mixing was not as homogeneous in the boundary layer during the partly cloudy case. The elevated layers exhibited greater temporal and spatial variability in aerosol size distribution, indicating a lack of mixing. New particle formation was observed in the boundary layer during the clear sky case, and nucleation mode particles were also seen in the elevated layers that were not mixing with the boundary layer. Interpreting local measurements of elevated layers in terms of long-range transport can be achieved using back trajectories from Lagrangian models, but care should be taken in selecting appropriate arrival heights, since the modelled and observed layer heights did not always coincide. We conclude that higher confidence in attributing elevated aerosol layers with their air mass origin is attained when back trajectories are combined with lidar and radiosonde profiles.

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In situ regeneration of commercial NH3-SCR catalysts with high-temperature water vapor

Catalysis Communications ◽

10.1016/j.catcom.2018.08.009 ◽

2018 ◽

Vol 116 ◽

pp. 57-61 ◽

Cited By ~ 11

Author(s):

Yao Shi ◽

Pei Zhang ◽

Tuotuo Fang ◽

Erhao Gao ◽

Fujuan Xi ◽

...

Keyword(s):

Water Vapor ◽

High Temperature ◽

Nh3 Scr ◽

High Temperature Water ◽

In Situ Regeneration ◽

Scr Catalysts ◽

Temperature Water

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Estimating Surface Soil Heat Flux in Permafrost Regions Using Remote Sensing-Based Models on the Northern Qinghai-Tibetan Plateau under Clear-Sky Conditions

Remote Sensing ◽

10.3390/rs11040416 ◽

2019 ◽

Vol 11 (4) ◽

pp. 416 ◽

Cited By ~ 1

Author(s):

Cheng Yang ◽

Tonghua Wu ◽

Jiemin Wang ◽

Jimin Yao ◽

Ren Li ◽

...

Keyword(s):

Remote Sensing ◽

Land Surface ◽

Surface Soil ◽

Ground Surface ◽

Soil Heat Flux ◽

Parameterization Scheme ◽

Clear Sky ◽

Sky Conditions ◽

Permafrost Regions

The ground surface soil heat flux (G0) quantifies the energy transfer between the atmosphere and the ground through the land surface. However; it is difficult to obtain the spatial distribution of G0 in permafrost regions because of the limitation of in situ observation and complication of ground surface conditions. This study aims at developing an improved G0 parameterization scheme applicable to permafrost regions of the Qinghai-Tibet Plateau under clear-sky conditions. We validated several existing remote sensing-based models to estimate G0 by analyzing in situ measurement data. Based on the validation of previous models on G0; we added the solar time angle to the G0 parameterization scheme; which considered the phase difference problem. The maximum values of RMSE and MAE between “measured G0” and simulated G0 using the improved parameterization scheme and in situ data were calculated to be 6.102 W/m2 and 5.382 W/m2; respectively. When the error of the remotely sensed land surface temperature is less than 1 K and the surface albedo measured is less than 0.02; the accuracy of estimates based on remote sensing data for G0 will be less than 5%. MODIS data (surface reflectance; land surface temperature; and emissivity) were used to calculate G0 in a 10 x 10 km region around Tanggula site; which is located in the continuous permafrost region with long-term records of meteorological and permafrost parameters. The results obtained by the improved scheme and MODIS data were consistent with the observation. This study enhances our understanding of the impacts of climate change on the ground thermal regime of permafrost and the land surface processes between atmosphere and ground surface in cold regions.

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