scholarly journals Assessment of Aerosol Radiative Forcing with 1-D Radiative Transfer Modeling in the U. S. South-East

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 271 ◽  
Author(s):  
Erica Alston ◽  
Irina Sokolik
Keyword(s):  
Radiative Transfer ◽  
Radiative Forcing ◽  
Global Climate Model ◽  
Regional Scale ◽  
Climate Impacts ◽  
Radiative Properties ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Layer ◽  
Potential Implication

Aerosols and their radiative properties play an integral part in understanding Earth’s climate. It is becoming increasingly common to examine aerosol’s radiative impacts on a regional scale. The primary goal of this research is to explore the impacts of regional aerosol’s forcing at the surface and top-of-atmosphere (TOA) in the south-eastern U.S. by using a 1-D radiative transfer model. By using test cases that are representative of conditions common to this region, an estimate of aerosol forcing can be compared to other results. Speciation data and aerosol layer analysis provide the basis for the modeling. Results indicate that the region experiences TOA cooling year-round, where the winter has TOA forcings between −2.8 and −5 W/m2, and the summer has forcings between −5 and −15 W/m2 for typical atmospheric conditions. Surface level forcing efficiencies are greater than those estimated for the TOA for all cases considered i.e., urban and non-urban background conditions. One potential implication of this research is that regional aerosol mixtures have effects that are not well captured in global climate model estimates, which has implications for a warming climate where all radiative inputs are not well characterized, thus increasing the ambiguity in determining regional climate impacts.

Radiative forcing over the Arctic of aerosols from the August 2017 Canadian and Greenlandic wildfires

2021 ◽  
Author(s):  
Filippo Calì Quaglia ◽  
Daniela Meloni ◽  
Alcide Giorgio di Sarra ◽  
Tatiana Di Iorio ◽  
Virginia Ciardini ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Radiative Forcing ◽  
Solar Zenith Angle ◽  
Surface Albedo ◽  
High Arctic ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Layer ◽  
Radiative Effect

<p>Extended and intense wildfires occurred in Northern Canada and, unexpectedly, on the Greenlandic West coast during summer 2017. The thick smoke plume emitted into the atmosphere was transported to the high Arctic, producing one of the largest impacts ever observed in the region. Evidence of Canadian and Greenlandic wildfires was recorded at the Thule High Arctic Atmospheric Observatory (THAAO, 76.5°N, 68.8°W, www.thuleatmos-it.it) by a suite of instruments managed by ENEA, INGV, Univ. of Florence, and NCAR. Ground-based observations of the radiation budget have allowed quantification of the surface radiative forcing at THAAO. </p><p>Excess biomass burning chemical tracers such as CO, HCN, H2CO, C2H6, and NH3 were  measured in the air column above Thule starting from August 19 until August 23. The aerosol optical depth (AOD) reached a peak value of about 0.9 on August 21, while an enhancement of wildfire compounds was  detected in PM10. The measured shortwave radiative forcing was -36.7 W/m2 at 78° solar zenith angle (SZA) for AOD=0.626.</p><p>MODTRAN6.0 radiative transfer model (Berk et al., 2014) was used to estimate the aerosol radiative effect and the heating rate profiles at 78° SZA. Measured temperature profiles, integrated water vapour, surface albedo, spectral AOD and aerosol extinction profiles from CALIOP onboard CALIPSO were used as model input. The peak  aerosol heating rate (+0.5 K/day) was  reached within the aerosol layer between 8 and 12 km, while the maximum radiative effect (-45.4 W/m2) is found at 3 km, below the largest aerosol layer.</p><p>The regional impact of the event that occurred on August 21 was investigated using a combination of atmospheric radiative transfer modelling with measurements of AOD and ground surface albedo from MODIS. The aerosol properties used in the radiative transfer model were constrained by in situ measurements from THAAO. Albedo data over the ocean have been obtained from Jin et al. (2004). Backward trajectories produced through HYSPLIT simulations (Stein et al., 2015) were also employed to trace biomass burning plumes.</p><p>The radiative forcing efficiency (RFE) over land and ocean was derived, finding values spanning from -3 W/m2 to -132 W/m2, depending on surface albedo and solar zenith angle. The fire plume covered a vast portion of the Arctic, with large values of the daily shortwave RF (< -50 W/m2) lasting for a few days. This large amount of aerosol is expected to influence cloud properties in the Arctic, producing significant indirect radiative effects.</p>

scholarly journals Regional radiative impact of volcanic aerosol from the 2009 eruption of Mt. Redoubt

2012 ◽  
Vol 12 (8) ◽  
pp. 3699-3715 ◽  
Author(s):  
C. L. Young ◽  
I. N. Sokolik ◽  
J. Dufek
Keyword(s):  
Radiative Transfer ◽  
Environmental Conditions ◽  
Radiative Forcing ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Layer ◽  
Volcanic Aerosol ◽  
High Northern Latitude ◽  
Arctic Environment

Abstract. High northern latitude eruptions have the potential to release volcanic aerosol into the Arctic environment, perturbing the Arctic's climate system. We present assessments of shortwave (SW), longwave (LW) and net direct aerosol radiative forcing efficiencies and atmospheric heating/cooling rates caused by volcanic aerosol from the 2009 eruption of Mt. Redoubt by performing radiative transfer modeling constrained by NASA A-Train satellite data. The optical properties of volcanic aerosol were calculated by introducing a compositionally resolved microphysical model developed for both ash and sulfates. Two compositions of volcanic aerosol were considered in order to examine a fresh, ash rich plume and an older, ash poor plume. Optical models were incorporated into a modified version of the SBDART radiative transfer model. Our results indicate that environmental conditions, such as surface albedo and solar zenith angle (SZA), can influence the sign and the magnitude of the radiative forcing at the top of the atmosphere (TOA) and at the surface and the magnitude of the forcing in the aerosol layer. We find that a fresh, thin plume (~2.5–7 km) at an AOD (550 nm) range of 0.18–0.58 and SZA = 55° over snow cools the surface and warms the TOA, but the opposite effect is seen for TOA by the same layer over ocean. The layer over snow also warms by 64 W m−2AOD−1 more than the same plume over seawater. The layer over snow at SZA = 75° warms the TOA 96 W m−2AOD−1 less than it would at SZA = 55° over snow, and there is instead warming at the surface. We also find that plume aging can alter the magnitude of the radiative forcing. An aged plume over snow at SZA = 55° would warm the TOA and layer by 146 and 143 W m−2AOD−1 less than the fresh plume, while the aging plume cools the surface 3 W m−2AOD−1 more. Comparing results for the thin plume to those for a thick plume (~3–20 km), we find that the fresh, thick plume with AOD(550 nm) = 3, over seawater, and SZA = 55° heats the upper part of the plume in the SW ~28 K day−1 more and cools in the LW by ~6.3 K day−1 more than a fresh, thin plume under the same environmental conditions. We compare our assessments with those reported for other aerosols typical to the Arctic environment (smoke from wildfires, Arctic haze, and dust) to demonstrate the importance of volcanic aerosols.

Inverse Design of Spectrally Selective Thickness Sensitive Pigmented Coatings for Solar Thermal Applications

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Refet A. Yalçın ◽  
Hakan Ertürk
Keyword(s):  
Radiative Transfer ◽  
Effective Medium Theory ◽  
Collection Efficiency ◽  
Radiative Properties ◽  
Solar Thermal ◽  
Inverse Design ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectrally Selective ◽  
Pigmented Coatings

Inverse design of thickness sensitive spectrally selective pigmented coatings that are used in absorbers of solar thermal collectors is considered. The objective is to maximize collection efficiency by achieving high absorptance at solar wavelengths and low emittance at the infrared (IR) wavelengths to minimize heat loss. Radiative properties of these coatings depend on coating thickness, pigment size, concentration, and the optical properties of binder and pigment materials, and a unified radiative transfer model of the pigmented coatings is developed in order to understand the effect of these parameters on the properties. The unified model (UM) relies on Lorenz–Mie theory (LMT) for independent scattering regime in conjunction with extended Hartel theory (EHT) to incorporate the multiple scattering effects, T-matrix method (TMM) for dependent scattering, and effective medium theory (EMT) for very small particles. A simplified version of the UM (SUM) ignoring dependent scattering is also developed for improving computational efficiency. Through the solution of the radiative transfer equation by the four flux method (FFM), spectral properties are predicted. The developed model is used in conjunction with inverse design for estimating design variables yielding the desired spectral emittance of the ideal coating. The nonlinear inverse design problem is solved by optimization by using simulated annealing (SA) method that is capable of finding global minimum regardless of initial guess.

scholarly journals Climatological and radiative properties of midlatitude cirrus clouds derived by automatic evaluation of lidar measurements

2016 ◽  
Vol 16 (12) ◽  
pp. 7605-7621 ◽  
Author(s):  
Erika Kienast-Sjögren ◽  
Christian Rolf ◽  
Patric Seifert ◽  
Ulrich K. Krieger ◽  
Bei P. Luo ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Cirrus Clouds ◽  
Radiative Properties ◽  
Radiation Budget ◽  
Shortwave Radiation ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Data Set ◽  
Detection Scheme ◽  
Lidar Measurements

Abstract. Cirrus, i.e., high, thin clouds that are fully glaciated, play an important role in the Earth's radiation budget as they interact with both long- and shortwave radiation and affect the water vapor budget of the upper troposphere and stratosphere. Here, we present a climatology of midlatitude cirrus clouds measured with the same type of ground-based lidar at three midlatitude research stations: at the Swiss high alpine Jungfraujoch station (3580 m a.s.l.), in Zürich (Switzerland, 510 m a.s.l.), and in Jülich (Germany, 100 m a.s.l.). The analysis is based on 13 000 h of measurements from 2010 to 2014. To automatically evaluate this extensive data set, we have developed the Fast LIdar Cirrus Algorithm (FLICA), which combines a pixel-based cloud-detection scheme with the classic lidar evaluation techniques. We find mean cirrus optical depths of 0.12 on Jungfraujoch and of 0.14 and 0.17 in Zürich and Jülich, respectively. Above Jungfraujoch, subvisible cirrus clouds (τ < 0.03) have been observed during 6 % of the observation time, whereas above Zürich and Jülich fewer clouds of that type were observed. Cirrus have been observed up to altitudes of 14.4 km a.s.l. above Jungfraujoch, whereas they have only been observed to about 1 km lower at the other stations. These features highlight the advantage of the high-altitude station Jungfraujoch, which is often in the free troposphere above the polluted boundary layer, thus enabling lidar measurements of thinner and higher clouds. In addition, the measurements suggest a change in cloud morphology at Jungfraujoch above ∼ 13 km, possibly because high particle number densities form in the observed cirrus clouds, when many ice crystals nucleate in the high supersaturations following rapid uplifts in lee waves above mountainous terrain. The retrieved optical properties are used as input for a radiative transfer model to estimate the net cloud radiative forcing, CRFNET, for the analyzed cirrus clouds. All cirrus detected here have a positive CRFNET. This confirms that these thin, high cirrus have a warming effect on the Earth's climate, whereas cooling clouds typically have cloud edges too low in altitude to satisfy the FLICA criterion of temperatures below −38 °C. We find CRFNET = 0.9 W m−2 for Jungfraujoch and 1.0 W m−2 (1.7 W m−2) for Zürich (Jülich). Further, we calculate that subvisible cirrus (τ < 0.03) contribute about 5 %, thin cirrus (0.03 < τ < 0.3) about 45 %, and opaque cirrus (0.3 < τ) about 50 % of the total cirrus radiative forcing.

scholarly journals Thermodynamic and Radiative Structure of Stratocumulus-Topped Boundary Layers*

2015 ◽  
Vol 72 (1) ◽  
pp. 430-451 ◽  
Author(s):  
Virendra P. Ghate ◽  
Mark A. Miller ◽  
Bruce A. Albrecht ◽  
Christopher W. Fairall
Keyword(s):  
Radiative Transfer ◽  
Boundary Layers ◽  
Great Plains ◽  
Potential Temperature ◽  
Radiative Properties ◽  
Radiative Transfer Model ◽  
Cloud Base ◽  
Transfer Model ◽  
Flux Divergence ◽  
Liquid Water Path

Abstract Stratocumulus-topped boundary layers (STBLs) observed in three different regions are described in the context of their thermodynamic and radiative properties. The primary dataset consists of 131 soundings from the southeastern Pacific (SEP), 90 soundings from the island of Graciosa (GRW) in the North Atlantic, and 83 soundings from the U.S. Southern Great Plains (SGP). A new technique that makes an attempt to preserve the depths of the sublayers within an STBL is proposed for averaging the profiles of thermodynamic and radiative variables. A one-dimensional radiative transfer model known as the Rapid Radiative Transfer Model was used to compute the radiative fluxes within the STBL. The SEP STBLs were characterized by a stronger and deeper inversion, together with thicker clouds, lower free-tropospheric moisture, and higher radiative flux divergence across the cloud layer, as compared to the GRW STBLs. Compared to the STBLs over the marine locations, the STBLs over SGP had higher wind shear and a negligible (−0.41 g kg−1) jump in mixing ratio across the inversion. Despite the differences in many of the STBL thermodynamic parameters, the differences in liquid water path at the three locations were statistically insignificant. The soundings were further classified as well mixed or decoupled based on the difference between the surface and cloud-base virtual potential temperature. The decoupled STBLs were deeper than the well-mixed STBLs at all three locations. Statistically insignificant differences in surface latent heat flux (LHF) between well-mixed and decoupled STBLs suggest that parameters other than LHF are responsible for producing decoupling.

Greenhouse effects of aircraft emissions as calculated by a radiative transfer model

1995 ◽  
Vol 13 (4) ◽  
pp. 413-418 ◽  
Author(s):  
J. P. F. Fortuin ◽  
R. van Dorland ◽  
W. M. F. Wauben ◽  
H. Kelder
Keyword(s):  
Water Vapor ◽  
Radiative Transfer ◽  
Indirect Effect ◽  
Radiative Forcing ◽  
Combustion Products ◽  
Ozone Production ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aircraft Emissions ◽  
The North

Abstract. With a radiative transfer model, assessments are made of the radiative forcing in northern mid-latitudes due to aircraft emissions up to 1990. Considered are the direct climate effects from the major combustion products carbon dioxide, nitrogen dioxide, water vapor and sulphur dioxide, as well as the indirect effect of ozone production from NOx emissions. Our study indicates a local radiative forcing at the tropopause which should be negative in summer (–0.5 to 0.0 W/m2) and either negative or positive in winter (–0.3 to 0.2 W/m2). To these values the indirect effect of contrails has to be added, which for the North Atlantic Flight Corridor covers the range –0.2 to 0.3 W/m2 in summer and 0.0 to 0.3 W/m2 in winter. Apart from optically dense non-aged contrails during summer, negative forcings are due to solar screening by sulphate aerosols. The major positive contributions come from contrails, stratospheric water vapor in winter and ozone in summer. The direct effect of NO2 is negligible and the contribution of CO2 is relatively small.

scholarly journals Seasonal variations in brightness temperature for central Antarctica

1993 ◽  
Vol 17 ◽  
pp. 300-306 ◽  
Author(s):  
C.J. Van Der Veen ◽  
K. C. Jezek
Keyword(s):  
Radiative Transfer ◽  
Brightness Temperature ◽  
Scattering Theory ◽  
Rayleigh Scattering ◽  
Source Term ◽  
Radiative Properties ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Temperature Model ◽  
One Dimensional

The radiative-transfer model developed by Zwally (1977) is modified and coupled to a one-dimensional time-dependent temperature model, to calculate the seasonal variation in brightness temperature. By comparing this with observed records, the radiative properties of firn can be determined. By retaining scattering as a source term in the radiative transfer function, agreement between model-derived scattering and absorption coefficients and those calculated from the Mie/Rayleigh scattering theory can be obtained. The horizontal brightness temperature is not linked to the vertical one through a constant power reflection coefficient.

scholarly journals Improved estimate of global dust radiative forcing using a coupled chemical transport-radiative transfer model

2013 ◽  
Vol 13 (1) ◽  
pp. 2415-2456 ◽  
Author(s):  
L. Zhang ◽  
Q. B. Li ◽  
Y. Gu ◽  
K. N. Liou ◽  
B. Meland
Keyword(s):  
Radiative Transfer ◽  
Vertical Profile ◽  
Radiative Forcing ◽  
Chemical Transport ◽  
Dust Particles ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Vertical Profiles ◽  
Dust Source ◽  
Source Regions

Abstract. Atmospheric mineral dust particles exert significant direct radiative forcings and are critical drivers of climate change. Here, we use the GEOS-Chem global three-dimensional chemical transport model (3-D CTM) coupled online with the Fu-Liou-Gu (FLG) radiative transfer model (RTM) to investigate the dust radiative forcing and heating rates based on different dust vertical profiles. The coupled calculations using a realistic dust vertical profile simulated by GEOS-Chem minimize the physical inconsistencies between 3-D CTM aerosol fields and the RTM. The use of GEOS-Chem simulated aerosol optical depth (AOD) vertical profiles as opposed to the FLG prescribed AOD vertical profiles leads to greater and more spatially heterogeneous changes in estimated radiative forcing and heating rate produced by dust. Both changes can be attributed to a different vertical structure between dust and non-dust source regions. Values of the dust AOD are much larger in the middle troposphere, though smaller at the surface when the GEOS-Chem simulated AOD vertical profile is used, which leads to a much stronger heating rate in the middle troposphere. Compared to FLG vertical profile, the use of GEOS-Chem vertical profile reduces the solar radiative forcing effect by about 0.2–0.25 W m−2 and the Infrared (IR) radiative forcing over the African and Asia dust source regions by about 0.1–0.2 W m−2. Differences in the solar radiative forcing at the surface between using the GEOS-Chem vertical profile and the FLG vertical profile are most significant over the Gobi desert with a value of about 1.1 W m−2. The radiative forcing effect of dust particles is more pronounced at the surface over the Sahara and Gobi deserts by using FLG vertical profile, while it is less significant over the downwind area of Eastern Asia.

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