scholarly journals Aerosol direct radiative effects over the northwest Atlantic, northwest Pacific, and North Indian Oceans: estimates based on in-situ chemical and optical measurements and chemical transport modeling

2006 ◽  
Vol 6 (1) ◽  
pp. 175-362 ◽  
Author(s):  
T. S. Bates ◽  
T. L. Anderson ◽  
T. Baynard ◽  
T. Bond ◽  
O. Boucher ◽  
...  
Keyword(s):  
Climate Change ◽  
Radiative Transfer ◽  
Chemical Transport ◽  
Radiative Flux ◽  
Northwest Pacific ◽  
Radiative Effects ◽  
Anthropogenic Aerosols ◽  
Northwest Atlantic ◽  
Aerosol Properties

Abstract. The largest uncertainty in the radiative forcing of climate change over the industrial era is that due to aerosols, a substantial fraction of which is the uncertainty associated with scattering and absorption of shortwave (solar) radiation by anthropogenic aerosols in cloud-free conditions (IPCC, 2001). Quantifying and reducing the uncertainty in aerosol influences on climate is critical to understanding climate change over the industrial period and to improving predictions of future climate change for assumed emission scenarios. Measurements of aerosol properties during major field campaigns in several regions of the globe during the past decade are contributing to an enhanced understanding of atmospheric aerosols and their effects on light scattering and climate. The present study, which focuses on three regions downwind of major urban/population centers (North Indian Ocean (NIO) during INDOEX, the Northwest Pacific Ocean (NWP) during ACE-Asia, and the Northwest Atlantic Ocean (NWA) during ICARTT), incorporates understanding gained from field observations of aerosol distributions and properties into calculations of perturbations in radiative fluxes due to these aerosols. This study evaluates the current state of observations and of two chemical transport models (STEM and MOZART). Measurements of burdens, extinction optical depth (AOD), and direct radiative effect of aerosols (DRE – change in radiative flux due to total aerosols) are used as measurement-model check points to assess uncertainties. In-situ measured and remotely sensed aerosol properties for each region (mixing state, mass scattering efficiency, single scattering albedo, and angular scattering properties and their dependences on relative humidity) are used as input parameters to two radiative transfer models (GFDL and University of Michigan) to constrain estimates of aerosol radiative effects, with uncertainties in each step propagated through the analysis. Constraining the radiative transfer calculations by observational inputs increases the clear-sky, 24-h averaged AOD (34±8%), top of atmosphere (TOA) DRE (32±12%), and TOA direct climate forcing of aerosols (DCF – change in radiative flux due to anthropogenic aerosols) (37±7%) relative to values obtained with "a priori" parameterizations of aerosol loadings and properties (GFDL RTM). The resulting constrained TOA DCF is −3.3±0.47, −14±2.6, −6.4±2.1 Wm−2 for the NIO, NWP, and NWA, respectively. Constraining the radiative transfer calculations by observational inputs reduces the uncertainty range in the DCF in these regions relative to global IPCC (2001) estimates by a factor of approximately 2. Such comparisons with observations and resultant reductions in uncertainties are essential for improving and developing confidence in climate model calculations incorporating aerosol forcing.

scholarly journals Aerosol direct radiative effects over the northwest Atlantic, northwest Pacific, and North Indian Oceans: estimates based on in-situ chemical and optical measurements and chemical transport modeling

2006 ◽  
Vol 6 (6) ◽  
pp. 1657-1732 ◽  
Author(s):  
T. S. Bates ◽  
T. L. Anderson ◽  
T. Baynard ◽  
T. Bond ◽  
O. Boucher ◽  
...  
Keyword(s):  
Climate Change ◽  
Radiative Transfer ◽  
Chemical Transport ◽  
Climate Forcing ◽  
Northwest Pacific ◽  
Anthropogenic Aerosols ◽  
Northwest Atlantic ◽  
Clear Sky ◽  
Aerosol Properties

Abstract. The largest uncertainty in the radiative forcing of climate change over the industrial era is that due to aerosols, a substantial fraction of which is the uncertainty associated with scattering and absorption of shortwave (solar) radiation by anthropogenic aerosols in cloud-free conditions (IPCC, 2001). Quantifying and reducing the uncertainty in aerosol influences on climate is critical to understanding climate change over the industrial period and to improving predictions of future climate change for assumed emission scenarios. Measurements of aerosol properties during major field campaigns in several regions of the globe during the past decade are contributing to an enhanced understanding of atmospheric aerosols and their effects on light scattering and climate. The present study, which focuses on three regions downwind of major urban/population centers (North Indian Ocean (NIO) during INDOEX, the Northwest Pacific Ocean (NWP) during ACE-Asia, and the Northwest Atlantic Ocean (NWA) during ICARTT), incorporates understanding gained from field observations of aerosol distributions and properties into calculations of perturbations in radiative fluxes due to these aerosols. This study evaluates the current state of observations and of two chemical transport models (STEM and MOZART). Measurements of burdens, extinction optical depth (AOD), and direct radiative effect of aerosols (DRE – change in radiative flux due to total aerosols) are used as measurement-model check points to assess uncertainties. In-situ measured and remotely sensed aerosol properties for each region (mixing state, mass scattering efficiency, single scattering albedo, and angular scattering properties and their dependences on relative humidity) are used as input parameters to two radiative transfer models (GFDL and University of Michigan) to constrain estimates of aerosol radiative effects, with uncertainties in each step propagated through the analysis. Constraining the radiative transfer calculations by observational inputs increases the clear-sky, 24-h averaged AOD (34±8%), top of atmosphere (TOA) DRE (32±12%), and TOA direct climate forcing of aerosols (DCF – change in radiative flux due to anthropogenic aerosols) (37±7%) relative to values obtained with "a priori" parameterizations of aerosol loadings and properties (GFDL RTM). The resulting constrained clear-sky TOA DCF is −3.3±0.47, −14±2.6, −6.4±2.1 Wm−2 for the NIO, NWP, and NWA, respectively. With the use of constrained quantities (extensive and intensive parameters) the calculated uncertainty in DCF was 25% less than the "structural uncertainties" used in the IPCC-2001 global estimates of direct aerosol climate forcing. Such comparisons with observations and resultant reductions in uncertainties are essential for improving and developing confidence in climate model calculations incorporating aerosol forcing.

scholarly journals Determining the infrared radiative effects of Saharan dust: a radiative transfer modelling study based on vertically resolved measurements at Lampedusa

2018 ◽  
Vol 18 (6) ◽  
pp. 4377-4401 ◽  
Author(s):  
Daniela Meloni ◽  
Alcide di Sarra ◽  
Gérard Brogniez ◽  
Cyrielle Denjean ◽  
Lorenzo De Silvestri ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Radiative Transfer ◽  
Size Distribution ◽  
Radiative Forcing ◽  
Mineral Dust ◽  
Reliable Estimate ◽  
Radiative Effects ◽  
Aerosol Properties

Abstract. Detailed measurements of radiation, atmospheric and aerosol properties were carried out in summer 2013 during the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) campaign in the framework of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx) experiment. This study focusses on the characterization of infrared (IR) optical properties and direct radiative effects of mineral dust, based on three vertical profiles of atmospheric and aerosol properties and IR broadband and narrowband radiation from airborne measurements, made in conjunction with radiosonde and ground-based observations at Lampedusa, in the central Mediterranean. Satellite IR spectra from the Infrared Atmospheric Sounder Interferometer (IASI) are also included in the analysis. The atmospheric and aerosol properties are used as input to a radiative transfer model, and various IR radiation parameters (upward and downward irradiance, nadir and zenith brightness temperature at different altitudes) are calculated and compared with observations. The model calculations are made for different sets of dust particle size distribution (PSD) and refractive index (RI), derived from observations and from the literature. The main results of the analysis are that the IR dust radiative forcing is non-negligible and strongly depends on PSD and RI. When calculations are made using the in situ measured size distribution, it is possible to identify the refractive index that produces the best match with observed IR irradiances and brightness temperatures (BTs). The most appropriate refractive indices correspond to those determined from independent measurements of mineral dust aerosols from the source regions (Tunisia, Algeria, Morocco) of dust transported over Lampedusa, suggesting that differences in the source properties should be taken into account. With the in situ size distribution and the most appropriate refractive index the estimated dust IR radiative forcing efficiency is +23.7 W m−2 at the surface, −7.9 W m−2 within the atmosphere, and +15.8 W m−2 at the top of the atmosphere. The use of column-integrated dust PSD from AERONET may also produce a good agreement with measured irradiances and BTs, but with significantly different values of the RI. This implies large differences, up to a factor of 2.5 at surface, in the estimated dust radiative forcing, and in the IR heating rate. This study shows that spectrally resolved measurements of BTs are important to better constrain the dust IR optical properties, and to obtain a reliable estimate of its radiative effects. Efforts should be directed at obtaining an improved description of the dust size distribution and its vertical distribution, as well as at including regionally resolved optical properties.

scholarly journals Determining the infrared radiative effects of Saharan dust: a radiative transfer modelling study based on vertically resolved measurements at Lampedusa

2017 ◽  
Author(s):  
Daniela Meloni ◽  
Alcide di Sarra ◽  
Gérard Brogniez ◽  
Cyrielle Denjean ◽  
Lorenzo De Silvestri ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Size Distribution ◽  
Radiative Forcing ◽  
Refractive Indices ◽  
Radiative Effects ◽  
Brightness Temperatures ◽  
Dust Size Distribution ◽  
Aerosol Properties

Abstract. Detailed atmospheric and aerosol properties, and radiation measurements were carried out in summer 2013 during the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) campaign in the framework of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx) experiment. This study focusses on the characterization of infrared (IR) optical properties and direct radiative effects of mineral dust, based on three vertical profiles of atmospheric and aerosol properties and IR broadband and narrowband radiation from airborne measurements, made in conjunction with radiosonde and ground-based observations at Lampedusa, in the central Mediterranean. Satellite IR spectra from IASI are also included in the analysis. The atmospheric and aerosol properties are used as input to a radiative transfer model, and various IR radiation parameters (upward and downward irradiance, nadir and zenith brightness temperature at different altitudes) are calculated and compared with observations. The model calculations are made for different sets of dust size distribution and refractive indices, derived from observations and from the literature. The main results of the analysis are that the IR dust radiative forcing is non negligible, and strongly depends on size distribution (SD) and refractive index (RI). When calculations are made using the in situ measured size distribution, it is possible to identify the refractive index that produces the best match with observed IR irradiances and brightness temperatures (BTs). The most appropriate refractive indices correspond to those determined from independent measurements of mineral dust aerosols from the source regions (Tunisia, Algeria, Morocco) of dust transported over Lampedusa, suggesting that differences in the source properties should be taken into account. With the in situ size distribution and the most appropriate refractive index the estimated dust IR radiative forcing efficiency is +23.7 W m-2 at the surface, -7.9 W m-2 within the atmosphere, and +15.8 W m-2 at the top of the atmosphere. The use of column integrated dust SD from AERONET may also produce a good agreement with measured irradiances and BTs, but with significantly different values of the RI. This implies large differences, up to a factor of 2.5 at surface, in the estimated dust radiative forcing, and in the IR heating rate. This study shows that spectrally resolved measurements of brightness temperatures are important to better constrain the dust IR optical properties, and to obtain a reliable estimate of its radiative effects. Efforts should be directed at obtaining an improved description of the dust size distribution, its vertical distribution, and at including regionally-resolved optical properties.

scholarly journals Shortwave direct radiative effects of above cloud aerosols over global oceans derived from eight years of CALIOP and MODIS observations

2015 ◽  
Vol 15 (18) ◽  
pp. 26357-26421 ◽  
Author(s):  
Z. Zhang ◽  
K. Meyer ◽  
H. Yu ◽  
S. Platnick ◽  
P. Colarco ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Global Ocean ◽  
Retrieval Algorithm ◽  
Northwest Pacific ◽  
Radiative Effects ◽  
Atlantic Region ◽  
Aerosol Absorption ◽  
Absorbing Aerosols ◽  
Global Oceans

Abstract. In this paper, we studied the frequency of occurrence and shortwave direct radiative effects (DRE) of above-cloud aerosols (ACAs) over global oceans using eight years of collocated CALIOP and MODIS observations. Similar to previous work, we found high ACA occurrence in four regions: Southeast (SE) Atlantic region where ACAs are mostly light-absorbing aerosols, i.e., smoke and polluted dust according to CALIOP classification, originating from biomass burning over African Savanna; Tropical Northeast Atlantic and Arabian Sea where ACAs are predominantly windblown dust from the Sahara and Arabian desert, respectively; and Northwest Pacific where ACAs are mostly transported smoke and polluted dusts from Asian. From radiative transfer simulations based on CALIOP-MODIS observations and a set of the preselected aerosol optical models, we found the DREs of ACAs at the top of atmosphere (TOA) to be positive (i.e., warming) in the SE Atlantic and NW Pacific regions, but negative (i.e., cooling) in TNE Atlantic and Arabian Sea. The cancellation of positive and negative regional DREs results in a global ocean annual mean diurnally averaged cloudy-sky DRE of 0.015 W m−2 (range of −0.03 to 0.06 W m−2) at TOA. The DREs at surface and within atmosphere are −0.15 W m−2 (range of −0.09 to −0.21 W m−2), and 0.17 W m−2 (range of 0.11 to 0.24 W m−2), respectively. The regional and seasonal mean DREs are much stronger. For example, in the SE Atlantic region the JJA (July ~ August) seasonal mean cloudy-sky DRE is about 0.7 W m−2 (range of 0.2 to 1.2 W m−2) at TOA. The uncertainty in our DRE computations is mainly cause by the uncertainties in the aerosol optical properties, in particular aerosol absorption, and uncertainties in the CALIOP operational aerosol optical thickness retrieval. In situ and remotely sensed measurements of ACA from future field campaigns and satellite missions, and improved lidar retrieval algorithm, in particular vertical feature masking, would help reduce the uncertainty.

On the use of satellites to obtain information on the occurrence of natural and anthropogenic aerosols over the boreal eurasian forest

2011 ◽  
Vol 8 (4) ◽  
pp. 8451-8483 ◽  
Author(s):  
G. de Leeuw ◽  
A. Arola ◽  
L. Sogacheva ◽  
N. Kivekäs ◽  
V.-M. Kerminen ◽  
...  
Keyword(s):  
Satellite Data ◽  
Spatial Information ◽  
Anthropogenic Aerosols ◽  
Model Calculations ◽  
Optical Instruments ◽  
In Situ Data ◽  
Natural Aerosols ◽  
Along Track ◽  
Aerosol Properties

Abstract. The ALANIS-Aerosols project is a feasibility study on the use of existing satellite data for discriminating between natural aerosols emitted by boreal Eurasian forests and long-range transported anthropogenic aerosols. In this paper an overview is provided of different satellite products which are potentially useful to obtain this kind of information. Approaches that have been followed in the past are briefly summarized. Secondary production of aerosols from their precursor gases, in particular biogenic volatile organic compounds which play an important role in the formation of new particles through nucleation, is briefly discussed. These newly formed particles are initially too small to observe directly with optical instruments used for earth observation (EO) but through the use of proxies information can be obtained on global nucleation mode aerosol concentrations. Next we focus on aerosols with particle sizes in the optically active size range, roughly particles with a diameter larger than 50–100 nm, depending on wavelength. These particles can be observed with EO instruments as well as using several different types of in situ observations. The satellite data used are aerosol properties retrieved from the Advanced Along Track Scanning Radiometer (AATSR, flying on ENVISAT since 2002) using both the forward and nadir view with the AATSR dual view algorithm (ADV). Ground-based in situ data used here are aerosol properties measured in Hyytiälä, Finland. These observations are complemented with model calculations using the global atmospheric aerosol and chemistry model GLOMAP. Examples show the complementarity of different data sources to obtain information on the temporal and spatial information on the nature of aerosols over the Boreal forest.

Top-of-atmosphere albedo bias from neglecting three-dimensional cloud radiative effects

2021 ◽  
Author(s):  
Clare E. Singer ◽  
Ignacio Lopez-Gomez ◽  
Xiyue Zhang ◽  
Tapio Schneider
Keyword(s):  
Radiative Transfer ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
3D Structure ◽  
Three Dimensional ◽  
Radiative Flux ◽  
Monte Carlo Code ◽  
Radiative Effects ◽  
Cloud Radiative Effects ◽  
The Impact

AbstractClouds cover on average nearly 70% of Earth’s surface and regulate the global albedo. The magnitude of the shortwave reflection by clouds depends on their location, optical properties, and three-dimensional (3D) structure. Due to computational limitations, Earth system models are unable to perform 3D radiative transfer calculations. Instead they make assumptions, including the independent column approximation (ICA), that neglect effects of 3D cloud morphology on albedo. We show how the resulting radiative flux bias (ICA-3D) depends on cloud morphology and solar zenith angle. We use high-resolution (20–100 m horizontal resolution) large-eddy simulations to produce realistic 3D cloud fields covering three dominant regimes of low-latitude clouds: shallow cumulus, marine stratocumulus, and deep convective cumulonimbus. A Monte Carlo code is used to run 3D and ICA broadband radiative transfer calculations; we calculate the top-of-atmosphere (TOA) reflected flux and surface irradiance biases as functions of solar zenith angle for these three cloud regimes. Finally, we use satellite observations of cloud water path (CWP) climatology, and the robust correlation between CWP and TOA flux bias in our LES sample, to roughly estimate the impact of neglecting 3D cloud radiative effects on a global scale. We find that the flux bias is largest at small zenith angles and for deeper clouds, while the albedo bias is most prominent for large zenith angles. In the tropics, the annual-mean shortwave radiative flux bias is estimated to be 3.1±1.6 W m−2, reaching as much as 6.5 W m−2 locally.

scholarly journals Spatial Ecology of Atlantic Halibut across the Northwest Atlantic: A Recovering Species in an Era of Climate Change

2021 ◽  
pp. 1-25
Author(s):  
Nancy L. Shackell ◽  
Jonathan A. D. Fisher ◽  
Cornelia E. den Heyer ◽  
Daniel R. Hennen ◽  
Andrew C. Seitz ◽  
...  
Keyword(s):  
Climate Change ◽  
Spatial Ecology ◽  
Atlantic Halibut ◽  
Northwest Atlantic

scholarly journals Modeling the radiative effects of desert dust on weather and regional climate

2013 ◽  
Vol 13 (11) ◽  
pp. 5489-5504 ◽  
Author(s):  
C. Spyrou ◽  
G. Kallos ◽  
C. Mitsakou ◽  
P. Athanasiadis ◽  
C. Kalogeri ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Regional Climate ◽  
Lower Troposphere ◽  
Integrated Approach ◽  
Dust Particles ◽  
Radiative Transfer Model ◽  
Limited Area ◽  
Transfer Model ◽  
Radiative Effects ◽  
Desert Dust

Abstract. Mineral dust aerosols exert a significant effect on both solar and terrestrial radiation. By absorbing and scattering, the solar radiation aerosols reduce the amount of energy reaching the surface. In addition, aerosols enhance the greenhouse effect by absorbing and emitting outgoing longwave radiation. Desert dust forcing exhibits large regional and temporal variability due to its short lifetime and diverse optical properties, further complicating the quantification of the direct radiative effect (DRE). The complexity of the links and feedbacks of dust on radiative transfer indicate the need for an integrated approach in order to examine these impacts. In order to examine these feedbacks, the SKIRON limited area model has been upgraded to include the RRTMG (Rapid Radiative Transfer Model – GCM) radiative transfer model that takes into consideration the aerosol radiative effects. It was run for a 6 year period. Two sets of simulations were performed, one without the effects of dust and the other including the radiative feedback. The results were first evaluated using aerosol optical depth data to examine the capabilities of the system in describing the desert dust cycle. Then the aerosol feedback on radiative transfer was quantified and the links between dust and radiation were studied. The study has revealed a strong interaction between dust particles and solar and terrestrial radiation, with several implications on the energy budget of the atmosphere. A profound effect is the increased absorption (in the shortwave and longwave) in the lower troposphere and the induced modification of the atmospheric temperature profile. These feedbacks depend strongly on the spatial distribution of dust and have more profound effects where the number of particles is greater, such as near their source.

scholarly journals Comparison of Radiative Energy Flows in Observational Datasets and Climate Modeling

2016 ◽  
Vol 55 (1) ◽  
pp. 93-117 ◽  
Author(s):  
Ehrhard Raschke ◽  
Stefan Kinne ◽  
William B. Rossow ◽  
Paul W. Stackhouse ◽  
Martin Wild
Keyword(s):  
Climate Modeling ◽  
Radiative Flux ◽  
Radiative Energy ◽  
Trade Wind ◽  
Radiative Effects ◽  
Ancillary Data ◽  
Global Modeling ◽  
Lower Altitude ◽  
Clear Sky ◽  
Cloud Radiative Effects

AbstractThis study examines radiative flux distributions and local spread of values from three major observational datasets (CERES, ISCCP, and SRB) and compares them with results from climate modeling (CMIP3). Examinations of the spread and differences also differentiate among contributions from cloudy and clear-sky conditions. The spread among observational datasets is in large part caused by noncloud ancillary data. Average differences of at least 10 W m−2 each for clear-sky downward solar, upward solar, and upward infrared fluxes at the surface demonstrate via spatial difference patterns major differences in assumptions for atmospheric aerosol, solar surface albedo and surface temperature, and/or emittance in observational datasets. At the top of the atmosphere (TOA), observational datasets are less influenced by the ancillary data errors than at the surface. Comparisons of spatial radiative flux distributions at the TOA between observations and climate modeling indicate large deficiencies in the strength and distribution of model-simulated cloud radiative effects. Differences are largest for lower-altitude clouds over low-latitude oceans. Global modeling simulates stronger cloud radiative effects (CRE) by +30 W m−2 over trade wind cumulus regions, yet smaller CRE by about −30 W m−2 over (smaller in area) stratocumulus regions. At the surface, climate modeling simulates on average about 15 W m−2 smaller radiative net flux imbalances, as if climate modeling underestimates latent heat release (and precipitation). Relative to observational datasets, simulated surface net fluxes are particularly lower over oceanic trade wind regions (where global modeling tends to overestimate the radiative impact of clouds). Still, with the uncertainty in noncloud ancillary data, observational data do not establish a reliable reference.

Sign in / Sign up

Export Citation Format

Share Document