scholarly journals Direct observations of clear-sky aerosol radiative forcing from space during the Indian Ocean Experiment

2001 ◽  
Vol 106 (D15) ◽  
pp. 17221-17235 ◽  
Author(s):  
K. Rajeev ◽  
V. Ramanathan
Keyword(s):  
Indian Ocean ◽  
Radiative Forcing ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Direct Observations ◽  
The Indian Ocean ◽  
Aerosol Radiative

Direct observations of aerosol radiative forcing over the tropical Indian Ocean during the January-February 1996 pre-INDOEX cruise

1998 ◽  
Vol 103 (D12) ◽  
pp. 13827-13836 ◽  
Author(s):  
A. Jayaraman ◽  
D. Lubin ◽  
S. Ramachandran ◽  
V. Ramanathan ◽  
E. Woodbridge ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Radiative Forcing ◽  
Tropical Indian Ocean ◽  
Aerosol Radiative Forcing ◽  
Direct Observations ◽  
Aerosol Radiative

scholarly journals Direct Aerosol Radiative Forcing Uncertainty Based on a Radiative Perturbation Analysis

2010 ◽  
Vol 23 (19) ◽  
pp. 5288-5293 ◽  
Author(s):  
Norman G. Loeb ◽  
Wenying Su
Keyword(s):  
Radiative Forcing ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Radiative Perturbation ◽  
Sky Conditions ◽  
Global Mean ◽  
Aerosol Properties ◽  
Aerosol Radiative

Abstract To provide a lower bound for the uncertainty in measurement-based clear- and all-sky direct aerosol radiative forcing (DARF), a radiative perturbation analysis is performed for the ideal case in which the perturbations in global mean aerosol properties are given by published values of systematic uncertainty in Aerosol Robotic Network (AERONET) aerosol measurements. DARF calculations for base-state climatological cloud and aerosol properties over ocean and land are performed, and then repeated after perturbing individual aerosol optical properties (aerosol optical depth, single-scattering albedo, asymmetry parameter, scale height, and anthropogenic fraction) from their base values, keeping all other parameters fixed. The total DARF uncertainty from all aerosol parameters combined is 0.5–1.0 W m−2, a factor of 2–4 greater than the value cited in the Intergovernmental Panel on Climate Change’s (IPCC’s) Fourth Assessment Report. Most of the total DARF uncertainty in this analysis is associated with single-scattering albedo uncertainty. Owing to the greater sensitivity to single-scattering albedo in cloudy columns, DARF uncertainty in all-sky conditions is greater than in clear-sky conditions, even though the global mean clear-sky DARF is more than twice as large as the all-sky DARF.

scholarly journals MACv2-SP: a parameterization of anthropogenic aerosol optical properties and an associated Twomey effect for use in CMIP6

2017 ◽  
Vol 10 (1) ◽  
pp. 433-452 ◽  
Author(s):  
Bjorn Stevens ◽  
Stephanie Fiedler ◽  
Stefan Kinne ◽  
Karsten Peters ◽  
Sebastian Rast ◽  
...  
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Industrial Emissions ◽  
Max Planck ◽  
Aerosol Optical Properties ◽  
Anthropogenic Aerosol ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Aerosol Forcing ◽  
Aerosol Radiative

Abstract. A simple plume implementation of the second version (v2) of the Max Planck Institute Aerosol Climatology, MACv2-SP, is described. MACv2-SP provides a prescription of anthropogenic aerosol optical properties and an associated Twomey effect. It was created to provide a harmonized description of post-1850 anthropogenic aerosol radiative forcing for climate modeling studies. MACv2-SP has been designed to be easy to implement, change and use, and thereby enable studies exploring the climatic effects of different patterns of aerosol radiative forcing, including a Twomey effect. MACv2-SP is formulated in terms of nine spatial plumes associated with different major anthropogenic source regions. The shape of the plumes is fit to the Max Planck Institute Aerosol Climatology, version 2, whose present-day (2005) distribution is anchored by surface-based observations. Two types of plumes are considered: one predominantly associated with biomass burning, the other with industrial emissions. These differ in the prescription of their annual cycle and in their optical properties, thereby implicitly accounting for different contributions of absorbing aerosol to the different plumes. A Twomey effect for each plume is prescribed as a change in the host model's background cloud-droplet population density using relationships derived from satellite data. Year-to-year variations in the amplitude of the plumes over the historical period (1850–2016) are derived by scaling the plumes with associated national emission sources of SO2 and NH3. Experiments using MACv2-SP are performed with the Max Planck Institute Earth System Model. The globally and annually averaged instantaneous and effective aerosol radiative forcings are estimated to be −0.6 and −0.5 W m−2, respectively. Forcing from aerosol–cloud interactions (the Twomey effect) offsets the reduction of clear-sky forcing by clouds, so that the net effect of clouds on the aerosol forcing is small; hence, the clear-sky forcing, which is more readily measurable, provides a good estimate of the total aerosol forcing.

scholarly journals The direct observations of large aerosol radiative forcing in the Himalayan region

2004 ◽  
Vol 31 (5) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. V. Ramana ◽  
V. Ramanathan ◽  
I. A. Podgorny ◽  
Bidya B. Pradhan ◽  
Basanta Shrestha
Keyword(s):  
Radiative Forcing ◽  
Himalayan Region ◽  
Aerosol Radiative Forcing ◽  
Direct Observations ◽  
Aerosol Radiative

Clear-sky infrared aerosol radiative forcing at the surface and the top of the atmosphere

2003 ◽  
Vol 129 (594) ◽  
pp. 2927-2947 ◽  
Author(s):  
Krzysztof M. Markowicz ◽  
Piotr J. Flatau ◽  
Andrew M. Vogelmann ◽  
Patricia K. Quinn ◽  
Ellsworth J. Welton
Keyword(s):  
Radiative Forcing ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Aerosol Radiative

scholarly journals Clear-sky direct aerosol radiative forcing variations over mega-city Delhi

2010 ◽  
Vol 28 (5) ◽  
pp. 1157-1166 ◽  
Author(s):  
S. Singh ◽  
K. Soni ◽  
T. Bano ◽  
R. S. Tanwar ◽  
S. Nath ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Dust Concentration ◽  
Transfer Model ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Angstrom Exponent ◽  
Monthly Average ◽  
Ångström Exponent ◽  
Ångstrom Exponent ◽  
Aerosol Radiative

Abstract. The direct aerosol radiative forcing (DARF) has been estimated for the clear-sky conditions over Delhi from January 2006 to January 2007 using Santa Barbara DISORT Atmospheric Radiative Transfer model (SBDART) in the wavelength range 300–3000 nanometer. The single scattering albedo (SSA) and the asymmetry parameter used in this model were estimated using the Optical Properties of Aerosol and Cloud (OPAC) model. The annual average AOD observed at 500 nm was ~0.86±0.42 with an average Angstrom exponent ~0.68±0.35. The average monthly AOD throughout the year over Delhi was found to be in the range 0.56 to 1.22 with the Angstrom exponent in the range 0.38 to 0.96. A high monthly average BC concentration in the range 4–15 μg m−3 led to monthly average SSA in the range 0.90±0.4 to 0.74±0.3 during the year. Consequently, the monthly average clear-sky DARF at the surface was found to vary in the range −46±8 W m−2 to −110±20 W m−2, at TOA in the range −1.4±0.4 to 21±2 W m−2, whereas in the atmosphere it was in the range 46±9 W m−2 to 115±19 W m−2 throughout the year. As the dust concentration in the atmosphere was highest (May–June) the SSA showed an increase with wavelength however when dust concentration was low the SSA decreased with the wavelength.

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