Direct Insertion of MODIS Radiances in a Global Aerosol Transport Model

2007 ◽  
Vol 64 (3) ◽  
pp. 808-827 ◽  
Author(s):  
Clark Weaver ◽  
Arlindo da Silva ◽  
Mian Chin ◽  
Paul Ginoux ◽  
Oleg Dubovik ◽  
...  
Keyword(s):  
Wind Speed ◽  
Radiative Forcing ◽  
Transport Model ◽  
Radiation Transport ◽  
Surface Wind ◽  
Forward Model ◽  
Optical Parameters ◽  
Gocart Model ◽  
Aerosol Types ◽  
Assimilation System

Abstract In this paper results are presented from a simple offline assimilation system that uses radiances from the Moderate Resolution Imaging Spectroradiometer (MODIS) channels that sense atmospheric aerosols over land and ocean. The MODIS information is directly inserted into the Goddard Chemistry and Aerosol Radiation Transport model (GOCART), which simulates the following five aerosol types: dust, sea salt, black carbon, organic carbon, and sulfate. The goal is to produce three-dimensional fields of these aerosol types for radiative forcing calculations. Products from this assimilation system are compared with ground-based measurements of aerosol optical depth (AOD) from the Aerosol Robotic Network (AERONET). Insertion of MODIS radiances draws the GOCART model closer to the AERONET AOD. However, there are still uncertainties with surface reflectivity over moderately bright surfaces and with the amount of absorbing aerosol. Also described is the assimilation cycle. The forward model takes the aerosol information from the GOCART model and calculates radiances based on optical parameters of the aerosol type, satellite viewing angle, and the particle growth from relative humidity. Because the GOCART model is driven by previously assimilated meteorology, these forward model radiances can be directly compared with the observed MODIS level-2 radiances. The offline assimilation system simply adjusts the aerosol loading in the GOCART model so that the observed minus forward model radiances agree. Minimal change is made to the GOCART aerosol vertical distribution, size distribution, and the ratio of the five different aerosol types. The loading in the GOCART model is updated with new MODIS observations every 6 h. Since the previously assimilated meteorology provides surface wind speed, radiance sensitivity to wind speed over rough ocean is taken into account. Over land the dark target approach, also used by the MODIS–atmosphere group retrieval, is used. If the underlying land surface is deemed dark enough, the surface reflectances at the 0.47- and 0.66-μm wavelengths are constant multiples of the observed 2.13-μm reflectance. Over ocean the assimilation AOD compares well with AERONET, over land less so. The results herein are also compared with AERONET-retrieved single-scattering albedo. This research is part of an ongoing effort at NASA Goddard to integrate aerosols into the Goddard Modeling and Assimilation Office (GMAO) products.

scholarly journals Validation and Development of Melting Layer Models Using Constraints by Active/Passive Microwave Observations of Rain and the Wind-Roughened Ocean Surface

2007 ◽  
Vol 24 (4) ◽  
pp. 543-563 ◽  
Author(s):  
Shannon T. Brown ◽  
Christopher S. Ruf
Keyword(s):  
Wind Speed ◽  
Brightness Temperature ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Forward Model ◽  
Dual Frequency ◽  
Layer Model ◽  
Atmospheric Absorption ◽  
Melting Layer ◽  
Stratiform Rain

Abstract A physically based method is developed to estimate the microphysical structure of the melting layer in stratiform rain using airborne observations by a dual-frequency radar and a 10.7-GHz radiometer. The method employs a nonlinear optimal estimation approach to find two parameters of the gamma drop size distribution (DSD) at each radar range gate from the Ku/Ka-band reflectivities. The DSD profile is used to determine the atmospheric absorption/extinction profile, which enables the surface contribution to the measured brightness temperature to be estimated. The surface wind speed is estimated from the surface emissivity by inverting the forward model, which relates the two. Retrievals in stratiform precipitation require a model to describe the thermodynamic and electromagnetic properties of melting hydrometeors. The melting layer can contribute a majority of the total atmospheric absorption, making it a key component for accurate retrievals in stratiform rain. Several melting layer models were evaluated based on their fit to the dual-frequency reflectivity measurements in the melting layer. A candidate model is selected and tuned to match the radar measurements. The melting layer model is then incorporated into the full forward model for the brightness temperature observed by the radiometer. The surface wind speed assumed in the forward model is forced by the radiometer observations. If the actual surface wind speed is known, this approach provides a powerful constraint on the possible melting layer model. A case study is presented from an airborne campaign over areas of precipitation off the coast of Vancouver Island, British Columbia, Canada. The estimated wind speeds are found to be uncorrelated with the reflectivity and their average value is within 1 m s−1 of that retrieved in a clear area adjacent to the rain.

scholarly journals Aerosol Effective Radiative Forcing in the Online Aerosol Coupled CAS-FGOALS-f3-L Climate Model

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1115
Author(s):  
Hao Wang ◽  
Tie Dai ◽  
Min Zhao ◽  
Daisuke Goto ◽  
Qing Bao ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Transport Model ◽  
Radiation Transport ◽  
Coupled Model ◽  
Global Ocean ◽  
Spectral Radiation ◽  
Anthropogenic Aerosol ◽  
Aerosol Cloud ◽  
Effective Radiative Forcing

The effective radiative forcing (ERF) of anthropogenic aerosol can be more representative of the eventual climate response than other radiative forcing. We incorporate aerosol–cloud interaction into the Chinese Academy of Sciences Flexible Global Ocean–Atmosphere–Land System (CAS-FGOALS-f3-L) by coupling an existing aerosol module named the Spectral Radiation Transport Model for Aerosol Species (SPRINTARS) and quantified the ERF and its primary components (i.e., effective radiative forcing of aerosol-radiation interactions (ERFari) and aerosol-cloud interactions (ERFaci)) based on the protocol of current Coupled Model Intercomparison Project phase 6 (CMIP6). The spatial distribution of the shortwave ERFari and ERFaci in CAS-FGOALS-f3-L are comparable with that of most available CMIP6 models. The global mean 2014–1850 shortwave ERFari in CAS-FGOALS-f3-L (−0.27 W m−2) is close to the multi-model means in 4 available models (−0.29 W m−2), whereas the assessing shortwave ERFaci (−1.04 W m−2) and shortwave ERF (−1.36 W m−2) are slightly stronger than the multi-model means, illustrating that the CAS-FGOALS-f3-L can reproduce the aerosol radiation effect reasonably well. However, significant diversity exists in the ERF, especially in the dominated component ERFaci, implying that the uncertainty is still large.

scholarly journals Regional air pollution and its radiative forcing: Studies with a single-column chemical and radiation transport model

2001 ◽  
Vol 106 (D22) ◽  
pp. 28751-28770 ◽  
Author(s):  
R. J. Park ◽  
G. L. Stenchikov ◽  
K. E. Pickering ◽  
R. R. Dickerson ◽  
D. J. Allen ◽  
...  
Keyword(s):  
Air Pollution ◽  
Radiative Forcing ◽  
Transport Model ◽  
Radiation Transport ◽  
Single Column ◽  
Radiation Transport Model ◽  
Regional Air Pollution

scholarly journals Effect of Vertical Profile of Aerosols on the Local Shortwave Radiative Forcing Estimation

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 187
Author(s):  
Francisco Molero ◽  
Alfonso Javier Fernández ◽  
María Aránzazu Revuelta ◽  
Isabel Martínez-Marco ◽  
Manuel Pujadas ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Vertical Profile ◽  
Radiative Forcing ◽  
Accurate Information ◽  
Optical Parameters ◽  
Aerosol Radiative Forcing ◽  
Radiative Forcings ◽  
Lidar Measurements ◽  
Aerosol Types ◽  
Aerosol Radiative

In this work, the effect of the aerosol vertical distribution on the local shortwave aerosol radiative forcing is studied. We computed the radiative forcing at the top and bottom of the atmosphere between 0.2 and 4 microns using the libRadTran package and compared the results with those provided by AERONET (AErosol RObotic NETwork). Lidar measurements were employed to characterize the aerosol vertical profile, and collocated AERONET measurements provided aerosol optical parameters required to calculate its radiative forcing. A good correlation between the calculated radiative forcings and those provide by AERONET, with differences smaller than 1 W m−2 (15% of estimated radiative forcing), is obtained when a gaussian vertical aerosol profile is assumed. Notwithstanding, when a measured aerosol profile is inserted into the model, differences between radiative forcings can vary up to 6.54 W m−2 (15%), with a mean of differences = −0.74 ± 3.06 W m−2 at BOA and −3.69 W m−2 (13%), with a mean of differences = −0.27 ± 1.32 W m−2 at TOA due to multiple aerosol layers and aerosol types. These results indicate that accurate information about aerosol vertical distribution must be incorporated in the radiative forcing calculation in order to reduce its uncertainties.

scholarly journals Global NO<sub>x</sub> emission estimates derived from an assimilation of OMI tropospheric NO<sub>2</sub> columns

2012 ◽  
Vol 12 (5) ◽  
pp. 2263-2288 ◽  
Author(s):  
K. Miyazaki ◽  
H. J. Eskes ◽  
K. Sudo
Keyword(s):  
Data Assimilation ◽  
Radiative Forcing ◽  
Transport Model ◽  
A Priori ◽  
Eastern China ◽  
Atmospheric Environment ◽  
Nox Emissions ◽  
Tropospheric No2 ◽  
Data Assimilation System ◽  
Assimilation System

Abstract. A data assimilation system has been developed to estimate global nitrogen oxides (NOx) emissions using OMI tropospheric NO2 columns (DOMINO product) and a global chemical transport model (CTM), the Chemical Atmospheric GCM for Study of Atmospheric Environment and Radiative Forcing (CHASER). The data assimilation system, based on an ensemble Kalman filter approach, was applied to optimize daily NOx emissions with a horizontal resolution of 2.8° during the years 2005 and 2006. The background error covariance estimated from the ensemble CTM forecasts explicitly represents non-direct relationships between the emissions and tropospheric columns caused by atmospheric transport and chemical processes. In comparison to the a priori emissions based on bottom-up inventories, the optimized emissions were higher over eastern China, the eastern United States, southern Africa, and central-western Europe, suggesting that the anthropogenic emissions are mostly underestimated in the inventories. In addition, the seasonality of the estimated emissions differed from that of the a priori emission over several biomass burning regions, with a large increase over Southeast Asia in April and over South America in October. The data assimilation results were validated against independent data: SCIAMACHY tropospheric NO2 columns and vertical NO2 profiles obtained from aircraft and lidar measurements. The emission correction greatly improved the agreement between the simulated and observed NO2 fields; this implies that the data assimilation system efficiently derives NOx emissions from concentration observations. We also demonstrated that biases in the satellite retrieval and model settings used in the data assimilation largely affect the magnitude of estimated emissions. These dependences should be carefully considered for better understanding NOx sources from top-down approaches.

scholarly journals Dust aerosols over India and adjacent continents retrieved using METEOSAT infrared radiance Part II: quantification of wind dependence and estimation of radiative forcing

2006 ◽  
Vol 24 (1) ◽  
pp. 63-79 ◽  
Author(s):  
S. Deepshikha ◽  
S. K. Satheesh ◽  
J. Srinivasan
Keyword(s):  
Soil Moisture ◽  
Wind Speed ◽  
Radiative Forcing ◽  
Surface Wind ◽  
Dust Production ◽  
Dust Aerosols ◽  
Infrared Radiance ◽  
Source Regions ◽  
Dust Events

Abstract. Long-range transport of continental dust makes these particles a significant constituent even at locations far from their sources. It is important to study the temporal variations in dust loading over desert regions and the role of meteorology, in order to assess its radiative impact. In this paper, infrared radiance (10.5-12.5 µm), acquired by the METEOSAT-5 satellite (~5-km resolution) during 1999 and 2003 was used to quantify wind dependence of dust aerosols and to estimate the radiative forcing. Our analysis shows that the frequency of occurrence of dust events was higher during 2003 compared to 1999. Since the dust production function depends mainly on the surface wind speed over regions which are dry and without vegetation, the role of surface wind on IDDI was examined in detail. It was found that an increase of IDDI with wind speed was nearly linear and the rate of increase in IDDI with surface wind was higher during 2003 compared to 1999. It was also observed that over the Indian desert, when wind speed was the highest during monsoon months (June to August), the dust production rate was lower because of higher soil moisture (due to monsoon rainfall). Over the Arabian deserts, when the wind speed is the highest during June to August, the dust production rate is also highest, as soil moisture is lowest during this season. Even though nothing can be said precisely on the reason why 2003 had a greater number of dust events, examination of monthly mean soil moisture at source regions indicates that the occurrence of high winds simultaneous with high soil moisture could be the reason for the decreased dust production efficiency in 1999. It appears that the deserts of Northwest India are more efficient dust sources compared to the deserts of Saudi Arabia and Northeast Africa (excluding Sahara). The radiative impact of dust over various source regions is estimated, and the regionally and annually averaged top of the atmosphere dust radiative forcing (short wave, clear-sky and over land) over the entire study region (0-35° N; 30°-100° E) was in the range of -0.9 to +4.5 Wm-2. The corresponding values at the surface were in the range of -10 to -25 Wm-2. Our studies demonstrate that neglecting the diurnal variation of dust can cause errors in the estimation of long wave dust forcing by as much as 50 to 100%, and nighttime retrieval of dust can significantly reduce the uncertainties. A method to retrieve dust aerosols during nighttime is proposed. The regionally and annually averaged long wave dust radiative forcing was +3.4±1.6 Wm-2.

scholarly journals Effects of sea surface winds on marine aerosols characteristics and impacts on longwave radiative forcing over the Arabian Sea

2008 ◽  
Vol 8 (4) ◽  
pp. 15855-15899 ◽  
Author(s):  
Vijayakumar S. Nair ◽  
S. Suresh Babu ◽  
S. K. Satheesh ◽  
K. Krishna Moorthy
Keyword(s):  
Wind Speed ◽  
Radiative Forcing ◽  
Arabian Sea ◽  
Near Infrared ◽  
Surface Wind ◽  
Sea Surface ◽  
Surface Winds ◽  
Near Surface ◽  
Sea Surface Winds ◽  
Direct Radiative Forcing

Abstract. Collocated measurements of spectral aerosol optical depths (AODs), total and BC mass concentrations, and number size distributions of near surface aerosols, along with sea surface winds, made onboard a scientific cruise over southeastern Arabian Sea, are used to delineate the effects of changes in the wind speed on aerosol properties and its implication on the shortwave and longwave radiative forcing. The results indicated that an increase in the sea-surface wind speed from calm to moderate (<1 to 8 m s−1) values results in a selective increase of the particle concentrations in the size range 0.5 to 5 μm, leading to significant changes in the size distribution, increase in the mass concentration, decrease in the BC mass fraction, a remarkable increase in AODs in the near infrared and a flattening of the AOD spectrum. The consequent increase in the longwave direct radiative forcing almost entirely offsets the corresponding increase in the short wave direct radiative forcing (or even overcompensates) at the top of the atmosphere; while the surface forcing is offset by about 50%.

scholarly journals Aerosol forecast over the Mediterranean area during July 2013 (ADRIMED/CHARMEX)

2015 ◽  
Vol 15 (14) ◽  
pp. 7897-7911 ◽  
Author(s):  
L. Menut ◽  
G. Rea ◽  
S. Mailler ◽  
D. Khvorostyanov ◽  
S. Turquety
Keyword(s):  
Wind Speed ◽  
Mediterranean Region ◽  
Transport Model ◽  
Mineral Dust ◽  
Regional Climate ◽  
Surface Wind ◽  
Dust Emission ◽  
Mediterranean Area ◽  
Atmospheric Composition ◽  
The Mediterranean

Abstract. The ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) project was dedicated to study the atmospheric composition during the summer 2013 in the European Mediterranean region. During its campaign experiment part, the WRF (Weather Research and Forecast Model) and CHIMERE models were used in the forecast mode in order to decide whether intensive observation periods should be triggered. Each day, a simulation of 4 days was performed, corresponding to (D-1) to (D+2) forecast leads. The goal of this study was to determine whether the model forecast spread is lower or greater than the model biases compared to observations. It is shown that the differences between observations and the model are always higher than those between the forecasts. Among all forcing types used in the chemistry-transport model, it is shown that the strong bias and other related low forecast scores are mainly due to the forecast accuracy of the wind speed, which is used both for the mineral dust emissions (a threshold process) and for the long-range transport of aerosol: the surface wind speed forecast spread can reach 50%, leading to mineral dust emission forecast spread of up to 30%. These variations are responsible for a moderate forecast spread of the surface PM10 (a few percentage points) and for a large spread (more than 50%) in the mineral dust concentration at higher altitudes, leading to a mean AOD (aerosol optical depth) forecast spread of ±10%.

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