Anu-Maija Sundström

Finnish Meteorological Institute · Earth Observation Programme

In this work satellite observations from the NASA's A-Train constellation were used to derive the values of primary emission and regional nucleation proxies over South Africa to estimate the potential for new particle formation. As derived in Kulmala et al. (2011), the satellite based proxies consist of source terms (NO2, SO2 and UV-B radiation), a...

We describe a height estimate algorithm based on radiances measured at the top of the atmosphere (TOA) by the Advanced Along Track Scanning Radiometer (AATSR) aboard the ENVISAT satellite. The algorithm is designed to estimate volcanic ash plume top heights, but it can be used for other high contrast features as well, such as dust and smoke plumes,...

During the COVID-19 lockdown, the dramatic reduction of anthropogenic emissions provided a unique opportunity to investigate the effects of reduced anthropogenic activity and primary emissions on atmospheric chemical processes and the consequent formation of secondary pollutants. Here, we utilize comprehensive observations to examine the response o...

Atmospheric aerosols have significant effects on human health and the climate. A large fraction of these aerosols originates from secondary new particle formation (NPF), where atmospheric vapors form small particles that subsequently grow into larger sizes. In this study, we characterize NPF events observed at a rural background site of Hada Al Sha...

Although increased aerosol concentration modifies local air temperatures and boundary layer structure in urban areas, little is known about its effects on the urban hydrological cycle. Changes in the hydrological cycle modify surface runoff and flooding. Furthermore, as runoff commonly transports pollutants to soil and water, any changes impact urb...

Atmospheric aerosols have significant effects on human health and the climate. A large fraction of these aerosols originates from secondary new particle formation (NPF), where atmospheric vapors form small particles that subsequently grow into larger sizes. In this study, we characterize NPF events observed at a rural background site of Hada Al Sha...

Although, air pollution modifies local air temperatures and boundary layer structure in urban areas, little is known about its effects on the urban hydrological cycle. To explore this, changes in the urban surface water balance during different haze levels are modelled in Beijing using the Surface Urban Energy and Water Balance Scheme (SUEWS), forc...

Climate-aerosol model ECHAM5-HAM is employed to study effects of aerosol air pollution on rainfall in southern Africa. Aerosols effect the climate through light scattering and absorption, modification of cloud properties, and other indirect effects. The simulation model simulates the global climate on a grid and aerosol emissions from all major eco...

Pyrometallurgical smelters consume significant amounts of fossil fuels. Notwithstanding emission abatement technologies, these smelters emit various gaseous pollutants and fine particulate matter, which are important from an air quality perspective. Additionally, carbon dioxide (CO2) and black carbon (BC), the two most important atmospheric climate...

Aerosol–cloud interactions are the largest source of uncertainty in the radiative forcing of the global climate. A phenomenon not included in the estimates of the total net forcing is the potential increase in upper tropospheric humidity (UTH) by anthropogenic aerosols via changes in the microphysics of deep convection. Using remote sensing data ov...

Aerosol-cloud interactions are the largest source of uncertainty in the radiative forcing of the global climate. A phenomenon not included in the estimates of the total net forcing is the potential increase in upper tropospheric humidity (UTH) by anthropogenic aerosols via changes in the microphysics of deep convection. Using remote sensing data ov...

The Advanced Along-Track Scanning Radiometer (AATSR) on board the ENVISAT satellite is used to study aerosol properties. The retrieval of aerosol properties from satellite data is based on the optimized fit of simulated and measured reflectances at the top of the atmosphere (TOA). The simulations are made using a radiative transfer model with a var...

http://onlinelibrary.wiley.com/wol1/doi/10.1002/2014JD022792/abstract The single-scattering properties of volcanic ash particles are modeled here by using ellipsoidal shapes. Ellipsoids are expected to improve the accuracy of the retrieval of aerosol properties using remote sensing techniques, which are currently often based on oversimplified assu...

In this study, a method is presented to retrieve the surface reflectance using the radiances measured at the top of the atmosphere for the two views provided by the Advanced Along-Track Scanning Radiometer (AATSR). In the first step, the aerosol optical depth (AOD) is obtained using the AATSR dual-view algorithm (ADV) by eliminating the effect of t...

A satellite-based approach to derive the aerosol direct shortwave (SW) radiative effect (ADRE) was studied in an environment with highly variable aerosol conditions over eastern China from March to October 2009. The method is based on using coincident SW top-of-the-atmosphere (TOA) fluxes from the Clouds and the Earth's Radiant Energy System (CERES...

In this work satellite observations from the NASA's A-Train constellation were used to derive the values of primary emission and regional nucleation proxies over South Africa to estimate the potential for new particle formation. As derived in Kulmala et al. (2011), the satellite based proxies consist of source terms (NO2, SO2 and UV-B radiation), a...

The retrieval of aerosol properties from satellite data is based on the optimized fit of simulated and measured radiances at the top of the atmosphere (TOA). The simulations are made using a radiative transfer model with a variety of representative aerosol properties.The optimum fit is obtained for a certain combination of aerosol components, which...

An algorithm is presented for the estimation of volcanic ash plume top height using the stereo view of the Advanced Along Track Scanning Radiometer (AATSR) aboard Envisat. The algorithm is based on matching top of the atmosphere (TOA) reflectances and brightness temperatures of the nadir and 55° forward views, and using the resulting parallax to ob...

Volcanic eruptions release ash in the atmosphere that may be transported over great distances. These particles impact atmospheric radiation transfer by absorbing, emitting and scattering electromagnetic radiation. While in the atmosphere, dust particles may interfere with aviation activities causing considerable economic losses. Remote detection an...

In this study, a method is presented to retrieve the surface reflectance using reflectance measured at the top of the atmosphere for the two views provided by the Along-Track Scanning Radiometer (AATSR). In the first step, the aerosol optical depth (AOD) is obtained using the AATSR dual view algorithm (ADV) by eliminating the effect of the surface...

A satellite-based approach to derive the aerosol direct short wave (SW) radiative effect (ADRE) was studied in an environment with highly variable aerosol conditions over Eastern China from March to October 2009. The method is based on using coincident SW Top of the Atmosphere (TOA) fluxes from the Clouds and the Earth's Radiant Energy System (CERE...

An algorithm is presented for estimation of volcanic ash plume top height using the stereo view of the Advanced Along Track Scanning Radiometer (AATSR) aboard ENVISAT. The algorithm is based on matching the top of atmosphere (TOA) reflectances and brightness temperatures of the nadir and 55° forward views, and using the resulting parallax to obtain...

In this work satellite based observations were used to estimate the concentration of nucleation mode aerosols over South Africa. The nucleation mode aerosols can not be detected directly with satellite instruments since they are much smaller than the optically active aerosols, hence the concentrations were estimated using proxies introduced by Kulm...

Aerosol particles have a significant effect on the Earth climate on regional and global scales by perturbing the radiation balance both directly due to scattering and absorption of solar radiation and indirectly due to their effect on cloud macroscopic and microphysical properties (IPCC 2007 [1]). One of the main contributors to the radiative effec...

The uncertainty associated with satellite-retrieved aerosol properties is needed when these data are used to constrain chemical transport or climate models by using data assimilation. Global uncertainty as provided by comparison with independent ground-based observations is usually not adequate for that purpose. Rather the per-pixel uncertainty is...

The quantification of aerosol radiative effects is complex and large uncertainties still exist, mainly due to the high spatial and temporal variation of the aerosol concentration and mass as well as their relatively short lifetime in the atmosphere. In this work a multi-sensor satellite based approach is studied for defining the direct short wave a...

Two or three consecutive daytime nucleation events followed by subsequent growth were observed in a polluted industrial and moderately-polluted rural environment in South Africa on 108 and 31 days, respectively, based on two years of measurement at each site. In order to describe and understand these observations we analysed particle size distribut...

Aerosol optical depth (AOD) has been retrieved over Finland, using the dual-view Advanced Along Track Scanning Radiometer (AATSR). The results are in good agreement with ground-based measurements. The background AOD value over Finland is very low and is about 0.06-0.08. AOD is higher in the air masses arrived to Southern Finland from Russia (0.33)...

Aerosols influence the radiative budget of the Earth-atmosphere system directly by scattering and absorbing solar and thermal infrared radiation, and indirectly by modifying the microphysical, and hence the radiative properties and lifetimes of clouds. However, the quantification of aerosol radiative effects is complex and large uncertainties still...

Satellites offer the opportunity to determine the spatial distribution of aerosol properties. In this study the AATSR (Advanced Along Track Scanning Radiometer) Dual View (ADV) algorithm is applied for observing aerosol optical depth (AOD) over Eastern China. A preliminary selection of representative aerosol models was made by a comparison of ADV r...

The retrieval of the optical properties of atmospheric aerosols is based on the measurement of earth reflectance by a satellite instrument. This is the so-called top-of-atmosphere (TOA) reflectance. The most common approach in the retrieval is to compare the measured and modeled reflectance. Both atmospheric and surface reflectance have to be taken...

Aerosol physical and optical properties were measured at two locations in Northern India during 2006–2010. The first measurement station was a background site in Mukteshwar, about 350 km northeast of New Delhi, in the foothills of the Indian Himalayas. The second measurement site was located in Gual Pahari, about 25 km south of New Delhi. At both s...

A climate-aerosol model is employed to study spatial and temporal variability of aerosol properties over India and China for recent (year 2006) and future conditions (year 2020) under different emission pathways. We present results for aerosol mass concentration in different size classes and optical properties for the five different aerosol species...

Aerosol physical and optical properties were measured at two locations in northern India. The first measurement station was a background site in Mukteshwar, about 350 km northeast of New Delhi, in the foothills of the Indian Himalayas, with data from 2006 to 2009. The second measurement site was located in Gual Pahari, about 25 km south of New Delh...

A climate-aerosol model is employed to study spatial and temporal variability of aerosol properties over India and China for recent (year 2006) and future conditions (year 2020) under different emission pathways. We present results for aerosol mass concentration in different size classes and optical properties for the five different aerosol species...

Climate is significantly influenced by the distribution of aerosol particles in the atmosphere. The characteristics which influence climate must be considered on a global scale. Satellites provide a way to obtain information on atmospheric composition on regional and global scales. In particular the spatial distribution of aerosol parameters such a...

The increase of anthropogenic pollutants in Asia is evident along with the continuously increasing population and strong economic growth. Several studies have shown, that the mean aerosol mass concentration can be well above national and international standards especially in the Asian mega cities, such as Shanghai, Beijing, and New Delhi. Large emi...

The AATSR Dual-View (ADV) algorithm employs the forward and nadir views of the Advanced Along Track Scanning Radiometer (AATSR). The AATSR instrument is on board the Envisat satellite. The measurement data that is used for the retrieval of atmospheric aerosol properties is the top-of-atmosphere (TOA) reflectance which is modeled as the sum of atmos...

The Eyjafjallajökull volcano erupted on 14 April 2010 and huge amounts of volcanic ash were ejected into the atmosphere. The ash cloud was transported to NW Europe, resulting in the closure of part of the European air space, which in turn had enormous financial consequences. Models were used to forecast the transport of the ash plume, but initially...

Aerosols produced over the African continent have important consequences for climate. In particular, large amounts of desert dust are produced over the Sahara and transported across the North Atlantic where desert dust deposition influences the eco system by iron fertilization, and further North over Europe with outbreaks as far as Scandinavia. Bio...

The objective of this work is to investigate whether a commercial ceilometer-type lidar can be used as a quantitative aerosol measurement instrument. To this end, lidar backscattering measurements are compared with exact theoretical calculations of backscattering, which are based on in situ-measured size distributions and account for uncertainties...

The AATSR dual-view algorithm has been developed for the retrieval of aerosol optical properties over land. The two views of AATSR, forward and near nadir, are utilized in the algorithm by assuming that the a ratio, the so-called k-ratio, of the ground reflectances of the views is independent of wavelelength. One way to test this assumption is to c...

The optical properties of urban aerosol particles are calculated using exact methods at 910 nm wavelength under different assumptions about particle composition and shape. Results show that spherical particles backscatter light on the average about 40 percent more than the corresponding nonspherical particles, the difference generally being larger...

Aerosols play an important role in climate and air quality. They have a direct effect on climate by scattering and/or absorbing the incoming solar radiation [Haywood and Boucher, 2000]. Reflection of solar radiation increases the atmospheric albedo, causing a negative radiative effect and therefore cooling of the atmosphere. On local scales absorbi...