A3: ID.10529 Atmospheric Dynamics &Cities
Wednesday, 06/Jul/2016:
10:30am - 11:30am

Session Chair: Erkki Kyrölä
Session Chair: Yi Liu
Workshop: Atmosphere & Climate
Location: Lecture Hall, 2nd Floor, LIESMARS, Wuhan University

Oral presentation

Retrieval of Aerosol Optical Depth and Land Surface Reflectance from FY3/MERSI

Yong Xue1, Chen Fan2, Jie Guang2

1London Metropolitan University, United Kingdom; 2RADI, CAS

Medium Resolution Spectral Imager (MERSI), which enables images of the Earth with high spatial resolution and high temporal resolution, is an important sensor carried by on-orbit Chinese polar orbiting meteorological satellite Feng-Yun (FY-3). A new synergistic approach for retrieving BRDF (Bi-directional Reflectance Distribution Function) and aerosol optical depth (AOD) is developed. This new model was applied to FY3A/MERSI and FY3B/MERSI for retrieving AOD and surface reflectance over land in China. Results show that the correlation coefficients (R) between retrieved AOD from FY3 and AERONET sites is 0.68 at 550 nm. Therefore, FY-3/MERSI can serve a reliable and new data source for quantifying global environmental change.

Xue-Retrieval of Aerosol Optical Depth and Land Surface Reflectance_Cn_version.pdf

Oral presentation

Implementation Of The New Approach For The Dose-Response Functions Development For The Case Of Athens And Greece

Ioannis Christodoulakis, Christos G. Tzanis, Costas A. Varotsos, Giorgos Kouremadas

National & Kapodistrian University of Athens, Greece

Dose-response functions (DRFs) are functions used for estimating corrosion and/or soiling levels of materials used in constructions and cultural monuments. In order to achieve this, DRFs lean on ground-based measurements of specific air pollution and climatic parameters like nitrogen oxides, ozone, temperature and others. In DRAGON 3 2015 Symposium we presented a new approach which proposed a technique for using satellite-based data for the necessary parameters instead of ground-based expanding in this way: a) the usage of DRFs in cases/areas where there is no availability of in situ measurements, b) the applicability of satellite-based data. In this work we present mapping results of deterioration levels (corrosion and soiling) for the case of Athens, Greece but also for the whole Greece country.

Christodoulakis-Implementation Of The New Approach For The Dose-Response Functions Development For The Case_Cn_version.pdf

Oral presentation

Image fusion of AATSR AOD products based on the maximum likelihood estimate method

Yong Xue2, Yanqing Xie1

1London Metropolitan University, United Kingdom; 2RADI, CAS

The traditional station measurement of aerosol optical depth (AOD) is currently widely employed. But this traditional approach has limitations with respect to wide-range coverage and spatial continuity. Comparing with traditional station observation, satellite remote sensing provides a possibility to high frequency monitor continuously spatial coverage of AOD (Xue et al., 2014). Based on these advantages, satellite measurements are widely applied to the monitoring of aerosol AOD in recent decades. However, the values of the AOD provided by different satellites show spatial and temporal differences due to the instrument characteristics and aerosol retrieval algorithms used for each instrument (Xu et al., 2015). This greatly limits its application in the direction of climate change and quantitative remote sensing. Through fusion of image from different remote sensors and methods, we can improve the image spatial coverage of valid values and accuracy, and further improve its application range (Xu et al., 2015).

In this paper, we use the maximum likelihood method to determine the weights of various images involved in fusion to produce an Asian regional AOD data set in 2008 based on three AOD products: ADV, ORAC and SU that obtained from the Advanced Along-Track Scanning Radiometer (AATSR) according to the error size of each pixel. First of all, we compare the values of various products with the ground observation values obtained from the Aerosol Robotic Network (AERONET) and the China Aerosol Remote Sensing Network (CARSNET) to determine the error size of the pixels of the various products. Then, we study and determine the relationship between the values of the remote sensing observations and the value and surface albedo, so as to determine the error size of the observation value in the absence of the ground sensing station. Finally, we determine the weight of the fusion according to the root mean square error of the different products (Xu et al., 2015).

After comparing the original data and the fused data with the CARSNET observations, we find that the absolute error of the fused image is smaller than any of the original data. Meanwhile, the proportion of the fused AOD image with valid value is greatly large than any of the original products. Thus, the fusion increases the spatial coverage.

Xue-Image fusion of AATSR AOD products based on the maximum likelihood estimate method_Cn_version.pdf

Oral presentation

Validation and comparison of AATSR AOD L2 products over china

Yong Xue2, Yahui Che1

1London Metropolitan University, United Kingdom; 2RADI, CAS

The Advanced Along-Track Scanning Radiometer (AATSR) aboard on ENVISAT has been used to observe the Earth for more than 10 years since than 2002. One of main applications of AATSR instrument is to observe atmospheric aerosol, especially in retrieval of aerosol optical depth (AOD), taking advantage of its dual-view that helps to separate the contribution of aerosol from top of atmosphere reflectance. The project of Aerosol_CCI, as part of European Space Agency's Climate Change Initiative (CCI), has released new AATSR aerosol AOD products by the of 2015, including the SU v4.21 product from Swansea algorithm, ADV v2.3 product from the ATSR-2/AATSR dual view aerosol retrieval algorithm (ADV) and ORAC v03.04 product from the Oxford-RAL Retrieval of Aerosol and Cloud algorithm. In this paper, we validated these AATSR AOD products with latest versions in mainland China in 2007, 2008 and 2010 by the means of comparison with the AErosol RObotic NETwork (AERONET) and the China Aerosol Remote Sensing Network (CARSNET). The combination of AERONET and CARSNET helps to make up for the disadvantages of small number and uneven distribution of AEROENT cites. The validation results show different performance of these AOD products over China. The performances of SU and ADV products seem to be the same with close correlation coefficient (CC) about 08~0.9 and root mean square (RMS) within 0.15 in all three years, and sensitive to high AOD values (AOD >1): more AODs and more underestimated. However, these two products do exist difference, which is that the SU algorithm retrieves more high AODs, leading to more space-time validation matches with ground-based data. The ORAC algorithm is different from the others, it can be not only used to retrieve low AODs but also high AODs over different land cover types. Even though ORAC algorithm has ability in retrieving AODs in different values, it shows largest uncertainty in retrieving different AODs.

Xue-Validation and comparison of AATSR AOD L2 products over china_Cn_version.pdf


Total Ozone Dynamics Over Athens, Greece And Beijing, China

Christos G. Tzanis, Ioannis Christodoulakis, Panagiotis K. Varotsos

National & Kapodistrian University of Athens, Greece

We present the analysis of total ozone daily values, over Athens, Greece, and Beijing, China, for the period 2002–2012. The data for the analysis were derived from SCIAMACHY (ENVISAT) observations. The aim of the analysis is the identification of time scaling in the total ozone time series, by using a data analysis technique that would not be affected by the non-stationarity of the data. The appropriate technique satisfying this criterion is the Detrended Fluctuation Analysis (DFA), which stems from random walk theory and permits the detection of intrinsic self-similarity in non-stationary time series. For the deseasonalization of time series the classic Wiener method is applied.

Tzanis-Total Ozone Dynamics Over Athens, Greece And Beijing, China_Cn_version.pdf


Study Of The Impact Of Clouds And Aerosol Loading On The Radiative Forcing At Athens, Greece And Beijing, China

Ioannis Christodoulakis, Christos G. Tzanis, Panagiotis K. Varotsos, Kapsalis Nikos

National & Kapodistrian University of Athens, Greece

We present a study of the impact of clouds and aerosol loading on the radiative forcing at two different places, Athens, Greece and Beijing, China lying in the same latitudinal zone. Aerosol loading data were derived from Along Track Scanning Radiometer-2 (ATSR2) on board European Remote Sensing Satellite-2 (ERS-2) and Advanced Along-Track Scanning Radiometer (AATSR) on board ENVIronmental SATellite (ENVISAT) through ESA Aerosol CCI database for the period 2000-2012. Monthly mean energy fluxes data at the top of the atmosphere and the surface were derived from Clouds and the Earth's Radiant Energy System (CERES) for the period 2000-2015.

Christodoulakis-Study Of The Impact Of Clouds And Aerosol Loading_Cn_version.pdf