Many people in Asia regions have been suffering from disastrous rainfalls year by year. The rainfall from typhoons or tropical cyclones (TCs) is one of their key water supply sources, but from another perspective such TCs may also bring forth unexpected heavy rainfall, thereby causing flash floods, mudslides or other disasters. So far we cannot stop or change a TC route or intensity via present techniques. Instead, however we could significantly mitigate the possible heavy casualties and economic losses if we can earlier know a TC’s formation and can estimate its rainfall amount and distribution more accurate before its landfalling. In light of these problems, this short article presents methods to detect a TC’s formation as earlier and to delineate its rainfall potential pattern more accurate in advance. For this first part, the satellite-retrieved air-sea parameters are obtained and used to estimate the thermal and dynamic energy fields and variation over open oceans to delineate the high-possibility typhoon occurring ocean areas and cloud clusters. For the second part, an improved tropical rainfall potential (TRaP) model is proposed with better assumptions then the original TRaP for TC rainfall band rotations, rainfall amount estimation, and topographic effect correction, to obtain more accurate TC rainfall distributions, especially for hilly and mountainous areas, such as Taiwan.
Long range transport leads mineral dusts to internally/externally mix with the ambient aerosols, such as soot particles,
naturally. The physicochemical characteristics of dust particles thus are dramatically altered after mixing with soot
aggregates. Therefore, the investigation on the optical properties of mineral dust along with their pathway causes a
significant topic for understanding the impacts of Asian dust storm on regional air quality, environment and climate.
Unfortunately, the previous researches regarding to the optical properties of dust/soot mixture for satellite remote sensing
are scarce. Consequently, the objective of this study is to simulate the effects of mixing with soot aggregates on the
optical properties of dust particles for satellite observations based on the well developed models. A tri-axial ellipsoidal
model for dust particles by introducing the third morphological freedom to improve the symmetry of spheroids has been
developed and showed in good agreement for the retrievals of dust optical properties from remote sensing measurements
and ground based observations. For the model of soot aggregation, the scattering properties of fractal aggregates can be
obtained with the Rayleigh-Debye-Gans (RDG), superposition T-matrix and Generalized Multiple Mie (GMM) methods.
The results show that the AOD (aerosol optical depth) retrievals of dust particle will be underestimated while the SSA
(single scattering albedo) will be overestimated when neglecting the combination of soot aggregates. The simulations
also suggest that simultaneously retrieve AOD and SSA based on the apparent reflectance may induce large uncertainty
for the dust/soot mixtures.
The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument is considered a very versatile tool in studying environmental changes. The multi-spectral sensor owns a high revisit period, a large scanning area, plus a handful of other advantages. The main purpose of this study is to employ reflectance data retrieved by the MODIS sensor in detecting smoke plumes, estimating their respective intensity and retrieving the AOD (Aerosol Optical Depth). Specifically, in the detection of the smoke plumes, biomass burning cases are studied in delineating the reflective characteristics. Following the detection, the Deep-Blue Aerosol Index (DAI) is utilized to evaluate the intensity. Relevant AOD information is retrieved by analyzing the relationship between the DAI and AOD. Results show a high correlation between the satellite-retrieved AOD and Sun Photometer-observed AOD data, thus demonstrating the feasibility in obtaining the aerosol distribution over highly reflective areas. As the proposed approach in this study is capable of accurately portraying the spatial distribution and intensity of smoke plumes, it can be effectively used in monitoring biomass burning hazards.
Conference Committee Involvement (2)
Remote Sensing of Aerosol and Chemical Gases, Model Simulation/Assimilation, and Applications to Air Quality
13 August 2006 | San Diego, California, United States
Remote Sensing in Atmospheric Pollution Monitoring and Control