In order to examine the effect of Asian dusts and apply to retrieval of dust properties, radiances measured by AIRS were
simulated using the RTTOV-9 model. The model has been implemented with new optical properties for Asian dusts;
refractive indices of mineral dust in the OPAC library and size distribution of Asian dusts retrieved from 10 years of
skyradiometer measurements at Dunhuang, China. The simulations were performed using the implemented model, but
with specification of AOT and height of dust layers obtained from CALIOP measurements. In the simulations, surface
and atmospheric temperatures are from AIRS level 2 products while surface emissivity is specified with UW/CIMSS
monthly mean global infrared surface emissivity data. Results show that effect of Asian dusts on AIRS spectra is
substantial over infrared window regions (i.e.: 3.7 - 4.1 μm, 8.8 - 9.3 μm, 10 - 13 μm) for moderate and strong dust
cases (AOT ≥ 0.5), while surface effect is dominant for weak dust cases (AOT < 0.5). Over 10 - 13 μm and 3.6 - 4.1 μm
ranges, the simulation performances are improved when the dust effect is added. However, on the spectral range of 8.8 - 9.3 μm, the simulation overestimates radiances in comparison with AIRS measurements, probably because the mineral
dust composition of OPAC does not coincide with the Asian dust. The comparison of simulated radiances with AIRS
measurements shows a comparable quality for both clear and dusty conditions on the 10 - 13 μm and 3.6 - 4.1 μm
ranges, suggesting that results can be incorporated for developing dust retrieval algorithm from hyperspectral images
such as AIRS and IASI.
Temperature and moisture profiles retrieved from Infrared Atmospheric Sounding Interferometer (IASI) were evaluated
by using radiosonde observations and model forecasts over East Asia. We used the level 2 products provided by National
Oceanic and Atmospheric Administration/National Environmental Satellite, Data, and Information Service
(NOAA/NESDIS) for IASI retrievals. Numerical model outputs from Regional Data Assimilation and Prediction System
(RDAPS), Korea Weather Research and Forecasting (KWRF), and UK Met Office model (UM) were also matched with
the satellite and radiosonde profiles for examining the model performances, in comparison with satellite data. The
statistics of temperature and water vapor profiles were calculated by using the collocated radiosonde measurements as a
reference. Both of temperature and moisture retrievals from satellite showed degraded performances over land and in dry
conditions. Moist bias of the lower-troposphere is significant in dry condition especially over land, whereas dry bias of
the mid-troposphere is significant in moist condition both over land and ocean. Based on the validation results, we
discuss which factors can contribute to the improvement of the retrieval results over East Asia.
Based on the comparison of TMI measurements and the AWS rain rates, characteristics of rain systems over the Korean
Peninsula during summer were examined. It was found that the TMI brightness temperatures (TBs) at high frequency (85
GHz) are generally higher than those in GPROF database for the same rain rate. With these characteristics kept in mind,
cloud resolving model simulations were performed by modifying intercept values in the Marshall-Palmer size
distribution relationship. The intercept values of graupel and snow were assumed to twice the default value (snow: 1.0 ×
108 m-4, Graupel: 4.0 × 106 m-4).
Microwave brightness temperatures at passive microwave radiometer frequencies and vertical reflectivity at precipitation
radar frequency are calculated by repeated application of the one-dimensional version of Eddington's approximation1.
The hydrometeor profiles were selected by comparing with TRMM PR reflectivities. By adding those selected profiles to
the convective profiles of GPROF database, we modified database for the rain retrieval over the Korean Peninsula.
Rainfall retrievals by using the new database show that quality is significantly improved, indicating the need of
algorithm locally more suitable.
The Korean Geostationary satellite (COMS) to fly in year 2009 will carry a meteorological sensor from which visible
channel measurements will be available. We developed a method utilizing satellite-derived BRDFs for the solar channel
calibration over the bright desert area. The 6S model has been incorporated to account for directional effects of the
surface using MODIS-derived BRDF parameters within the spectral interval in interest. Simulated radiances over the
desert targets were compared with MODIS and SeaWiFS measured spectral radiances in order to examine the feasibility
of the developed calibration algorithm. It was shown that simulated 16-day averaged radiances are in good agreement
with the satellite-measured radiances within about ±5% uncertainty range for the year 2005, suggesting that the
developed algorithm can be used for calibrating the COMS visible channel within about 5% uncertainty level.
The presentation focuses on the peculiarity of Asian waters with respect to the atmospheric correction of the satellite ocean color data such as of Ocean Color and Temperature Scanner (OCTS). We first demonstrate the effect of highly turbid case 2 waters on the atmospheric correction via non- zero water reflectance in the near infrared region. The results of applying the OCTS standard correction scheme to typical Chinese coastal OCTS scenes reveal that a significant portion of the area is masked due to the negative water reflectance retrieved by the scheme, even using 765 nm and 865 nm bands instead of 670 and 865 nm pair to determine aerosol contribution. An optical model that relates suspended solid (SS) and chlorophyll-a (Chl-a) concentrations to the near infrared water reflectances was implemented into the atmospheric correction, together with a neural network that estimates Chl-a and SS concentrations. The new iterative scheme is applied to the Chinese coastal scenes and the results are assessed to be favorable. The paper then discuss the modeling of Asian dust aerosol in hope of establishing aerosol models that can be used for atmospheric correction. A set of models are designed with varying controlling parameters such as size distribution, vertical profile, and imaginary part of the refractive index. A series of radiative transfer simulation is conducted and the spectrum of the top-of- atmosphere radiance is compared to that of a Sea Wide Filed- of-view Scanner (SeaWiFS) data obtained under Asian dust event. The results of the comparison suggest that the Asian dust aerosol has unique spectral absorption feature at the blue region (in 412 nm band, i.e.).
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