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- Front Matter: Volume 7856
- Clouds and Precipitation
- Aerosols and Clouds
- Climate Remote Sensing and Modeling
- Monsoon and Tropical Cyclone Applications
- Poster Session
Front Matter: Volume 7856
Front Matter: Volume 7856
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This PDF file contains the front matter associated with SPIE
Proceedings Volume 7856, including the Title Page, Copyright
information, Table of Contents, and the Conference Committee listing.
Clouds and Precipitation
Daily precipitation analysis of using a dense network of rain gauges and satellite estimates over South Asia: quality control
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Precipitation data measured by rain gauges are important in validating estimates from satellite data and model simulation.
Gridded precipitation products based on rain-gauge data improve the accuracy of forecasts. However, it is not widely
understood that quality control is important in developing a rain-gauge-based precipitation product. In this study, we
present examples of abnormal precipitation data for South Asia found in the work of the Asian Precipitation-Highly
Resolved Observational Data Integration Towards Evaluation of the Water Resources (APHRODITE) project. We also
discuss the use of satellite-based estimates in the quality control of rain-gauge records.
Instantaneous vertical profiling of precipitation using passive microwave radiometers
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Several methods have been proposed to train microwave radiometers to retrieve precipitation rates estimated by a radar
which observed the same location at the same time. These radar-trained passive-microwave algorithms differ in the
quantities that are estimated: some estimate the vertically-integrated liquid water, while others estimate the near-surface
precipitation. Since it is no more or less credible to estimate the rain rate at the surface than it is to estimate the rain rate
at any discrete altitude, it is particularly interesting to quantify the accuracy with which vertical profiles of precipitation
can be estimated from a passive microwave radiometer, what the obstacles are, and what vertical resolution would be
achievable. To that end, we conducted several studies to 1) establish that the main impediment to the vertical profiling is
the unknown signature of the sea surface in the non-precipitating portions of the field of view, and 2) use surfaceinsensitive
principal components of the brightness temperatures to retrieve the vertical principal components of the
precipitation. We report on the results of our studies in the case of mid-latitudes regions, in the case of the Atlantic Inter-
Tropical Convergence Zone during May 2009 where we produced unique estimates that quantify the vertical structure of
the convection in which flight AF447 disappeared, and in the case of polar precipitation where the dearth of instruments
and the radiometrically cold frozen surface present additional challenges.
A principal component-based radiative transfer forward model (PCRTM) for vertically inhomogeneous cloud
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A principal-component based radiative transfer model (PCRTM) is developed for simulating the infrared spectral
radiance at the top of the atmosphere (TOA). The PCRTM approach removes the redundancy in radiative transfer
calculation in high-resolution infrared spectra, and saves significant amount of computational time with great accuracy.
In PCRTM, both ice and water clouds are treated as effective transmissivity and reflectivity stored in a pre-calculated
lookup tables. These quantities are calculated using cloud single scattering properties such as cloud optical depth, cloud
particle size, cloud phase, etc. The cloud can be inserted into any pressure layer in the PCRTM model (up to 100
layers). The effective temperature of each cloud layer is treated as a function of its optical depth. To test the accuracy of
this approximation, the results are compared with the more rigorous DISORT model, which treats cloud as plane parallel
layers. The root-mean-square error of PCRTM, with respect to DISORT results, is generally less than 0.4 K in brightness
temperature. However, the CPU time required by PCRTM was at least two orders of magnitude less than that required
by DISORT.
Detection of cirrus based on refractive index using MODIS data
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Cirrus is important in the energy balance of the earth-atmosphere system. Previous studies are based on the forward
models using the single scattering in the cirrus. In this study, we provide a unique method to detect the cirrus using the
polarized reflectivities, single-scattering, and optical properties of water and ice with Moderate Resolution Imaging
Spectrometer (MODIS) observations. Consequently, the polarized reflectivities at MODIS 1.375 μm channel show the
reasonable characteristics of the cirrus. The effective refractive indexes are retrieved approximately from 1.1 to 1.4. This
investigation provides an effective inversion procedure for detecting the cirrus using the physical characteristics in the
cirrus on the basis of the polarization and refractive index.
Aerosols and Clouds
Validation of the dust layer structure over the Taklimakan Desert, China, by the CALIOP space-borne lidar using ground-based lidar: Part II
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A ground-based lidar observation was carried out in the northwest of China to validate the space-borne lidar CALIOP on 23 - 25 March 2009. Combining backscatter profiles of the ground-based lidar and CALIOP, lidar ratio (extinction to backscattering ratio) was retrieved for 532nm and 1064nm wavelengths by using performance function that minimizing the difference between the ground-based lidar and CALIOP for backscattering coefficient. The correlation coefficients between them were 0.98 for 532nm and 0.95 1064nm, respectively. Using the retrieved lidar ratio, the color ratio and aerosol optical depth (AOD) were calculated. The observed aerosols and clouds were classified into three groups (boundary layer dust, free tropospheric aerosol and cirrus cloud) according to a relationship between color ratio and 532nm-backscattering coefficient. We also validate the backscattering coefficient for CALIPSO level 2 data. The result shows that it is underestimated by 21 % compared to this study.
Red tide detection by means of peak shift of remote sensing reflectance and possibility of red tide detection with polarized radiance measurements
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A method for detection of red tide by means of remote sensing reflectance peak shift is proposed together with suspended solid
influence eliminations. Although remote sensing reflectance peak is situated at around 550nm for sea water without suffered from red
tide, the peak is shifted to the longer wavelength when sea water is suffered from red tide. Based on this fact, it is capable to detect
red tide using high wavelength resolution of spectral-radiometers. The proposed system uses web camera with band-pass filter on the
optics surface. Acquired imagery data can be transmitted through wireless LAN to Internet terminal and can be archived in server
through Internet. Validity of the proposed method is confirmed with the system deployed in Ariake Sea which is situated in northern
Kyushu, Japan. Also a method for red tide detection with satellite imagery data is attempted with suspended solid influence
eliminations. Furthermore, a possibility of red tide detection with polarized radiance measurements is discussed through polarization
camera derived sue surface imagery data, in particular, for non-spherical shape of red tide.
Observation-based estimation of cloud-top height by geostationary satellite split-window measurements trained with CloudSat data
Atsushi Hamada,
Noriyuki Nishi
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Look-up table for estimating the cloud-top height of upper-tropospheric clouds by the infrared brightness temperature
(TB) at 10.8 μm (T11) and its difference from TB at 12 μm (ΔT11-12) measured by a geostationary
satellite are presented. The look-up table was constructed by regressing the cloud radar measurements by the
CloudSat satellite over the infrared measurements by the Japanese geostationary satellite MTSAT-1R. Standard
deviations of measurements around the estimates were also displayed as an indicator of the ambiguity in the
estimates, and were less than 1 km for the upper-tropospheric clouds with T11 < 240 K. The dependences of
the estimates of cloud-top height at each point in T11-ΔT11-12 space on latitude, season, satellite zenith angle,
day-night, and land-sea differences were examined. It was shown that these dependences were considered as
being uniform in tropics, except for the region with large satellite zenith angle. The presented look-up tables
can provide hourly estimates of cloud-top height at a specified location, and are fairly useful in comparing them
with ground-based observations such as vertical profiles of humidity and/or wind.
Impact of carbonaceous aerosols on Indian monsoon rainfall
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Aerosols - liquid or solid particles suspended in the air - are important constituents of the global atmosphere.
Asia is the region of the great source of global carbon emission and this trend is expected to increase in the near
future. There are two kinds of carbonaceous aerosols i.e. organic matter (OM) and black carbon (BC). Black
carbon stands after only carbon dioxide (CO2) in the list of climate change contributors. BC can directly absorb
solar radiation or mix with other aerosols to form atmospheric brown clouds which absorb incoming solar
radiation and prevent it from reaching the surface, thereby warming the atmosphere. Thus, in this study, the
Laboratoire de Meteorologie Dynamique model (LMD, version 3.3) is used to investigate the possible effect of
carbonaceous aerosols over India for the monsoon periods on the atmospheric radiation transfer and over the
precipitation. LMDZ.3.3 is integrated for different years for the Indian southwest monsoon periods (seasonal
experiments) over the globe for the resolution 96x72x19 (approx. 300 km). Model simulated aerosol optical
depth at 550 nm has been validated with satellite data (MODIS). The simulation results show that BC aerosol
induce a positive radiative forcing, while organic matter show negative radiative forcing at the top of the
atmosphere and a negative radiative forcing at the surface in this region. However, the impact of BC and OM
over rainfall is different and complex for different places. The sensitivity studies for carbonaceous aerosols have
been done for 21 years (1987-2007) for the monsoon period, and the rainfall is compared with GPCP (Global
Precipitation Climatology Project) with the help of Principal component analysis.
Climate Remote Sensing and Modeling
Downscaled multi-model superensemble and probabilistic forecasts of seasonal rains over the Asian monsoon belt
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This is a study on seasonal climate forecasts for the Asian Monsoon region. The unique
aspect of this study is that it became possible to use the forecast results from as many as 16 state of
the art coupled atmosphere-ocean models. A downscaling component, with respect to observed
rainfall estimates uses data sets from TRMM and a dense rain gauge distriburion; this enables the
forecasts of each model to be bias corrected to a common 25 km resolution. The downscaling
statistics for each model, at each grid location is developed during a training phase of the model
forecasts; the forecasts from all of the member models use the downscaling coefficients of the
training phase. These forecasts are next used for the construction of a multimodel superensemble. A
major result of this paper is on the climatology of the model rainfall. From the downscaled
multimodel superensemble which shows a correlation of nearly 1.0 with respect to the observed
climatology. This high skill is important for addressing the rainfall anomaly forecasts, which are
defined in terms of departures from the observed (rather than a model based) climatology.
The second part of this study addresses seasonal climate forecasts of Asian monsoon
precipitation anomalies. Seasonal climate forecasts over the larger monsoon Asia domain and over
the regional belts are evaluated. The superensemble forecasts invariably carry the highest skill
compared to the member models globally and regionally. This relates largely to the presence of large
systematic errors in models that carry low seasonal prediction skills. Such models carry persistent
signatures of systematic errors, and their errors are recognized by the multimodel superensemble.
One of the conclusions of this study is that given the uncertainties in current modeling for seasonal
rainfall forecasts, post processing of multimodel forecasts, using the superensemble methodology,
seems to provide the most promising results for the rainfall anomaly forecasts.
Using water vapor measurements from hyperspectral advanced IR sounder for tropical cyclone forecast
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Hyperspectral IR sounders such as AIRS onboard NASA's EOS Aqua platform
and IASI onboard the Europe's METOP-A satellite provide unprecedented global
atmospheric temperature and moisture soundings with high accuracy and vertical
resolution. The AIRS and IASI radiance measurements have been used in the global
Numerical Weather Prediction (NWP) models with positive impact on weather forecasts.
We also applied the full spatial resolution soundings retrieved with CIMSS Hyperspectral
IR Sounding Retrieval (CHISR) algorithm from AIRS to tropical cyclone track and
intensity forecasts within a regional model - WRF. We found that through assimilating
the AIRS full spatial resolution temperature and moisture soundings, the tropical cyclone
track and intensity forecasts are significantly improved, the water vapor information
plays more important role in the forecast than the temperature information.
Monsoon and Tropical Cyclone Applications
Sensitivity of target size, pixel selection, and height assignment in satellite-derived atmospheric motion vectors
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The satellite-derived atmospheric motions vectors (AMVs) are useful for weather analysis such as tropical low, wind
shear, and jet location and data assimilation into numerical weather prediction model. The AMV's accuracy is sensitive
to the various components like target selection approaches, height assignment (HA) methods and so on, which should be
optimized and improved. AMVs are retrieved by identifying and tracking targets dynamically through the use of
advanced pattern-matching techniques based on cross-correlation statistics. In tracking targets, the optimal target box
size, grid size, satellite image time interval and target location decision method should be determined for detecting cloud
structure. The pixel selection method for the representative cloudy radiance on HA is also investigated. The current
operational algorithm uses 15% coldest pixel temperature for infrared and water vapor channels and the method would
be modified through sensitivity tests for each channel. In addition, the correction method for cloud base height and its
effects are validated.
Dual-frequency radar (DPR) and the global precipitation measurement (GPM) in Japan
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The Global Precipitation Measurement (GPM) is a successor of the Tropical Rainfall Measuring Mission (TRMM)
which has opened a new era for precipitation system measurement from space including much better global rain maps.
The scope of GPM is much wider than that of TRMM. GPM will provide three hourly precipitation measurement over
the globe, that is, much higher temporal resolution with wider coverage than TRMM. Current precipitation measurement
is far from enough for the water resources management which requires very high spatial and temporal resolution. The
three hourly global precipitation measurement with GPM will greatly contribute not only to the precipitation sciences but
to real-world applications. The GPM core satellite will be equipped with a dual-wavelength radar (DPR) and a
microwave radiometer, and will work as a reference standard for the GPM constellation radiometers. The development
of the space segment is going well, and the core satellite launch is scheduled in the middle of 2013. DPR is a 14/35 GHz
radar system. The 14 GHz radar is similar to the TRMM precipitation radar but the 35 GHz radar is a new one with
scanning ability. The rain retrieval algorithms using DPR is underway. The basic idea is to use the difference of rain
attenuation at two frequencies in the liquid layer, and the deviation from the Rayleigh scattering in the solid precipitation
layer. Field experiments for the DPR algorithm development are also designed. A dual Ka-band radar system which is
now being developed will be a powerful tool for the field experiments. The dual Ka-radar system can measure both the
specific attenuation and the equivalent radar reflectivity at Ka-band.
Poster Session
Study on X-band polarization ratio with TerraSAR-X images
Yongzheng Ren,
Susanne Lehner,
Mingxia He
Show abstract
A new X-band wind field algorithm (XMOD) based on a linear approach is discussed in another paper to describe the
relationship between normalized radar cross section (NRCS), wind speed, wind direction and incidence angle. But
XMOD could only be applied with VV polarization SAR data. To be use the HH polarization SAR data, two C-band
polarization ratio models were analysed and modified to X-band. To demonstrate the applicability of the two models,
10m height wind speeds were computed with XMOD from several VV/HH TerraSAR-X images and validated by
QuikScat and DWD model results. In addition, the wind speeds were retrieved and compared to each other from the HH
and VV polarization TerraSAR-X images of the same scene at the same time.
Internal wave location and parameters estimation from ENVISAT SAR images
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The manifestation of internal wave (IW) in synthetic aperture radar (SAR) ocean images has always
been of considerable interest to oceanographers. In this paper, the location of IW is carried out by the
edge extraction algorithm based on wavelet transform modulus maxima, which shows the moment IW
distribution on time and space. The propagation direction of IW is extracted by the fourier analysis and
the division processing. The IW wavelength is extracted from the wavelet transform technology for the
non-periodicity of IW signal. Based on the former research about the relation between the relative
normalized radar cross section (NRCS) variations and the IW parameters, we adopt a iteration method
to inverse some IW parameters including the mixed layer depth, amplitude and the propagation speed.
From the results, the location image can basically catch IW information except a too weak IW signal.
The inversed wavelength has minor larger values in the light wave rupture of the SAR image but it is
consistent to the SAR image. The IW direction, mixed layer depth and propagation speed present a
uniform distribution for the value in each position and show that these parameter are basically
invariable for a IW packet at least. But the IW amplitude in different points varies intensely deviated
from the mean, which means that it is vulnerable for the sea bottom topography and hydrodynamic
modulation.