Proceedings Volume 7154

Microwave Remote Sensing of the Atmosphere and Environment VI

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Proceedings Volume 7154

Microwave Remote Sensing of the Atmosphere and Environment VI

View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 8 December 2008
Contents: 7 Sessions, 15 Papers, 0 Presentations
Conference: SPIE Asia-Pacific Remote Sensing 2008
Volume Number: 7154

Table of Contents

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Table of Contents

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  • Front Matter: Volume 7154
  • Keynote Session I
  • Application of Microwave Remote Sensing Data to Weather and Climate I
  • Application of Microwave Remote Sensing Data to Weather and Climate II: Algorithms and Modeling
  • Keynote Session II
  • Results from Microwave Imagery
  • Poster Session
Front Matter: Volume 7154
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Front Matter: Volume 7154
This PDF file contains the front matter associated with SPIE Proceedings Volume 7154, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
Keynote Session I
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Remote sensing of the global environment with satellite scatterometry
Son V. Nghiem, Gregory Neumann
This paper presents an overview of satellite scatterometry for remote sensing of the global environment from the tropics to polar regions. Results were derived from microwave backscatter data acquired by the NASA SeaWinds scatterometer aboard the QuikSCAT (QSCAT) satellite. QSCAT observed two successive super cyclones that hit the Orissa coastal region of India, affecting 15 million people in 1999. The extent of soil moisture change was delineated after Cyclone Nargis made landfall in Myanmar in May 2008. QSCAT detected excessive rainwater followed by a severe drought leading to widespread wildfires in California, U.S., in 2007. QSCAT tracked vegetation change in an extreme drought in Nairobi, Kenya, affecting 3 million people in 2000. QSCAT monitored snowmelt patterns over the Northern Hemisphere, which showed poleward oscillations of melt bands. QSCAT revealed a record reduction in Arctic perennial sea ice in this decade and a further drastic decline of perennial ice in 2008. At 1-km posting, QSCAT identified urban and suburban areas where backscatter was shown to correlate with population density. QSCAT delineated wind shadow areas near small islands in the Asia-Pacific region. These results demonstrate that satellite scatterometer can provide numerous crucial data products to the Global Earth Observation System of Systems.
Application of Microwave Remote Sensing Data to Weather and Climate I
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Analysis on an extreme torrential rainfall in arid northwest China area with remote sensing data
Wendong Hu, Guangping Zhao, Xiaoyu Huang, et al.
Using remote sensing data of satellite and the new generation weather radar, together with NWP products and conventional observation, a study on an extreme torrential rainfall in the arid area of northwest China was conducted. The results show that 1. The extreme torrential rainfall happened under a unique circulation background of west stretching subtropical high pressure in the medium latitude which is caused by landing tropical cyclone. 2. The data of radar indicated the train-effect caused by the low centroid strong echoes lead to severe precipitation. 3. The meso-γ scale gust nucleus, corresponding convergence-divergence, and vertical motion are major affect systems. 4. High efficient vapor transportation of southwest jet at low altitude indicated by VWP of radar and satellite image was the key factor of the extreme torrential rainfall. 5. The cold air invasion at med-high altitude and the moist air coming from the mid-low altitude revealed by satellite provided favorable condition for the heavy precipitation.
Analysis and application of remote sensing data in a severe convective storm in Hunan, China
Xiaoyu Huang, Yuan Chen, Hongwu Liu, et al.
A severe convective storm with thunder, shower and gust as well as hailstone in Hunan province, China on April 8, 2008 was investigated using the remote sensing data such as FY-2C satellite, Doppler radar and automatic surface weather network. The results show that 1. The previous warmer weather provided abundant unstable energy, and the vertical wind shear, thermo-dynamic factors are favorable for severe convection. 2. The mesoscale torrential rain clouds triggered by the tail of front-cyclone clouds caused the event. 3. The phenomenon that the thunder storm clouds were triggered by frontal cyclone clouds was revealed clearly by FY-2C satellite image. Cloud-Derived Wind image indicated the strong divergence at the high level. 4. The PPIs manifest as the isolated massive echoes, and the intense echo cores of storms is higher than 65dBz at the 3-6km altitude on reflectivity vertical section, the echo higher than 50dBz located at 9km high-level and the temperature is approximately - 30°C, the echo top height is higher than 12km. the PPIs at different levels show that the character of "three-body scattering spike" at 16:18, 16:36 and 16:54 respectively, namely typical character of hail echo. 5. For velocity, at the low and middle altitude, there were the cyclonic convergence and divergence at the high altitude.
Influences of snow over the Tibetan Plateau on the summer precipitation of East Asia
The spatial and temporal distributions of snow depth on Tibetan Plateau are revealed by comparing the data retrieved from satellite remote sensing i.e. SSMR and SSM/I with station observations. All of the results show that snow depth on the Tibetan plateau plays an important role in East Asia summer precipitation anomalies and in consequence, some possible mechanisms are proposed.
Application of Microwave Remote Sensing Data to Weather and Climate II: Algorithms and Modeling
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Neural network microwave precipitation retrievals and modeling results
R. Vincent Leslie, William J. Blackwell, Laura J. Bickmeier, et al.
We describe a simulation methodology used to develop and validate precipitation retrieval algorithms for current and future passive microwave sounders with emphasis on the NPOESS (National Polar-orbiting Operational Environmental Satellite System) sensors. Precipitation algorithms are currently being developed for ATMS, MIS, and NAST-M. ATMS, like AMSU, will have channels near the oxygen bands throughout 50-60 GHz, the water vapor resonance band at 183.31 GHz, as well as several window channels. ATMS will offer improvements in radiometric and spatial resolution over the AMSU-A/B and MHS sensors currently flying on NASA (Aqua), NOAA (POES) and EUMETSAT (MetOp) satellites. The similarity of ATMS to AMSU-A/B will allow the AMSU-A/B precipitation algorithm developed by Chen and Staelin to be adapted for ATMS, and the improvements of ATMS over AMSU-A/B suggest that a superior precipitation retrieval algorithm can be developed for ATMS. Like the Chen and Staelin algorithm for AMSU-A/B, the algorithm for ATMS to be presented will also be based a statisticsbased approach involving extensive signal processing and neural network estimation in contrast to traditional physics-based approaches. One potential advantage of a neural-network-based algorithm is computational speed. The main difference in applying the Chen-Staelin method to ATMS will consist of using the output of the most up-to-date simulation methodology instead of the ground-based weather radar and earlier versions of the simulation methodology. We also present recent progress on the millimeter-wave radiance simulation methodology that is used to derive simulated global ground-truth data sets for the development of precipitation retrieval algorithms suitable for use on a global scale by spaceborne millimeter-wave spectrometers. The methodology utilizes the MM5 Cloud Resolving Model (CRM), at 1-km resolution, to generate atmospheric thermodynamic quantities (for example, humidity and hydrometeor profiles). These data are then input into a Radiative Transfer Algorithm (RTA) to simulate at-sensor millimeter-wave radiances at a variety of viewing geometries. The simulated radiances are filtered and resampled to match the sensor resolution and orientation.
Data fusion of significant wave height from multiple satellite altimeters
Jingsong Yang, Xioyan Chen, Juan Wang, et al.
Data fusion methods such as inverse distance to a power method, Kriging method and successive correction method are studied in this paper. The appropriate model and parameters for these methods are achieved for the fusion of ocean wave significant wave height (SWH) data from GFO, Jason-1 and Envisat altimeters in China seas and nearby. The factors which influence the fusion results are also analyzed. It is shown that (1) the characteristics and distribution of merged SWH data are consistent with the statistical data in the study area; (2) there is little difference between the merged results for different fusion methods in case the altimeter data are not sparse; (3) the window size of the filters is about 2.5°×2.5°-3°×3° to reach reasonable results; (4) data from at least 3 satellites are needed in the fusion processes.
Microwave remote sensing to help astronomical observations: the Atacama Large Millimeter Array project
This contribution is aimed at reviewing the impact of the atmosphere for millimeter and submillimeter wave observations performed from platforms inside the Earth's atmosphere with special focus on interferometry and, in particular, on the Atacama Large Millimeter Array (ALMA) project. The reference atmospheric radiative transfer code for ALMA will be discussed along with some examples of its applications related to ground-based submillimeter astronomy.
Keynote Session II
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On-orbit radiometric validation and field-of-view calibration of spaceborne microwave sounding instruments
William J. Blackwell, Laura J. Bickmeier, Laura G. Jairam, et al.
Two calibration/validation efforts planned for current and future spaceborne microwave sounding instruments will be presented. First, the NPOESS Aircraft Sounder Testbed-Microwave (NAST-M) airborne sensor is used to directly validate the microwave radiometers (AMSU and MHS) on several operational satellites. Comparison results for underflights of the Aqua, NOAA, and MetOp-A satellites will be shown. Second, a potential approach will be presented for on-orbit field-of-view (FOV) calibration of the Advanced Technology Microwave Sounder (ATMS). A variety of proposed spacecraft maneuvers that could facilitate the characterization of the radiometric boresight of all 22 ATMS channels will be discussed. Radiance observations from the NAST-M airborne sensor can be used to directly validate the radiometric performance of spaceborne sensors. NAST-M includes a total of four spectrometers, with three operating near the oxygen lines at 50-57, 118.75, and 424.76 GHz, and a fourth spectrometer centered on the water vapor absorption line at 183.31 GHz. All four feedhorns are co-located, have 3-dB (full-width at half-maximum) beamwidths of 7.5° (translating to 2.5-km nominal pixel diameter at nadir incidence), and are directed at a single mirror that scans cross-track beneath the aircraft with a nominal swath width of 100 km. We will present results for two recent validation efforts: 1) the Pacific THORpex (THe Observing-system Research and predictability experiment) Observing System Test (PTOST 2003, Honolulu, HI) and 2) the Joint Airborne IASI Validation Experiment (JAIVEx 2007, Houston, TX). Radiance differences between the NAST-M sensor and the Advanced Microwave Sounding Unit (AMSU) and the Microwave Humidity Sensor (MHS) were found to be less than 1K for most channels. Comparison results for ocean underflights of the Aqua, NOAA, and MetOp-A satellites are shown. We also present an approach for on-orbit FOV calibration of the ATMS satellite instrument using vicarious calibration sources with high spatial frequency content (the Earths limb, for example). The antenna beam is slowly swept across the target of interest and a constrained deconvolution approach is used to recover antenna pattern anomalies. Various proposed spacecraft maneuvers will be considered, with the intent to illustrate how each maneuver will help to identify and characterize possible FOV artifacts. Radiative transfer simulations that quantitatively assess the benefit of each satellite maneuver will also be presented.
Results from Microwave Imagery
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Damage analysis of 12 May 2008 Sichuan earthquake with satellite data
Xiaoqian Cheng, Wen Wang, Tao Yu, et al.
The devastating earthquake (Ms=8.0) of 12 May 2008 in Sichuan, China struck the whole world. To detect the large damaged area in less time and identify seismogenic structure, remote sensing technology is strongly recommended. This paper attempts to focus on seismic area to analyze the earthquake damage from different aspects. Firstly, pre- and post-earthquake Landsat TM/ETM images, CBERS-02B CCD images, DEM and relating data is used to observe ground changes. The analysis assumption is testified by the Tangjia Mountain dammed lake in Beichuan county and landslide in Anxian county in relative news and reports. Furthermore, Radarsat data is used to complement the analysis, since it could provide the seismic area surface deformation and a better 3-D vision. Also specific information of local fault, landslide and sub-block features in seismic area could be observed and got, which helps to perfect the damage analysis. All these analysis results could be useful for improving and revising the interpretations of geological, geodetic and seismological data. Finally, the possibility of estimating and inducing earthquake damage using remote sensing data is discussed.
A new method for significant wave height retrieval from SAR imagery
Jingsong Yang, He Wang, Xiaoyan Chen, et al.
A new method for retrieving significant wave height (SWH) directly from synthetic aperture radar (SAR) imagery without prior knowledge of ocean wave spectra is presented. It is based on the azimuthal high-wavenumber cutoff effect and the empirical relationship between mean period and peak period of ocean waves. Envisat ASAR wave mode data are used in case studies. Comparison shows that the retrieved SWHs are in good agreement with data from GFO, TOPEX/Poseidon altimetry and ECMWF.
Unconstrained ocean wave spectra retrieval from SAR SLC imagery
Jingsong Yang, He Wang, Rong Zhang, et al.
A new approach for directional ocean wave spectra retrieval from synthetic aperture radar (SAR) single look complex (SLC) imagery is presented. This method takes the advantages of both Engen's cross spectra method and Lyzenga's unconstrained inversion method. It consists of following three main steps: (1) split-look processing and cross-spectra estimation of SLC imagery; (2) unconstrained iteration of ocean wave spectra with 180° direction ambiguity from real part of cross-spectra; (3) remove the 180° ambiguity from imaginary part of cross-spectra. Envisat ASAR data are used in cases studies. Wavelength, wave direction and significant wave height (SWH) are also derived from retrieved ocean wave spectra. Case studies with comparisons show that this method reaches better results than the one used by ESA. It can avoid the inherent error of the latter.
Contribution of radar polarimetric data for the cartography in tropical environment
C. Lardeux, P-L. Frison, J-C. Souyris, et al.
The Support Vector Machine (SVM) algorithm is assessed for the classification of polarimetric radar data for the cartography of natural vegetation. Fully polarimetric data has been acquired in L and P bands during an AIRSAR mission over the French Polynesian Island named Tubuai. The results show significant improvement when compared to those obtained with the classification based on the maximum likehood criterion applied to the theoretical Wishart distribution that are supposed a priori to be verified by radar data. Obviously, this hypothesis is not verified with the present experimental data over the study site. The addition of other polarimetric indicators to the elements of the polarimetric coherency matrix still improves the classification accuracy. The evaluation of different partial polarimetric modes shows that even the best results are obtained for fully polarimetric data, the π4 mode gives the best compromise with respect to the ASAR Alternate Polarization mode or the PALSAR Dual Polarization mode. This latter shows in turn better results than the Alternate Polarization mode, indicating the significant contribution of the polarimetric differential phase between 2 polarization channels.
Poster Session
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Retracking Jason1 altimeter waveform over China coastal zone
Modern microwave satellite altimeters can measure the instantaneous sea surface height to a precision of approximately 4.1 cm in the open ocean. One limiting factor is that if land appears within the altimeter footprint the data is flagged as useless due to land contamination of the altimeter return waveforms and inappropriate geophysical corrections. This means that many valuable coastal altimetry data values are simply edited out. In order to make improved use of the altimetry waveform data near the coastal area, we derived the altimeter ranges from one year (March, 2006 to February, 2007; cycle 155 to cycle 188) of Jason1 waveform off the China coast (14-45°N, 105-130°E) by using four specialized retrackers: Ocean, Ice-2, OCOG (Offset Centre of Gravity), and Threshold retracking algorithms, which are employed by Envisat RA2 altimeter standard processing. In order to compare the four retracking algorithms quantitatively, we calculated the bias, root mean square, and standard deviation of the sea level anomaly difference between the ascending and descending tracks at crossovers. In addition, we compared the sea surface height derived from the four retracking algorithms and in-situ tide gauge station measurements. The comparisons showed that the OCOG algorithm provides more accurate results than the other three in coastal waters.
Evaluation of the estimation method for nonuniformity of rainfall within a footprint of TRMM/PR using the data during 180-degree yaw maneuver
The Tropical Rainfall Measuring Mission (TRMM) satellite performs 180-degree yaw maneuver (yaw-around) when the solar beta angle which is the angle between the satellite orbit plane and the direction to the sun crosses the 0-degree The yaw-maneuver is completed about 16 minutes (about 7000 km in flight length on the Earth) in the TRMM case. During the yaw-around, the Precipitation Radar (PR) onboard TRMM continues nominal observation (but data processing is limited to level-1 algorithms). Therefore very dense observation is realized during the yaw-around. Since nearly fixed target (rain echo and surface echo) is observed by different incident angles in a short time, new information can be obtained that cannot be obtained nominal observation. On the incident angle dependency of the sea surface echo, we can avoid the uncertainties comes from the changes in the target. Range profiles of the sea surface echo of different incident angles can be compared with the long-term global average data. The same approach can be used to quantitative estimation of bright band structure such as blurring effect of the off-nadir incident angles. For convective echoes, the non-uniform beam filling (NUBF) effect can be estimated by the different incident angle data and the data which location is slightly offset from the center. More reliable path integrated attenuation (PIA) can be obtained from different incident angle data and the NUBF can be estimated both by the range profiles of surface echo of off-nadir angle bin data with an approach by Takahashi et al. (2006) and their change with the location within a footprint. Two NUBF cases are demonstrated in this paper showing the horizontal sub-footprint size distribution of PIA. The results are confirmed by the consistency of different angle data with slight offset location. In addition, this method is evaluated by the PIA pattern data obtained from densely distributed (because of 180-degree yaw maneuver) data using the method similar to the standard algorithm for TRMM/PR.