Download or read book Investigation of Microphysical Assumptions in TRMM Radiometer s Rain Profile Algorithm Using KWAJEX Satellite Aircraft and Surface Datasets written by Steven T. Fiorino and published by . This book was released on 2002-07-01 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Tropical Rainfall Measuring Mission (TRMM) level 2 radiometer precipitation profile algorithm employs assumed (cloud model- derived) vertical microphysical structures and radiative transfer within the inversion process to generate rainrate estimates. To date, this algorithm has been evaluated through raingauge and ground radar intercomparisons, algorithm- to-algorithm intercomparisons, diagnostic moisture budget analyses, and physical hypothesis testing. None of these approaches has specifically addressed the underlying microphysical properties of the algorithm itself. Therefore, what remains is perhaps the most fundamental check -- direct intercomparison of the assumed profile microphysics with actual three- dimensional microphysical observations.

Download or read book The Remote Sensing of Tropospheric Composition from Space written by John P. Burrows and published by Springer Science & Business Media. This book was released on 2011-01-15 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: The impact of anthropogenic activities on our atmospheric environment is of growing public concern and satellite-based techniques now provide an essential component of observational strategies on regional and global scales. The purpose of this book is to summarise the state of the art in the field in general, while describing both key techniques and findings in particular. It opens with an historical perspective of the field together with the basic principles of remote sensing from space. Three chapters follow on the techniques and on the solutions to the problems associated with the various spectral regions in which observations are made. The particular challenges posed by aerosols and clouds are covered in the next two chapters. Of special importance is the accuracy and reliability of remote sensing data and these issues are covered in a chapter on validation. The final section of the book is concerned with the exploitation of data, with chapters on observational aspects, which includes both individual and synergistic studies, and on the comparison of global and regional observations with chemical transport and climate models and the added value that the interaction brings to both. The book concludes with scientific needs and likely future developments in the field, and the necessary actions to be taken if we are to have the global observation system that the Earth needs in its present, deteriorating state. The appendices provide a comprehensive list of satellite instruments, global representations of some ancillary data such as fire counts and light pollution, a list of abbreviations and acronyms, and a set of colourful timelines indicating the satellite coverage of tropospheric composition in the foreseeable future. Altogether, this book will be a timely reference and overview for anyone working at the interface of environmental, atmospheric and space sciences.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2003 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Earth Observer written by and published by . This book was released on 2001 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Validation of Level 2 TRMM Rain Profile Algorithms by Intercomparison and Hypothesis Testing written by Throy D. Hollis and published by . This book was released on 2000-02 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Satellite algorithms are currently the methodology showing most promise for obtaining more accurate global precipitation estimates. However, a general problem with satellite methods is that they do not measure precipitation directly, but through inversion of radiation-rain relationships. Because of this, procedures are needed to verify algorithm-generated results. The most common method of verifying satellite rain estimates is by comparison with ground truth' derived from measurements obtained by raingage networks, ground weather radar, or a combination of the two. However, these types of measurements often have uncertainty magnitudes on the order or greater than the satellite algorithms, motivating the search for alternate approaches. The purpose of this research is to explore a new type of approach for validating the level 2 TRMM facility rain profile algorithms. This is done by an algorithm-to-algorithm intercomparison analysis in the context of physical hypothesis testing. Beginning with the four algorithms' strengths and weaknesses garnered from the physics used to develop the algorithms, seven hypotheses were formed detailing expected performance characteristics of the algorithms. Procedures were developed to test these hypotheses and applied to 48 storms from all ocean basins within the tropical and subtropical zones over which TRMM coverage is available (approx. 35N - 35S). The testing resulted in five hypotheses verified, one partially verified, and one inconclusive. These findings suggest that the four level 2 TRMM facility profile algorithms are performing in a manner consistent with the underlying physical limitations in the measurements (or, alternatively, the strengths of the physical assumptions), providing an independent measure of the level 2 algorithms' validity.

Download or read book Report of the Science Steering Group for a Tropical Rainfall Measuring Mission TRMM written by Tropical Rainfall Measuring Mission. Science Steering Group and published by . This book was released on 1988 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The Tropical Rainfall Measuring Mission (TRMM), a satellite program now being studied jointly by the United States and Japan, would carry out the systematic study of tropical rainfall required for major strides in weather and climate research ... This report presents the scientific justification for TRMM and outlines the implementation process for the scientific community."--Preface.

Download or read book Total Precipitable Water and Rainfall Determinations Form the SEASAT Scanning Multichannel Microwave Radiometer SMMR written by John C. Alishouse and published by . This book was released on 1982 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book TRMM written by and published by . This book was released on 1989 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sampling Errors of Ssm I and Trmm Rainfall Averages written by Thomas L. Bell and published by BiblioGov. This book was released on 2013-08 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantitative use of satellite-derived maps of monthly rainfall requires some measure of the accuracy of the satellite estimates. The rainfall estimate for a given map grid box is subject to both remote-sensing error and, in the case of low-orbiting satellites, sampling error due to the limited number of observations of the grid box provided by the satellite. A simple model of rain behavior predicts that Root-mean-square (RMS) random error in grid-box averages should depend in a simple way on the local average rain rate, and the predicted behavior has been seen in simulations using surface rain-gauge and radar data. This relationship was examined using satellite SSM/I data obtained over the western equatorial Pacific during TOGA COARE. RMS error inferred directly from SSM/I rainfall estimates was found to be larger than predicted from surface data, and to depend less on local rain rate than was predicted. Preliminary examination of TRMM microwave estimates shows better agreement with surface data. A simple method of estimating rms error in satellite rainfall estimates is suggested, based on quantities that can be directly computed from the satellite data.

Download or read book Spatial and Temporal Rainfall Gauge Data Analysis and Validation with TRMM Microwave Radiometer Surface Rainfall Retrievals written by M.R. Sandoval Gómez and published by . This book was released on 2007 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Tmi Rain Rate Estimation Over Land and Ocean Utilizing Convective and Stratiform Discrimination written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-11 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometer brightness temperature data in the 85 GHz channel (T85) reveal distinct local minima in a regional map containing a Mesoscale Convective System (MCS). This is because of relatively small footprint size (approximately 5.5 km) and strong extinction properties in this channel of the TMI. A map of rain rate for that region, deduced from simultaneous measurements made by the Precipitation Radar (PR) on board the TRMM satellite, reveals that these T85 minima, produced by scattering, correspond to local PR rain maxima. Utilizing the PR rain rate map as a guide, we infer from TMI data the presence of three different kinds of thunderstorms or Cbs. They are young, mature, and decaying Cbs that have a scale of about 20 km on the average. Two parameters enable us to infer these three kinds of Cbs objectively: a) the magnitude of scattering depression deduced from local T85 minima and b) the mean horizontal gradient of T85 around such minima. Knowing the category of a given Cb, we can estimate the rain rate associated with it. Such estimation is done with the help of relationships linking T85 minimum to rain rate in each Cb type. Similarly, a weak background rain rate in all the areas where T85 is less than 260 K is deduced with another relationship linking T85 to rain rate. In our rain retrieval model, this background rain constitutes the stratiform rain where the Cbs are absent. Initially, these relationships are optimized or tuned utilizing the PR and TMI data of a few MCS events. After such tuning, the model is applied to independent MCS cases. The areal distribution of light (1-10 mm/hr), moderate (10-20 mm/hr), and intense (> 20 mm/hr) rain rates are retrieved satisfactorally. Accuracy in the estimates of the light, moderate and intense rain areas and the mean rain rates associated with such areas in these independent MCS cases is on the average about 15%. Taking advantage of this ability of ou

Download or read book A Method to Retrieve Rainfall Rate Over Land from Trmm Microwave Imager Observations written by C. Prabhakara and published by BiblioGov. This book was released on 2013-07 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over tropical land regions, rain rate maxima in mesoscale convective systems revealed by the Precipitation Radar (PR) flown on the Tropical Rainfall Measuring Mission (TRMM) satellite are found to correspond to thunderstorms, i.e., Cbs. These Cbs are reflected as minima in the 85 GHz brightness temperature, T85, observed by the TRMM Microwave Imager (TMI) radiometer. Because the magnitude of TMI observations do not discriminate satisfactorily convective and stratiform rain, we developed here a different TMI discrimination method. In this method, two types of Cbs, strong and weak, are inferred from the Laplacian of T85 at minima. Then, to retrieve rain rate, where T85 is less than 270 K, a weak (background) rain rate is deduced using T85 observations. Furthermore, over a circular area of 10 km radius centered at the location of each T85 minimum, an additional Cb component of rain rate is added to the background rain rate. This Cb component of rain rate is estimated with the help of (T19-T37) and T85 observations. Initially, our algorithm is calibrated with the PR rain rate measurements from 20 MCS rain events. After calibration, this method is applied to TMI data taken from several tropical land regions. With the help of the PR observations, we show that the spatial distribution and intensity of rain rate over land estimated from our algorithm are better than those given by the current TMI-Version-5 Algorithm. For this reason, our algorithm may be used to improve the current state of rain retrievals on land.

Download or read book Performance Assessment of Satellite Rainfall Products for Hydrologic Modeling written by Hojjat Seyyedi and published by . This book was released on 2014 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rain Rate Retrieval Algorithm for Aquarius SAC D Microwave Radiometer written by Rosa Ana Menzerotolo and published by . This book was released on 2011 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microwave radiometers are used to measure blackbody microwave emissions emitted by natural targets. Radiative transfer theory provides a well founded physical relationship between the atmosphere and surface geophysical parameters and the brightness temperature measured by these radiometers. The atmospheric brightness temperature is proportional to the integral of the microwave absorption of water vapor, oxygen, and liquid water between the top of the atmosphere and the surface. Inverse radiative transfer models use to retrieve the water vapor, cloud liquid and oxygen content in the atmosphere are very well known; however, the retrieval of rain rate in the atmosphere is still a challenge. This project presents a theoretical basis for the rain rate retrieval algorithm, which will be implemented in the Aquarius/SAC-D Microwave Radiometer (MWR). This algorithm was developed based on the radiative transfer model theory for a single layer atmosphere using four WindSat channels. Transmissivity due to liquid water (rain and cloud liquid water) is retrieved from the four channel brightness temperatures, and a statistical regression is performed to relate the rain rate, rain physical temperature and rain height to the liquid water transmissivities at 24 GHz and 37 GHz. Empirical validation results are presented using the WindSat radiometer observations.

Download or read book Satellite Remote Sensing of Global Rainfall Using Passive Microwave Radiometry written by and published by . This book was released on 1994 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global rainfall over land and ocean is estimated using measurements of upwelling microwaves by a satellite passive microwave radiometer. Radiative transfer calculations through a cloud model are used to parameterize an inversion technique for retrieving rain rates from brightness temperatures measured by the Special Sensor Microwave Imager (SSM/I). The rainfall retrieval technique is based on the interaction between multi-spectral microwave radiances and millimeter sized liquid and frozen hydrometeors distributed in the satellite's field of view. The rain rate algorithm is sensitive to both hydrometeor emission and scattering while being relatively insensitive to extraneous atmospheric and surface effects. Separate formulations are used over ocean and land to account for different background microwave characteristics and the algorithm corrects for inhomogeneous distributions of rain rates within the satellite's field of view. Estimates of instantaneous and climate scale rainfall are validated through comparisons with modeled clouds, surface radars, rain gauges and alternative satellite estimates. The accuracy of the rainfall estimates is determined from a combination of validation comparisons, theoretical sampling error calculations, and modeled sensitivity to variations in atmospheric and surface radiative properties. An error budget is constructed for both instantaneous rain rates and climate scale global estimates. At a one degree resolution, the root mean square errors in instantaneous rain rate estimates are 13% over ocean and 20% over land. The root mean square errors in global rainfall totals over a four month period are found to be 46% over ocean and 63% over land. Global rainfall totals are computed on a monthly scale for a three year period from 1987 to 1990. The time series is analyzed for climate scale rainfall distribution and variability.

Download or read book Assessment of the Benefits of Extending the Tropical Rainfall Measuring Mission written by Committee on the Future of the Tropical Rainfall Measuring Mission and published by . This book was released on 2006-08-22 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Launched jointly in 1997 by the National Aeronautics and Space Administration (NASA) and the Japan Aerospace Exploration Agency (JAXA), the Tropical Rainfall Measuring Mission (TRMM) is a satellite mission that placed a unique suite of instruments, including the first precipitation radar, in space. These instruments are used to monitor and predict tropical cyclone tracks and intensity, estimate rainfall, and monitor climate variability (precipitation and sea surface temperature). TRMM has been collecting data for seven years; this data is used by the Joint Typhoon Warning Center, the National Center for Environmental Prediction, and the National Hurricane Center, among others worldwide. In July 2004, NASA announced that it would terminate TRMM in August 2004. At the request of the National Oceanic and Atmospheric Administration (NOAA), the White House, and the science community, NASA agreed to continue TRMM operations through the end of 2004. Meanwhile, NASA asked a National Research Council (NRC) committee to provide advice on the benefits of keeping TRMM in operation beyond 2004. After holding a workshop with a number of experts in the field, the committee found that TRMM will contribute significantly to operations and science if the mission is extended; and therefore, strongly recommends continued operation of TRMM with the caveat that cost and risk will need to be further examined before a final decision about the future of TRMM can be made.

Download or read book Characterization and Modeling of Satellite Based Precipitation Uncertainty Over Complex Terrain written by Yagmur Derin and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The availability and quality of precipitation estimates is essential to the accuracy and reliability of hydrological modeling studies. Difficulties in the representation of high rainfall variability over mountainous areas using ground-based sensors make satellite-based precipitation products (SPPs) attractive for hydrological studies over such regions, since these products are quasi-global and available at high spatial resolution. Evaluation of several SPPs using rain gauge networks over ten mountainous regions across the globe has shown their performance is highly dependent on advancing the quality of primary data sources, one of which is passive microwave (PMW) retrievals. The evaluation of PMW retrievals is challenging, since it requires reference datasets with high temporal and spatial resolution. This difficulty can be overcome through the use of experimental ground radar (GR) X-band polarimetric radar observations. The Self-Consistent Optimal Parameterization-Microphysics Estimation (SCOP-ME), an algorithm that uses best-fitted functions of specific attenuation coefficients and backscattering differential phase shifts is used to retrieve rainfall rates and microphysical characteristics from GR. GR deployments over mountainous regions are used to evaluate the error characteristics of SCOP-ME retrieval and provide high-resolution estimates of the 4D rainfall variability. These estimates represented the benchmark precipitation dataset, which are then used in the error characterization and modeling of the PMW retrievals. To understand the source of uncertainties, a sampling volume-matching methodology is implemented between PMW and GR. The PMW retrievals showed weaker covariation than GR, with magnitude-dependent systematic error going from overestimation of light precipitation to, mainly, underestimation of heavier precipitation. Overall, these investigations indicated that PMW retrievals have uncertainties that necessitate the use of error characterization and correction procedures, especially over complex terrain. This called for error modeling of the PMW retrievals, which is conducted with quantile regression forests (QRF), a nonparametric tree-based model. The ensembles generated through the QRF model are validated by independent matchups of PMW and GR data from four complex terrains. Validation of the error model is conducted in two ways, the k-fold and leave-one region out cross validation techniques. The study showed that the error model significantly reduces both mean relative error and the random component of the error compared to the original PMW products. Moreover, it demonstrated transferability of this error model among complex terrain regions around the globe, which will allow algorithm developers to integrate it to produce Level 3 products.