scholarly journals Integrated water vapour from GPS

MAUSAM ◽  
2021 ◽  
Vol 58 (1) ◽  
pp. 101-106
Author(s):  
R. K. GIRI ◽  
L. R. MEENA ◽  
S. S. BHANDARI ◽  
R. C. BHATIA
Keyword(s):  
Water Vapour ◽  
Global Climate ◽  
Spatial Scales ◽  
Limited Area ◽  
Gps Data ◽  
Massachusetts Institute Of Technology ◽  
Stochastic Filtering ◽  
Wide Range ◽  
Integrated Water Vapour ◽  
Institute Of Technology

Water vapour is highly variable in space and time, and plays a large role in atmospheric processes that act over a wide range of temporal and spatial scales on global climate to micrometeorology. This paper deals with a new approach to remotely sense the water vapour based on the Global Position System (GPS). The signal propagating from GPS satellites to ground based receivers is delayed by atmospheric water vapour. The delay is parameterized in terms of time varying Zenith-Wet Delay (ZWD), which is retrieved by stochastic filtering of GPS data. With the help of surface pressure and temperature readings at the GPS receiver, the retrieved ZWD can be transformed into Integrated Water Vapour (IWV) overlying at the receiver with little additional uncertainties. In this study the Zenith Total time Delay (ZTD) data without met package is retrieved using the GAMIT (King and Bock, 1997) GPS data processing software developed by Massachusetts Institute of Technology (MIT) for the period of January 2003 to February 2003 for two stations New Delhi and Bangalore .The IWV retrieved from GPS and its comparison with Limited Area Model (LAM) retrieved IWV shows fairly good agreement.

Ferroelectricity: The Foundation of a Field from Form to Function

MRS Bulletin ◽  
2005 ◽  
Vol 30 (11) ◽  
pp. 845-848 ◽  
Author(s):  
R.E. Newnham ◽  
L. Eric Cross
Keyword(s):  
Perovskite Structure ◽  
Mixed Oxides ◽  
The United States ◽  
Molecular Engineering ◽  
Temperature Phase ◽  
Massachusetts Institute Of Technology ◽  
Domain Structures ◽  
Wide Range ◽  
Sonar Systems ◽  
Institute Of Technology

AbstractThis article highlights the major role Arthur von Hippel and the Laboratory for Insulation Research at the Massachusetts Institute of Technology played in the early development of the field of ferroelectricity in mixed oxides with the perovskite structure and, in particular, in the identification of ferroelectricity in barium titanate following its discovery in industrial laboratories in the United States during World War II.Very early optical and x-ray studies highlighted the characteristics of the ferroelectric domain structures in both ceramic and single-crystal BaTiO3, the elimination of domains at the Curie temperature TC, and the salient characteristics of the two low-temperature phase transitions. Perhaps the culmination of this work was the detailed studies of lamella 90° domains by Peter Forsbergh and the gorgeous patterns these could generate. This article also traces the manner in which the early studies contributed to whole industries based on perovskite ferroelectrics. The ceramic capacitor industry is now fabricating sophisticated, cofired multilayer capacitors (MLCs) with up to a thousand 1-µm-thick dielectric layers interleaved with base metal electrodes, addressing a market for some 1013 capacitors per year.Manufacturers of large piezoelectric transducers depend almost exclusively on perovskite-structure oxide ceramics. Navy sonar systems are major customers, but spinoff has occurred into a wide range of commercial and medical ultrasound systems. The capability of current materials has improved more than tenfold over the original BaTiO3 ceramics as a result of the effective application of molecular engineering, a strong testament to the insight of the founder of this area of study.

scholarly journals The uncertainty of the atmospheric integrated water vapour estimated from GNSS observations

2015 ◽  
Vol 8 (8) ◽  
pp. 8817-8857 ◽  
Author(s):  
T. Ning ◽  
J. Wang ◽  
G. Elgered ◽  
G. Dick ◽  
J. Wickert ◽  
...  
Keyword(s):  
Water Vapour ◽  
Global Climate ◽  
Measurement Techniques ◽  
Weather Conditions ◽  
Total Delay ◽  
Error Sources ◽  
Integrated Water Vapour ◽  
Input Variables ◽  
The Impact ◽  
Gnss Observations

Abstract. Within the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) there is a need for an assessment of the uncertainty in the Integrated Water Vapour (IWV) in the atmosphere estimated from ground-based GNSS observations. All relevant error sources in GNSS-derived IWV is therefore essential to be investigated. We present two approaches, a statistical and a theoretical analysis, for the assessment of the uncertainty of the IWV. It will be implemented to the GNSS IWV data stream for GRUAN in order to obtain a specific uncertainty for each data point. In addition, specific recommendations are made to GRUAN on hardware, software, and data processing practices to minimize the IWV uncertainty. By combining the uncertainties associated with the input variables in the estimations of the IWV, we calculated the IWV uncertainties for several GRUAN sites with different weather conditions. The results show a similar relative importance of all uncertainty contributions where the uncertainties in the Zenith Total Delay (ZTD) dominate the error budget of the IWV contributing with over 75 % to the total IWV uncertainty. The impact of the uncertainty associated with the conversion factor between the IWV and the Zenith Wet Delay (ZWD) is proportional to the amount of water vapour and increases slightly for moist weather conditions. The GRUAN GNSS IWV uncertainty data will provide a quantified confidence to be used for the validation of other measurement techniques, taking the uncertainty into account from diurnal to decadal time scales.

Future water availability in West Africa: Estimates from high-resolution RCM modeling and multivariate bias correction

2020 ◽  
Author(s):  
Diarra Dieng ◽  
Cornelius Hald ◽  
Patrick Laux ◽  
Christof Lorenz ◽  
Harald Kunstmann
Keyword(s):  
High Resolution ◽  
West Africa ◽  
Water Availability ◽  
Bias Correction ◽  
Wrf Model ◽  
Correction Method ◽  
Dew Point ◽  
Limited Area ◽  
Wide Range ◽  
Institute Of Technology

<p><strong>Future water availability in West Africa: Estimates from high-resolution RCM modeling and multivariate bias correction </strong></p><p>Diarra Dieng<sup>1</sup>, Cornelius Hald<sup>1</sup>, Patrick Laux<sup>1,2</sup>, Christof Lorenz<sup>1</sup>, Harald Kunstmann<sup>1,2</sup></p><p><sup>1</sup>Institute of Meteorology and Climate Research (IMK-IFU), Campus Alpine, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany,</p><p><sup>2</sup>Institute of Geography, University of Augsburg, Augsburg, Germany,</p><p> </p><p>With a wide range of ecological, climatic, and cultural diversities, West Africa is a rapidly developing region whose agricultural systems remain largely rain-fed and underdeveloped. In this study we examine the potential impacts of climate variability and climate change on the water availability in the mid-21st century in West 
Africa by using high resolution simulations (12km) from the Weather and Research Forecasting (WRF) model and the COSMO-Climate Limited area Modelling (CCLM) for the RCP 4.5 scenario. Our approach is based on the simplified Penman-Monteith (PM) equation for daily ET, which requires the joint information on relative humidity, maximum and minimum daily temperatures, dew point temperature, solar radiation and wind speed. It is not only crucial that the statistical behavior of these modelled variables is close to observations, but also that the interplay between these variables is realistic. We therefore further adapted, applied and analyzed a subsequent bias-correction method for the WRF and CCLM simulations using a nonparametric, trend-preserving quantile mapping approach and a multivariate bias correction approach (MBCn). We present the details of the method and the derived implications for expected water availability in West Africa.</p>

scholarly journals Retrieval of column-integrated water vapour from MODIS and analysis of its monthly and seasonal variability over several typical cities in China

MAUSAM ◽  
2021 ◽  
Vol 67 (3) ◽  
pp. 571-576
Author(s):  
ZHANG JINYE ◽  
CHENG CHUNFU ◽  
ZHU JINRONG ◽  
YU XIULI
Keyword(s):  
Water Vapour ◽  
Global Climate ◽  
Low Cost ◽  
Precipitable Water ◽  
Spatial And Temporal Variability ◽  
Precipitable Water Vapour ◽  
Integrated Water Vapour ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Good Tracer

Column-integrated water vapour also called Precipitable Water Vapour (PWV), is one of the main parameters influencing the global climate change. Due to its high spatial and temporal variability PWV has been found to be a good tracer of atmospheric motions. Retrieving PWV from Moderate Resolution Imaging Spectroradiometer (MODIS) data has the merits of high spatial resolution and low cost. In this paper, an algorithm for retrieving PWV using several MODIS near-IR channels data is first presented. Six typical cities in China with different climate are selected for study. These are Beijing, Shanghai, Guangzhou, Chengdu, Wuhan and Lanzhou. The variations of PWV in recent13 years (2001-2013) over six cities have been analyzed. The study brings out an increasing trend of annual average of water vapour over these cities in recent 13 years. The results also indicate that PWV reaches the highest value in summer, decreases in autumn, further decrease in spring, and is lowest in winter. PWV in summer over the six cities have been increasing in recent 13 years, but PWV in autumn and winter have been decreasing over inland cities, such as Wuhan and Beijing. Possible reasons for such observed trends are given in this paper.  

Preface

2009 ◽  
Vol 81 (12) ◽  
pp. iv
Author(s):  
Bryan R. Henry
Keyword(s):  
Molecular Electronics ◽  
Gas Adsorption ◽  
Dna Nanotechnology ◽  
Porous Metal ◽  
Massachusetts Institute Of Technology ◽  
Max Planck ◽  
Past President ◽  
Selection Committee ◽  
Wide Range ◽  
Institute Of Technology

IUPAC is a global, scientific organization that contributes to the worldwide understanding of chemistry and the chemical sciences. It is certainly true that young chemists are shaping our science, and it is important for IUPAC to provide encouragement to our young colleagues. IUPAC accomplishes this goal through the IUPAC Prize for Young Chemists. This prestigious annual prize honors four to five chemists for important and outstanding research carried out during recent Ph.D. studies. The work is mainly judged on the basis of a 1000-word essay which is supported by recommendations from the senior scientist(s) with whom the candidate collaborated.As immediate Past President of IUPAC, I have had the pleasure of chairing an international prize selection committee of eminent chemists with a wide range of expertise in chemistry that adjudicated essays from 36 applicants from 19 countries. Reading these outstanding essays provided a wonderful overview of new trends in chemistry. Due to the large number of excellent candidates, it was not an easy task to pick the winners, but in the end the committee arrived at a unanimous decision and awarded the 2009 IUPAC Prize for Young Chemists to the following five chemists:- Faisal A. Aldaye, McGill University, Montréal, Canada; "Supramolecular DNA nanotechnology: Discrete nanoparticle organization, three dimensional DNA construction, and molecule-mediated DNA self-assembly"- Christopher Bettinger, Massachusetts Institute of Technology, Cambridge, MA, USA; "Synthesis and microfabrication of elastomeric biomaterials for advanced tissue engineering scaffolds"- Xinliang Feng, Max Planck Institute for Polymer Research, Mainz, Germany: "C3-symmetric discotic liquid-crystalline materials for molecular electronics: Versatile synthesis and self-organization"- Xing Yi Ling, University of Twente, Enschede, The Netherlands: "From supramolecular chemistry to nanotechnology: Assembly of 3D nanostructures"- Shengqian Ma, Miami University, Oxford, OH, USA; "Gas adsorption applications of porous metal–organic frameworks"Each winner received a cash prize of USD 1000 and a trip to the 42nd IUPAC World Chemistry Congress, which took place in Glascow, Scotland, 2-7 August, 2009. Here the winners had the opportunity to present their work, which is an important stage of any research project. The prize winners also were invited to submit manuscripts on aspects of their research for publication in Pure and Applied Chemistry (PAC). It is a pleasure to see that all five prize winners have taken advantage of this offer. The result is five refereed papers which contain critical reviews of high quality and appear in PAC.Finally, it is an honor and a pleasure to congratulate each of the winners (and their supervisors) for winning the 2009 IUPAC Prize. It is IUPAC's hope that each of them has been encouraged to continue to do exciting research that will contribute to a bright future for the molecular-based sciences, which are so important for our common future.Bryan R. HenryIUPAC Immediate Past President and Chair of the IUPAC Prize Selection Committee

scholarly journals The uncertainty of the atmospheric integrated water vapour estimated from GNSS observations

2016 ◽  
Vol 9 (1) ◽  
pp. 79-92 ◽  
Author(s):  
T. Ning ◽  
J. Wang ◽  
G. Elgered ◽  
G. Dick ◽  
J. Wickert ◽  
...  
Keyword(s):  
Water Vapour ◽  
Global Climate ◽  
Measurement Techniques ◽  
Weather Forecast ◽  
Weather Conditions ◽  
Satellite System ◽  
Total Delay ◽  
Integrated Water Vapour ◽  
The Impact ◽  
Gnss Observations

Abstract. Within the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) there is a need for an assessment of the uncertainty in the integrated water vapour (IWV) in the atmosphere estimated from ground-based global navigation satellite system (GNSS) observations. All relevant error sources in GNSS-derived IWV are therefore essential to be investigated. We present two approaches, a statistical and a theoretical analysis, for the assessment of the uncertainty of the IWV. The method is valuable for all applications of GNSS IWV data in atmospheric research and weather forecast. It will be implemented to the GNSS IWV data stream for GRUAN in order to assign a specific uncertainty to each data point. In addition, specific recommendations are made to GRUAN on hardware, software, and data processing practices to minimise the IWV uncertainty. By combining the uncertainties associated with the input variables in the estimations of the IWV, we calculated the IWV uncertainties for several GRUAN sites with different weather conditions. The results show a similar relative importance of all uncertainty contributions where the uncertainties in the zenith total delay (ZTD) dominate the error budget of the IWV, contributing over 75 % of the total IWV uncertainty. The impact of the uncertainty associated with the conversion factor between the IWV and the zenith wet delay (ZWD) is proportional to the amount of water vapour and increases slightly for moist weather conditions. The GRUAN GNSS IWV uncertainty data will provide a quantified confidence to be used for the validation of other measurement techniques.

The Mit Specular and Diffuse Neutron Reflectometer for the Investigation of Surfaces & Interfaces

1994 ◽  
Vol 376 ◽  
Author(s):  
Chwen-Yuan Ku ◽  
Xiao-Lin Zhou
Keyword(s):  
Nuclear Reactor ◽  
Dynamic Range ◽  
Sample Surface ◽  
Massachusetts Institute Of Technology ◽  
Neutron Reflectometer ◽  
Wide Range ◽  
Diffuse Reflectivity ◽  
Institute Of Technology ◽  
Beam Motion ◽  
Diffuse Neutron

ABSTRACTA specular and diffuse neutron reflectometer was designed at the Massachusetts Institute of Technology nuclear reactor, MITR-II, and the description of the facility is presented in this paper. This reflectometer uses a horizontal sample geometry so that both solid and liquid samples can be measured. To minimize sample or beam motion and reduce measurement time, two neutron beams are extracted from the same beam port and are incident simultaneously on the same sample surface at grazing incident angles of 0.2 and 1.5 degrees, respectively. The reflected neutrons are detected by a linear position sensitive detector and energy-analyzed by the time-of-flight method. The reflection flight path is enclosed in an evacuated chamber to reduce background counts. The reflectometer performance is estimated as 0.004-0.33 Å-1 dynamic range, 5% Q resolution, 1-10-7 measurable specular reflectivity range, and a 4 orders of magnitude range in diffuse reflectivity counts. Diffuse reflectivity can be measured as a two-dimensional function of both the wavelength and the in-plane diffuse reflection angle. The instrument can be used to investigate a wide range of surface systems of condensed and soft-condensed matters.

scholarly journals Quantifying the value of redundant measurements at GCOS Reference Upper-Air Network sites

2014 ◽  
Vol 7 (11) ◽  
pp. 3813-3823 ◽  
Author(s):  
F. Madonna ◽  
M. Rosoldi ◽  
J. Güldner ◽  
A. Haefele ◽  
R. Kivi ◽  
...  
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Global Climate ◽  
Microwave Radiometer ◽  
Raman Lidar ◽  
Mutual Correlation ◽  
Random Uncertainty ◽  
Lidar Measurements ◽  
Integrated Water Vapour ◽  
Microwave Radiometers

Abstract. The potential for measurement redundancy to reduce uncertainty in atmospheric variables has not been investigated comprehensively for climate observations. We evaluated the usefulness of entropy and mutual correlation concepts, as defined in information theory, for quantifying random uncertainty and redundancy in time series of the integrated water vapour (IWV) and water vapour mixing ratio profiles provided by five highly instrumented GRUAN (GCOS, Global Climate Observing System, Reference Upper-Air Network) stations in 2010–2012. Results show that the random uncertainties on the IWV measured with radiosondes, global positioning system, microwave and infrared radiometers, and Raman lidar measurements differed by less than 8%. Comparisons of time series of IWV content from ground-based remote sensing instruments with in situ soundings showed that microwave radiometers have the highest redundancy with the IWV time series measured by radiosondes and therefore the highest potential to reduce the random uncertainty of the radiosondes time series. Moreover, the random uncertainty of a time series from one instrument can be reduced by ~ 60% by constraining the measurements with those from another instrument. The best reduction of random uncertainty is achieved by conditioning Raman lidar measurements with microwave radiometer measurements. Specific instruments are recommended for atmospheric water vapour measurements at GRUAN sites. This approach can be applied to the study of redundant measurements for other climate variables.

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