scholarly journals Comparison of satellite limb-sounding humidity climatologies of the uppermost tropical troposphere

2007 ◽  
Vol 7 (4) ◽  
pp. 12617-12655
Author(s):  
M. Ekström ◽  
P. Eriksson ◽  
W. G. Read ◽  
D. P. Murtagh
Keyword(s):  
Probability Density ◽  
Probability Density Functions ◽  
Climate Modelling ◽  
Density Functions ◽  
Upper Troposphere ◽  
Clear Sky ◽  
Upper Tropospheric Humidity ◽  
Tropical Troposphere ◽  
Sky Conditions ◽  
Good Agreement

Abstract. Humidity climatologies of the tropical uppermost troposphere from satellite limb emission measurements have been compared. Four instruments are considered; UARS-MLS, Odin-SMR, and Aura-MLS operating in the microwave region, and MIPAS in the IR region. A reference for the comparison is obtained by MOZAIC in-situ measurements. The upper tropospheric humidity products were compared on basis of their empirical probability density functions and seasonally averaged horizontal fields at two altitude layers, 12 and 15 km. The probability density functions of the microwave datasets were found to be in very good agreement with each other, and are also consistent with MOZAIC. The average seasonal humidities differ with less than 10%RHi between the instruments, indicating that stated measurement accuracies of 20–30% are conservative estimates. The systematic uncertainty in Odin-SMR data due to cloud correction was also independently estimated to be 10%RHi. MIPAS humidity profiles were found to suffer from cloud contamination, with only 30% of the measurements reaching into the upper troposphere, but under clear-sky conditions there is a good agreement between MIPAS, Odin-SMR and Aura-MLS. Odin-SMR and the two MLS datasets can be treated as independent, being based on different underlying spectroscopy and technology. The good agreement between the microwave limb-sounders, and MOZAIC, is therefore an important step towards understanding the upper tropospheric humidity. The found accuracy of 10%RHi is approaching the level required to validate climate modelling of the upper troposphere humidity. The comparison of microwave and IR also stresses that microwave limb-sounding is necessary for a complete view of the upper troposphere.

scholarly journals Comparison of satellite limb-sounding humidity climatologies of the uppermost tropical troposphere

2008 ◽  
Vol 8 (2) ◽  
pp. 309-320 ◽  
Author(s):  
M. Ekström ◽  
P. Eriksson ◽  
W. G. Read ◽  
M. Milz ◽  
D. P. Murtagh
Keyword(s):  
Probability Density ◽  
Infrared Region ◽  
Probability Density Functions ◽  
Climate Modelling ◽  
Density Functions ◽  
Upper Troposphere ◽  
Upper Tropospheric Humidity ◽  
Tropical Troposphere ◽  
Sky Conditions ◽  
Good Agreement

Abstract. Humidity climatologies of the tropical uppermost troposphere from satellite limb emission measurements have been compared. Four instruments are considered; UARS-MLS, Odin-SMR, and Aura-MLS operating in the microwave region, and MIPAS in the infrared region. A reference for the comparison is obtained by MOZAIC in-situ measurements. The upper tropospheric humidity products were compared on basis of their empirical probability density functions and seasonally averaged horizontal fields at two altitude layers, 12 and 15 km. The probability density functions of the microwave datasets were found to be in very good agreement with each other, and were also consistent with MOZAIC. The average seasonal humidities differ with less than 10%RHi between the instruments, indicating that stated measurement accuracies of 20–30% are conservative estimates. The systematic uncertainty in Odin-SMR data due to cloud correction was also independently estimated to be 10%RHi. MIPAS humidity profiles were found to suffer from cloud contamination, with only 30% of the measurements reaching into the upper troposphere, but under clear-sky conditions there is a good agreement between MIPAS, Odin-SMR and Aura-MLS. Odin-SMR and the two MLS datasets can be treated as independent, being based on different underlying spectroscopy and technology. The good agreement between the microwave limb-sounders, and MOZAIC, is therefore an important step towards understanding the upper tropospheric humidity. The found accuracy of 10%RHi is approaching the level required to validate climate modelling of the upper troposphere humidity. The comparison of microwave and infrared also stresses that microwave limb-sounding is necessary for a complete view of the upper troposphere.

Bimodal and multimodal descriptions of soil-water characteristic curves for structural soils

2013 ◽  
Vol 67 (8) ◽  
pp. 1740-1747 ◽  
Author(s):  
Shiyu Liu ◽  
Noriyuki Yasufuku ◽  
Qiang Liu ◽  
Kiyoshi Omine ◽  
Hazarika Hemanta
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Soil Water ◽  
Lognormal Distribution ◽  
Probability Density Functions ◽  
Density Functions ◽  
Characteristic Curves ◽  
Physically Based ◽  
Soil Water Characteristic Curves ◽  
Good Agreement

In the last decades several approaches have been developed to describe bimodal or multimodal soil-water characteristic curves (SWCCs). Unfortunately, most of these models were derived empirically. In the presented study, physically based bimodal and multimodal SWCC functions have been developed for structural soils. The model involved two or more continual pore series; the probability density functions for each pore series were assumed to be lognormal distribution and can be superposed to obtain the overall probability density function of the structural soils. The proposed functions were capable of simulating bimodal or multimodal SWCCs using parameters which can be related to physical properties of the structural soils. The experimental SWCC data were used to verify the proposed method. The fitting results showed that the proposed approaches resulted in good agreement between measurement and simulation. These functions can potentially be used as effective tools for indentifying hydraulic porosities in the structural mediums.

scholarly journals Cloud discrimination in probability density functions of limb scattered sunlight measurements

2013 ◽  
Vol 6 (4) ◽  
pp. 6491-6516
Author(s):  
E. N. Normand ◽  
A. E. Bourassa ◽  
D. A. Degenstein
Keyword(s):  
Probability Density ◽  
Lower Stratosphere ◽  
Infrared Imaging ◽  
Imaging System ◽  
Probability Density Functions ◽  
Density Functions ◽  
Cirrus Cloud ◽  
Upper Troposphere ◽  
Solar Occultation ◽  
Continuum Measurement

Abstract. A technique characterizing the distribution of cirrus cloud top occurrences from the Optical Spectrograph and Infrared Imaging System (OSIRIS) limb scattering radiance profiles is presented. The technique involves computing scattering residual profiles by comparing normalized measured radiance and modelled molecular radiance profiles where enhancements in the measured radiance indicate the presence of clouds. Probability density functions of scattering residuals show the distribution is not a continuum measurement; there is a distinction between the cloudy and cloud-free conditions. Observations show high cloud top occurrences in the upper troposphere and lower stratosphere region above Indonesia and Central America. Results obtained using this technique with OSIRIS measurements are compared to those obtained by Sassen et al. (2008) with CALIPSO nadir measurements and to those obtained by Wang et al. (1996) with SAGE II solar occultation measurements.

scholarly journals Analysis of electron density calculations using deterministic-probabilistic model of the ionospheric D-region

2018 ◽  
Vol 4 (3) ◽  
pp. 84-94
Author(s):  
Сусанна Беккер ◽  
Susanna Bekker
Keyword(s):  
Probability Density ◽  
Electron Density ◽  
Probabilistic Model ◽  
Ionization Rate ◽  
Probability Density Functions ◽  
Density Functions ◽  
Component System ◽  
D Region ◽  
Number Of Iterations ◽  
Good Agreement

The work is devoted to the development of a fundamentally new way of modeling the ionospheric D-region — deterministic-probabilistic. The results of electron density (Ne) calculations using this technique are analyzed. Research of this kind is of fundamental importance, related to the rejection of a purely deter-ministic description of a continuously changing envi-ronment such as the ionosphere. In this work, Ne is cal-culated using a five-component system of ionization-recombination cycle equations. Probability density functions (PDFs) of input parameters of the model are used to solve the system. The most important sources of the D-region ionization are taken into account to calculate PDFs of the ionization rate. The necessary number of iterations is determined by the convergence of PDFs of the electron density from 50 to 85 km at midlatitudes under different heliogeophysical conditions. Theoretical Ne PDFs have been shown to be in good agreement with two experimental databases on electron density, especially at large D-region heights. The next important stage of modeling is the thorough verification of PDFs from experimental radiophysical data on VLF—LF propagation.

scholarly journals Cloud discrimination in probability density functions of limb-scattered sunlight measurements

2013 ◽  
Vol 6 (12) ◽  
pp. 3359-3368 ◽  
Author(s):  
E. N. Normand ◽  
J. T. Wiensz ◽  
A. E. Bourassa ◽  
D. A. Degenstein
Keyword(s):  
Probability Density ◽  
Infrared Imaging ◽  
Imaging System ◽  
Stratospheric Aerosol ◽  
Probability Density Functions ◽  
Density Functions ◽  
Cirrus Cloud ◽  
Upper Troposphere ◽  
Solar Occultation ◽  
Continuum Measurement

Abstract. A technique characterizing the distribution of cirrus cloud-top occurrences from the Optical Spectrograph and Infrared Imaging System (OSIRIS) limb-scattering radiance profiles is presented. The technique involves computing scattering residual profiles by comparing normalized measured radiance and modelled molecular radiance profiles where enhancements in the measured radiance indicate the presence of clouds. Probability density functions of scattering residuals show the distribution is not a continuum measurement; there is a distinction between the cloudy and cloud-free conditions. Observations show high cloud-top occurrences in the upper troposphere and lower stratosphere region above Indonesia and Central America. Results obtained using this technique with OSIRIS measurements are compared to those obtained by Sassen et al. (2008) with Cloud-Aerosol Lidar Pathfinder Satellite Observations (CALIPSO) nadir measurements and to those obtained by Wang et al. (1996) with Stratospheric Aerosol and Gas Experiment (SAGE) II solar occultation measurements.

scholarly journals Modeling Diameter Distributions with Six Probability Density Functions in Pinus halepensis Mill. Plantations Using Low-Density Airborne Laser Scanning Data in Aragón (Northeast Spain)

2021 ◽  
Vol 13 (12) ◽  
pp. 2307
Author(s):  
J. Javier Gorgoso-Varela ◽  
Rafael Alonso Ponce ◽  
Francisco Rodríguez-Puerta
Keyword(s):  
Probability Density ◽  
Linear Models ◽  
Pinus Halepensis ◽  
Beta Function ◽  
Probability Density Functions ◽  
Lidar Data ◽  
Density Functions ◽  
Minimum Diameter ◽  
Location Parameters ◽  
Diameter Distributions

The diameter distributions of trees in 50 temporary sample plots (TSPs) established in Pinus halepensis Mill. stands were recovered from LiDAR metrics by using six probability density functions (PDFs): the Weibull (2P and 3P), Johnson’s SB, beta, generalized beta and gamma-2P functions. The parameters were recovered from the first and the second moments of the distributions (mean and variance, respectively) by using parameter recovery models (PRM). Linear models were used to predict both moments from LiDAR data. In recovering the functions, the location parameters of the distributions were predetermined as the minimum diameter inventoried, and scale parameters were established as the maximum diameters predicted from LiDAR metrics. The Kolmogorov–Smirnov (KS) statistic (Dn), number of acceptances by the KS test, the Cramér von Misses (W2) statistic, bias and mean square error (MSE) were used to evaluate the goodness of fits. The fits for the six recovered functions were compared with the fits to all measured data from 58 TSPs (LiDAR metrics could only be extracted from 50 of the plots). In the fitting phase, the location parameters were fixed at a suitable value determined according to the forestry literature (0.75·dmin). The linear models used to recover the two moments of the distributions and the maximum diameters determined from LiDAR data were accurate, with R2 values of 0.750, 0.724 and 0.873 for dg, dmed and dmax. Reasonable results were obtained with all six recovered functions. The goodness-of-fit statistics indicated that the beta function was the most accurate, followed by the generalized beta function. The Weibull-3P function provided the poorest fits and the Weibull-2P and Johnson’s SB also yielded poor fits to the data.

scholarly journals A synergy of the velocity gradients technique and the probability density functions for identifying gravitational collapse in self-absorbing media

2021 ◽  
Vol 502 (2) ◽  
pp. 1768-1784
Author(s):  
Yue Hu ◽  
A Lazarian
Keyword(s):  
Magnetic Fields ◽  
Probability Density ◽  
Column Density ◽  
Mass Density ◽  
Probability Density Functions ◽  
Emission Lines ◽  
Density Functions ◽  
Star Forming ◽  
Velocity Gradients ◽  
Self Gravity

ABSTRACT The velocity gradients technique (VGT) and the probability density functions (PDFs) of mass density are tools to study turbulence, magnetic fields, and self-gravity in molecular clouds. However, self-absorption can significantly make the observed intensity different from the column density structures. In this work, we study the effects of self-absorption on the VGT and the intensity PDFs utilizing three synthetic emission lines of CO isotopologues 12CO (1–0), 13CO (1–0), and C18O (1–0). We confirm that the performance of VGT is insensitive to the radiative transfer effect. We numerically show the possibility of constructing 3D magnetic fields tomography through VGT. We find that the intensity PDFs change their shape from the pure lognormal to a distribution that exhibits a power-law tail depending on the optical depth for supersonic turbulence. We conclude the change of CO isotopologues’ intensity PDFs can be independent of self-gravity, which makes the intensity PDFs less reliable in identifying gravitational collapsing regions. We compute the intensity PDFs for a star-forming region NGC 1333 and find the change of intensity PDFs in observation agrees with our numerical results. The synergy of VGT and the column density PDFs confirms that the self-gravitating gas occupies a large volume in NGC 1333.

scholarly journals Interactive design of probability density functions for shape grammars

2015 ◽  
Vol 34 (6) ◽  
pp. 1-13 ◽  
Author(s):  
Minh Dang ◽  
Stefan Lienhard ◽  
Duygu Ceylan ◽  
Boris Neubert ◽  
Peter Wonka ◽  
...  
Keyword(s):  
Probability Density ◽  
Probability Density Functions ◽  
Interactive Design ◽  
Density Functions ◽  
Shape Grammars
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