Clarity Index Analysis and Modeling Using Probability Distribution Functions in Campo Grande-MS, Brazil

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Amaury de Souza ◽  
Razika Ihaddadene ◽  
Nabila Ihaddadene ◽  
Pelumi E. Oguntunde
Keyword(s):  
Low Frequency ◽  
Distribution Functions ◽  
Data Sets ◽  
Atmospheric Conditions ◽  
Mato Grosso ◽  
Clear Sky ◽  
Probability Distribution Functions ◽  
Index Analysis ◽  
Sky Conditions ◽  
Mato Grosso Do Sul

The importance of statistical analysis in the field of energy for environmental engineering is shown in this research paper, in which the adequacy of the data sets of clarity index with the model of “best” probability (based on the criteria used) was studied. In Campo Grande which is the capital of the Brazilian state of Mato Grosso do Sul, located in the Center-West region of the country, there is a predominance of the atmospheric conditions of low cloudiness, with a high frequency of days with a clear sky and in consequence a low-frequency of days with cloudy sky. The aerosols resulting from the burning of sugarcane influence the sky conditions in Campo Grande thus reducing the frequency of the clear sky.

scholarly journals Continuous detection and characterization of the Sea Breeze in clear sky conditions using Meteosat Second Generation

2011 ◽  
Vol 11 (12) ◽  
pp. 33357-33377
Author(s):  
I. M. Lensky ◽  
U. Dayan
Keyword(s):  
Second Generation ◽  
Field Measurements ◽  
Sea Breeze ◽  
Atmospheric Conditions ◽  
Clear Sky ◽  
Synoptic Conditions ◽  
Desert Regions ◽  
Convergence Zones ◽  
Sky Conditions ◽  
The Impact

Abstract. The sea breeze (SB) is a thermally induced boundary layer phenomenon that occurs at coastal locations throughout the world. Previous satellite remote sensing studies used low-level clouds formed over the sea-breeze convergence zones to identify the SB. In this study continuous thermal infrared data from a geostationary satellite (Meteosat Second Generation) and concurrent field measurements were used to detect and characterize the SB in clear sky conditions during the summer. Surface data (wind speed and direction) from 11 sites over Israel for ten summer days in July 2010 for three different synoptic circulation categories were selected. In order to assess the impact of the synoptic induced flow on the SB, we looked for the best agreement between surface and satellite SB timing. An independent classification of synoptic categories performed for the ten summer days revealed two distinct patterns of the SB. During weak horizontal pressure gradient (Weak Persian Trough and High to the West), which enables full development of the SB, the timing of the SB from satellite and field measurements were well correlated (R2=0.75), as compared to unfavorable atmospheric conditions (Deep Persian Trough) yielding lower value (R2=0.5). The SB was identified by surface measurements in an earlier time of the day, with respect to the satellite column integrated measurements. Visualizing a product of time series analysis of the satellite data enabled clear distinction of SB behavior under different synoptic categories. Over desert regions the strong thermal contrast enables detection of the SB even under suppressing synoptic conditions (Deep Persian Trough). This method enables detection and timing of the SB over desert regions where clouds and field measurements are scarce, and is applicable worldwide.

scholarly journals Total Column Water Vapour Retrieval from S-5P/TROPOMI in the Visible Blue Spectral Range

2020 ◽  
Author(s):  
Christian Borger ◽  
Steffen Beirle ◽  
Steffen Dörner ◽  
Holger Sihler ◽  
Thomas Wagner
Keyword(s):  
Water Vapour ◽  
Spectral Range ◽  
Input Data ◽  
Reference Data ◽  
Boreal Summer ◽  
Data Sets ◽  
Clear Sky ◽  
Sky Conditions ◽  
Total Column ◽  
Good Agreement

Abstract. Total column water vapour has been retrieved from TROPOMI measurements in the visible blue spectral range and compared to a variety of different reference data sets for clear-sky conditions during boreal summer and winter. The retrieval consists of the common two-step DOAS approach: first the spectral analysis is performed within a linearized scheme and then the retrieved slant column densities are converted to vertical columns using an iterative scheme for the water vapour a priori profile shape which is based on an empirical parameterization of the water vapour scale height. Moreover, a modified albedo map was used combining the OMI LER albedo and scaled MODIS albedo map. The use of the alternative albedo is especially important over regions with very low albedo and high probability of clouds like the Amazon region. The errors of the TCWV retrieval have been theoretically estimated considering the contribution of a variety of different uncertainty sources. For observations during clear-sky conditions, over ocean surface, and at low solar zenith angles the error typically is around values of 10–20 % and during cloudy-sky conditions, over land surface, and at high solar zenith angles it reaches values around 20–50 %. In the framework of a validation study the retrieval demonstrates that it can well capture the global water vapour distribution: the retrieved H2O VCDs show very good agreement to the reference data sets over ocean for boreal summer and winter whereby the modified albedo map substantially improves the retrieval's consistency to the reference data sets in particular over tropical landmasses. However over land the retrieval underestimates the VCD by about 10 %, particularly during summertime. Our investigations show that this underestimation is likely caused by uncertainties within the surface albedo and the cloud input data: Low level clouds cause an underestimation but for mid to high level clouds good agreement is found. In addition, our investigations indicate that these biases can probably be further reduced by the use of updated cloud input data. The TCWV retrieval can be easily applied to further satellite sensors (e.g. GOME-2 or OMI) for creating uniform measurement data sets on longterm which is particularly interesting for climate and trend studies of water vapour.

scholarly journals Quality assessment of integrated water vapour measurements at the St. Petersburg site, Russia: FTIR vs. MW and GPS techniques

2017 ◽  
Vol 10 (11) ◽  
pp. 4521-4536 ◽  
Author(s):  
Yana A. Virolainen ◽  
Yury M. Timofeyev ◽  
Vladimir S. Kostsov ◽  
Dmitry V. Ionov ◽  
Vladislav V. Kalinnikov ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Water Vapour ◽  
Measurement Errors ◽  
Microwave Radiometer ◽  
Reference Method ◽  
Atmospheric Conditions ◽  
Assessment Protocol ◽  
Clear Sky ◽  
Integrated Water Vapour ◽  
Sky Conditions

Abstract. The cross-comparison of different techniques for atmospheric integrated water vapour (IWV) measurements is the essential part of their quality assessment protocol. We inter-compare the synchronised data sets of IWV values measured by the Bruker 125 HR Fourier-transform infrared spectrometer (FTIR), RPG-HATPRO microwave radiometer (MW), and Novatel ProPak-V3 global navigation satellite system receiver (GPS) at the St. Petersburg site between August 2014 and October 2016. As the result of accurate spatial and temporal matching of different IWV measurements, all three techniques agree well with each other except for small IWV values. We show that GPS and MW data quality depends on the atmospheric conditions; in dry atmosphere (IWV smaller than 6 mm), these techniques are less reliable at the St. Petersburg site than the FTIR method. We evaluate the upper bound of statistical measurement errors for clear-sky conditions as 0.29 ± 0.02 mm (1.6 ± 0.3 %), 0.55 ± 0.02 mm (4.7 ± 0.4 %), and 0.76 ± 0.04 mm (6.3 ± 0.8 %) for FTIR, GPS, and MW methods, respectively. We propose the use of FTIR as a reference method under clear-sky conditions since it is reliable on all scales of IWV variability.

scholarly journals Atmospheric effect on the ground-based measurements of broadband surface albedo

2012 ◽  
Vol 5 (11) ◽  
pp. 2675-2688 ◽  
Author(s):  
T. Manninen ◽  
A. Riihelä ◽  
G. de Leeuw
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Surface Albedo ◽  
Test Site ◽  
Empirical Method ◽  
Atmospheric Conditions ◽  
Atmospheric Effect ◽  
Clear Sky ◽  
Using Data ◽  
Sky Conditions

Abstract. Ground-based pyranometer measurements of the (clear-sky) broadband surface albedo are affected by the atmospheric conditions (mainly by aerosol particles, water vapour and ozone). A new semi-empirical method for estimating the magnitude of the effect of atmospheric conditions on surface albedo measurements in clear-sky conditions is presented. Global and reflected radiation and/or aerosol optical depth (AOD) at two wavelengths are needed to apply the method. Depending on the aerosol optical depth and the solar zenith angle values, the effect can be as large as 20%. For the cases we tested using data from the Cabauw atmospheric test site in the Netherlands, the atmosphere caused typically up to 5% overestimation of surface albedo with respect to corresponding black-sky surface albedo values.

Channel Attenuation Models over Ka Band Satellite Systems at Venezuelan Amazonian Area

2016 ◽  
Vol 841 ◽  
pp. 260-265
Author(s):  
Gustavo Guedez ◽  
Gao Qiang
Keyword(s):  
Low Frequency ◽  
Amazon Region ◽  
Atmospheric Gases ◽  
Ka Band ◽  
Satellite Systems ◽  
Clear Sky ◽  
Multipath Effects ◽  
Link Budget ◽  
Attenuation Models ◽  
Sky Conditions

The progressive congestion of the spectrum at low frequency bands, has obliged the need to use new systems which operate in higher frequencies, such as the Ka bands. The quality and availability of the signals in Ka band are seriously degraded by various climate phenomena, especially in the Amazon area. To keep the link properties in normal conditions (similar to clear sky conditions), is necessary to know the attenuation losses over the service area or footprint. For the Venezuelan Amazon region only Attenuation by atmospheric gases, Attenuation by rain and Scintillation and multipath effects, could be considered according to the ITU. The attenuation calculation is the first step to estimate the link budget and implement any communication service over Ka Band in the Venezuelan Amazon region. The aim of this research is modeling the channel attenuation for Ka band satellite signals and find a suitable attenuation data.

scholarly journals Cloud and aerosol classification for 2 1/2 years of MAX-DOAS observations in Wuxi (China) and comparison to independent data sets

2015 ◽  
Vol 8 (5) ◽  
pp. 4653-4709 ◽  
Author(s):  
Y. Wang ◽  
M. Penning de Vries ◽  
P. H. Xie ◽  
S. Beirle ◽  
S. Dörner ◽  
...  
Keyword(s):  
Classification Scheme ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Original Algorithm ◽  
Clear Sky ◽  
Cloud Parameters ◽  
Cloud Classification ◽  
Aerosol Classification ◽  
Cloud Optical Thickness ◽  
Sky Conditions

Abstract. Multi-Axis-Differential Optical Absorption Spectroscopy (MAX-DOAS) observations of trace gases can be strongly influenced by clouds and aerosols. Thus it is important to identify clouds and characterise their properties. In a recent study Wagner et al. (2014) developed a cloud classification scheme based on the MAX-DOAS measurements themselves with which different "sky conditions" (e.g. clear sky, continuous clouds, broken clouds) can be distinguished. Here we apply this scheme to long term MAX-DOAS measurements from 2011 to 2013 in Wuxi, China (31.57° N, 120.31° E). The original algorithm has been modified, in particular in order to account for smaller solar zenith angles (SZA). Instrumental degradation is accounted for to avoid artificial trends of the cloud classification. We compared the results of the MAX-DOAS cloud classification scheme to several independent measurements: aerosol optical depth from a nearby AERONET station and from MODIS, visibility derived from a visibility meter; and various cloud parameters from different satellite instruments (MODIS, OMI, and GOME-2). The most important findings from these comparisons are: (1) most cases characterized as clear sky with low or high aerosol load were associated with the respective AOD ranges obtained by AERONET and MODIS, (2) the observed dependences of MAX-DOAS results on cloud optical thickness and effective cloud fraction from satellite indicate that the cloud classification scheme is sensitive to cloud (optical) properties, (3) separation of cloudy scenes by cloud pressure shows that the MAX-DOAS cloud classification scheme is also capable of detecting high clouds, (4) some clear sky conditions, especially with high aerosol load, classified from MAX-DOAS observations corresponding to the optically thin and low clouds derived by satellite observations probably indicate that the satellite cloud products contain valuable information on aerosols.

scholarly journals Comparison of GOME tropospheric NO<sub>2</sub> columns with NO<sub>2</sub> profiles deduced from ground-based in situ measurements

2006 ◽  
Vol 6 (11) ◽  
pp. 3211-3229 ◽  
Author(s):  
D. Schaub ◽  
K. F. Boersma ◽  
J. W. Kaiser ◽  
A. K. Weiss ◽  
D. Folini ◽  
...  
Keyword(s):  
Standard Deviation ◽  
A Priori ◽  
Relative Difference ◽  
In Situ Measurements ◽  
Data Sets ◽  
Clear Sky ◽  
Tropospheric No2 ◽  
The Mean ◽  
Sky Conditions

Abstract. Nitrogen dioxide (NO2) vertical tropospheric column densities (VTCs) retrieved from the Global Ozone Monitoring Experiment (GOME) are compared to coincident ground-based tropospheric NO2 columns. The ground-based columns are deduced from in situ measurements at different altitudes in the Alps for 1997 to June 2003, yielding a unique long-term comparison of GOME NO2 VTC data retrieved by a collaboration of KNMI (Royal Netherlands Meteorological Institute) and BIRA/IASB (Belgian Institute for Space Aeronomy) with independently derived tropospheric NO2 profiles. A first comparison relates the GOME retrieved tropospheric columns to the tropospheric columns obtained by integrating the ground-based NO2 measurements. For a second comparison, the tropospheric profiles constructed from the ground-based measurements are first multiplied with the averaging kernel (AK) of the GOME retrieval. The second approach makes the comparison independent from the a priori NO2 profile used in the GOME retrieval. This allows splitting the total difference between the column data sets into two contributions: one that is due to differences between the a priori and the ground-based NO2 profile shapes, and another that can be attributed to uncertainties in both the remaining retrieval parameters (such as, e.g., surface albedo or aerosol concentration) and the ground-based in situ NO2 profiles. For anticyclonic clear sky conditions the comparison indicates a good agreement between the columns (n=157, R=0.70/0.74 for the first/second comparison approach, respectively). The mean relative difference (with respect to the ground-based columns) is −7% with a standard deviation of 40% and GOME on average slightly underestimating the ground-based columns. Both data sets show a similar seasonal behaviour with a distinct maximum of spring NO2 VTCs. Further analysis indicates small GOME columns being systematically smaller than the ground-based ones. The influence of different shapes in the a priori and the ground-based NO2 profile is analysed by considering AK information. It is moderate and indicates similar shapes of the profiles for clear sky conditions. Only for large GOME columns, differences between the profile shapes explain the larger part of the relative difference. In contrast, the other error sources give rise to the larger relative differences found towards smaller columns. Further, for the clear sky cases, errors from different sources are found to compensate each other partially. The comparison for cloudy cases indicates a poorer agreement between the columns (n=60, R=0.61). The mean relative difference between the columns is 60% with a standard deviation of 118% and GOME on average overestimating the ground-based columns. The clear improvement after inclusion of AK information (n=60, R=0.87) suggests larger errors in the a priori NO2 profiles under cloudy conditions and demonstrates the importance of using accurate profile information for (partially) clouded scenes.

scholarly journals Comparison of GOME tropospheric NO<sub>2</sub> columns with NO<sub>2</sub> profiles deduced from ground-based in situ measurements

2006 ◽  
Vol 6 (2) ◽  
pp. 2189-2239
Author(s):  
D. Schaub ◽  
K. F. Boersma ◽  
J. W. Kaiser ◽  
A. K. Weiss ◽  
D. Folini ◽  
...  
Keyword(s):  
Standard Deviation ◽  
A Priori ◽  
Relative Difference ◽  
In Situ Measurements ◽  
Data Sets ◽  
Clear Sky ◽  
Tropospheric No2 ◽  
The Mean ◽  
Sky Conditions

Abstract. Nitrogen dioxide (NO2) vertical tropospheric column densities (VTCs) retrieved from the Global Ozone Monitoring Experiment (GOME) are compared to coincident ground-based tropospheric NO2 columns. The ground-based columns are deduced from in situ measurements at different altitudes in the Alps for 1997 to June 2003, yielding a unique long-term comparison of GOME NO2 VTC data retrieved by KNMI/BIRA with independently derived tropospheric NO2 profiles. A first comparison relates the GOME columns to the ground-based NO2 profiles that are directly integrated to tropospheric columns. A second comparison includes averaging kernel (AK) information, which makes the comparison independent from the a priori NO2 profile used in the GOME retrieval. This allows splitting the total difference between the column data sets into two contributions: one that is due to differences between the a priori and the ground-based NO2 profile shapes, and another that can be attributed to uncertainties in both the remaining retrieval parameters and the ground-based in situ NO2 profiles. For anticyclonic clear sky conditions the comparison indicates a good agreement between the columns (n=157, R=0.70/0.74 without/with AK included). Both data sets show a similar seasonal behaviour with a distinct maximum of spring NO2 VTCs. The mean relative difference (with respect to the ground-based columns) is −7% with a standard deviation of 40% and GOME on average slightly underestimating the ground-based columns. Further analysis indicates small GOME columns being systematically smaller than the ground-based ones. The influence of different shapes in the a priori and the ground-based NO2 profile is analysed by considering AK information. It is moderate and indicates similar shapes of the profiles for clear sky conditions. Only for large GOME columns, differences between the profile shapes explain the larger part of the relative difference. In contrast, the other error sources give rise to the larger relative differences found towards smaller columns. Further, for the clear sky cases, errors from different sources are found to compensate each other partially. The comparison for cloudy cases indicates a poorer agreement between the columns (n=60, R=0.61). The mean relative difference between the columns is 60% with a standard deviation of 118% and GOME on average overestimating the ground-based columns. The clear improvement after inclusion of AK information (n=60, R=0.87) suggests larger errors in the a priori NO2 profiles under cloudy conditions and demonstrates the importance of using the kernel information for (partially) clouded scenes.

scholarly journals Continuous detection and characterization of the Sea Breeze in clear sky conditions using Meteosat Second Generation

2012 ◽  
Vol 12 (14) ◽  
pp. 6505-6513 ◽  
Author(s):  
I. M. Lensky ◽  
U. Dayan
Keyword(s):  
Second Generation ◽  
Field Measurements ◽  
Sea Breeze ◽  
Atmospheric Conditions ◽  
Clear Sky ◽  
Synoptic Conditions ◽  
Desert Regions ◽  
Convergence Zones ◽  
Sky Conditions ◽  
The Impact

Abstract. The sea breeze (SB) is a thermally induced boundary layer phenomenon that occurs at coastal locations throughout the world. Previous satellite remote sensing studies used low-level clouds formed over the sea-breeze convergence zones to identify the SB. In this study continuous thermal infrared data from a geostationary satellite (Meteosat Second Generation) and concurrent field measurements were used to detect and characterize the SB in clear sky conditions during the summer. Surface data (wind speed and direction) from 11 sites over Israel for ten summer days in July 2010 for three different synoptic circulation categories were selected. In order to assess the impact of the synoptic induced flow on the SB, we looked for the best agreement between surface and satellite SB timing. An independent classification of synoptic categories performed for the ten summer days revealed two distinct patterns of the SB. During weak horizontal pressure gradient (Weak Persian Trough and High to the West), which enables full development of the SB, the timing of the SB from satellite and field measurements were well correlated (R2 = 0.75), as compared to unfavorable atmospheric conditions (Deep Persian Trough) yielding lower value (R2 = 0.5). The SB was identified by surface measurements in an earlier time of the day, with respect to the satellite column integrated measurements. Visualizing timing of the SB retrieved from satellite data enabled distinction of SB behavior under different synoptic categories. Over desert regions the strong thermal contrast enables detection of the SB even under suppressing synoptic conditions (Deep Persian Trough). This method enables detection and timing of the SB over desert regions where clouds and field measurements are scarce, and is applicable worldwide.

scholarly journals Atmospheric effect on the ground-based measurements of broadband surface albedo

2012 ◽  
Vol 5 (1) ◽  
pp. 385-409 ◽  
Author(s):  
T. Manninen ◽  
A. Riihelä ◽  
G. de Leeuw
Keyword(s):  
Optical Depth ◽  
Zenith Angle ◽  
Surface Albedo ◽  
New Method ◽  
Test Case ◽  
The Sun ◽  
Atmospheric Conditions ◽  
Atmospheric Effect ◽  
Clear Sky ◽  
Sky Conditions

Abstract. Ground-based pyranometer measurements of broadband surface albedo values are affected by the atmospheric conditions. A new method for estimating the magnitude of this effect in clear sky conditions is presented. Global and reflected radiation values and AOD values at two wavelengths are needed to apply the method. Depending on the atmospheric optical depth and the sun zenith angle values the effect can be as large as 20%. For the test case of Cabauw the atmosphere caused typically 5% higher surface albedo values than the corresponding black-sky surface albedo values.

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