Spatial and Temporal Variation of Clearness Index in Iraq

2021 ◽  
Vol 14 (2) ◽  
pp. 129-138
Keyword(s):  
Time Series ◽  
Seasonal Variation ◽  
Temporal Variation ◽  
Annual Variation ◽  
Geographical Location ◽  
Global Solar Radiation ◽  
Summer Season ◽  
Spatial And Temporal Variation ◽  
Clearness Index ◽  
Radiation Time

Abstract: This study deals with the spatial and temporal variation of clearness index (KT) in different meteorological stations, well distributed in Iraq, during the period between 1995 and 2015. The results indicate that the clearness index varies with the geographical location and period of the year. Monthly values of clearness index (KT) in the months of January and December show the lowest values of the index ranging between 0.38 and 0.64. Meanwhile, August shows the highest values ranging between 0.53 and 0.71. Seasonal variation of KT is well noted. The range of (0.40 to 0.58) has been measured in winter, while the range of (0.53 to 0.70) has been detected in summer season. The annual variation of KT shows a range between (0.47 - 0.64) in all stations. The standard deviation (SD) of the monthly values of KT ranged between (0.01-0.06) for all stations, while the coefficient of variation (CV) for the monthly values of KT ranged between (2-10) percent. Keywords: Clearness index, Global solar radiation, Extraterrestrial radiation, Time series, CV, SD.

scholarly journals Variação Espacial e Temporal de NDVI na Lagoa do Peixe, RS (Spatial and Temporal Variation of NDVI in the Peixe Lagoon, RS)

2012 ◽  
Vol 4 (5) ◽  
pp. 897 ◽  
Author(s):  
Luana Portz ◽  
Laurindo Antonio Guasselli ◽  
Iran Carlos Stalliviere Corrêa
Keyword(s):  
Time Series ◽  
Temporal Variation ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Analysis Data ◽  
Landsat Tm ◽  
Spatial And Temporal Variation ◽  
Rainfall Analysis ◽  
Ndvi Time Series ◽  
High Precipitation

Neste estudo foram analisadas as variações espaciais e temporais do Índice de Vegetação por Diferença Normalizada (NDVI) na lagoa do Peixe, no litoral do Rio Grande do Sul. Para alcançar o objetivo proposto foram utilizadas imagens de satélite Landsat TM5, entre os anos de 1986 e 2009, seguindo os procedimentos de elaboração de mosaico das cenas, verificação de campo, geração das imagens de NDVI, análise de dados de precipitação acumulada, geração dos mapas finais e análise qualitativa dos resultados obtidos. Os resultados obtidos com a geração de imagens de NDVI mostraram que a análise espaço-temporal associada aos dados de precipitação fornecem informações de valiosa importância sobre a dinâmica da lagoa do Peixe. A importância  do NDVI neste estudo se destaca pelo contraste existente entre água e vegetação, realçando os diferentes níveis de água sobre os bancos vegetados presentes na borda oeste da lagoa. Estes bancos são um importante controlador da dinâmica de circulação lagunar, onde em períodos de seca ocorre a compartimentação da lagoa, enquanto que em épocas de grande precipitação e acumulação de água estes bancos ficam submersos. Palavras-chave: Landsat TM, série temporal, Parque Nacional.  Spatial and Temporal Variation of NDVI in the Peixe Lagoon, RS  ABSTRACTThis paper analyzed the spatial and temporal variation of Normalized Difference Vegetation Index (NDVI) in the Peixe lagoon. To reach the purpose,  the NDVI time-series were collected from the study area between year 1986 and 2009 derived from Landsat TM5 satellite. The adopted methodology may be subdivided into the following steps: mosaic of scenes, fild verification, generation of NDVI time-series and qualitative analysis, in addition, it was complemented with rainfall analysis.  The results obtained with the NDVI time-series associated with the rainfall analysis data provide valuable information about the environmental dynamics. The importance of NDVI in this work is given by the contrast between water and vegetation, highlighting the different levels of water over vegetated banks present on the western edge of the lagoon. These banks are an important driver circulation in the lagoon, where in periods of drought occurs the partitioning of the lagoo, while in periods of high precipitation and accumulation of water they are submerged.    Keywords: Landsat TM, time-series, National Park.

scholarly journals Reconstruction of global solar radiation time series from 1933 to 2013 at the Izaña Atmospheric Observatory

2014 ◽  
Vol 7 (9) ◽  
pp. 3139-3150 ◽  
Author(s):  
R. D. García ◽  
E. Cuevas ◽  
O. E. García ◽  
V. E. Cachorro ◽  
P. Pallé ◽  
...  
Keyword(s):  
Time Series ◽  
Solar Radiation ◽  
North Atlantic ◽  
Sunshine Duration ◽  
Global Solar Radiation ◽  
Global Scale ◽  
High Mountain ◽  
Atlantic Region ◽  
Clear Sky ◽  
Radiation Time

Abstract. This paper presents the reconstruction of the 80-year time series of daily global solar radiation (GSR) at the subtropical high-mountain Izaña Atmospheric Observatory (IZO) located in Tenerife (The Canary Islands, Spain). For this purpose, we combine GSR estimates from sunshine duration (SD) data using the Ångström–Prescott method over the 1933/1991 period, and GSR observations directly performed by pyranometers between 1992 and 2013. Since GSR measurements have been used as a reference, a strict quality control has been applied based on principles of physical limits and comparison with LibRadtran model. By comparing with high quality GSR measurements, the precision and consistency over time of GSR estimations from SD data have been successfully documented. We obtain an overall root mean square error (RMSE) of 9.2% and an agreement between the variances of GSR estimations and GSR measurements within 92%. Nonetheless, this agreement significantly increases when the GSR estimation is done considering different daily fractions of clear sky (FCS). In that case, RMSE is reduced by half, to about 4.5%, when considering percentages of FCS > 40% (~ 90% of days in the testing period). Furthermore, we prove that the GSR estimations can monitor the GSR anomalies in consistency with GSR measurements and, then, can be suitable for reconstructing solar radiation time series. The reconstructed IZO GSR time series between 1933 and 2013 confirms change points and periods of increases/decreases of solar radiation at Earth's surface observed at a global scale, such as the early brightening, dimming and brightening. This fact supports the consistency of the IZO GSR time series presented in this work, which may be a reference for solar radiation studies in the subtropical North Atlantic region.

scholarly journals Re-construction of global solar radiation time series from 1933 to 2013 at the Izaña Atmospheric Observatory

2014 ◽  
Vol 7 (4) ◽  
pp. 4191-4227 ◽  
Author(s):  
R. D. García ◽  
E. Cuevas ◽  
O. E. García ◽  
V. E. Cachorro ◽  
P. Pallé ◽  
...  
Keyword(s):  
Time Series ◽  
Solar Radiation ◽  
North Atlantic ◽  
Sunshine Duration ◽  
Global Solar Radiation ◽  
Global Scale ◽  
High Mountain ◽  
Clear Sky ◽  
Downward Radiation ◽  
Radiation Time

Abstract. This paper presents the re-construction of the 80 year time series of daily global shortwave downward radiation (SDR) at the subtropical high-mountain Izaña Atmospheric Observatory (IZO, Spain). For this purpose, we combine SDR estimates from sunshine duration (SD) data using the Ångström–Prescott method over the 1933/1991 period, and SDR observations directly performed by pyranometers between 1992 and 2013. Since SDR measurements have been used as a reference, a strict quality control has been applied, when it was not possible data have been re-calibrated by using the LibRadtran model. By comparing to high quality SDR measurements, the precision and consistency over time of SDR estimations from SD data have successfully been documented. We obtain a overall root mean square error (RMSE) of 9.2% and an agreement between the variances of SDR estimations and SDR measurements within 92% (correlation coefficient of 0.96). Nonetheless, this agreement significantly increases when the SDR estimation is done considering different daily fractions of clear sky (FCS). In that case, RMSE is reduced by half, up to about 4.5%, when considering percentages of FCS > 40% (90% of days in the testing period). Furthermore, we prove that the SDR estimations can monitor the SDR anomalies in consistency with SDR measurements and, then, can be suitable for re-constructing solar radiation time series. The re-constructed IZO global SDR time series between 1933 and 2013 confirms discontinuities and periods of increases/decreases of solar radiation at Earth's surface observed at a global scale, such as the early brightening, dimming and brightening. This fact supports the consistency of the IZO SDR time series presented in this work, which may be a reference for solar radiation studies in the subtropical North Atlantic region.

Party and the Dynamics of Congressional Committee Composition in the US House, 1947–96

2003 ◽  
Vol 33 (4) ◽  
pp. 659-679 ◽  
Author(s):  
GARRY YOUNG ◽  
VALERIE HEITSHUSEN
Keyword(s):  
Time Series ◽  
Temporal Variation ◽  
Cross Section ◽  
Spatial And Temporal Variation ◽  
Congressional Committee ◽  
Majority Party ◽  
The Us ◽  
Resource Levels ◽  
Section Analysis

Renewed scholarly interest in the role of US congressional parties has recently coincided with a continuing interest in legislative committee influence and the extent to which that influence relies on committee preference composition. We argue that majority party incentives to influence composition vary by committee salience and party margins. In turn, the party’s ability to influence composition of salient committees is constrained, but varies by party resource levels. We present data on committee composition for the 80th to 104th US Houses and test these expectations using time-series cross-section analysis. The evidence provides support for the predictions – which have been hypothesized or tested anecdotally but have not heretofore been systematically tested – explaining both spatial and temporal variation.

Time series analysis of spatial and temporal variation in egg prices of Tamil Nadu

2016 ◽  
Vol 51 (1) ◽  
pp. 120
Author(s):  
A. Serma Saravana Pandian ◽  
J. Shilpa Shree ◽  
Boopathy Raja M. ◽  
Vetrivel D.
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Temporal Variation ◽  
Tamil Nadu ◽  
Spatial And Temporal Variation ◽  
Series Analysis

scholarly journals Seasonal Variation of SST in Mediterranean Sea

2017 ◽  
Vol 28 (1) ◽  
pp. 10
Author(s):  
Monim H. Khalaf
Keyword(s):  
Time Series ◽  
Seasonal Variation ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Mediterranean Sea ◽  
Summer Season ◽  
Climate System ◽  
Sea Surface ◽  
The Earth ◽  
Analysis Technique

The study of sea surface temperature (SST) is fairly essential for solving many meteorological and oceanographic problem and climate system of the earth. The aim of this study is to explore the variation of SST of Mediterranean Sea during the period (1980-2009) by using statistical analysis technique such as time series and trend. The data obtained from the Europe center (ECMWF) and the resolution of the grid of the variable is 0.5°*0.5° and selects three locations (points) in the Mediterranean Sea. The seasonal variation of SST has the highest value of trend in summer season (0.06) for the points I, II, III, while the lowest value in the transition season, i.e. in spring (0.01) for point I and III and in Autumn (0.04) for point III.

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