Statistical Investigation and Mapping of Monthly Modified Refractivity Gradient over Pakistan at the 700 Hectopascal Level

Saleem, Muhammad

doi:10.4236/ojapr.2016.42005

Cited by 6 publications

(10 citation statements)

References 17 publications

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“…Baluchistan border with Afghanistan is a drier region. The overall climate of Pakistan is drier [27]. Its coastal areas facing 0.6 C to 1.0 C rise in temperature since the 1900 s [28].…”

Section: Study Areamentioning

confidence: 99%

“…Average rainfall varies from area to area but overall has about 10 inches of annually. Desert regions of Baluchistan get less than 5 inches of annual rainfall while Punjab got 20 inches of annual rainfall [27]. Northern mountainous areas face average coldest temperature of 23.88˚C in summer while on Baluchistan, it is about 26.66˚C.…”

Section: Study Areamentioning

confidence: 99%

“…Northern mountainous areas face average coldest temperature of 23.88˚C in summer while on Baluchistan, it is about 26.66˚C. On the Indus plain, a temperature range of high of 32.22˚C to 48.88˚C [27] in summer, to a low 12.77˚C in winters. Hottest months in a year are May and June where temperature can reach to 50˚C and coldest month is January with temperature of 5˚C.…”

Section: Study Areamentioning

confidence: 99%

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Missing Data Imputations for Upper Air Temperature at 24 Standard Pressure Levels over Pakistan Collected from Aqua Satellite

Saleem¹,

Ahmed²

2016

JDAIP

Self Cite

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This research was an effort to select best imputation method for missing upper air temperature data over 24 standard pressure levels. We have implemented four imputation techniques like inverse distance weighting, Bilinear, Natural and Nearest interpolation for missing data imputations. Performance indicators for these techniques were the root mean square error (RMSE), absolute mean error (AME), correlation coefficient and coefficient of determination (2 R) adopted in this research. We randomly make 30% of total samples (total samples was 324) predictable from 70% remaining data. Although four interpolation methods seem good (producing <1 RMSE, AME) for imputations of air temperature data, but bilinear method was the most accurate with least errors for missing data imputations. RMSE for bilinear method remains <0.01 on all pressure levels except 1000 hPa where this value was 0.6. The low value of AME (<0.1) came at all pressure levels through bilinear imputations. Very strong correlation (>0.99) found between actual and predicted air temperature data through this method. The high value of the coefficient of determination (0.99) through bilinear interpolation method, tells us best fit to the surface. We have also found similar results for imputation with natural interpolation method in this research, but after investigating scatter plots over each month, imputations with this method seem to little obtuse in certain months than bilinear method.

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“…Baluchistan border with Afghanistan is a drier region. The overall climate of Pakistan is drier [27]. Its coastal areas facing 0.6 C to 1.0 C rise in temperature since the 1900 s [28].…”

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

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Missing Data Imputations for Upper Air Temperature at 24 Standard Pressure Levels over Pakistan Collected from Aqua Satellite

Saleem¹,

Ahmed²

2016

JDAIP

Self Cite

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“…For the best use of relative humidity data, it is necessary to have best estimate of the gaps in satellite captured data with imputation techniques [1] [4] [5] [6]. Sa-DOI: 10.4236/ojg.2018.810059 988 Open Journal of Geology leem [6] mentioned that for the filling of such data, it was mandatory to have the finest understanding of the spatial and temporal variations of climatic variables.…”

Section: Introductionmentioning

confidence: 99%

“…Upper meteorological observation and monitoring were also not available in Pakistan. However, Saleem[5]; Saleem[6] and Wazir[32] were a few dominant initiatives efforts on upper-level atmospheric observations.…”

mentioning

confidence: 99%

Accurate Imputation for Relative Humidity over Pakistan Gathered from AQUA Satellite

Saleem¹,

Akram²,

Ullah³

et al. 2018

OJG

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The relative humidity in the atmosphere captured by AQUA satellite contains missing matrices. In order to fill such missing values four very popular imputation techniques: Bilinear, Inverse Distance Weighting, Natural Neighbor and Nearest Interpolations were tested. Mean Absolute Error (MAE), Root Mean Square Error (RMSE), Coefficient of Determination (R 2) and Correlation Coefficient (Corr), were used to check the accuracy of these interpolations. It was found that the Inverse Distance Weighting and Nearest Interpolation were proved not to be suited. Natural interpolation gave accurate results than the aforementioned two interpolations. Missing values of relative humidity were accurately refilled with Bilinear Interpolation. This interpolation produced RMSE of ±0.543 for relative humidity over 100, 150, 200, 250, 300, 400, 500 hPa while for 600, 700, 850 and 925 hPa RMSE remainnear to 1. A perfect fit to the surface and very strong correlation (value near to 0.99) was found between actual and imputed relative humidity data through Bilinear Interpolation. Therefore it was concluded that the Bilinear Interpolation is the most accurate and best imputation for missing values of relative humidity form 100 to 1000 hPa levels.

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Linkage of meteorological parameters and anomalous radio propagation profile over Nigeria

Emmanuel

2019

Journal of Atmospheric and Solar-Terrestrial Physics

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Statistical Investigation and Mapping of Monthly Modified Refractivity Gradient over Pakistan at the 700 Hectopascal Level

Abstract: This study is an effort to investigate the spatial-temporal variability of the modified refractivity gradient at the 700 hPa pressure level over Pakistan and its neighbouring regions of Afghanistan, India, Iran and the Arabian Sea using the remote sensing data of the AQUA (

Cited by 6 publications

References 17 publications

Missing Data Imputations for Upper Air Temperature at 24 Standard Pressure Levels over Pakistan Collected from Aqua Satellite

Missing Data Imputations for Upper Air Temperature at 24 Standard Pressure Levels over Pakistan Collected from Aqua Satellite

Accurate Imputation for Relative Humidity over Pakistan Gathered from AQUA Satellite

Linkage of meteorological parameters and anomalous radio propagation profile over Nigeria

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