Abstract

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 (R2) 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.

Highlights

  • Metrological data collected from satellites mostly contain gaps

  • Missing values of relative humidity were accurately refilled with Bilinear Interpolation

  • 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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Summary

Introduction

Metrological data collected from satellites mostly contain gaps. Such gaps in data set occur due to less efficient sampling of satellite subsystem [1] [2]. The first meteorological satellite was Mariner −2 Venus Probe, with the task to determine water content in the planet Venus [25] After this successful experiment, two satellites Cosmos 243 and 384 were lunched to measure relative humidity of the earth [26]. The relative humidity is defined as the relative amount of water vapors in the atmosphere as a percentage of the amount required for saturation at the same temperature. The relative humidity can change in the atmosphere by either changing the number of water vapors or by variation of temperature in the atmosphere [20]. The actual thrust of this research work was to devise a workable methodology for carrying out scientific observation of upper atmospheric meteorology over Pakistan in spite of lack of modern equipment and technological resource. Saleem [5]; Saleem [6] and Wazir [32] were a few dominant initiatives efforts on upper-level atmospheric observations

Data Used
Imputations of Missing Dataset in Relative Humidity
Performance Indicators for Each Interpolation
Results
Discussions
Conclusion
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