Abstract:
Without precise temperature data, hydro-climatology analysis is challenging. This thesis
developed high-resolution (0.08°x 0.08°) gridded maximum and minimum datasets for
Afghanistan spanning 60 years (1961–2021). First, the linear regression technique filled in
the observed data gaps using neighboring stations and the gridded datasets (CRU, ERA5,
and TerraClimate). Then, with a 0.08° grid resolution, the gap-filled data was extrapolated
using the GIS interface and the ordinary kriging (OK) interpolation spatial approach. This
study assessed the accuracy of multiple gauge-based and reanalysis datasets, including
CRU, ERA5, PGFv2.1, NCEP/NCAR Reanalysis1, and TerraClimate. Standard statistical
measures like KGE (Kling Gupta Efficiency), R2 (Coefficient of Determination), and MAE
(Mean Absolute Errors) were used to complete the assessment. The more accurate
approach—among quantile mapping and linear scaling—was selected to generate a longterm result and bias correct the dataset that performed better. Using the generated dataset,
we investigated spatiotemporal annual and seasonal trends using Man Kendel and Sen's
Slop estimator techniques. It was clear from the results that CRU was the most accurate
available dataset. Moreover, the average of MAE dropped from 3.84 to 1.15 for the
maximum temperature, while the average of R2 and KGE increased from 0.93 and 0.33 to
0.94 and 0.95. These results indicate that linear scaling was superior to quantile mapping
in the setting of bias correlations. The MAE dropped from 3.48 to 1.17 at the minimum
temperatures, but the average of R2 and KGE increased from 0.84 and 0.21 to 0.86 and
0.89. In addition, the annual trend analysis results showed that both the minimum and
maximum temperatures were trending upward. The maximum temperatures in Winter
(DJF), Spring (MAM), Autumn (SON), and Summer (JJA) increased, according to
seasonal trend studies, with the exception of the east and south-west regions, which include
Nangarhar, Kunar, Laghman, Nuristan, and the northern districts of Paktika. On the other
side, the season trend research shows that the minimum temperature is trending upward for
all four seasons: winter (DJF), spring (MAM), summer (JJA), and autumn (SON).
