Assessment of Multi-Satellite Precipitation Products over the Himalayan Mountains of Pakistan, South Asia

Abstract

Performance assessment of satellite-based precipitation products (SPPs) is critical for their application and development. This study assessed the accuracies of four satellite-based precipitation products (PERSIANN-CDR, PERSIANN-CCS, PERSIANN-DIR, and PERSIANN) using data of in situ weather stations installed over the Himalayan Mountains of Pakistan. All SPPs were evaluated on annual, seasonal, monthly, and daily bases from 2010 to 2017, over the whole spatial domain and at point-to-pixel scale. The assessment was conducted using widely used evaluation indices (root mean square error (RMSE), correlation coefficient (CC), bias, and relative bias (rBias)) along with categorical indices (false alarm ratio (FAR), probability of detection (POD), success ratio (SR), and critical success index (CSI)). Results showed: (1) PERSIANN and PERSIANN-DIR products efficiently traced the spatio-temporal distribution of precipitation over the Himalayan Mountains. (2) On monthly scale, the estimates of all SPPs were more consistent with the reference data than on the daily scale. (3) On seasonal scale, PERSIANN and PERSIANN-DIR showed better performances than the PERSIANN-CDR and PERSIANN-CCS products. (4) All SPPs were less accurate in sensing daily light to medium intensity precipitation events. Subsequently, for future hydro-meteorological investigations in the Himalayan range, we advocate the use of monthly PERSIANN and PERSIANN-DIR products.

Evaluation of Soil Moisture-Based Satellite Precipitation Products over Semi-Arid Climatic Region

“…The results of previous studies also indicated that the performance of SPPs was strongly influenced by the topography and climatic conditions of the study area [32][33][34]. For instance, Nadeem et al [22] assessed the variety of SPPs over diverse topographic and climatic conditions. The findings of their study also documented that the accuracy of satellite precipitation products showed significant variation with respect to in-situ topography and climatic conditions.…”

“…The evaluation of soil moisture products (SM2Rain, SM2Rain-ASCAT, SM2Rain-CCI, and GPM-SM2Rain) was assessed using in-situ ground observations. In the validation process, the methodology of previously published studies [3,22] was used. We only considered SPP grids with at least one benchmark measuring station.…”

“…For this purpose, previously recommended statistical indices were considered. The details of statistical indices and their acceptable ranges as indicated by previously published studies [22,24] used for the evaluation assessment of soil moisture-based satellite products are shown in Table 2. The Probability Density Function (PDF) of the daily and seasonal estimations of in-situ gauging stations was examined at different thresholds for a more accurate assessment of the soil moisture-based products.…”

“…All the SPPs data has been accessed on 25 September 2022. In recent times, many satellite-based precipitation products were introduced to obtain reliable precipitation [9,[21][22][23]. Most of the precipitation satellites were assessed in the upper Indus region and some were evaluated in the mountainous region of Pakistan [5,22,24].…”

“…In recent times, many satellite-based precipitation products were introduced to obtain reliable precipitation [9,[21][22][23]. Most of the precipitation satellites were assessed in the upper Indus region and some were evaluated in the mountainous region of Pakistan [5,22,24]. However, the evaluation of soil moisture-based products over the whole country has not been carried out yet.…”