Long-term evaluation of temperature profiles derived from space-based GPS meteorology with radiosonde measurements over Iran

In recent years, space-based GPS Radio occultation (RO) data have been recognized as a valuable resource in the advancement of various fields such as meteorology, numerical weather forecasting, climate studies, and ionospheric research. Although the atmospheric temperature profiles derived from this space-based technique have been used in a few national studies, long-term evaluation of these data and their widespread use has not been performed, especially by Iranian meteorologists. In this paper, RO temperature profiles obtained from COSMIC, SACC, GRACE, TerraSAR-X, KOMPSAT5, METOP-A, and METOP-B satellite missions were compared with their corresponding radiosonde measurements in five different geographic regions of Iran. Based on the data collected from 2006 to 2018, statistical assessments were carried out at 4km height intervals between the altitudes 0–36 km. The RO temperature data that occur 300 km away and 2 hours from radiosonde measurements were selected for comparison. The results in all stations show that, compared to radiosonde, GPS RO is acceptable for measuring the atmospheric temperature over the study area. Agreement of space-based GPS RO derived temperature below 28 km with respective values obtained from radiosonde in terms of mean bias and standard deviation were 1. 0.24 K and 1.5 K, respectively. Overall, seasonal comparisons indicated that there is no significant relationship between the behavior of mean bias and seasonal changes.