Analyzing the relationship between geographical elements and precipitation patterns in the southern shores of the Caspian Sea

The present study focuses on the distribution of precipitation in different spatial and temporal patterns based on monthly, seasonal and annual time scales using TRMM data derived from 92 different cells in the south of the Caspian Sea. In addition, to account for the impact of the geographical conditions such as elevation, latitude and longitude on rain values, the Pearson correlation method was used. In terms of the average monthly precipitation in the south of the sea, the results showed that the highest average belonged to November (87 mm), followed by December (74 mm), and finally March and October (67 mm and 66 mm), respectively. The highest negative correlation (0.862) between rain and longitude was observed in autumn at a significant level of 0.01. In addition, the highest negative correlation (0.87) between rain and longitude was found in November at a significant level of 0.01. The maximum annual rain was 892-1305 mm measured in Guilan Province. Precipitation showed a tendency to decline toward the east of Golestan Province, so that the minimum annual precipitation (321-393 mm) was recorded in its western and northeastern parts. The precipitation was positively correlated with elevation and there was a strong inverse relationship between rain and longitude.