Spatial and temporal variations of aridity indices in Montenegro

Abstract

Abstract In this article, we examine the spatial pattern and trend in aridity in Montenegro from 1961 until 2020. We use temperature and precipitation observational records from 18 weather stations to calculate three aridity (climate) indices: the De Martonne aridity index (IDM), the Lang’s rain factor (RF), and the Pinna combinative index (IP). On an annual scale, all of these three indices show humid to extreme humid atmospheric conditions in Montenegro. At the seasonal and monthly level, calculations are performed for IDM only due to methodological limitations regarding calculation of RF and IP at the seasonal and monthly scale. It was observed that winter, autumn and spring seasons exhibit very humid to extremely humid conditions Based on IDM, while the summer seasons show semi arid conditions mainly in the coastal parts of Montenegro, and neighboring inland. On the monthly level, the period from September to April characterizes humid climate conditions. The month of May shows less humid conditions, while IDM for June belongs to a category of the Mediterranean type climates. July and August exhibit semi arid conditions. Monthly results further show that IDM for the majority of the country trends negative, thus implying a general tendency towards a drier hydroclimate. Statistically significant negative IDM trends are calculated for April and August. The observed tendencies towards arid climate at the start of the vegetative season in April can significantly cause soil moisture deficit. Increasingly arid August conditions of generally high temperature and low water availability can be more detrimental to vegetation and potentially increase the risk of more frequent droughts and wildfires in Montenegro.