Long-term statistical analysis on hot days and heat wave in Mongolia

Abstract:

In this study, 40 years of hot day and heat wave in Mongolia is investigated. Hot days carry difficulties and losses for Mongolian economy and daily life, such as people and livestock fell unfavorable (ill affected), agriculture losses, drying small rivers and lakes, causing steppe fires and etc.

 The hot day is one of the severe weather extreme in Mongolia, and their frequency and intensity have been increasing and becoming more severe. Intensive and longer-lasted hot days break out a heat wave event. Therefore, a monitoring of hot day and heat wave’s occurrence and its long-term change are in nationwide scale.

Longer prolonged heat wave may one of the causes for drought initiation while occurrence of drought has noticeably increased since last decade, which it is consistent with the heat wave occurrence. We analyzed maximum air temperature and precipitation data at 12 stations obtained from National Agency for Meteorology and Environment Monitoring (NAMEM) of Mongolia. Definition of the hot day is calculated by each station from reference period (1971-2000) and the heat wave is defined by when the daily maximum air temperature is 5K higher than the daily climatology of the reference period and lasted more than 4 consecutive days.

Spatial distribution of long-term mean heat wave occurrence suggests that two areas, in Siberia and Mongolia, show high frequency. Those two areas are separated each other. Time series analysis indicates that the frequency kept similar level in 1970s and 1980s. In last two decade, however, heat wave was increased in central Mongolia in 1990s and northern half of Mongolia in 2000s as well as Western and Eastern Siberia.