Abstract
The livelihood of people inhabiting drylands in the middle-high latitudes (such as seen in Mongolia) long has been jeopardized repeatedly by summer droughts and harsh winter conditions. Since 2000, high livestock mortality has occurred during three cold seasons in the Bulgan state, northern Mongolia. Using meteorological data from 1980 to 2012 and livestock numbers and mortality rates from 2000 to 2011, we explored features of weather conditions at the local ground level and westerlies meandering at the 500 hPa level during those high mortality cold seasons. For each cold season from October to April, we calculated the intensity of cold surges, the number and duration of days with daily temperatures below -30 °C (used as critical cold days for livestock), and the amplitude of westerlies meandering inferred from the frequency of easterly winds within a particular area, including the climatological trough of westerlies. It has been shown that the intensity of cold surges were larger (r = -0.78; P < 0.01) and critical cold days for livestock continued longer (r = 0.72; P < 0.01) when westerlies meandering were enhanced and maintained. Timely forecasting of strengthened meandering would help early warnings to mitigate or prevent livestock mortality.
