Evaluating the effect of heat waves on early melting of snow covers of Karkheh catchment in Iran

The present study aims to evaluate the effect of heat waves on early melting snow cover in Karkheh catchment Iran. After collecting daily data maximum temperature meteorological stations during statistical period (2000–2019), three indices WSDI, Baldi, and ocular method were used determine threshold days with wave. By extracting hot applying programming, maps drawn Google Earth Engine system area ​​snow zones was calculated Model Builder. Finally, atmospheric received from NCEP/NCAR site their generating patterns examined after drawing Grads software environment determining synoptic patterns. results indicated that slope trend is increasing at level. average annual frequency extracted for growth (November–May) equal 24 year. Regarding ground pressure conditions high levels, two dominant identified region as follows: (1) Siberian high-pressure pattern level Saudi-African ridge levels. This reduces by an 40% highest occurrence this February March. (2) Pakistan-Africa low-pressure which higher April May months more than 55%.