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Abstract

Results from idealized model simulations (a relationship between Caspian Sea level [CSL] with its change of the Caspian Sea [CS] size and CS surface temperature [SST]) are validated and connections are explained. Energy budgets for CS water using proxy observational data (ERA5) are used, especially for the comparison of 1979 and 1995, the two extreme values of the CSL. In 1995, when CSL reached a maximum, there were many El Niño events. Investigations on the effects of ENSO on the position of the jet stream over the CS had previously been shown. A jet stream requires a region of baroclinicity beneath it, usually associated with precipitation and cloud cover. This leads to an increase in CSL. A possible forcing of El Niño events by the CS size was found in recent idealized model simulations. Evidence of this is also documented here in analysis of observational data. The size of the CS could have an impact on the occurrence of El Niño events that affect atmospheric circulation. There is much evidence of such a relationship in the observed atmosphere. Real proof is extremely difficult to obtain, only one historical event provides further evidence for such a connection. © 2022 Royal Meteorological Society.