كليدواژه :
الگوهاي دور پيوندي , حوضه درياي كاسپين , مدلهاي آماري , MEI , SOI
چكيده لاتين :
Introduction and Objective: Teleconnection patterns are one of the effective hydroclimatological
factors in predicting precipitation, temperature and discharge on a large scale.
Oppositely, comprehensive and integrated management of water resources requires that rainfall
variables and consequently runoff flow can be predicted. From a dynamic and synoptic
approach, teleconnection patterns can affect the precipitation pattern of different regions. The
purpose of this study is to inspect the relationship between these indicators and autumn rainfall
in the Caspian Sea basin and forecast it using various statistical models.
Material and Methods: Therefore, in this study, Caspian Sea sub-basins were selected and
autumn rainfall in the 28-year period from 1987 to 2015 was calculated. Then the correlation of
MEI, SOI, NCP, NAO, AO, CSST, P-SST and MSST indices with autumn rainfall in July, Aug,
Sep, Oct, Nov, summer, Aug-Sep-Oct and Sep-Oct-Nov was calculated. and the most important
ones that had the highest correlation were considered as inputs to different models. Finally,
autumn rainfall forecasting was done using a statistical model and three artificial intelligence
models with different structures.
Results: The study showed that various teleconnection patterns were effective depending on the
type of sub-basin and time step. Prediction results showed that the difference between
observational and modeled data in the training period was small and increased somewhat in the
test period and reached about -25.7 to 47.6 mm in the whole sub-basins. Thoughtfulness of the
type of analytical model showed that both SVR and MLP models had higher accuracy than
GRNN and MLR models, so that the Root Mean Square Error by SVR model in Aras, Atrak,
Haraz-Sefidrood, Qarahsu-Gorgan, Serazod-Haraz, and Haraz-Qarahsu sub-basins. 6.18, 7.34,
35.44, 18.25, 19.58, 17.68 and 47.22 mm, respectively, and the coefficient of determination will
be 0.94, 0.91, 0.92, 0.84, 0.88, 0.88 and 0.87, respectively.
Conclusion: Therefore, the results show a strong relationship between teleconnection indices
with autumn rainfall in the study basin. These include NAO, SOI, AO and Caspian and
Mediterranean Sea surface temperatures at different time delays. With these results, steps can be
taken to more accurately predict and manage the water resources of the Caspian Sea basin.
