Innovative Polygonal Trend Analysis (IPTA) in detecting the seasonal trend behavior of statistically downscaled precipitation for the Eastern Black Sea Basin of Turkey

ABSTRACT

This study compares projected and past seasonal precipitation trends in the Eastern Black Sea Basin, Turkey. Historical data from twelve stations representing the basin during 1981–2010 was used, while statistically downscaled data from two representative concentration pathway scenarios (RCP4.5 and RCP8.5) outputs of the GFDL-ESM2M general circulation model were utilized for 2021–2050. To determine the seasonal trend behaviors of precipitation variables and transitions between consecutive months, the Innovative Polygon Trend Analysis (IPTA) was implemented. Furthermore, the star concept was employed to illustrate the changing sizes between consecutive periods. Both scenarios showed considerable summer and autumn declines at almost all locations, with low seasonal precipitation variability. These scenarios indicated January to be the important month for trend shift, except for Rize, Pazar, and Hopa stations. The formation of several polygons, polygons intersecting, and polygons not forming on the global regression line show that the hydro-climatic cycle might be chaotic.

KEYWORDS:

• Climate change
• Eastern Black Sea Basin
• Innovative polygon trend method (IPTA)
• star concept

Acknowledgements

All the authors thank all anonymous contributors to the study for their ideas, physical efforts, literary and language, technical and software support, and in a compilation.

Availability of data and materials

Some or all data that support this study’s findings are available from the corresponding author upon reasonable request.

Code availability

The models or codes used to develop this study are available from the corresponding author upon reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed https://doi.org/10.1080/1573062X.2024.2312496.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.