Hershfield Factor Datasets for India

Information on the original time distribution and rainfall magnitude is lost when rainfall observations are discretely sampled/recorded. As a consequence, the return levels estimated using the annual maximum series derived from a discretized dataset (fixed-window annual maximum series) would possess an underestimation bias relative to those derived from a finer-temporal resolution dataset (sliding-window annual maximum series). This temporal discretization effect is resolved by hydrologists using a multiplicative factor called the 'Hershfield Factor'. Multiple quantitative definitions of the factor exist in the literature, depending on whether the correction is applied directly to the return levels or to the annual maximum series, followed by estimation of return levels. We present a comprehensive dataset on Hershfield Factors at 20,060 sites across India at 0.12 degree spatial resolution (with information on latitude & longitude included). We provide the at-site estimates of average Hershfield Factors based on the definitions of the Ratio of Average, the Ratio of Standard Deviation (Papalexiou et al., 2016), and the Average of Ratios (Ghate & Timbadiya, 2023; Saltalippi et al., 2024). In addition, the maximum and minimum ratios between sliding- and fixed-window annual maximum series are presented. Further, the Hershfield Factors observed at return levels (Hershfield & Wilson, 1958; Hershfield, 1961; Harihara Ayya & Tripathi, 1973) of 12-, 24-, 48-, 72-hour extreme rainfall at 2-, 5-, 10-, 25-, 50-, and 100-year return periods are provided. We also provide the information on the slope and intercept of the polynomial HF-Fmax relation (proposed in the under-review study titled ' Hershfield Factor Curves for Resolving the Temporal Discretization Effect on Extreme Rainfall Analysis') for the users. The presented datasets can be utilized to correct extreme rainfall and/or their return levels for hydrometeorological applications. References: Ghate, A. S., & Timbadiya, P. V. (2023). True interval non-stationary Intensity-Duration-Frequency curves under changing climate and effect of temporal discretisation on rainfall extremes. Journal of Hydrology, 618, 129136. Harihara Ayyar, P. S., & Tripathi, N. (1973). Relation of the clock-hour to 6o-min and the observational day to 1440-min rainfall. Mausam, 24(3), 279-282. Hershfield, D. M., & Wilson, W. T. (1957). Generalizing of rainfall-intensity-frequency data. AIHS. Gen. Ass. Toronto, 1, 499-506. Hershfield, D. M. (1961). Rainfall frequency atlas of the United States. Technical paper, 40, 1-61. Papalexiou, S. M., Dialynas, Y. G., & Grimaldi, S. (2016). Hershfield factor revisited: Correcting annual maximum precipitation. Journal of hydrology, 542, 884-895. Saltalippi, C., Morbidelli, R., Corradini, C., Flammini, A., Barca, E., & Dari, J. (2024). Investigation of new approaches for the determination of the annual maximum rainfall depths of different durations. Journal of Hydrology, 631, 130809.