Rangno and Hobbs (1995) cite a paper by the author (Ben-Zvi 1988) as providing information on the total number of days with rain in the Israeli II experiment. Unfortunately, this citation is not correct because that number is not written in the cited paper. The number of days in the paper by Ben-Zvi (1988) is for rain days over the studied watershed and its control area during the entire six meteorological years of the Israeli II experiment. Gagin and Neumann (1981) clearly and objectively limit the experiment to the season of November–April and to days on which a measurable depth of rain was recorded by three stations located at the buffer area. Consequently, the number of days in the experiment is smaller than that in the entire experimental period.
Rangno and Hobbs (1995) cite Ben-Zvi’s (1988) finding that the depth of intense rainfall on seeded days at the analyzed target stations was heavier than that on unseeded days and that this difference was statistically significant. This citation is exaggerated, as no statistical test is mentioned in the original paper (Ben-Zvi 1988).
Rangno and Hobbs (1995) present an apparent contradiction between the results of Gagin and Gabriel (1987) and those of Ben-Zvi (1988) regarding the effect of seeding on rainfall intensity. Yet Rangno and Hobbs (1995) do not refer to the difference in definition of the analyzed variables. The variable in the former paper is the distribution of mean daily intensity (i.e., the ratio of daily depth to duration), while that in the latter paper is total rainfall depth during the entire experimental period, sorted with respect to momentary intensities. These variables are quite different from each other, and hence their analyses need not lead to the same conclusions.
Rangno and Hobbs (1995) cite Benjamini and Harpaz (1986) as analyzing runoff in the Lake Kinneret catchment region and cite Sharon (1990) as reanalyzing runoff over a wider area of the north target area watershed. This difference in location is wrongly stated. Sharon (1990) reanalyzed the data of Benjamini and Harpaz (1986) and provided the same location map as theirs. Observing this map, one can easily deduce that the citation of Rangno and Hobbs (1995) regarding Benjamini and Harpaz (1986) is incorrect and that Benjamini and Harpaz (1986) analyzed hydrologic data for the entire north target area.
It is worth mentioning here three papers not cited by Rangno and Hobbs (1995). These are Ben-Zvi et al. (1987) and Ben-Zvi (1990), which analyzed spring flow data for the entire north target area, and Ben-Zvi and Langerman (1989), which analyzed data for the entire Lake Kinneret catchment. These indicate that the statement by Rangno and Hobbs (1995), claiming that analyses of rainfall runoff for the Israeli II have been confined generally to local watersheds within the catchment region of Lake Kinneret rather than to the entire north target area, is not based upon a thorough survey of the literature.
Rangno and Hobbs (1995) state that the overall correlation coefficient between the two target areas of the Israeli I experiment was approximately 0.80. In contast, the coefficients published in the final statistical tables of this experiment (Gabriel and Baras 1970) were 0.61 for the north seeded days, 0.69 for the center seeded days, and 0.72 for the years 1940–60. These figures are quite far from the one presented by Rangno and Hobbs (1995). Noting that those authors refer to the final tables regarding other subjects, their neglecting to cite these tables with respect to the correlation coefficient looks strange.
This correspondence draws attention to errors in the extraction of information from published articles and to the use of out-of-date figures by Rangno and Hobbs (1995). These circumstances are believed to contribute to faulty conclusions regarding outcomes of the Israeli cloud seeding experiments.
REFERENCES
Benjamini, Y., and Y. Harpaz, 1986: Observational rainfall-runoff analysis for estimating effects of cloud seeding on water resources in northern Israel. J. Hydrol.,83, 299–306.
Ben-Zvi, A., 1988: Enhancement of runoff from a small watershed by cloud seeding. J. Hydrol.,101, 291–303.
——, 1990: Springflow enhancement in northern Israel due to cloud seeding. Isr. J. Earth Sci.,39, 103–117.
——, and M. Langerman, 1989: Estimation of flow enhancement in the Kinneret watershed due to cloud seeding. J. Stochastic Hydrol. Hydraulics,3, 203–216.
——, S. Massoth, and B. Anderman, 1987: Changes in springflow following rainfall enhancement. Isr. J. Earth Sci.,36, 161–172.
Gabriel, K. R., and M. Baras, 1970: The Israeli Rainmaking Experiment 1961–1967: Final Statistical Tables and Evaluation. The Hebrew University of Jerusalem, 47 pp.
Gagin, A., and J. Neumann, 1981: The second Israeli randomized cloud seeding experiment: Evaluation of the results. J. Appl. Meteor.,20, 1301–1311.
——, and K. R. Gabriel, 1987: Analysis of recording raingage data for the Israeli II experiment. Part I: Effects of cloud seeding on the components of daily rainfall. J. Climate Appl. Meteor.,26, 913–926.
Rangno, A. L., and P. V. Hobbs, 1995: A new look at the Israeli cloud seeding experiments. J. Appl. Meteor.,34, 1169–1193.
Sharon, D., 1990: Meta-analytic reappraisal of statistical results in the environmental sciences: The case of hydrological effect of cloud seeding. J. Appl. Meteor.,29, 390–395.
