Moving beyond Marshall and Palmer

Hourly rainfall accumulations graph
Hourly rainfall accumulations measured by raingauges and corresponding radar rainfall estimates from Hameldon Hill radar between 01:00 and 06:00 GMT, 4 June 2015.

It’s nearly 70 years since Marshall and Palmer (1948) published their paper on the distribution of raindrops with size and the empirical scaling relationship equating the measured radar reflectivity, Z with the rainfall rate, R: Z= aRb. Since then, the relationship has been widely used to generate rainfall estimates from radar. With the roll-out of dual-polarisation to the UK radar network nearing completion, the Met Office is now making use of this new technology to improve radar rainfall estimates and supplement the Marshall–Palmer relationship.

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