Anemometer turbines usually requires a refresh rate of wind speed measurements of 3 Hz, easily achieved by sonic anemometers. Three-dimensional sonic anemometers are widely used to measure gas emissions and ecosystem fluxes using the eddy covariance method when used with fast-response infrared gas analyzers or laser-based analyzers. Two-dimensional wind sensors are of two types: Acoustic resonance anemometers are a more recent variant of sonic anemometer. The technology was invented by Dr Savvas Kapartis and patented in 2000. Whereas conventional sonic anemometers rely on time of flight measurement, acoustic resonance sensors use resonating acoustic (ultrasonic) waves within a small purpose-built cavity in
Measure S and the quote "I Agree". The other showed a letter written by him on city letterhead, with "I agree" following many pro-Measure S talking points. It was headed "Mayor Garcetti finds a lot to like about Measure S". The mailer implied that Garcetti supported Measure S, which in fact he strongly opposed. He called it a "dirty trick". A CPLA spokesperson said in response that "[t]his was just a friendly reminder on what these City Hall insiders promised and what they've yet to deliver to the voters of Los Angeles." A week before the vote, an editorial in the "Los