University of Arizona
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Raw data: Unreported Characteristics of the North American Monsoon

posted on 2023-08-11, 18:48 authored by Frank ReichenbacherFrank Reichenbacher, William Peachey

Raw data for "Unreported Characteristics of the North American Monsoon".

The North American Monsoon (NAM) in southern Arizona continues to be a topic of interest to ecologists, climatologists, and citizens as well as the triggers and characteristics of plant growth and reproduction in relation to the onset of the monsoon. In researching the onset of the North American Monsoon (NAM) in south-central Arizona relative to the phenology of Saguaro cactus (Carnegiea gigantea) and other Sonoran Desert species we identified interesting and previously unreported features in the NAM rainfall data. We present preliminary descriptive analyses of (1) monsoon onset as measured by the first day after June 1 with precipitation ≥10 mm (1990-2022), (2) first day of year warming of Sea Surface temperatures (SST) in the Gulf of California to ≥29º C measured across five open-sea blocks (mean 9452 km2), and (3) El Niño Southern Oscillation (ENSO) anomaly with a threshold of +/- 0.5º C for the Oceanic Niño Index (ONI) in the Niño 3.4 region (5ºN-5ºS, 120º-170ºW). Three patterns emerge from our analyses: (1) The day of the year of monsoon onset occurs approximately 12 days earlier in the year from 1990-2022 in Pima County, Arizona. (2) There appears to be a signal in the rainfall onset data very roughly approximating cycles of ENSO Oceanic Niño Index (ONI) anomalies in Niño region 3.4. (3) Gulf of California sea surface temperature (SST) and monsoon onset data support an expected link between the timing of SST warming and monsoon rainfall onset.

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