Desert Climate Regionalization for Joshua Tree National Park and Surrounding Areas Using New Climate Network Observations

Abstract

Abstract A new amalgamation of weather stations in and around Joshua Tree National Park in southeastern California has allowed for objective climate analysis regionalization at a much finer scale than past studies. First, it sets a baseline for many regions within the park’s boundaries that were not subject to direct observations. Second, these new observations are key to understanding shifting microclimate regimes in a desert ecosystem prone to the effects of climate change. Principal component analysis was used to regionalize the climate network based on monthly temperature and precipitation climate observations and standardized anomalies. Both the observation values and standardized climate anomalies identified regional boundaries. In general, these boundaries align with traditional ideas and past studies of the Mojave and Sonoran Deserts based on elevation (specifically the 1000-m contour) for the National Park Service. Standardized anomaly values identified a boundary based on seasonal precipitation, whereas observation values identified a boundary based on elevation. The boundary line within the park is similar for both data approaches, with the boundary running along the higher western one-third of the park. Conversely, the two methods differ significantly in the Coachella Valley, where low elevations and low precipitation meet winter-dominated seasonal precipitation. This study highlights the importance and opportunity of field observations to create climatological and ecological regionalization, and it also constructs a baseline to monitor and manage shifting desert regions in the future. Significance Statement This study identifies a high-resolution climate boundary zone in Joshua Tree National Park between the Sonoran and Mojave Deserts. The new transition zone presents the seasonal and elevational temperature and precipitation components of the two deserts, connecting with the unique ecology of the deserts. This finding highlights just one study opportunity of new field observation networks in arid or topographically diverse regions. It also provides a baseline for climate change as a resource for environmental management groups to better understand and preserve our natural spaces.