Heterogeneity in monsoon precipitation across space and time: An analysis of the northern Chihuahuan Desert, USA

Background/Question/Methods

Monsoon precipitation exhibits a strong control on the ecology and hydrology of the Chihuahuan Desert of North America. The monsoon period accounts for approximately 60% of annual precipitation totals and combinations of event timing, magnitude, and intensity influence pulses of vegetation productivity and nutrient cycling that are critical to ecosystem functioning. Both long and short-term variability in precipitation influence ecosystem structure and dynamics, but the magnitude, variation and temporal change of these properties have not been assessed in the northern Chihuahuan Desert.

Results/Conclusions

To better understand the way precipitation dynamics influence the ecology and hydrology of the monsoon season, we used Historical Climate Network daily precipitation data to assess differences in precipitation event timing and magnitude trends for the region. We also assessed the spatial heterogeneity of precipitation event magnitude and intensity using hourly data from stations at the Sevilleta National Wildlife Refuge in central New Mexico, USA, and compared station data to NWS/NOAA National Climate Prediction Center (NCP) gridded hourly precipitation data at larger-scale resolution. Results show significant change in the long-term properties of monsoon precipitation for the Chihuahuan Desert (P < 0.05) over the past 120 years, with a trend of increased precipitation event timing and lesser event magnitude. A significant difference (P < 0.05) also exists for precipitation event magnitude and intensity between sites at the Sevilleta, and also between Sevilleta average values and NCP gridded data during the monsoon season. This suggests monsoon precipitation is highly variable across small (< 5 km) spatial scales and that the region may be experiencing a trend towards increased soil moisture limitation. These analyses provide insight on how precipitation shapes the ecohydrology of the Chihuahuan Desert and how additional variation in growing season precipitation could induce changes in ecosystem functioning.