CLIMATE AND ATMOSPHERE

The climate of Central Coastal California is typical Mediterranean, with wet and cool winters and dry hot summers. Since BORR lies 10-50 miles (16-80 km) inland from the Pacific Ocean, and coastal ranges like the Santa Lucia Range and the Santa Cruz Mountains block Pacific incoming moisture, it receives half the precipitation seen along the coastline. Winters are mild with moderate rainfall; mean precipitation ranges from 376 mm near sea level in downtown San Jose, to 600 mm on Mount Hamilton at an elevation of 4,360’ (1,330m), but summers are very dry and hot. Areas above 2,500 feet get light to moderate snow in the winter, especially at the highest point, the 5,241 ft (1,597 m) San Benito Mountain in the remote southeastern section of the range.

Blue Oak Ranch Reserve anchors a network of sites dedicated to providing an early warning indication of climate change and understanding the resulting ecosystem and biodiversity responses to change. The region is at the intersection of the coastal-inland fog line. The extensive development of lichens dependent on fog shows dependence of a large fraction of the biodiversity dependent upon fog. This region has a greater percentage of fog than southern California, but somewhat less than regions with redwoods. Fog is dependent upon ocean temperatures, and shifting ocean temperatures, associated with El Nino-La Nina intensities feedback regulating fog. Urbanization also reduces fog through the heat island effect. Together these factors have the potential to dramatically affect coastal ecosystems, with unknown ramifications to the interior regions. California is expected to experience temperature increases, along a north-south gradient, and especially in the Sierra Nevada and Central Valley, of 2 to 4oC in winter and 2 to 8 oC in summer, depending on emissions scenario and modeling approach (Hayhoe et al., 2004). Fog formation, snow-rain transition, and temperature gradients north/south and east/west are likely interrelated processes. Monitoring stations at BORR, and other Berkeley field stations, will provide data from the western, leading edge of these responses. BORR can also provide close to coast monitoring of the land-ocean-atmosphere coupling that is a likely driver of continental climate shifts.

ATMOSPHERIC CHEMISTRY

There are approximately 100 monitoring stations for O3 and NOx in California. Monthly maximum O3 (in the vicinity of BORR) was
29.7 ppb, but only 35 km to the east, the average was 50 ppb. Current models suggest that both O3 and NOx are relatively low at
BOR (see adjacent figures), but with suburbanization of the surrounding landscape, the potential for impacts on ecosystem functioning in BORR has the same implications as for the California Central Valley and Sierra front as well as other regions of the country, such as the Great Lakes, mid-Atlantic region, southern Appalachia, and the Front Range of the Rocky Mountains.

Posted on March 7, 2014 06:36 AM by infomgr