Climate

Runoff event
A coastal stream in high flow conditions.

Rainfall

The SBC-LTER region is characterized by a Mediterranean climate with mild, moist winters and moderately warm, generally rainless summers. Winter rainstorms provide the majority of freshwater input to rivers, streams, and the nearshore marine environment. To a large degree, intermittent and often intense rain events also control the amount and form of material constituents (e.g., nutrients, sediment, organisms, and pollutants) that discharge from the land into the coastal marine ecosystems of the Santa Barbara Channel (kelp forests, as well as salt marshes, lagoons, beaches, rocky shores, subtidal rocky reefs, and subtidal soft sediment habitats).

climate

Average precipitation in the SBC-LTER region is 430 mm per year with peak rainfall generally occurring between December and March. However, large variation in annual precipitation occurs in the region with totals ranging from less than 180 to more than 1100 mm in the past 150 years. Peak rainfall years are often associated with El Nino Southern Oscillation (ENSO) events (see chart at left). This high variability is key to the transport of materials from land to ocean and the ecological processes and responses of kelp forests under study by the SBC-LTER.


Current weather, marine observations, forecasts, and rain totals for the Santa Barbara region can be found at:

climate
ENSO index since 1950 (red indicates warm (El Niño) and blue indicates cool (La Niña) conditions, from http://www.cdc.noaa.gov/people/klaus.wolter/MEI/).

Strong El Niño Signature

Semi-decadal El Nino Southern Oscillation (ENSO) events are associated with large scale changes in oceanography, rainfall, and climate in North and South America. Physical and biological responses to ENSO events are particularly striking in the Santa Barbara Channel. Terrestrial runoff and the associated transport of sediments, nutrients, and pollutants increase dramatically because of elevated precipitation during ENSO events (see precipitation chart above). Sea surface temperatures increase and offshore nutrient levels decline as the thermocline deepens. Large-scale patterns of ocean circulation also change dramatically, and storm disturbance from waves is often extreme. Increases of over 30 cm in monthly mean sea level have been reported during recent ENSO events (1982-83 and 1997-98). Corresponding with these physical changes are dramatic changes in marine biota including: northward range extensions of southern species, precipitous declines in the abundance of giant kelp Macrocystis pyrifera,and unusual variation in the abundance and recruitment of many species of algae, invertebrates, and fish.

Unprecedented Long Term Climate Record

Deep ocean floor cores
Varved sediments from the deep ocean floor of the Santa Barbara Channel

The varved sediments of the anoxic deep basins of the Santa Barbara Channel offer one of the highest resolution data sets available of climate change over the past 100,000 years. These records show a strong connection between local climate changes affecting the Santa Barbara Channel and global changes in ocean circulation.

Climatic Record
Rapid oscillations in benthic foraminiferan assemblages in the Santa Barbara Basin during some of the warm/cold intervals of the last glacial episode.

They also include records of biotic changes over the same time scales for several taxa, such as the variation in abundance of benthic foraminifera in deep basin sediments of the Santa Barbara Channel as shown in the graph to the left. These types of records provide an unmatched opportunity to place fluctuations observed at LTER sites in the context of much longer climatic records.