HR: 1340h
AN: B43B-0261    [Abstracts]
TI: Assessing Global Vegetation-Climate Feedbacks from Observations
AU: * Liu, Z
EM: zliu3@wisc.edu
AF: Center for Climatic Research UW Madison, 1225 West Dayton Street, Madison, WI 53706 United States
AU: Notaro, M
EM: mnotaro@wisc.edu
AF: Center for Climatic Research UW Madison, 1225 West Dayton Street, Madison, WI 53706 United States
AB: The feedback between global vegetation greenness and surface air temperature and precipitation is assessed using remote sensing observations of monthly FPAR (fraction of photosynthetically active radiation) for 1982-2000. Lead/lag correlations are used to infer vegetation-climate interactions. A statistical method is used to quantify the efficiency of vegetation feedback on climate. This feedback analysis provides a first quantitative assessment of global vegetation feedback on climate. In the northern mid-high latitudes, vegetation variability is found to be driven predominantly by temperature; in the meantime, vegetation also exerts a strong positive feedback on temperature, with the feedback accounting for over 10-25% of the total monthly temperature variance. The strongest positive feedback occurs in the boreal regions of southern Canada/northern United States, northern Europe, and southern Siberia, where the feedback efficiency exceeds 1C/0.1FPAR. Over most of the tropics and subtropics (outside of the equatorial rainbelt), vegetation is driven primarily by precipitation. However, little vegetation feedback is found on local precipitation when averaged year-round, with the feedback explained variance usually accounting for less than 5% of the total precipitation variance. Nevertheless, in a few isolated small regions such as Northeast Brazil, East Africa, and northern Australia, there appears to be some positive vegetation feedback on local precipitation, with the feedback efficiency over 1 cm/month/0.1FPAR. The assessed vegetation feedback is shown to be valuable for the evaluation of vegetation-climate feedback in coupled climate-vegetation models.
DE: 0400 BIOGEOSCIENCES
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
SC: Biogeosciences [B]
MN: Fall Meeting 2005