Dry deposition is one of the driving factors behind ozone-meteorology
relationships. We examine the response of ozone deposition to heat and
dry anomalies using three long-term co-located ecosystem-scale carbon
dioxide, water vapor and ozone flux measurement records. We find that,
as expected, canopy stomatal conductance generally decreases during days
with dry air or soil. However, during hot days, concurrent increases in
non-stomatal conductance are inferred at all three sites, which may be
related to several temperature-sensitive processes not represented in
the current generation of big-leaf models. This may offset the reduction
in stomatal conductance, leading to smaller net reduction, or even net
increase, in total deposition velocity. We find the response of
deposition velocity to soil dryness may be related to its impact on
photosynthetic activity, though considerable variability exists. Our
findings emphasize the need for better understanding and representation
of non-stomatal ozone deposition processes.