This study is the first to analyze the mechanisms that drive
precipitation recycling variability at the daily to intraseasonal
timescale. A new Dynamic Precipitation Recycling model is
developed which, unlike previous models, includes the moisture
storage term in the equation of conservation of atmospheric
moisture. As shown using scaling analysis, the moisture storage
term is non-negligible at small time scales, so the new model
enables us to analyze precipitation recycling variability at
shorter timescales than traditional models. The daily to
intraseasonal analysis enables us to uncover key relationships
between recycling and the moisture and energy fluxes. In the
second phase of this work, a spatiotemporal analysis of daily
precipitation recycling is performed over two regions of North
America : the Midwestern United States, and the North American
Monsoon System (NAMS) region. These regions were chosen
because they present contrasting land-atmosphere interactions.

Different physical mechanisms drive precipitation recycling in
each region. In the Midwestern United States, evapotranspiration
is not significantly affected by soil moisture anomalies, and
there is a high recycling ratio during periods of reduced total
precipitation. The reason is that, during periods of drier
atmospheric conditions, transpiration will continue to provide
moisture to the overlying atmosphere and contribute to total
rainfall. Consequently, precipitation recycling variability in not
driven by changes in evapotranspiration. Precipitable water,
sensible heat and moisture fluxes are the main drivers of
recycling variability in the Midwest. However, the drier soil
moisture conditions over the NAMS region limit
evapotranspiration, which will drive recycling variability. In this
region, evapotranspiration becomes an important contribution
to precipitation after Monsoon onset when total precipitation
and evapotranspiration are highest. The precipitation
recycling process in the NAMS region relocates moisture from
regions of high evapotranspiration like the seasonally dry
tropical forests of Mexico to drier regions downwind. During
long monsoons, when soil moisture is abundant for a prolonged
period of time, precipitation recycling significantly contributes to
precipitation during periods of reduced total rainfall. In both the
moisture abundant Midwestern region and the drier NAMS
region, precipitation recycling plays an important role in
maintaining a favorable hydroclimatological environment for
vegetation.