Mechanisms for Persistence of Summer Floods and
Droughts over North America
The Midwest region of North America experiences significant floods and
droughts during the summer season. The 1988 drought and the 1993 floods are good examples
for these extreme events.
Summer Preciptation (May June and July) Anomalies (mm/day)
Findell and Eltahir (1997) analyzed
direct observations on soil moisture and subsequent precipitation from Illinois. They
suggest a significant role for spring and early summer soil moisture levels as initial
conditions for the subsequent development of the hydroclimatologic conditions during
Correlation between initial soilin the rest of the summer (through September 19)
for (a) top 10 cm, (b) top 50 cm, (c) top 90 cm. Solid line is the 21-day
average. Level of significance lines refer to the daily values (not the
Eltahir (1998) proposed the following
mechanism for describing the implied soil moisture-rainfall feedback.
The proposed hypothesis for relating soil moisture conditions and suqsequent
This theoretical mechanism has been tested in (Eltahir, 1998) using field data from FIFE. Some of the
ongoing research focuses on regional climate modeling of North America with the
objective of studying the role of the large-scale spring soil moisture distribution in
shaping summer climate.
Back to Highlights of Research