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7-2015
Facilitating the Use of Drought Early Warning Information through Facilitating the Use of Drought Early Warning Information through
Interactions with Agricultural Stakeholders Interactions with Agricultural Stakeholders
Jason A. Otkin
Mark Shafer
Mark Svoboda
Brian Wardlow
Martha C. Anderson
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Authors Authors
Jason A. Otkin, Mark Shafer, Mark Svoboda, Brian Wardlow, Martha C. Anderson, Christopher Hain, and
Jeffrey Basara
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E
xtreme drought events across the United States
in recent years have led to large societal impacts
and contributed to lower agricultural productivity
in major farming and ranching areas of the country.
The total cost associated with these events has been
high, with the 2012 drought alone costing more than
$35 billion, making it one of the most expensive
natural disasters in U.S. history. Because droughts
impact more people than any other type of natural
disaster, robust drought early warning systems that
effectively characterize and disseminate information
to vulnerable stakeholders are necessary to assist
drought mitigation and climate adaptation efforts.
A prime example is the National Integrated Drought
Information System (NIDIS), which has a defined
goal of creating a drought early warning system that
provides probabilistic forecasts with sufficient spatial
Facilitating the Use of Drought Early
Warning Information through Interactions
with Agricultural Stakeholders
by Jason a. otkin, Mark shafer, Mark svoboda, brian WardloW, Martha C. anderson,
Christopher hain, and Jeffrey basara
and temporal resolutions for users to make informed
management decisions.
Drought is often thought of as being a slowly devel-
oping climate phenomenon that takes many months
or even years to reach its full intensity; however, recent
events across the central United States have shown
that drought development can occur very rapidly if
extreme weather anomalies remain over the same
area for periods as short as a few weeks. Low rainfall
combined with anomalously high temperatures, strong
winds, and sunny skies can act together to quickly
deplete root zone soil moisture, thereby leading to the
rapid emergence of agricultural drought conditions.
It has become common in recent years to refer to
these rapid-onset drought events as “flash droughts”
to better distinguish them from other droughts that
develop more slowly. Flash droughts can have an
impact on agriculture that is more severe than that
associated with a slower developing but longer lasting
drought simply because there is less time to prepare
for the adverse effects of drought when it develops so
quickly. For example, according to the U.S. Drought
Monitor (USDM), many locations across the central
United States during the 2011 and 2012 flash droughts
experienced up to a three-category increase in drought
severity in only one month, meaning that areas that
were drought free at the beginning of the month were
characterized by severe to extreme drought conditions
by the end of the month. Drought early warning during
these rapidly evolving situations, however, is difficult
to obtain using existing drought forecasting products
that tend to focus on seasonal time scales and may only
be updated on a monthly basis. Early warning systems
could be significantly enhanced by integrating new
datasets that provide information over subseasonal
time scales (< 3 months) with frequent update cycles
(weekly), both of which are necessary for early detec-
tion of rapidly evolving flash drought events.
AFFILIATIONS: otkin—Cooperative Institute for Meteorological
Satellite Studies, University of Wisconsin—Madison, Madison,
Wisconsin; shafer—Oklahoma Climatological Survey, University
of Oklahoma, Norman, Oklahoma; svoboda—National Drought
Mitigation Center, University of Nebraska—Lincoln, Lincoln,
Nebraska; WardloW—National Drought Mitigation Center,
and Center for Advanced Land Management Information
Technologies (CALMIT), University of Nebraska—Lincoln,
Lincoln, Nebraska; anderson—Agricultural Research Services,
United States Department of Agriculture, Hydrology and Remote
Sensing Laboratory, Beltsville, Maryland; hain—Earth System
Interdisciplinary Center, University of Maryland—College Park,
College Park, Maryland; basara—Oklahoma Climatological Survey,
and School of Meteorology, University of Oklahoma, Norman,
Oklahoma
CORRESPONDING AUTHOR: Jason A. Otkin, 1225 W. Dayton
St., Madison, WI 53706
E-mail: jason.otkin@ssec.wisc.edu
DOI:10.1175/BAMS-D-14-00219.1
©2015 American Meteorological Society
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Recent research has shown that drought early
warning signals can be identified using drought
indicators such as the Evaporative Stress Index (ESI),
which depicts standardized anomalies in evapotrans-
piration (ET; the combination of evaporation from
bare soil and transpiration from vegetation) using
land surface temperature data retrieved from satellite
thermal infrared imagery and a land surface energy
balance model. Early warning is possible because,
in the absence of other stressors such as disease, the
amount of water vapor transpired by vegetation will
be dependent on the root zone soil moisture content,
with below-average ET during the growing season
indicating that plants are experiencing moisture
stress. Drought early warning signals often occur
in the ESI several weeks prior to their appearance
in other drought indices because stress-induced im-
pacts on transpiration and canopy temperature often
precede a visible decrease in green vegetation cover.
Furthermore, energy balance methods for retriev-
ing ET explicitly capture the major drivers of flash
drought development, including increased evaporative
demand and stronger winds—each of which enhance
evaporative loss of soil moisture to the atmosphere.
To better understand how this drought early warn-
ing information could be used to mitigate drought risk,
focus group meetings were convened with stakeholders
in two NIDIS pilot regions in the central United States.
This article presents results from these meetings and
discusses how they facilitated valuable interactions
that serve as an example of how drought early warn-
ing information can be more effectively disseminated.
FOCUS GROUP MEETINGS. Two focus group
meetings were convened in August 2014 with stake-
holders in the NIDIS Southern Plains and Missouri
River basin regional drought early warning system
pilot regions that were impacted by severe droughts in
recent years. The first meeting was held in Norman,
Oklahoma, and the second convened two days later in
Lincoln, Nebraska. All attendees were invited based
on their prior interest in drought mitigation, with a
total of 30 people from diverse backgrounds attending
the meetings. Overall, 70% of the attendees were from
university, federal, and nonprofit scientific organiza-
tions, 20% were from state and local government, and
10% were full-time farmers or ranchers, with most
either directly or indirectly involved in agriculture.
Each focus group meeting included an interactive
discussion on the characteristics of flash drought
events and their societal impacts, along with several
presentations introducing the attendees to the ESI
and associated drought monitoring products. These
include ESI “change anomalies” that show how rapidly
the ESI is changing with time compared to climatol-
ogy, and the Rapid Change Index (RCI) depicting the
accumulated moisture stress change occurring over
longer time periods. The RCI and ESI change anoma-
lies can be used to identify regions with unusually
rapid increases in moisture stress, which prior work
has shown often precede periods of rapid drought
development as depicted by the USDM. Experimental
drought intensification forecasts derived from the RCI
were also shown. These forecasts provide a probabi-
listic likelihood of drought intensification occurring
over a 2–8-week time period based on the value of
the RCI. All datasets are routinely computed at 4-km
spatial resolution across the contiguous United States,
with weekly updates during the growing season that
promote early warning of flash drought development
at regional-to-local scales. The attendees were asked to
assess the usefulness of these datasets for drought plan-
ning and mitigation efforts through group discussions,
analysis of recent flash drought events, and a written
questionnaire provided at the end of each meeting.
FLASH DROUGHT CHARACTERISTICS AND
IMPACTS. As discussed earlier, flash droughts are
more likely to develop when dry weather, hot tempera-
tures, strong winds, and sunny skies occur together.
Many attendees noted that these conditions often lead
to the rapid depletion of stock water ponds, greater
heat stress on livestock, and the rapid deterioration
of crop and rangeland health. It was also noted that
differences in local farming practices strongly influ-
ence the vulnerability of an individual farm to extreme
weather anomalies and to flash drought development.
For example, soil management practices such as plant-
ing cover crops and using conservation tillage can
impact drought severity at the farm scale through
changes in evaporation and water transfer within the
soil column. Different soil characteristics such as soil
type, water-holding capacity, and infiltration rate also
influence local resiliency to flash drought. At the re-
gional scale, differences in vegetation type and farm-
ing practices may also impact the timing and severity
of drought. Across the Southern Plains, widespread
tillage after the winter wheat harvest in the spring
produces large areas of bare soil that absorb more solar
radiation than surrounding vegetated areas. This may
lead to hotter air and soil temperatures that intensify
local drought conditions and influence surrounding
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Fig. 1. Domain images showing (a) ESI anomalies computed over a four-
week period, (b) standardized ESI change anomalies depicting changes
in the ESI during the preceding week, (c) RCI, and (d) the RCI-derived
probability of a one-category increase in the USDM drought severity
occurring during the next two weeks. All images are valid on 1 Jul 2011.
areas through changes in boundary layer structure
and mesoscale circulations. It was also suggested that
early spring green-up could lead to earlier drought
onset during the summer because the vegetation will
begin to deplete soil moisture earlier than normal,
thereby leaving it more susceptible to drought if spring
rains are less than normal.
ASSESSMENT OF THE ESI DATASETS AS
DROUGHT EARLY WARNING TOOLS. During
each meeting, the attendees were shown results from
several drought case studies depicting the evolution
of the ESI, ESI change anomalies, RCI, and drought
intensification probabilistic forecasts. They were
then asked to assess their drought early warning
utility through comparison with the USDM, Palmer
Drought Severity Index, Palmer Z-Index, Standard-
ized Precipitation Index (SPI), and soil moisture
anomalies from the North American Land Data
Assimilation System. These datasets were presented
either as domain maps (examples shown in Fig. 1)
or as a visualization tool referred to as a “plume dia-
gram” (example shown in Fig. 2) that was developed
to display time sequences of multiple
datasets on a single image. These
diagrams allow the user to quickly
evaluate the evolution of multiple
datasets over a specific region—such
as an individual county—without
the need to examine potentially
dozens of domain maps.
Overall, most attendees had a fa-
vorable opinion of the ESI, RCI, and
drought intensification probabilistic
forecasts, with positive ratings of
89%, 68%, and 89%, respectively.
The attendees generally preferred to
use the ESI and RCI variables in map
form (e.g., Fig. 1) when diagnosing
current drought conditions. These
variables were considered very help-
ful when used together because the
current conditions could be evalu-
ated with the ESI, whereas the RCI
provides a longer view of how condi-
tions have been changing in recent
weeks. The probabilistic drought
forecasts allowed the participants to
anticipate which regions were most
susceptible to drought development,
which also influenced their opinion
on current drought conditions. Each group was asked
if these probabilistic forecasts would be useful dur-
ing their decision-making process since they are not
deterministic forecasts. Though some concerns were
expressed regarding the potential for false alarms, the
consensus was that these forecasts would be beneficial
because most farmers and ranchers are accustomed
to dealing with uncertainty when making decisions.
Any tool that can provide reliable information is
potentially useful.
Attendee feedback was more neutral when evaluat-
ing the ESI change anomalies because many people
found them difficult to interpret, with the confusion
primarily arising from the method used to compute
the change anomalies. To more easily compare the
magnitude of ESI changes occurring during differ-
ent years and seasons, the change anomalies are not
simple numerical differences between two weeks.
Instead, they are standardized anomalies in which
the observed difference in the ESI is normalized
using a long-term climatology of ESI changes from
2000 to 2013. This conversion caused some confusion
because, for example, a decrease in the ESI from –0.1
