Drought and its Impacts: What additional information is needed? Kelly T. Redmond Western Regional Climate Center Desert Research Institute Reno Nevada 33 rd Annual Climate Diagnostics and Prediction Workshop CLIVAR/NIDIS Drought Workshop Lincoln, Nebraska 2008 October 20-24

Issues Drought fundamentally involves the concept of a water budget Supply minus Demand Drought as accumulated Supply minus Demand Need status of components of the water balance Supply components Demand components Ideally, everywhere in space, at the necessary resolution Past, present, future Drought is defined by its impacts A Working Definition of Drought (very hard to avoid this approach) : Insufficient water to meet needs

Subjective / Objective Issue What does “objective” mean? An objective process is one that brings all relevant information to bear - RSP discussion There are many ground truths at once There are many droughts – simultaneously This approach is more complicated, but more useful What is the purpose of the Drought Monitor? Drought as a human construct (is there “natural” drought?) Reinforcement of this notion in presentations by Dave Stooksbury Tom Pagano Andrea Ray None of the foregoing decreases the need for quantitative measures of water inputs, outputs, storage (human and natural)

In general, the most consequential droughts occur in the wettest portion of the year … though not always. Temperature seasonality is nearly the same everywhere:

Monthly Precipitation Climatologies Jan-Dec

Madison Valley Seasonality Comparison Area.

Adapted from Phil Farnes, Western Snow Conference, 1995.

Oct-Mar Apr-May-June Fraction of Annual Total Precipitation, by Season July-Aug WRCC / OSU

K. Redmond, p 29-48, Water and Climate in the Western United States. U Colorado Press.

HCNM Grid 50 km Radius Green CRN Red TBD Yellow Survey Done Blue In prog

Chinle Airport, Arizona. HCNM prospect. View to the North, East, West, and South.

How to describe and depict drought when large spatial variations are present How to depict and describe drought when large time lags are present Different sectors simultaneously affected differently by same situation How to describe multiple simultaneous situations at once Users and sectors are not monolithic. Many flavors and nuances. These matter, if information is to be usable. Small relative impacts in large states vs large impacts in small states Major players versus minor players (in absolute or relative terms?) California as a kind of “Drought Depiction Test Bed” How large a Soil Moisture monitoring system is needed?

March 10, ” / 170 mm 12” / 300 mm 55” / 1400 mm 70” / 1800 mm

California’s Complex Water Distribution System

“Upper Colorado”

Lake Powell Storage Through Apr 3, 2008 Currently 45 % full Minimum: 33 % full on April 8, 2005

Lake Powell Elevation Through Apr 5, 2008 Water level on Apr 5, 2008 was ft, ft below full. Minimum level on April 8, 2005 was 3555 ft, -145 ft below full. Source:

R. Seager, M.F. Ting, I.M. Held, Y. Kushnir, J. Lu, G. Vecchi, H.-P. Huang, N. Harnik, A. Leetmaa, N.-C. Lau, C. Li, J. Velez, N. Naik, Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America. Science, DOI: /science Average of 19 climate models Figure by Gabriel Vecchi. es/div/ocp/drought/scienc e.shtml

Seager et al, Average of 19 climate models. Figure by Naomi Naik.

? ? ? Is the current Southwest drought a once-or-twice-a-century drought like those of the past 500 years … ? … or … a harbinger of things to come, a different type of drought that we have not observed before ?

Physical aspects Better forecasts in the 1-4 week range Better forecasts in the 2-10 year range Drought properties in Eastern US versus Western US A few months versus multiple years or decades How quickly can we get into drought? Timing of supply and demand It’s not just all about precipitation. Temperature effects. Other demand info: wind, humidity, solar. Sequencing often matters, often greatly.

Coupling of CFS (Climate Forecast System), or other numerical output, with hydrology Continuation of PRISM high resolution monthly maps

Masked for skill. All areas. Monthly Nov 08 – Apr 09

Masked for skill. All areas. Monthly NDJ 08 – MJJ 09

Seasonal Precipitation CPC Seasonal Temperature Dec-Jan-Feb Nov-Dec-Jan

Role of Research and Climate Test Bed in NIDIS Colorado River Pilot Project - Enhanced Reservoir Operations on Upper Colorado River and Lake Mead Including improved forecast info for Upper Colorado River Basin - Improved operations of Colorado – Big Thompson Project - Drought impacts on ecosystem and recreation management

Thank You

Panel Discussion Future Directions for Drought Research Moderator: Kelly Redmond Panelists: Jim Verdin Mike Hayes Siegfried Schubert Kingtse Mo

Role of Research and Climate Test Bed in NIDIS Colorado River Pilot Project - Enhanced Reservoir Operations on Upper Colorado River and Lake Mead Including improved forecast info for Upper Colorado River Basin - Improved operations of Colorado – Big Thompson Project -Drought impacts on ecosystem and recreation management Other aspects of drought research to assist NIDIS Physical understanding **Sponsors need to be satisfied that their needs are being addressed**

NIDIS pilot study (Kingtse Mo) Data  Survey of data sets available  Archive at one place so people can easily download Monitoring  Calibration and Verification of NLDAS  Bring together operational people and researchers Forecasts  Mechanisms to include local information  Reliability of the forecasts

Questions (from Siegfried Schubert Panel) To what extent can we simulate past droughts in AMIP-style simulations? –Do models agree on the important drivers and sources (e.g. oceans, soil moisture) of drought? Do they agree on the regions where droughts may be predictable? –To what extent are the simulated physical mechanisms consistent with observations? (seasonality, links to different ocean basins, role of land/atmosphere coupling, LLJ, weather, connections to ENSO, PDV, NAO etc.) To what extent do coupled models simulate realistic droughts? –Do they produce realistic links to SST variability? –Do they produce realistic distributions of drought (spatial distributions and temporal statistics) –Are the current (AR4) IPCC runs of sufficient quality to be used to assess the role of human-induced forcings (as compared to natural variability) in drought? What are the prospects for useful seasonal to multi-year drought predictions? –Current capabilities of coupled model simulations of interannual to decadal variability? ENSO, PDO, AMO, MOC, etc –How can attribution studies help advance drought research and provide important information to decision-makers? –What is our plan to develop a suite of regional drought forecasts?