Crop Insurance Today August 2013 - (Page 4)

CropInsurance TODAY The PRISM Climate and Weather System An Introduction By Christopher Daly, Oregon State University and Kirk Bryant, Risk Management Agency Weather and climate are arguably the most powerful drivers of both agricultural and natural systems, and have profound effects on how our society functions. Weather is what we experience day to day, while climate is a longer-term summary of expected weather conditions. In other words, climate is what you expect, and weather is what you get. Both are important in determining what crops can be grown successfully, what plants will thrive in your garden, how roads and buildings are constructed, and even the clothes you wear. With the advent of computer-based geographic information systems (GIS), global positioning systems, and remote sensing technologies that help us describe and visualize the earth’s surface, many planning and decision-making activities have gone spatial. A wide variety of agricultural, hydrologic, ecological, natural resource, and economic decision support tools are now linked to these technologies in new and exciting ways. Spatial decision support tools have an insatiable thirst for spatial data sets. Spatial weather and climate data, usually in the form of continuous grids of pixels, are often key inputs to these tools, and form the basis for scientific conclusions, management decisions, and other important outcomes. These grids typically describe minimum and maximum temperature and precipitation over a monthly or daily time step, and are especially useful because they provide wall-to-wall estimates of climate conditions, even where no weather stations exist. The most widely used spatial climate data sets in the United States are those developed by Oregon State University’s PRISM Climate 4 AUGUST2013 Group, named for the PRISM climate mapping system. PRISM products are the official spatial climate data sets of the USDA, and are used by thousands of agencies, universities, and companies worldwide. Now, PRISM is being put to work to improve the efficiency and integrity of the U.S. crop insurance program. In this article, we introduce you to the history of climate mapping, how the PRISM weather and climate mapping system was developed, and how it works. In a subsequent article, we will explain how PRISM is being used in crop insurance. A Little History Beginning in the early 20th century, official, 30-year average climate maps within the U.S. (most done by state), were created by expert climatologists with pen and paper. Observations from weather stations were plotted on a map, and generalized contours of temperature and precipitation drawn between the stations, based on the subjective opinion of the analyst. The process was tedious and time-consuming. It is not surprising that these maps were updated infrequently throughout the 20th century. Figure 1. Precipitation: Annual Climatology (1981-2010) PRISM map of mean annual precipitation, averaged over the years 1981-2010. Thirty years is considered the standard averaging period for describing the long-term climate of a region. The period typically moves forward once per decade (the next official period will be 1991-2020). This map is made up of over 20 million grid cells, each about ½-mile on a side.

Table of Contents for the Digital Edition of Crop Insurance Today August 2013

"It could be, it might be, it is!" Baseball Insights for Crop Insurance
The PRISM Climate and Weather System An Introduction
Crop Insurance In Action
2012 U.S. Crop-Hail & MPCI Loss Ratio By State
2012 Research Review
Incorporating Crop Insurance Decisions into a Risk Management Plan
Step 10-Documenting, Sharing and Revising
Dave Snider Retires

Crop Insurance Today August 2013