Progress 10/01/99 to 09/30/04
Outputs
Several major agro climatological innovations are reported, including some of the first successful efforts to collect and electronically enter data for agroclimatological studies and as well as proposing and championing the formation of regional climate centers which have now successfully provided data to the general public and performed research activities on regional climate for almost 20 years. Recent innovative work has resulted in a temporally and spatially consistent dataset for climate, soils, and crops over the North Central Region. At a county level, daily information for climate and annual cropping information is available from a single, comprehensive database. The most recent committee has evaluated methods to estimate daily solar radiation totals from existing climate information (Grant et al. 2004). The collection of data has not been simply a data gathering exercise, but innovation in spatiotemporal analysis and interpolation of data (Goe and Decker 1983).
Temporal interpolation was required because most climate records in the region have at least some missing data, which leads to problems when accumulating data over a period of time or when using these data in other data applications. Spatial interpolation was necessary in areas with few available individual station series or incomplete data. Creation of this internally consistent dataset has been a significant improvement for climate monitoring and crop modeling. The NC 94 database now includes most of the basic input information needed to run a variety of crop simulations for various applications, including regional yield prediction. Crop simulations for several counties and soil types in each state have been run and inter compared for model comparison and model consistency with observed data. Final results from these model runs are still pending. Another outcome from the data compilation has been a unique publication, the North Central Region Agricultural Climate Atlas (Gage et al.
2003b). This collection of pertinent climate, soil and crop information derived from the existing NC 1018 database. These will be published soon in a hard copy color publication. The committee has also presented a subset of recent research results in a special session at the American Society of Agronomy meeting in Denver, CO in November 2003. Twelve different papers highlighting various aspects of the committee results from regional climate and yield trends to application of the data in disease forecasting were part of the program (Andresen and Aichele, 2003; Arritt et al. 2003; Bowen and Hollinger, 2003; Gage et al. 2003a,b,c; Grant et al. 2003; Herzmann et al. 2003; Hu and Hubbard, 2003; Hollinger and Todey, 2003; Todey and Carlson, 2003; Todey and Chumley 2003).
Impacts
The results from this project are expected to guide producers in crop selection decisions and to point to any vulnerable areas where the risks may change abruptly with respect to sustained crop production
Publications
- R.H. Grant, S.E. Hollinger, K.G. Hubbard, G. Hoogenboom, R.L. Vanderlip. 2004. Ability to predict daily solar radiation values for use in crop simulation models. Agric. and Forest Meteorology. Accepted.
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Progress 10/01/02 to 09/30/03
Outputs
Data on soils, weather, and crops were updated for use in the project studies. The procedures for obtaining soils information from USDA-NRCS State Soil Geographic Database (STATSGO) were developed. This allows one to use latitude and longitude to obtain the following soil characteristics: Percent sand, silt, clay; field capacity, and bulk density. Using the information from above in the soil triangle allows one to obtain: field capacity, wilting point, and saturation capacity of the soil. In addition, quality control methods for soil temperature data from both the USDA NRCS SM-ST Network and the US NWS Coop stations network were developed. These methods have been applied to the historical soil temperature data and two soil temperature datasets were developed. To develop crop production predictive relationships, we first need to understand how ENSO has been affecting the precipitation and temperature during the growing season in the North Central region. Accordingly,
we analyzed the relationship of ENSO and summer rainfall variations and discovered that the ENSO has a strong effect on the rainfall. In particular, warm phase of the ENSO (El Nino) correspond to above average rainfall and cold phase (La Nina) correspond to below average rainfall. However, this ENSO effect is unsteady and has varied in the last century. The variation is fairly regular. This finding could be useful to guide the decisions as to when ENSO forecast may or may not be used in prediction of regional precipitation and crop growth and yield. Predictability of both the seasonal and diurnal rainfall in the North Central region has been analyzed. The summer season diurnal rainfall in the region has a mulitdecadal variation. The CSDI model requires weather inputs beyond temperature and precipitation which are: solar radiation, humidity and windspeed. These inputs are very scarce prior to 1980. For wind speed the model is not very sensitive and a climatically appropriate value can
be used. For solar radiation, an estimation method was devised and tested. Likewise, for dewpoint an estimation method was formulated and tested. In addition, efforts have gone forth to better represent the effect of prolonged wet spells on the yield of crops. This is being addressed by counting the number of days for which the soil water content exceeds a threshold (e.g. field capacity) in each growth stage. Preliminary results indicate the wet years, like 1993, are better simulated when the count of wet days is included.
Impacts
The results from this project are expected to guide producers in crop selection decisions and to point to any vulnerable areas where the risks may change abruptly with respect to sustained crop production
Publications
- Hu, Q. 2003: A multidecadal variation in summer season diurnal rainfall in the central United States. J. Clmate, 16 174-178.
- Hu, Q., S. Feng, and G. Shaefer, 2002: Quality control for USDA NRCS SM/ST Network soil temperatures: A method and a dataset. J. Appl. Meteorol., 41, 607-619.
- Hu, Q and S. Feng, 2003: A daily soil temperature datset and soil temperature climatology of the contiguous United States. J. Appl. Meteorol., 42, 1139-1156.
- Hubbard, K.G., R. Mahmood, and C. Carlson. 2003. Estimating daily dew point temperature for the Northern Great Plains using maximum and minimum temperature. J. Appl. Meteorol. 323-328.
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Progress 10/01/01 to 09/30/02
Outputs
To run crop models using historical data requires accurate estimates of ET. The Penman and the Penman-Monteith methods offer the most sound means of estimating ET. Both require temperature, dew point, solar radiation, and wind speed as input. Only temperature was measured before the 1950's so techniques are needed to esimate those variables that were not measured Techniques for estimated solar radiation and dew point have been derived and published. Efforts continue in the area of monitoring and modeling soil moisture. Studies into the effect of land use on soil moisture and ET were conducted as part of this study.
Impacts
Those who use the land and who manage production will be interested in the results of this study and in particular in reducing risks as they develop strategic plans for the future.
Publications
- Hubbard, K.G., R. Mahmood, and C. Carlson. 2002. Estimating daily dew point temperature for the Northern Great Plains, USA. J. Appl. Meteorol. (Accepted) (13313)
- Mahmood, R. and K.G. Hubbard. 2002. Effect of time of temperature observations and estimation on daily solar radiation for the Northern Great Plains, USA. Agron. J. 94(4):723-733.
- Hubbard, K.G. and X. Lin. 2002. Realtime data filtering models for air temperature measurements. Geophysical Research Letters. 29:X 1-4 (13257)
- Wilhelmi, O.V., K.G. Hubbard, and D.A. Wilhite. 2002. Agroclimatolgical factors influencing vulnerability to agricultural drought: a Nebraska case study. Ag. And Forest Meteorol. (Accepted) (13028)
- Adegoke, J.O. R.A. Pielke, Sr., J.Eastman, R. Mahmood, and K.G. Hubbard. 2002. A regional atmospheric model study of the impact of irrigation on midsummer surface energy budget in the U.S. High Plains. Monthly Weather Review. (Accepted).
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Progress 10/01/00 to 09/30/01
Outputs
Historically, weather measurements extend over a century in Nebraska and the western states. We currently are working to quality control the pre-1948 data. In Nebraska considerable effort has been devoted to determining the role of shields used to block solar radiation from the sensors used for measurement of air temperature. A developing resource for NC-94 is the weather data taken by automated weather stations in Networks operated by Universities and other state agencies. Many of these stations now have 20 years of data and it would appear that there is growing consistency in these networks. To run crop models using historical data requires accurate estimates of ET. The physically sound derivations of ET are the Penman and Penman-Montieth approaches. Both require temperature, dew point, solar radiation and wind speed as input. Only temperature was measured before the 1950's so techniques are needed to estimate those variables that were not measured. A study to
estimate Rs found a good estimator based on the daily range (ie.. Tmax-Tmin). This relationship performed well in both humid and semi-arid areas. It was further found that the success of using DR in this approach depends on the observation time. The best observation time was midnight. The effectiveness of estimating dewpoint was also examined and a methodology that explains 90% of the variance on daily data was developed. Efforts to determine the best estimator for spatial interpolations continued . Efforts continued in the area of monitoring and modeling soil moisture and estimates of soil moisture were further refined for use in historical applications and climatologies. The changes in land use have been considerable in the Great Plains as man has transformed the grasslands to crop lands in the plains areas. We have predicted the changes in water budget and the differences in energy partitioning from year to year as the prairie has been transformed into crop lands . Of course the
development of irrigation has continued at unprecedented levels and this too changes the local hydrological cycle and the partitioning of energy at the surface. The effect of irrigation then can also change the climate and a first look at this using a regional atmospheric model indicates that significant changes in dew point have occurred in the atmosphere. To understand growing season weather in the Great Plains we focused on the interannual summer rainfall variation. The ENSO effect on summer rainfall anomalies was found to vary in the last century. Its variation has a multidecadal rhythm and with the southerly flow (low-level jet) from the Gulf of Mexico an alternating influence on the summer rainfall variation in the Great Plains was found. The LLJ effect enhanced when the ENSO teleconnection weakened. These two primary causes of the summer rainfall variation in the region were further examined in GCMs to assure their presence so that the model predictions can be used to develop
climate change scenarios to evaluate crop production and food security in the future.
Impacts
We expect that decision makers will be better able to take account of risk due to weather and climate variability when developing a strategic plan for agricultural production
Publications
- Lin, X., K.G. Hubbard, and G.E. Meyer. 2001. Air flow characteristics of commonly used temperature radiation shields. J. Atmos. Oceanic Tech. 18(3):329-339. (13007)
- Hubbard, K.G., X.Lin, and E. Walter-Shea. 2001. The effectiveness of the ASOS, MMTS, Gill and CRS air temperature radiation shields. J. Atmos. Oceanic Tech. 18(6):851-864. (13013)
- Lin, X., K.G. Hubbard, E.A. Walter-Shea, J.Brandle, and G.E.Meyer. 2001. Some perspectives on recent in-situ air temperature observations: modeling the microclimate inside the radiation shields. J. Atmos. Oceanic Tech. 18:1470-1484. (13008)
- Merino, G.G. D.Jones, D.E. Stooksbury, and K.G. Hubbard. 2001. Determination of semivariogram models to krige hourly and daily solar irradiance in western Nebraska. J. Applied Met. 40:1085-1094. (12746)
- Hubbard, K.G. 2001. The history of weather observations in the Western United States. J. of the West. 40(3) 26-30.
- Hubbard, K.G. and M.V.K. Sivakumar, Eds. 2001. Automated weather stations for applications in agriculture and water resources management: current use and future perspectives. World Meterological Organization. Geneva, Switzerland. WMO/TD No. 1074. 248 pp.
- Hu, Q., and S. Feng, 2001: Variation of teleconnection of ENSO and interannual variation of summer rainfall in the central United States. J. Climate, 14, 2469-2480.
- Hu, Q., and S. Feng, 2001: Climatic role of the southerly flow from the Gulf of Mexico in interannual variations in summer rainfall in the central United States. J. Climate, 14, 3156-3170.
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