Progress 10/01/99 to 09/30/04
Outputs
We have assembled historical and current data into a unified format known as the Iowa Environmental Mesonet (IEM). The IEM is an interagency "network of networks" that serves as a centralized data collection, storage, and dissemination hub for current and historical observations on an Internet homepage. Participating networks include those from the Iowa Department of Transportation, the United States Geological Survey, the Iowa Agriculture and Home Economics Experiment Station and the National Resource Conservation Service. By capitalizing on existing resources, the IEM demonstrates efficiency through cooperation among agencies. Our data are used by agricultural interests, emergency managers and by the National Weather Service (NWS). We have also developed data quality control procedures that provide insight into reasons for anomalies in the network, so that we can more readily tell when unusual data represent real meteorological events rather than instrument errors.
In an extension of the Mesonet to emergency management, the Iowa Department of Transportation requested a bridge frost monitoring system superior to their current method. In response we produced a multi-layer overlay with pavement temperature, air temperature, and radar precipitation data. Soil temperature data are being used for an advisory on fall application of nitrogen. Temperature, humidity, wind, and rainfall conditions around the state are being used to develop a soil loss model to determine soil erosion loss potential statewide. IEM data also are being used to run a frost model for the IaDOT to better-predict frost formation on roadways. Other products include detailed maps of real-time and historical GDD accumulation over the state during the summer. Current products may be viewed at http://mesonet.agron.iastate.edu. The IEM project received the National Weather Association Larry R. Johnson Special Award for extraordinary accomplishments contributing to operational
meteorology. Other research indicated a relationship of Midwestern climate and crop yields with large scale climate anomalies such as El Nino/La Nina and the Pacific Decadal Oscillation (PDO). Preliminary indications are that corn yields are less variable during the cold phase of the PDO. Corn yields segregated by El Nino/La Nina region showed higher yields were associated with the El Nino phase and low yields were associated with the La Nina phase. The corn yield year-to-year variation during the cold phase of the PDO was less for major corn producing states then during the warm phase. Precipitation amounts were elevated during Event 1 (El Nino with PDO warm event) years over most of the grain-producing region of the U.S.
Impacts
Primary and secondary school teachers are using the Iowa Environmental Mesonet to enhance classroom teaching and scientific literacy. In an example of the timeliness and efficiency of the IEM, the NWS issued a severe storm warning based on IEM data with a turnaround time of less than two minutes from the time of observation to the issuance of the warning.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
We have assembled historical and current data into a unified format known as the Iowa Environmental Mesonet. Our data are used by agricultural interests, emergency managers and by the National Weather Service (NWS). We have also developed data quality control procedures that provide insight into reasons for anomalies in the network, so that we can more readily tell when unusual data represent real meteorological events rather than instrument errors. In an extension of the Mesonet to emergency management, the Iowa Department of Transportation requested a bridge frost monitoring system superior to their current method. In response we produced a multi-layer overlay with pavement temperature, air temperature, and radar precipitation data. We recently added soil moisture measurements to several of the Mesonet sites, which will allow real-time modeling of soil water availability for agricultural purposes.
Impacts
In an example of the timeliness and efficiency of the Mesonet, this summer the NWS issued a severe storm warning based on our data with a turnaround time of less than two minutes from the time of observation to the issuance of the warning. Primary and secondary school teachers are using the Iowa Environmental Mesonet to enhance classroom teaching and scientific literacy. We are in continual contact with the K-12 teachers who are suggesting products useful for educational purposes.
Publications
- Todey, D.P. and Herzmann, D.E. 2003. Improving the observation of the water cycle in Iowa using the Iowa Environmental Mesonet. Preprints Observing and understanding the variability of water in weather and climate. Amer. Meteor. Soc. p. 19.
- Todey, D.P. and Herzmann, D.E. 2003. Using GIS for environmental data in Iowa. Preprints 19th conference on IIPS for Meteorology, Hydrology and Oceanography. Amer. Meteor. Soc. p. 99.
- Pan, Z., Horton, R., Segal, M., Takle, E., Herzmann, D., Todey, D., Flory, D. and Roads, J. 2003. Seasonal soil moisture prediction using a climate-plant-soil coupled agroecosystem water management model. 17th Conf. on Hydrology. Amer. Meteor. Soc. p. 158-159.
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Progress 01/01/02 to 12/31/02
Outputs
Work during the past year has focused primarily on expansion of the climate observing network, most notably development of the Iowa Environmental Mesonet (IEM). The IEM is an interagency "network of networks" that serves as a centralized data collection, storage, and dissemination hub for current observations. The mesonet brings together diverse datasets and school-based weather stations on an Internet homepage with real-time access to the weather-forecasting community. Participating networks include those from the Iowa Department of Transportation, the United States Geological Survey, the ISU Agriculture and Home Economics Experiment Station and the National Resource Conservation Service. Networks include those from the Iowa Department of Transportation, the United States Geological Survey, the ISU Agriculture and Home Economics Experiment Station and the National Resource Conservation Service. Data are checked for comparability among networks, quality controlled,
and combined into a single database. Existing systems currently include over 300 stations and over 1100 instruments within the state. By capitalizing on existing resources, the IEM demonstrates efficiency through cooperation among agencies. Applications for the data are continually being developed. Soil temperature data are being used for an advisory on fall application of nitrogen. Temperature, humidity, wind, and rainfall conditions around the state are being used to develop a soil loss model to determine soil erosion loss potential statewide. IEM data also are being used to run a frost model for the IaDOT to better-predict frost formation on roadways.
Impacts
Data from the Iowa Environmental Mesonet are heavily used by agricultural practitioners and emergency-response personnel throughout the state. The Mesonet project was bestowed with the he National Weather Association Larry R. Johnson Special Award for extraordinary accomplishments contributing to operational meteorology.
Publications
- Todey DP, DE Herzmann, WA Gallus and BR Temeyer. 2002. An inter-comparison of RWIS data with AWOS and ASOS data in the state of Iowa. Preprints, 18th International Conference on Interactive Information Processing Systems. American Meteorological Society.
- Todey DP, ES Takle and SE Taylor. 2002. The Iowa Environmental Mesonet-Observing climate at the mesoscale. Preprints, 13th Conference on Applied Climatology. American Meteorological Society.
- Todey DP, DE Herzmann and ES Takle. 2002. The Iowa Environmental Mesonet-Combining observing systems into a single network. Preprints, Sixth Conference on Integrated Observing Systems. American Meteorological Society.
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Progress 01/01/01 to 12/31/01
Outputs
Work has continued relating large-scale climatic forcings (mainly sea-surface temperature anomalies with Midwestern climatic and yield anomalies). In addition to relationships with El Nino and La Nina, relationships with the Pacific Decadal Oscillation (PDO) have been investigated. Several preliminary findings have indicated a relationship among El Nino/La Nina, the PDO, and Midwestern climate and crop yields. Preliminary indications are that corn yields are less variable during the cold phase of the PDO. But the results are not conclusive and continue to be reviewed. The Iowa Ag-Climate Network has added another station in northeast Iowa, leaving a total of 12 stations across Iowa. Further expansion is being investigated in conjunction with the Iowa Environmental Mesonet (IEM). The IEM is an effort of Iowa State University in cooperation with several state and federal agencies to collect data from several different observing systems in the state. The effort is also
part of a goal of larger departmental effort to collect detailed databases of environmental and agricultural data to provide to the public and for validating research modeling efforts. The data from the various networks are being archived in a single database, compared for compatibility and used to create products for users in the state. This method is being used to achieve greater detail across the state without the expense of a great number of new stations. The initial goal of collecting the data in a single archive has been achieved. Data comparison is among the networks is continuing. Some data has been found to be quite useful. Data from the Iowa Department of transportation has been very useful. Data has been gathered from the USGS and Army COE at their river gauge sites. Products already in use have showed detailed GDD accumulation over the state during the summer. Daily plots and accumulation plots of precipitation are available for several stations. Current products may be
viewed at http://mesonet.agron.iastate.edu. Future goals are to expand the network to fill holes where no or little data is being collected around the state. Expansion of the types of data gathered will occur, also. The initial goal is to begin gathering soil moisture data across the state.
Impacts
Determining the climatic relationships with crop yields can have great benefit for crop producers in helping plan and manage their risk throughout the growing season. The development of the Iowa Environmental Mesonet will greatly benefit producers in tracking current weather and climatic conditions across the state. It has benefited forecasters in keeping track of detailed current conditions for forecasts. Other benefits will be developed as opportunities arise.
Publications
- No publications reported this period
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Progress 01/01/00 to 12/31/00
Outputs
Weather variables, crop yields, and various atmospheric indices were compiled for the 12-north central states. Corn yields were segregated by the Southern Oscillation (SOI) and North Pacific Oscillation Indices (NPO). Over much of the 12-state region higher (lower) yields were associated with the low (high) phase of the SOI. Over the 12 states, a 75%-25% success pattern was apparent for this relationship, but spatially related departures were noted across the southwestern parts of the region. The corn yield year-to-year variation during the cold phase of the NPO was less for major corn producing states then during the warm phase. The automated weather station network was expanded to 13 in number. The data are collected by the High Plains Climate Center and redistributed to Iowa State University. A web page was developed to display or distribute the data in various formats to any interested individuals. Atmospheric data were studied for the two extreme phases of the
NPO/SOI-warm/warm (event 1) and cold/cold (event 4) to ascertain linkages between atmospheric indices, precipitation, and corn yields for the north central states. These data began in 1951. Precipitation amounts were elevated during Event 1 years over most of the grain-producing region of the U.S. During July, contributions came from all levels of the atmosphere. The lower-levels provide lifting in the form of thermal advection and convergence. The moisture field depicted excess moisture on the order of 1 g per kg over a large region during Event 1 years. The 500 mb geopotential height field depicts lower (higher) height upstream (downsteam) of the region. August atmospheric parameters were favorable for producing additional (less) precipitation in an Event 1 (4) year. Precipitation decreases were associated with a decrease in the amount of low-level moisture present across the region during Event 4 years. An absence of low-level forcing diminished precipitation during Event 4 years.
Bt and Non-Bt corn Hybrids was subjected to drought stress. These hybrids did not differ in their response to moisture stress. Bt plants were affected less than Non-Bt hybrids, thus reflecting higher total plant weight and grain yield. These differences depended on variety.
Impacts
The year-to-year variation in Iowa, Illinois, Indiana, Missouri, and Nebraska in corn yield may be related to the North Pacific Decadal Oscillation. This may be important information for Midwestern corn producers because we are just entering into a new cold NPO phase. This information is used in our outreach program for production decision-making in the Midwest. By providing access to the weather data from the automated weather station network, the general public can be informed and kept abreast with current weather conditions in Iowa. During last July, we averaged 174 hits per day at this web site. The upper air research reflects a sense of cohesiveness in July and August between corn yields, precipitation, and the atmospheric parameters. This in turn affects corn yield variability. Results from this research can be used to infer tendencies in crop yields and precipitation fields over portions of the grain-producing regions of the U.S. based upon the phase of the SOI
and PDO.
Publications
- Traore SB, Carlson RE, Pilcher CD and Rice ME. 2000. Bt and Non-Bt maize growth and development as affected by temperature and drought stress. Agron. J. 92:1027-1035.
- Castleberry PS. 2000. The use of atmospheric parameters to account for warm season precipitation variability across the grain-producing region of the U.S. Ph.D. Dissertation. Iowa State Univ., Ames. 112 pp.
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Progress 01/01/99 to 12/31/99
Outputs
There appears to be significant linkages between El Nino/LaNina and yield corn, and maybe other crops of the Midwest. Generally for all north central states, except for Nebraska, Kansas, and Missouri, El Nino (La Nina) conditions result with above (below) trend corn yields. Classifications are based on the summer values of southern oscillation index (SOI). Outlier years associated with these relationships were examined by regressing preseason district precipitation (Oct through Apr) on relative corn yield (%) for each state after segregating by years as El Nino (n = 27), La Nina (n = 18), or Neutral (n = 54). The correlations within each class were low, but the corn yield response to the weather variable revealed spatially dependent patterns across the region. The western tier of states in this region (Kansas northward to North Dakota) shows a positive response, no matter what the SOI classification was. Under La Nina conditions, the positive response expanded
eastward, but Missouri, Illinois, Indiana, Ohio, and Michigan remained unresponsive to preseason precipitation. Under El Nino conditions, negative responses were noted for all states, except North Dakota, South Dakota, Nebraska, and Kansas. This appears related to the general water needs for corn and the ability of El Nino/La Ninas to provide needed, excess, or deficit levels of precipitation. If more water is provided than needed, the excess may be detrimental to the crop, etc. Partitioning of precipitation amounts by the phase of the SOI has shown that portions of the Midwestern U.S. generally experience an increase (decrease) in warm season precipitation (especially in July and August) during the low (high) phase of an SOI event. However, the interannual variability of SOI events can cloud the precipitation signal. It appears that there may be a coupling of the low (high) phase of SOI events with the high (low) phase of the North Pacific Oscillation (NPO). This partitioning of the
low phase of an SOI event with the high phase of the NPO produced a more robust precipitation signal across regions of the Midwestern U.S. It appears that increased moisture, and lifting provided by temperature advection, divergence, and convergence fields are spatially oriented in the optimal position to increase precipitation amounts during the low phase of the SOI coupled with the high phase of the NPO. The reverse phase of the pattern (high phase of the SOI coupled with the low phase of the NPO) shows decreased precipitation amounts. The results of the two year drought study did not show any significant difference between Bt and non-Bt corn plants in growth, development or water relations. http://pals/agron/iastate.edu/campbell/ was developed to manage and distribute automated Campbell weather data. http://www/agron.iastate.edu/climodat/ provided other climate data.
Impacts
The study of the influence of El Ninos (and its counterpart-La Ninas) in the Equatorial Pacific upon midwestern weather and crop production will help agricultural enterprises to better plan, manage, and market agricultural crops grown in the midwest.
Publications
- Traore, S.B. 1999. Growth and water relations of Bt and non-Bt corn plants subjected to soil moisture stress. Ph.D. Dissertation. Iowa State Univ., Ames. 168 pp.
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Progress 01/01/98 to 12/31/98
Outputs
IMPACTS OF RESEARCH. Previously, we found that El Nino/La Nina (ENSO) was related to monthly temperature and precipitation throughout the year in the Midwest. Additionally, a corn yield signal over the Midwest was identified relative to ENSO variability. Another variable, which combined both temperatures and precipitation was tested. This soil moisture stress index was examined over the 1933-1997 period. La Nina years averaged significantly more stressful than El Nino years. The degree of difference between year types was related to soil moisture levels time during the season. Various atmospheric parameters such as height, temperature, and moisture fields are being analyzed to discern anomalous features across North America. The fields are being segregated by El Nino and La Nina year-type. The motivation is to identify atmospheric features that play a direct role in crop yield variation in the Midwest and other regions across North America. With the help and
cooperation of the High Plains Climate Center in Nebraska, 9-10 automated Campbell weather stations have been in successful operation since 1997. Stem-flow gauge technology is being tested as a means to estimate plant transpiration. The main objective has been to assess how soil moisture stress affects Bt corn yield and resistance to European corn borer. Moisture stress was applied to Bt and non-Bt corn hybrids during the first and second corn borer generations during 1997 and 1998. Leaf temperature, stomatal conductance and sap flow were used as indicators of both moisture stress and corn borer damage. Complete analyses is not completed at this time.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/97 to 12/31/97
Outputs
A homepage providing access to climatological data for Iowa stations was completed. Another homepage is being created to provide access to hourly-specialized weather data from 8 newly placed automated weather stations located at outlying experiment farms. Examination of daily weather data (1900-1996) from 193 weather stations across the north central region revealed an increase in the number of precipitation events for most stations, especialy in the last two decades. Trends of precipitation amounts will be evaluated during the next reporting period. Corn yield variation over the 12 north central states was related to the Southern Oscillation (SO) and sunspots. Significant relative yield differences revealed spatial variation over the region with sunspots showing importance in the southwest half of the region and SO exhibiting impact in the northeastern half of the region. The data were further segregated into corn yields (> 10%, < 10%, and in between relative to
trend). 3-way contingency table analysis of this data showed that when the sunspot numbers were low, negative SO's (< -.8 El Nino) favored positive yield departures and vice versa with positive SO's (> .8 La Nina). With high sunspot numbers, the SO link seemed to vanish. This work is preliminary at this point in time. Bt genetics stability of corn under drought stress continues to be evaluated using specialized facilities.
Impacts
(N/A)
Publications
- CARLSON, R.E. and TODEY, D.P. 1997. A search for average, extremes, and runs of unusual weather in Iowa. Journ. Iowa Acad. Sci.
- CARLSON, R.E. 1997. Aug/Sept. Various cloud images. County Magazine.
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Progress 01/01/96 to 12/30/96
Outputs
A computer program was written to produce standard and specialized climatological summaries of air temperature and precipitation from Iowa daily weather data spanning 1900-1995 (34 stations) and 1951-1995 (99 stations). A homepage is nearing completion which will provide easy assess to this output which includes monthly temperature and precipitation, various growing degree days, heat stress, frost dates, extreme weather events, etc. The input daily weather data are stored on the university computer system and are updated frequently. Analyses of Iowa precipitation records indicate an approximate 10% increase in rainfall in recent decades. The increase is related to more precipitation events in Iowa. Data from each of the 11 other NC-94 member states are being acquired to assess the regionality of this phenomena. This work is just beginning. The first year of field research was completed to determine whether drought stress has an influence on the corn bore protection
provided by Bt genes. Corn was grown in specialized facilities which allow drought imposition. Stem-flow gauges, IR thermometry, and porometers were used to document drought. Plant samples were collected to ascertain protein stability and lethality to insects. Analyses are not complete at this date.
Impacts
(N/A)
Publications
- CARLSON, R. E., TODEY, D.P. and TAYLOR, S.E. 1996. Midwestern corn yields and weather in relation to extremes of the southern oscillation. J. Prod. Agric. 9:347-352.
- KLUBERTANZ, T. H., PEDIGO, L.P. and CARLSON, R.C. 1996. Reliability of yield models of defoliated soybean based on leaf area index versus leaf area removed. J. of Econ. Ent. 89:751-756 KLUBERTANZ, T.
- H., PEDIGO, L.P. and CARLSON, R.E. 1996. Soybean physiology, regrowth, and senescence in response to defoliation. Agron. J. 88:577-582.
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Progress 01/01/95 to 12/30/95
Outputs
Maximum likelihood techniques and highly correlated neighboring stations were used to adjust for inhomogeneities in max and min temperature records, and numerous derived variables for 99 stations spanning the 51-91 period. It worked very well for this spatially dense network. Each significant discontinuity was adjusted. The influence of the SOI (ENSO) on both midwestern corn yields and weather was investigated. Data were coded relative to monthly SOI values. Corn yield variation is controlled by many factors other than SOI, but there is a signal in the yield response. Years with negative SOI values during summer are associated with higher yields than positive SOI years because more rainfall is received and moderate summer temperatures are experienced. The opposite is true for positive SOI years. Similar results were found in IL, IN, and OH. Missouri responded somewhat differently. The differential yield response of corn and soybean was correlated with weekly values of
max and min temperature, precipitation, growing degree days, and heat stress. August weekly precipitation and min. air temperatures were found to significantly affect this relationship by favoring soybean yields. The year 1995 was interesting in that August min. temperatures were near record high levels, whereas max temperatures were only somewhat above normal. Soybeans were observed to yield better than corn relative to expectations in 1995.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Two corn varieties (B73xMo17 and B79xMo17) differing in their sensitivity to drought stress were tested in 1993 and 1994 in the movable weather shelter facility at the Hinds Irrigation Farm. Dry matter distributions from ear components were sampled throughout the ear growth period. Procedures were difficult in 1993 because of abnormal rainfall. In these experiments irrigation treatment differences were noted but varietal differences could not be consistently shown although varietal dry matter distributions differences were evident. Stem-flow gauges were successfully tested relative to plant transpiration measurements. Iowa climate data continues to be collected, digitized, updated and analyzed relative to agricultural production. A 50 mb daily data set for 99 Iowa weather stations on ISU's Vincent computer system is invaluable in this regard. The method of maximum likelihood is being successfully used to adjust the 99 1951-1991 weather data set for inhomogenieties of
maximum and minimum air temperatures. Similarly derived variables which include growing, cooling, and heating degree days, heat stress, and 32F bounded growing season are being adjusted.
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
On behalf of the 12 north central states, Iowa continues to evaluate methodologyto identify and adjust inhomogeneities in weather time series. This must be done before series can be evaluated for statistical trends. A maximum likelihood ratio estimating technique has been examined to accomplish this task. It was tested using Iowa's relatively dense 99 station network over the 1951-1991 time period. This test is important because it assigns statistical significance to discontinuities and allows direct adjustment. Seven weather variables were tested and the following number of stations were found to need adjustment at the 95% confidence level: heat stress (47%), cooling degree days (65%), heating degree days (63%), growing degree days (68%), growing season length (18%), and maximum (68%) and minimum (77%) air temperatures. This technique will be further evaluated across the region. Its success is still determined by the reference data set used for comparison to candidate
weather stations. The reference data set used above was merely a state-wide mean. Additional testing will be done in Iowa using standard interpolation methods for constructing reference data sets, and fewer neighboring weather stations. The daily weather data set stored on the ISU Vincent computer system has been updated through August of 1993. It has been invaluable for the above analysis. It has also been placed on a CDROM with other supporting Iowa weather data sets.
Impacts
(N/A)
Publications
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Progress 01/01/92 to 12/30/92
Outputs
Numerous weather stations (236) from the North Central region were analyzed to assess homogenous maximum and minimum temperature records. Methodology was produced to identify and adjust for air temperature inhomogeneities. Maximum and minimum temperatures required independent analyses. Homogeneous records were rare. In Iowa for 1951-1991, 100 weather stations were also analyzed and compared to station histories. Similar procedures were used to evaluate the influence of air temperature inhomogeneities upon derived weather variables for Iowa weather stations. Significant departures were noted for heating, cooling, and growing degree days, heat and cold stress, and the length of the growing season. The anomalous behavior of an aridity index was examined for Iowa. The index was calculated from monthly maximum air temperatures and precipitation averaged over 27 1900-1992 weather stations. It was highly correlated with both corn and soybean yields in Iowa where tested.
Analysis of variability patterns for this index indicated that variation has increased in the last decade compared to the 60s and 70s, becoming more like earlier times during this century. The monthly index was computed by subtracting standardized precipitation departures for comparable maximum temperature values. Daily weather data for 100 stations covering 1951-1991 were placed on a storage device in the Durham Computer Center with the Vincent system. The intent is to eventually provide easy public access to these data.
Impacts
(N/A)
Publications
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Progress 01/01/91 to 12/30/91
Outputs
Methodologies were developed to detect inhomogeneities in long-term monthly maximum and minimum air temperature records (1900-1990). The procedure utilizes the annual regression of individual stations versus a base data set. The later was produced from state or district-wide grand mean monthly values. These analyses are necessary because many stations exhibit variability produced by no climate factors, including time of observation, location and observer changes, or instrumentation problems. These sources of variation must be accounted for before any meaningful climate analyses can be made. To date, stations from Nebraska, North Dakota, Wisconsin, Illinois, and Iowa have been analyzed. These procedures will be used to analyze long-term data from the remaining north central states. In Iowa, this procedure was also applied to 100 stations for the period from 1951-90. It is significant to note that maximum and minimum temperature records must be analyzed separately.
Presently, identified inhomogeneities in Iowa are being related to existing station histories. Iowa's daily air temperature resources and station histories are being updated digitally for future computer analyses and to supplement the inhomogeneity analyses. Monthly temperature and precipitation data for three Iowa districts were related to "warm" and "cold" tropical Pacific anomalies (El Nino), but consistent patterns were not identified.
Impacts
(N/A)
Publications
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Progress 01/01/90 to 12/30/90
Outputs
Iowa's long-term daily climate data base continues to be updated. CDROM's are being used to extract post-1980 data. Raw daily data are being punched for the period from 1900 until 1950 for 3 stations (Clinton, Decorah, and Grinnell) to fill spatial gaps over Iowa. When completed 27 long-term stations will be available for analysis. Long-term climate analysis continues with the following variables being calculated to date: monthly and seasonal maximum, minimum, and average temperatures, the temperature range, heat stress, aridity indices, the 32 F bounded growing season, and heating degree days. These time series are being analyzed to identify trends or cyclical patterns, and periods of greater or lesser interannual variability. In many cases, statistical significance for the above has been difficult to establish because of year-to-year variation which produces "noisy" data sets. Precipitation is being related to ENSO events in the Equatorial Pacific, but this analysis
is not completed at this time. Soil moisture sampling throughout Iowa continues each fall and spring to maintain this valuable data resource which began in 1954. Cooperative field research with entomologists continues relative to soil moisture stress and simulated leaf feeding by insects in soybeans. In these studies seasonal dry matter sampling and leaf area determinations are being made.
Impacts
(N/A)
Publications
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Progress 01/01/89 to 12/30/89
Outputs
Research on climatological data: A time of observation (TOB) correction procedure has been partially completed using regression procedures to adjust any TOB to the standard 24 hour time for monthly and annual temperatures, growing degree days, and heat stress (accumulation of degrees above 30 degrees C.) Seasonal and annual temperatures for Iowa during 1900-1988 were examined. Multistage regression analysis indicated annual temperature trend changes around 1931 and 1979. Similar analysis of summer temperatures showed trend changes around 1936 and 1960. Winter temperatures had 1 trend change in the thirties, but a large amount of inter-annual variability after 1975 masks recent changes. Spring and fall temperatures showed no trends. The heat stress variable revealed no trends, but the interannual variability changes quite markedly over time revealing both periods of benign and hostile weather. For central Iowa, this heat stress variable was more highly correlated to
corn yield than any other monthly weather variable. It was used in conjunction with July 1 plant-available-soil moisture levels to develop a regression corn yield model. Trends for the length of the growing season and growing degree days are being examined, but considerable noise clouds the identification of possible trends. Various computer technologies are being tested relative to data collection and dissemination.
Impacts
(N/A)
Publications
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Progress 01/01/88 to 12/30/88
Outputs
Work has continued in 3 areas: data acquisition, data utilization, and weather-insect relations. In the first, 2 more Campbell system weather stations have been put in place and are linked with AGNET of Nebraska for use in both research and extension activities. Six such stations are in place throughout Iowa. This provides hourly and daily standard and non-standard weather variables. Also, SUN and DIFAX computer systems are being used to collect and utilize weather data as input for regional meteorology models. Second, long term (1900-1988) patterns of both standard and derived (heat index and growing degree days) weather variables are being analyzed relative to "Greenhouse Effect" ramifications. Most work has been directed to the correction of time of observation bias. This is necessary before true trends may be determined. Last, studies relating plant moisture stress and weather with red spider mite infestations in soybean showed that the fungal infection reduced the
red spider mite population. Proper weather conditions are necessary for the fungal development. In another aspect of insect-weather relationships, trajectory analysis procedures are being used to monitor the movement of insects into Iowa.
Impacts
(N/A)
Publications
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Progress 01/01/87 to 12/30/87
Outputs
The accumulation of maximum temperature over 86F during July and August has beenshown significantly related to corn and soybean yields in Iowa. Long-term trend and variations for this derived weather index are important, and are being examined. This index is affectd by time-of-observation bias. Thus, methods of correction for this bias are being studied to identify significant trends. In field studies, cooperative research between Agronomy and Entomology was initiated in 1987 to determine the relationship between red-spider mite and soil-moisture deficits for soybeans. These pests are a common problem in Iowa during periods of drought. The use of mini-computers and related software for management and dissemination of weather data is being actively investigated.
Impacts
(N/A)
Publications
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Progress 01/01/86 to 12/30/86
Outputs
Iowa phenological and derived weather data have been summarized by district. These nine publications provide the normal, or average, picture of crop development, along with some measure of the variation present over the observation period. Selected climatic parameters are summarized to show their relationship to the stage of crop development. Weather data summaries include growing degree days, monthly and annual precipitation, precipitation tallies by climatological week and amount, occurrence of significant frost dates in the spring and fall, potential and actual evapotranspiration, and soil moisture. Field research dealing with the response of determinate soybeans to limited soil moisture continues. Emphasis is on stress during reproductive stages, and subsequent yields, seed quality and micro-nutrient relationships.
Impacts
(N/A)
Publications
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Progress 01/01/85 to 12/30/85
Outputs
Daily weather data for Iowa on a magnetic tape acquired from Dr. Decker coveringthe period from 1900 until 1978 were updated through 1980. Length of record varies from station to station, but 99 temp and precip stations from 51-80 and 21 temp and precip stations from 00-80 were extracted. Missing temperatures were estimated and corrected, but missing precipitation days have only been listed. In addition, phenological data for Iowa for the period from 1974 until 1984 were acquired from the Iowa Crop Reporting Service and summarized. Both data sets are being merged by district to produce general weather-crop calendar publications. The effect of weather on the differential response of corn and soybeans was studied. August and July temperature and precip variables were shown most important. Green clover worm and black cutworm trap catch data were used to determine the first spring appearance of these pests in central Iowa. Trajectory data were plotted and analyzed
to determine if wind currents could transport the moths northward from overwintering habitats in the southern United States. The proper weather pattern is necessary but not sufficient in itself to produce a migration. A Moth Influx Potential (MIP) system was developed to use atmospheric trajectory forecast data provided by the National Weather Service to estimate the nights of significant migratory black cutworm moth movement into a designated area.
Impacts
(N/A)
Publications
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Progress 01/01/84 to 12/30/84
Outputs
Three-dimensional atmospheric trajectories, along with hourly precipitation and max-min temperatures across the south central U.S. were related to black cutworm moth trap data in Iowa and Illinois. A method was developed to project the spring arrival of these moths into the Midwest. Trajectory analysis was also used to show that synoptic scale wind patterns are important in transporting the migrating moths of the green clover work (Plathypena scabra). Insect trapping data for 1974-84 were used in this analysis. Air temperature, solar radiation, wind speed, relative humidity and pan evaporation data were collected at stations in central, west central and northeastern Iowa on an hourly and daily basis. T1ese data are being used to develop an empirical relation between the measured meteological factors and pan evaporation. Iowa's daily weather records are being consolidated onto magnetic tapes and IBM floppy disks to improve user availability. A program was written
to estimate missing temperature data. Currently 54 stations, 6/district, have been completed for the time period from 1951-1980. We have just begun working with 33 stations which extend back to approximately 1900. Daily max and min averages for 54 stations have been computed.
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Progress 01/01/83 to 12/30/83
Outputs
A computer-based data set is being developed for Iowa's historical weather records. Both the ISU main-frame computer and IBM Displaywriter are being used to set up these data. Existing computer-compatible records are being corrected, updated and missing observations filled in. As a first step the pesent 10 stations on tape are being expanded to 30-40 stations which can be readily accessed for data analysis. Radiation, air temperature, humidity and wind data were collected at three locations (west central, central, northeast Iowa) using Campbell systems. These data are being used to develop equations for estimation of evaporation pan data. Air trajectory data for 1975-1982, less 1976, have been assembled and are being used to develop procedures for predicting green clover worm moth migration and to revise the procedures now used to predict migration of the black cut worm moth.
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Progress 01/01/82 to 12/30/82
Outputs
Data from a Campbell system (Radiation, air temperature, relative humidity, and wind) are being used to estimate Class A evaporation pan data on a daily basis. The past summer one station was operated in central Iowa. Next year we plan on operating additional stations in west central and northeastern Iowa. Data assembled on air trajectories in the central and southern U.S., plus local weather data have been used to relate black cutwork moth catches to meteorological data. Results indicate that early season moth catches can be related to favorable meteorological conditions for development and transport of the moth from southern states. Spring soil temperature data are being examined with the goal of developing a technique by which soil temperatures can be estimated from air temperature and other meteorological parameters. Preliminary planning is underway which will result in a considerable amount of the Iowa climatic records being placed on disc storage to provide
quick access for data analysis.
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Progress 01/01/81 to 12/30/81
Outputs
Preliminary analysis has started on testing techniques for estimating pan evaporation from air temperature and dew point temperature data. Regional evaporation pan data will be edited if a satisfactory techniques can be developed. Preliminary analysis of spring soil temperature data have been started with the goal of developing a technique by which soil temperatures can be estimated from air temperature data, and other meterorological parameters. Data assembled on air trajectories have been used to relate black cutworm moth catches to meteorological conditions. Results indicate that early season moth catches can be related to favorable meteorlogical conditions for development and transport of the moth from selected southern states. Testing of a Campbell data logging system was made under Iowa conditions and procedures developed to provide satisfactory operation under moist conditions. An evaporation pan water-level recorder was also tested and found to operate
satisfactorily with the system.
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Progress 01/01/80 to 12/30/80
Outputs
An evaporation olimatology of Iowa was completed. Class A pan data were used todetermine the evaporation potential. The peak rate occurs in early July and ranges from 6.6 mm/day in EC to 7.4 mm/day in SW Iowa, with a consistent gradient across the state. Actual ET for corn was computed from mid-April through October using the Iowa soil-moisture program. Only a small gradient is present, with total ET ranging from 50 cm in NW Iowa to 55 cm in SE Iowa. Although the atmospheric demand for water is greater in Western Iowa, less available water results in less ET. For the April 15-October 31 period, actual state ET averaged 54 cm, percolation 5.6 cm and runoff at the soil-moisture sites 5.6 cm. Preliminary work is now under way to determine the feasibility of a regional analysis of pan data by weekly intervals. Data are being assembled to determine the effect of weather patterns on migration of the black cutworm moth. The response of corn to irrigation on sandy soils
was determined using the soil-moisture program. Average yield increases ranged from 2200 kg/ha in Western Iowa to 1200 kg/ha in Southeast Iowa.
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Progress 10/01/79 to 12/30/79
Outputs
Data collected on growth and dry matter accumulation of soybeans (irrigated and non-irrigated) at weekly intervals are being used to develop typical growth and development curves for use in physiological and growth models. Developmental work on a soybean moisture-stress-yield model is underway using data from moisture stress experiments on four different cultivars. (Coop Proj.2290). Data for Carlyle, IL, are being used to evaluate the irrigation potential of shallow rooting soils in Illinois. The Iowa soil moisture-stress program is being modified for this study (Coop. Eng. Res. Inst.). Extreme wet and dry periods have been shown to have statistically significant cyclical patterns of about 22 years for the United States. The areas affected by these wet and dry periods typically exceed 20% of the total area of the contiguous United States. Studies have also been indicated which show evidence that the ozone profile in the upper stratosphere is modulated by the
occurrence of interaction regions in the solar wind. The results of this study are expected to provide important clues to the physical mechanisms responsible for the so-called 22 year drought cycle.
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