EXECUTIVE SUMMARY

S1. Background

The GEWEX Continental-scale International Project (GCIP) was established in the Mississippi River basin in 1992. GCIP is contributing to the long-term goal of demonstrating skill in predicting changes in water resources on time scales up to seasonal, annual, and interannual as an integral part of the climate prediction system. GCIP research activities occur in a phased timetable and emphasize a particular region with special characteristics for a period of about two years. Four Large Scale Areas (LSAs) have been identified which encompass major river sub-basins of the Mississippi River basin and which, in aggregate, cover most of the GCIP domain, as shown in Figure S-1. The time phasing of activities within each of these areas is also shown in the figure. The GCIP Enhanced Observing Period started on 1 October 1995 and will continue for five years. Although the developmental activities are being initiated in limited regions; a fundamental thrust of the GCIP implementation strategy is that they lead toward an integrated continental-scale capability.

S2. The Large Scale Area - NorthWest (LSA-NW)

The LSA-NW, shown in Figure S-2, encompasses the Missouri River basin which covers an area of more than one-half million square miles. The significant features of the LSA-NW include large year-to-year variability in water cycle components, significant regulation of stream flow through dams, major orographic influences from the Rocky Mountains, relatively small runoff amounts, significant snow measurement problems, including snowmelt timing with regard to water budget components, and the Nebraska Sand Hills as a unique hydrology problem. In addition to the above, the LSA-NW has other noteworthy features which include extensive ground water transport through large aquifers such as the High Plains and Madison aquifers, the topographically-closed potholes of the northern prairie wetlands, and extensive karst topography in both the western and eastern regions of the Missouri River basin; all of which complicate estimates of basin-wide water budgets. As well, it encompasses some of the most extensively irrigated agricultural areas in North America; a feature whose impact on water and energy budgets, and thus climate, is largely unknown. The Missouri River basin also combines several of the features of the other major Mississippi River sub-basins: it has a strong east-west moisture gradient, as in the Arkansas-Red River basin; an extensive snow component in its water budget, as in the Upper Mississippi River watershed; and, extensively managed waterways, as in the Ohio and Tennessee Rivers.

Among the challenges for GCIP relevant research within the LSA-NW is an in-situ observation infrastructure that is less well developed than the other LSAs, particularly in the area of basin-wide surface energy and water vapor flux measurements. This problem must be addressed from three directions. First, improvements must be made to the existing infrastructure, through flux towers or other functionally similar observation strategies. Second, there will be an increased reliance on modeled quantities, which in turn relies heavily on model calibration and validation done in previous LSAs. Finally, observations of surface and atmospheric processes will rely more heavily on remotely sensed data than was the case for the other LSAs.

[LSAs]

Figure S-1. Boundaries for LSAs and temporal emphasis for each LSA from 1994 through 2000.

[LSANW]

FigureS-2. The LSA-NW Encompasses the Missouri River basin.

S3. LSA-NW Implementation

The LSA-NW implementation will follow the GCIP Research Approach set out in the GCIP Implementation Plan published in 1994. The schedule for the two-year Enhanced Annual Observing Period (EAOP) is set to run from 1 April 1999 through 31 March 2001.

The overall research theme for the LSA-NW research activities is:

The Hydrometeorological effects of land cover changes over the annual cycle.
Based on earlier GCIP research results and evidence shown by regional coupled hydrologic- atmospheric models we can safely assert that in the LSA-NW:
Coupled land-atmosphere interactions and terrain effects are significant modulators of the hydroclimate of the Missouri River basin.
The planning for the research activities in the LSA-NW at the Detailed Design workshop held in October 1998 led the participants to recommend the following research hypothesis:
Land-atmosphere interactions and terrain effects can be modeled with sufficient skill to provide useful predictions for hydrologic applications on daily to seasonal time scales.
The LSA-NW implementation is designed to test the validity of this research hypothesis in addition to contributing to the successful achievement of the GCIP science objectives. These research activities are divided into the following three components with their associated research objective:
Land surface and hydrological characteristics: To evolve from a static and coarse resolution representation of the land surface and hydrological characteristics to a more detailed and dynamic landscape characterized by a strong annual cycle with significant spatial and temporal variability.
Coupled hydrologic/atmospheric modeling: To diagnose and skillfully represent the significant regional effects of land/atmosphere interactions on the hydrometeorology and hydroclimate of the Missouri River Basin on spatial and temporal scales relevant for hydrologic applications and water resources .
Hydrometeorological prediction and water resources: To enhance the reliability of precipitation, streamflow and related hydrologic variables that impact the water supply and demand forecasts for water managers in temporal scales up to seasonal. This research objective constitutes a test of the GCIP research hypothesis for the LSA-NW stated above.
A summary of the high priority research plans for each of these three components is given in the next three sections.

S4. Land Surface and Hydrological Characteristics

The land surface and hydrological characteristics within the Missouri River Basin of the LSA-NW are quite variable in both space and time. The land cover and land use conditions are diverse throughout the LSA-NW, for example, including dryland and irrigated crops, rangelands, pastures, natural grasslands, and some forested areas. Agricultural land use can change from year-to-year due to economic, farm management, weather variability, or other factors. Regional land cover and land use patterns are also determined by the east-west precipitation gradient, north-south temperature gradient, and orographic/surface hydrologic effects ranging from mountainous terrain to prairie potholes. Especially in the semi-arid west, there is a strong annual cycle of heterogeneous snow cover during the cold season and seasonally variable vegetation in the warm season. Spatial and temporal variability of snow cover conditions (snow vs no snow) and land cover (percent bare ground vs vegetative cover) is a major determinant of land surface processes throughout the LSA-NW. Year-to-year variations in seasonal and monthly climatic conditions significantly determine this variability of land surface and hydrologic characteristics associated with the beginning, peak, and duration of the growing season.

The LSA-NW provides GCIP with an opportunity to move from static, coarse-resolution representations of the land surface to a more detailed, dynamic landscape characterized by a strong annual cycle with significant spatial and temporal variability. In this context, the three high priority research activities are:

(i)  Incorporation of spatially heterogeneous (~1km) and temporally variable (1-10 days) vegetation and snow cover conditions into the land/hydrology component of coupled models. This research should include:
(a)  Subgrid variability of surface characteristics and processes within 20-30 km model grid cells. Such studies would benefit from calibrated, atmospherically-corrected satellite-derived land surface reflectance and temperature data.

(b) Use of in-situ and high-resolution satellite data (e.g., 30 m Landsat 7) for selected land processes research (e.g., snow sublimation, snow cover heterogeneity, snow patchiness-albedo effects, snow drifting, subgrid fluxes given seasonally variable fractional bare soil-vegetation conditions, etc.). The LSA-NW snow cover and snow melt hydrologic processes are significantly influenced by snow cover patchiness including drifting effects, sublimation, and downslope winds which may differ from snow/cold season hydrologic processes under study in the LSA-NC (upper Mississippi River basin).

(c) Use of 1-km AVHRR (e.g., NDVI) for spatial and interannual vegetation seasonality analysis during 1999 (e.g., irrigated areas), as a step towards the use of potential MODIS land products, if available, during the year 2000.

(ii) Describe and model unique orographic and surface hydrologic processes such as the Sand Hills, prairie potholes and regional exposed aquifier recharge areas.
(iii) Develop a surface net radiation algorithm based on a combination of satellite and in-situ data for model validation and as input to energy budget studies.

S5. Coupled Hydrologic-Atmospheric Modeling

In the context of the GCIP, a coupled atmospheric-hydrologic model is defined to be a model or combination of models which simultaneously represent both atmospheric and hydrological processes, which can operate in predictive mode without the need to specify variables or exchanges at the interface between the two model components, and which can benefit from the assimilation of data to specify that interface.

The implementation of model development in GCIP has followed two paths as described in the GCIP Implementation Plan (IGPO, 1993) and shown in Figure S-3. On the "research" path are the longer term modeling and analysis activities needed to achieve the GCIP coupled modeling Research Goal - To identify and understand the coupled processes that influence predictability at temporal time scales ranging from diurnal to seasonal and spatial scales relevant to water resource applications , and to develop a coupled model which can be validated (at these scales ) using data for the Mississippi River basin.

An "operational" path was started in 1993 to develop and implement the improvements needed in the operational analysis and prediction schemes to produce the model assimilated and forecast output products for GCIP research, especially for energy and water budget studies. The regional mesoscale models also serve to test components of a regional climate model and can provide output for the evaluation of a coupled hydrologic/atmospheric model during the assimilation and early prediction time periods as a precursor to developing and testing a coupled hydrologic/atmospheric climate model. The output from three different regional mesoscale models is routinely compiled as part of the GCIP data set.

The overall research theme for coupled modeling in the LSA-NW region is to diagnose and skillfully represent the significant regional effects of land/atmosphere interactions on the hydrometeorology and hydroclimate of the Missouri River Basin on spatial and temporal scales relevant for hydrologic applications and water resources.

The regional effects include terrain characteristics, soil moisture, snow, land-use, vegetation cover, and other factors relating to the energy balances at the surface, and particularly, the Bowen ratio. The latter represents the partition of sensible and latent heat fluxes at the surface, and is a fundamental aspect needed to correctly represent land surface-atmosphere processes.

[GCIP_stategy]

Figure S-3 Strategy framework for implementing GCIP.

In this context, the following research activities are high priority for the GCIP LSA-NW region:

S5.1 Regional Coupled Models

(i) Conduct coupled model numerical experiments at large-scales to understand the effects of terrain and seasonal evolution of various land-surface forcing components (e.g., snow cover, ground water, irrigation, soil moisture, land-use, vegetation cover, etc.) on mean seasonal and diurnal land-surface/atmosphere interactions.

(ii) Assess and compare the regional performance of the three regional coupled mesoscale models in terms of energy interactions at the surface.

(iii)Investigate orographic precipitation processes during the warm season, including orographic uplift of an airmass over the U.S. Great Plains during large-scale easterly flow conditions.

S5.2 Land/Hydrology Models in Coupled and Uncoupled Models

(i) Develop and validate coupled model subcomponents and macro-scale hydrologic models in both stand-alone and coupled modes with emphasis on improving the precipitation and runoff processes related to spring snow accumulation and snowmelt. This includes the land-surface/hydrology model components that simulate snow accumulation and melt in the LSA-NW.

(ii) Conduct model and diagnostic case studies at Intermediate (ISA <104 km2) and Small Scale Areas (SSA<102 km2) for several anomalous occurrences. This should include studies of the physical processes and extreme events using extensive data collected in these ISA/SSA areas.

(iii)Initiate groundwater modeling studies for the High Plains and/or Madison aquifers. Interactions between surface soil storage and groundwater may be important fractions of the water budget in wetlands and in aquifer recharge zones. This type of study, however, requires consistent groundwater observations.

S6. Hydrometeorological Prediction and Water Resources

One of the eventual aims of the GCIP modeling effort is to generate inputs for operational hydrological and water resources management models over a range of time scales up to interannual. The specific GCIP objective for this area is to improve the utility of hydrologic predictions for water resources management up to seasonal and interannual time scales. The approach will be to link with GCIP coupled modeling and data collection activities to produce more accurate streamflow forecasts, and in turn, to develop methods of utilizing those forecasts for water management purposes.

The Missouri River basin provides an interesting variety of hydrometeorological prediction and water management challenges for the research community. These range from the analysis and prediction of snowpack in the headwaters along the Continental Divide in the high elevations of the Rockies to the High Plains runoff from glacial till and rich fertile soils of the lower basin. Mesoclimates of the Prairie Pothole Region of the Dakotas present challenges for surface runoff and simulation of local ponds and wetland surface energy balance feedbacks that impact regional-scale prediction models. Highly regulated flows in the Missouri River basin provide an opportunity to demonstrate the value of enhanced hydrometeorological forecasting for water resource management. Close partnerships with the end users and GCIP researchers will enable the program to demonstrate practical applications with immediate benefit to such users.

The scientific objective for research applications in hydrometeorological prediction and water resources is to enhance the prediction reliability of precipitation, streamflow and related hydrologic variables that impact the water supply and demand forecasts for water managers in temporal scales up to seasonal. This objective constitutes a test of the GCIP research hypothesis for the LSA-NW. Research to support improved use of short-range to seasonal and interannual predictions for the LSA-NW can be organized into three main activities:

(i) Improved application of coupled model outputs and other forecast products. This would include studies to use a wide range of forecast products as input to hydrologic forecast models as well as related demonstration projects with water resources applications agencies.
(ii) Improved hydrologic forecast models. This would include studies to evaluate present forecast models and to transfer what has been done to develop improved land surface parameterizations for atmospheric models for use in river forecasting.

(iii) Improved representation of precipitation in complex terrain. One of the main limitations in using both forecasts and precipitation observations as input to hydrologic models in the LSA-NW is that area average estimates over complex terrain are generally not very accurate, especially for short computational time steps.

S7. LSA-NW Data Requirements and Enhancements

GCIP research involves a systematic multiscale approach to accommodate physical process studies, model development, data assimilation, diagnostics, and validation topics. Such a multiscale developmental framework for the GCIP effort can provide support for a hierarchy of scales for observational work, algorithm and model development, and validation and diagnostic studies leading to a continental-scale capability. The data requirements for the LSA-NW can be summarized at least qualitatively. The Regional Model Output archive from the three regional mesoscale models will be continued with some enhancements. The Satellite Data Products from the operational satellites will be continued. More emphasis will be placed on the use of satellite data products by including data products from the Earth Observing System and the Landsat 7 which are expected to become available during the second year of the Enhanced Annual Observing Period. The In-Situ data collected is similar in type to that collected for the other LSAs in the Mississippi River basin.

The data requirements assembled at the Detailed Design workshop in October 1998 and supplemented by further analysis of the research activities were assembled into a comprehensive list. This listing provides the basis for the Draft Document entitled " Tactical Data Collection and Management Plan for the LSA-NW Enhanced Annual Observing Period".

S7.1 Focus Study Areas

Within each LSA, there are several intermediate and small scale areas identified as focus study areas for the two year enhanced observing period. The Work Sessions at the GCIP Detailed Design Workshop held in October, 1998 suggested 12 different sites as possible focus study areas.

These sites were analyzed for the suitability of existing infrastructure and their potential contributions to the GCIP research activities planned for the LSA-NW. As a result of this more detailed investigation, it was decided to identify only the Black Hills Region in this Major Activities Plan. Several other sites are being considered in the Missouri River basin and it is likely that one or more of these sites will become GCIP focus study locations.

The Black Hills of South Dakota and Wyoming cover a region of approximately 200 km in north-south extent by 100 km east-west. The Black Hills rise about 1.2 km above the surrounding plains. This region has been the focus of scientific studies by USGS, NASA, and NSF. The observation network in this region include 60 precipitation gages, 60 observational wells, and 70 streamflow gages. NASA is supporting an intensive field observation period in spring 1999, which will provide enhanced observations of atmospheric water vapor and condensate fluxes for water balance studies. This intensive observation period will include a research aircraft, a wind profiler, and a ground-based microwave radiometer (along with the WSR-88D and rawinsonde sites at Rapid City, SD). This intermediate scale area offers the opportunity to study the orographic effects of an isolated mountain range on the precipitation processes and its spatial distribution. Also, it is an excellent test-bed for evaluating the effect of coupled model resolution on precipitation forecasts.

S7.2 GCIP Enhancements for the LSA-NW

The sparsity of in-situ measurements in the LSA-NW is well known and it was recognized during the implementation planning for GCIP in 1992 and 1993 that some actions will be needed to alleviate this problem. Also, the implementation schedule for the Weather Services Modernization put this region at the end of the schedule for installing equipment such as the WSR-88D sites. For these reasons the study of the LSA-NW was scheduled for the end of the five-year Enhanced Observing Period.

At this time GCIP plans to use three approaches to enhance the data available for the LSA-NW:

GCIP can take advantage of the improvements to the current operational satellite remotely sensed data and resulting data products. The current schedules for the launch of the first Earth Observing System (TERRA, formerly EOS-AM1) and the Landsat 7 satellites makes it unlikely that GCIP can expect much data from these satellites before the second year of the EOP.

GCIP has placed a heavy emphasis on archiving of output data from three regional Mesoscale Models during the EOP which started in 1995:
 

These data have provided geographic coverage over the LSA-NW since the beginning and will provide a valuable set of enhanced data for GCIP research. GCIP will continue to archive the data from these same three regional mesoscale models for the remainder of the EOP. A one-year evaluation period for this model output is tentatively scheduled during the second year of the LSA-NW EOP. In addition some of the vertical profiles, identified as Model Location Time Series (MOLTS) are being relocated to the LSA-NW to further enhance the regional model output data available over this region.

The lack of surface flux data in the LSA-NW is particularly noteworthy. GCIP supported the installation of such sites in the LSA-SW and the LSA-NC. Among the recommendations at the LSA-NW Detailed Design workshop was one to install at least two flux sites in the LSA-NW. Specifically, it was recommended that one of the flux sites be collocated with the current Surface Radiation (SURFRAD) site now operating at Ft. Peck, MT. This recommendation is being implemented by GCIP.

The lack of soil moisture measurements is also particularly noteworthy. It was recommended at the LSA-NW Detailed Design Workshop that GCIP take steps to assemble a data set of soil moisture estimates. In particular, GCIP needs to extend the soil moisture data and analyses now ongoing in the Oklahoma region to the LSA-NW. GCIP plans to respond to the requirements for soil moisture information through a combination of approaches:

i) The Data Collection and Management (DACOM) will inventory and compile the data from all the available soil moisture measurement sites in the LSA-NW. The inventory is expected to identify less than 10 locations where such data will be available for the LSA-NW Enhanced Annual Observing Period.

ii) GCIP is currently supporting work in NCEP to develop and implement a Land Data Assimilation System (LDAS) as an off-line operation to provide inputs such as soil moisture to the Eta Model. When the LDAS is implemented as an operation in NCEP, DACOM will include these soil moisture data as part of the model output data archived from the Eta regional mesoscale model.

iii) GCIP will take steps to facilitate the analysis of soil moisture over the annual cycle across a range of latitudes by implementing enhancements to a North-South Transect along 96 degrees West longitude. A Soil Water and Temperature Transect along this longitude (SOWATT-96W) was started in 1996 which runs from Prairie View, TX (30N latitude) to Bemidji, MN (~47N latitude). The data collection from this Transect is currently on hold awaiting the calibration of the soil moisture data obtained from locations in the Oklahoma "Moistnet" network (ARM/CART site, Little Washita Micronet and Oklahoma Mesonet). It is planned to enhance the SOWATT-96W Transect by placing MOLTS locations for regional model output at key locations along the Transect.

S8. Data Collection and Management

The GCIP Data Management and Service System (DMSS) implementation strategy makes maximum use of existing data centers which are made an integral part of the GCIP-DMSS through data source modules that specialize by data types (i.e., in situ, model output, and satellite remote sensing). The intent of GCIP researchers to rely as much as possible on existing data centers as the archive location of GCIP data means that data sets will be geographically distributed among these data centers. The GCIP-DMSS is compiling a centralized set of information on the data sets. In some cases, this set consists of a directory and inventory of the data set, and in other cases it consists of only directory information with the inventory information available from the data center where the data set is stored. A tactical data collection and management plan is prepared for each definable data set compiled by the Project. This plan is converted to a data summary report when the compiled data set is completed.

The plan for compiling the LSA-NW EAOP data set are described in a draft document entitled "Tactical Data Collection and Management Plan for the LSA-NW Enhanced Annual Observing Period".

The Enhanced Annual Observing Period for the LSA-NW begins on 1 April 1999 and runs through 31 March 2001. This schedule spreads the observing period across three Water Years. (A Water Year in the USA includes the period from 1 October through 30 September the following year). Some of the GCIP data sets, such as the streamflow data are archived on a Water Year basis. A nominal schedule for completing the streamflow data processing is about nine months after the end of a Water Year. Given this schedule for data availability, the three components of the two-year Enhanced Annual Observing Period for the LSA-NW are projected to be available as follows:
 
 

Period                                                               GCIP Data Set Available

1 April - 30 September 1999                                      July 2000
1 October 1999 - 30 September 2000                        July 2001
1 October 2000 - 31 March 2001                               July 2002

It should be noted that these are the projected dates for the temporal component of the two-year data set to be completed. However, portions of the component data set will become available earlier than the projected completion dates shown above. Information on such data availability can be obtained through the GCIP Home Page (Data Access) at the URL address:
http://www.ogp.noaa.gov/gcip/#data.