COOPERATIVE INSTITUTE FOR MESOSCALE METEOROLOGICAL STUDIES (CIMMS)

ACCOMPLISHMENTS DURING CALENDAR YEAR 1998

Peter J. Lamb, Director
Randy A. Peppler, Associate Director

INFRASTRUCTURAL ACCOMPLISHMENTS

• During 1998, CIMMS played a national leadership role for the NOAA Joint Institutes (JIs). This resulted from the CIMMS Director being Chair of the JI Directors for 1998-99, and involved CIMMS hosting a JI Administrators' Meeting (April) and planning two JI Directors' Meetings scheduled for January and April 1999. These activities enhanced CIMMS' familiarity with NOAA's Office of Oceanic and Atmospheric Research and the ten other JIs that extend across the U.S., including in Hawaii and Alaska.

• The high level of CIMMS scientific activity during 1998 continued to involve increased research and development within the National Oceanic and Atmospheric Administration (NOAA) units participating in CIMMS. In particular, much research and development took place within the research themes of (1) Doppler Weather Radar Research and Development and (2) Basic Convective and Mesoscale Research. This research involved collaborations between CIMMS and federal employees at the Environmental Research Laboratories' National Severe Storms Laboratory (NSSL) and the three National Weather Service (NWS) units on the University of Oklahoma (OU) campus (Weather Forecast Office, WFO; WSR-88D Operational Support Facility, OSF; and Storm Prediction Center, SPC).

• Consistent with the above, there has been continued growth in the involvement of CIMMS scientists, engineers, and support personnel in the programs of the NSSL (88 individuals, who now substantially outnumber the Laboratory's 52 federal employees), WSR-88D OSF (10), and SPC (3). This level of activity constitutes a ten-fold increase over five years ago. The resulting infrastructural challenges are being successfully addressed, including through a January 1999 Workshop that was planned in late 1998.

INTERNATIONAL ACTIVITIES

• A high level of collaboration and cooperation occurred between CIMMS and the African Centre of Meteorological Applications for Development (ACMAD, Niamey, Niger) during 1998. These activities are funded by an ongoing grant from the International Activities Office of the U.S. National Weather Service. The 1998 interactions included the following -- extended (4-8 week) visits to CIMMS by two African meteorologists (Professor J. Bayo Omotosho, Federal University of Akure, Nigeria; Mr. Yaya Berte, National Meteorological Service, Ivory Coast); a brief visit to CIMMS by the ACMAD Director (Mr. Mohamed Boulahya); a 9-week visit to ACMAD by a CIMMS graduate student (Mr. Michael A. Bell), where he collaborated with Professor Omotosho; continued full-time research at CIMMS on East African rainfall variability and predictability by Mr. Charles Mutai (Kenya Meteorological Department/Drought Monitoring Centre-Nairobi ) for a University of Nairobi Ph.D. Dissertation; a 4-week visit by Mr. Mutai to Kenya and ACMAD during September for consultations and data acquisition concerning his Ph.D. research, and to present results from that research at ACMAD and two meetings in Mombasa (Climate Outlook Forum for Eastern Africa Short Rainy Season; Fourth Kenya Meteorological Society Workshop); and the visit of the CIMMS Director to the Economic Commission for Africa (Addis Ababa, Ethiopia) to give the lead scientific address to a "Conference on Climate as a Resource for Development" and to participate as a Partner Observer in the "Ninth Session of ACMAD Board of Governors"

• CIMMS scientists participated in several Regional Climate Outlook Forums in West Africa, East Africa, and Southern Africa, and a Training Workshop at ACMAD prior to the West African Forum. This Workshop led to national meteorological services from that region developing seasonal prediction schemes for their countries, using tropical Atlantic and Pacific sea surface temperature predictors. CIMMS scientists also undertook collaborative work with the Drought Monitoring Center-Harare, to develop the first system for verifying the forecast maps from the Regional Climate Outlook Forums. Further, as part of the World Bank funded "Environmental Management Project" in Malawi, CIMMS Senior Scientist M. Neil Ward made two visits to the Malawi Meteorological Service. Reports were written to assist the development of climate information and prediction services for the private and public sectors in that country, including recommendations on the technical infrastructure and training required.

• Collaboration between CIMMS and the Kingdom of Morocco continued to investigate the climate system causation of the interannual-to-decadal variability of Moroccan winter precipitation, and to use the resulting knowledge to develop a seasonal prediction capability. One Meteorological Engineer from the Moroccan Direction de la Météorologie Nationale (DMN) was in residence at CIMMS for most of 1998. The principal DMN-CIMMS collaborative activities were -- the development and issuance of "Experimental Precipitation Predictions for Morocco" for 1997-98 and 1998-99, both of which verified extremely well; the finalizing of a book chapter and scientific paper that summarize the results obtained to date; preparations for the continuation of the project, and associated transfer of the funding responsibility from USAID to the Moroccan government; and presentation of an overview paper on the project to the "ABIDJAN'98: International Conference on Water Resources Variability in Africa during the XXth Century" (Abidjan, Ivory Coast, November 16-19).

• In addition to the above collaborations, CIMMS Scientists are actively working with counterparts at Ben-Gurion University (Israel), the Instituto per lo studio delle Metodologie Geofisiche Ambientali (IMGA, Italy), the National Climate Center and Institute of Atmospheric Physics (P. R. China), the Institute of Atmospheric Physics (Russia), the Queensland Department of Primary Industry (Australia), the Australian Bureau of Meteorology Research Centre, and the Canadian Atmospheric Environmental Service.

NATIONAL FIELD PROGRAM LEADERSHIP

• As part of our Atmospheric Radiation Measurement (ARM) Site Scientist role, CIMMS scientists continue to provide vital day-to-day scientific guidance for the development and continuous operation of the Southern Great Plains ARM Site. This is the World's first comprehensive climate observatory, and now generates ~300 continuous data streams from 30 locations spread over 50,000 square miles in southern Kansas and northern and central Oklahoma. During 1998, the Site Scientist Team continued its increased responsibilities with respect to the quality assurance of the above data streams, and in the planning, execution, and initial analysis phases of several Intensive Observing Periods (IOPs). These activities were facilitated by a new CIMMS Scientist (Chad Bahrmann) being permanently located at the ARM Site's Central Facility (CF) in north-central Oklahoma, where he provides daily scientific guidance for the Site Operations staff. The most notable of the 1998 IOPs was a summer field program that featured experiments in the area of shortwave radiation. CIMMS staff were instrumental in the day-to-day success of this IOP.

• CIMMS scientists also played leadership roles in two major innovations at the ARM CF. First, they installed chilled mirror dewpoint hygometers to provide NIST traceable moisture measurement capabilities. These sensors act as calibration standards for other moisture measurements at the CF and provide a high level of confidence and accuracy. During 1998, CIMMS scientists also provided one of these systems to the University of Wisconsin for use in CAMES-III (Andros Island). Second, CIMMS scientists spearheaded the establishment of a NIST traceable temperature and relative humidity chamber at the ARM CF. This chamber will raise the quality of ARM measurements, including by establishing the absolute accuracy of the Vaisala radiosondes used by ARM and other agencies.

• In collaboration with NSSL and the OU School of Meteorology, CIMMS successfully administered the operations of the Joint Mobile Research Facility (JMRF) during its second year of existence in 1998. The JMRF coordinates the development and deployment of the mobile observing capabilities of those units. This facility is expected to increase the efficiency of field programs at the national and international levels, which will ultimately be reflected in improved forecast skill for severe weather.

• CIMMS scientists participated in the planning and implementation (including forecasting) of the pioneering MCS Electrification and Polarimetric Radar Study (MEaPRS), conducted in central Oklahoma from May 15 through June 15, 1998, and in a subsequent small adjunct field program. The two primary objectives of MEaPRS were (1) to investigate mesoscale convective system (MCS) electrification processes, and (2) improve understanding of polarimetric radar measurements. In the MCS electrification component, investigators participated in the mobile ballooning of instruments to record lightning field changes, particle charge, and X-rays. Electric field profiles and airborne radar data were obtained in two mesoscale convective systems. Electric field profiles and multiparameter radar data were also obtained in several isolated severe thunderstorms. These storms and storm systems included several in which the majority of ground flashes lowered positive charge, instead of the more usual negative charge. Acquiring data on such storms addressed the goals of a NSF grant to CIMMS. In some of the storms, the three-dimensional location of cloud flashes and ground flashes were mapped by a system developed by the New Mexico Institute of Mining and Technology and operated by them in cooperation with NSSL during the field program. These storms will be the subject of considerable research by CIMMS scientists and graduate research assistants during the next few years.

• In the polarization radar component of MEaPRS, emphasis was placed on collecting high quality microphysical data with which to compare polarimetric measurements made by the NSSL Cimarron radar. NOAA P-3 flights were conducted in seven mesoscale precipitation systems to document the microphysical structure of several MCS stratiform clouds. Complementary data sets were also collected using airborne Doppler radar and ground-based polarimetric radar. Over a three-month period that encompassed MEaPRS, a 2D-video-disdrometer (leased from Joanneum Research of Graz, Austria) collected data that documented drop size distributions. Disdrometer data were collected for ten distinct precipitation events. These included both convective and stratiform precipitation and at least one event that contained large hail. These data were collected approximately 41 km from the Cimarron radar. Initial analyses of these data indicate that polarimetric radar-derived rainfall is likely more dependent on drop size distribution than drop shape. CIMMS scientists also documented the performance of the NCEP Eta model during MEaPRS.

• The SubVORTEX-RFD (Rear Flank Downdraft) field program (May-June 1998), which included CIMMS scientists, collected excellent data on eight nontornadic supercells. The primary goal of this field program was to collect data on the RFD and determine the role that it, inflow, and near-ground circulation and divergence play in both tornadogenesis success and failure (i.e., production of tornadic and nontornadic supercells). Data analysis will include comparison with tornadic supercell data obtained during VORTEX.

• CIMMS scientists were involved in the CALJET experiment from January 15-March 30, 1998, conducted from a base in Monterey, California. They included staff operating the radar onboard the NOAA P-3 aircraft. The experiment investigated landfalling low-level jets that strike the western coast of the United States, including using dropwindsonde launches that enhanced forecast model performance significantly during the then ongoing El Niño event.

SCIENTIFIC HONORS, INNOVATION, AND ACTIVITY

• CIMMS Fellow Dr. David Stensrud received the American Meteorological Society's Clarence Leroy Meisinger Award for 1998 in recognition of his innovative research into the structure, dynamics, and predictability of mesoscale convective systems and their impact on larger scales; a graduate level text on The Electrical Nature of Storms (Oxford University Press) was published by CIMMS Resident Fellow Dr. Donald R. MacGorman and CIMMS Fellow Dr. W. David Rust; CIMMS Senior Scientist Dr. Erik N. Rasmussen was honored with a 1998 Presidential Early Career Award for Scientists and Engineers for his planning and direction of the VORTEX Program; CIMMS Fellow Michael D. Eilts received both the NOAA Administrator's Award and a FAA Special Recognition Award in 1998 for his contributions to the operational use of the WSR-88D radar system; and CIMMS Fellow Dr. Richard J. Doviak was elected a Fellow of the American Meteorological Society.

• In addition to the research already mentioned above, the following areas of CIMMS research activity were particularly prominent during 1998:

• use of a Monte-Carlo radiative transfer model linked with the CIMMS Large Eddy Simulation (LES) Explicit Microphysics Model to investigate radiative transfer in heterogeneous cloud media, especially the role of vertical inhomogeneity in determining the extinction coefficient, asymmetry parameter, and scattering functions;

• development of new methods to estimate the surface fluxes of latent and sensible heat from standard energy balance and surface mesonet systems, that overcame the major limitations of the conventional Bowen Ratio and Profile Methods;

• derivation of a set of nonlinear perturbation equations to investigate the balanced and unbalanced dynamics of fronts and frontal circulations, the numerical solution of which revealed how unbalanced perturbations were generated by fronts;

• incorporation and testing of parameterizations of electrical processes into the OU Advanced Regional Prediction System (ARPS) model, so that simulations of electrification can be performed using that model;

• development, testing, and implementation of stratiform cloud physics parameterizations into the ARPS and the U.S. Navy Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS);

• collaborative development (with NCAR and Penn State) of a mass-flux-based parameterization of shallow non-precipitating convective clouds that captures their complete life cycle, and its full integration into the NCAR/Penn State MM5 model where it is compatible with existing parameterizations of deep penetrating convection and non-convective precipitation processes as well as being designed to drive sophisticated air chemistry models;

• assessment of the utility of tornado vortex signatures (TVS) observed by the WSR-88D radars for very short-term tornado detection, which was found to depend on the mode of tornadogenesis (e.g., that within convective lines tends to be associated with non-descending TVSs) and the deleterious effects of radar sampling on TVS representativeness;

• confirmation that the NWS transition from on-site to distance-learning systems for training has not degraded forecast and warning skills, through a collaborative investigation with the OU College of Continuing Education;

• implementation and operation of NCEP's Eta and Regional Spectral Models in a research mode, including experimentation with the Kain-Fritsch convective parameterization in the Eta model that improved its resolution of mesoscale systems;

• development and testing of parameterizations of cloud drop effective radius for use in NWP and GCM models;

• definitive documentation of the effects of tropical Pacific sea surface temperature anomalies on North American precipitation east of the Rocky Mountains, using historical data since 1950;

• completion of a cloud and (using a semi-physical model) solar radiation climatology for the U.S. Great Plains for 1950-92, which identified the most important variability on a range of space- and time-scales;

• further application of phase-coding methods to simulated weather signals to identify the most appropriate scheme for the mitigation of radar range and velocity ambiguities, with the goal of implementation on the WSR-88D; and

• use of a large set of daily raingauge data to document the weather system changes (decreased size and intensity) that have produced the multi-decadal rainfall decrease in Sahelian West Africa since the early 1950s.

• During 1998, the external funding for CIMMS totaled more than $6 million and supported research that was reported in more than 50 refereed journal articles (published or accepted for publication) and many further articles that appeared in conference and workshop Proceedings.