Hanging Rock

Spring 2001

NCSU Seal North Carolina ClimateSCO Seal

A Newsletter of the State Climate Office of North Carolina

A Public Service Center for
Climate-Environment Interactions

Volume 5 | Number 1 | Spring 2001

In This Issue...

A Message from Dr. Richard Patty

Interim Head, Department of Marine, Earth, and Atmospheric Sciences

Richard Patty It is a pleasure to provide a comment on the State Climate Office since this unique facility contributes significantly to the vitality of our department and university, provides so much valuable information to state agencies, and responds effectively to many inquiries. Under the direction of Professor Sethu Raman, this office has evolved into a major educational resource for our students and now stands as an excellent example of a successful interdisciplinary activity demonstrating the value of collaborative projects involving not only different departments and colleges but also an array of state agencies. Indeed it is this collaborative work, principally between the College of Physical and Mathematical Sciences and the College of Agriculture and Life Sciences, that has allowed the SCO to evolve into a major asset for the university and for the state.

I believe it is particularly significant that Professor Raman combines an intimate involvement in teaching and research with his activities as director of the State Climate Office. His expertise in this combination of teaching, research and service provides a unique perspective which allows him to guide his students to the selection of meaningful projects. There are always undergraduates associated with the SCO who routinely present their work at the NC State Undergraduate Research Symposium where their presentations are polished and their research results always address significant problems. Indeed, this research experience is one of the most valuable aspects of our undergraduate curriculum. The State Climate Office not only encourages the participation of undergraduates but also is the source of meaningful dissertation topics for graduate students; within the past year three students have received M.S. degrees and one has received Ph.D. degree. Two of these recipients have been associated with the SCO for some time, and I am very pleased that they plan to continue this association; Ryan Boyles received his M.S. degree and has now been appointed Associate State Climatologist, and Devdutta Niyogi received his Ph.D. degree and is now appointed as a Research Assistant Professor in the Department of Marine, Earth and Atmospheric Sciences where he will continue his direction of the NC AgNet program. Retaining their expertise ensures the continuation of the excellent programs for which the SCO is known.

The State Climate Office was established as a "Public Service Center" in 1998, and the importance of the service aspect of the office cannot be overemphasized; this is its reason to be. It provides service to the citizens of North Carolina, and the quality of this service is enhanced by the academic activities mentioned above. NC ECONet involves the installation of stations that will gather weather and climate data that is transmitted to the State Climate Office for distribution to state agencies, farmers and companies. A station located in each of our 100 counties is envisioned, and twenty-four stations have been installed at this time. The NC AgNet program also provides important atmospheric information to farmers, and it is significant that real-time data was provided to the NC Division of Emergency Management during Hurricanes Dennis, Floyd and Irene. Although these are the major service activities, the outreach activities of the SCO cannot be neglected. The office receives many visitors throughout the year, and the staff visits local schools and museums to give presentations associated with weather and climate; and, numerous presentations to explain ECONet have been given throughout the state.

The opportunity for our students to participate in the programs of the State Climate Office greatly enhances their academic programs, and conversely our students contribute significantly to the vitality of this office. It is a very healthy interaction which ensures a bright future for the SCO.

Richard R. Patty
Interim Head, Department of Marine, Earth and Atmospheric Sciences

From the State Climatologist...

Sethu Raman Much has happened climate-wise since the last newsletter. We had a relatively hurricane free summer and the drought in western NC has eased by late fall.

It has been a great pleasure to work with our new Dean of the College of Physical and Mathematical Sciences, Dr. Dan Solomon. He has been very supportive of our initiatives. The SCO had its annual advisory committee meeting on Nov 11, 2000. The present advisory committee is chaired by Steve Harned, National Weather Service and consists of Katharine Perry, College of Agricultural and Life Sciences, Richard Patty, Department of Marine, Earth, and Atmospheric Sciences, and Karen Siderelis, USGS. During the past year we have increased our activities in Extension, Research, and Education aspects of the SCO.

Extension activities included improved data services, collaboration with several state agencies such as NC Emergency Management Division, Division of Air Quality, and Drought Monitoring Council. Automated weather network in North Carolina is expanding with the addition of 5 DAQ sponsored sites and one site in Aurora funded by North Carolina Emergency Management Division. These are in addition to 18 AgNet sites. They have increased data coverage across NC and efforts are under way to archive the NWS ASOS data in real time.

Intern programs involving undergraduate and graduate students are continuing. Six undergraduates and five graduate students participated in the past year. There has been significant improvement in data services during the past year and in the development of a client database. The undergraduate interns in the SCO are: Wendy Sellers, Kettyah Chhak, Peter Childs, Kibri Hutchinson, Aaron Pratt, and Robb Ellis. Jennifer Kehoe completed her thesis on NC hurricanes and graduated in December 2000. I am also glad to announce that Dev Niyogi graduated with a Ph.D degree and Ryan Boyles graduated with a M.S. degree in December 2000. They continue to work with the State Climate Office in its extension activities. Research on hurricanes and tornadoes that affect North Carolina is continuing. Also, the SCO recently concluded a study on the climate change in North Carolina. SCO plans to cooperate with the NWS in the area of climate services / climate forecasts in future. The SCO is keeping a close watch on the evolving Pacific Decadal Oscillation (PDO) and its effect on NC climate. There has been a tendency for negative PDO index over the past two years. If this trend continues, regions in North Carolina can be affected by extreme climatic conditions. A study on this topic is in progress at the SCO.

At the service of North Carolina,

Sethu Raman's Signature
Sethu Raman
State Climatologist of North Carolina
Professor of Atmospheric and Marine Sciences

Ground Hog Day Enjoyed Across North Carolina

Ground Hog On February 2nd, students from across North Carolina participated in Ground Hog Day activities with the NC Museum of Natural Sciences. The program culminated with Sir Water Wally, the official NC ground hog, telling Governor Easley that he did not see his shadow and that spring was on its way. Governor Easley announced this to hundreds of cheering children outside the Museum of Natural Sciences in Raleigh.

As part of the program, K-12 classes from all corners of the state took basic weather observations in the morning, including information on winds, cloud cover, and of course whether or not a ground hog would see its shadow. Students then sent their observation in via fax and the Internet. All observations were compiled to create a weather map for North Carolina.

The weather on February 2, 2001 was generally cool and wet, with a cold front moving across the state. In the far western part of the state, skies had cleared and students reported sunny conditions. Clouds were generally reported across the piedmont, and rain was reported along the coastal plain. This scenario provided an excellent learning situation, allowing students to see actual observations of how weather changes over space and time.

This is the second year the State Climate Office has participated in this annual event. Climate Office staff helped to prepare the weather observation forms, compile observations, and prepare the map for the activities. Additionally, the State Climate Office will keep a watch on the temperatures across North Carolina for the next six weeks to see if Sir Walter Wally's forecast is verified. Thanks to Carolina Biological Supply, UNC Department of Geography, and the Museum of Natural Sciences for helping make this annual activity such a huge success!

More information on the Ground Hog Day activities is available on the Museum of Natural Sciences web site: http://www.naturalsciences.org/education/groundhog/

Analysis of Climate Patterns and Trends in North Carolina (1949 - 1998)
by Ryan Boyles

North Carolina has one of the most complex climates in the United States, and analysis of the climate in this state is critical for agricultural and planning purposes. In this investigation, climate patterns and trends in North Carolina are analyzed for the period 1949–1998. Using data collected from the National Weather Service Cooperative Observer Network, precipitation, minimum temperature, and maximum temperature are analyzed on seasonal and annual time scales. Additionally, changes in patterns of the occurrence of the last spring freeze and first fall freeze are investigated. Linear time series slopes and ten-year anomalies are analyzed to investigate the spatial and temporal trends of climate variability in North Carolina. Spatial analysis of climate variability across North Carolina is performed using a geographic information system.

While most trends are local in nature, there are some general statewide patterns. Precipitation in North Carolina has increased over the past 50 years during the fall and winter seasons, but decreased during the summer. Temperatures during the last ten years are warmer than average, but are not warmer than those experienced during the 1950s. The warm season has become longer, as measured by the dates of the last spring freeze and first fall freeze. Generally, the last ten were the warmest and wettest of the study period.

These conclusions are consistent with those by other investigators that show that the difference between the maximum and minimum temperatures is decreasing, possibly due to increased cloud cover and precipitation. These results also show that temperature patterns are in phase with the North Atlantic Oscillation and precipitation patterns are correlated with the Pacific Decadal Oscillation. This study was part of a M.S. thesis submitted to NCSU in Fall 2000.

Details on this research is available on our website under EDUCATION AND RESEARCH.

Climatology of North Carolina Hurricanes

A climatology of hurricanes that affected NC over the past 100 years was studied. Since about 1970, there appears to be an increase in the number of hurricanes in the North Atlantic Ocean and Gulf of Mexico. The study also showed an increasing trend in the number of hurricanes that made landfall over North Carolina or passed through NC as a tropical storm after making landfall elsewhere. Another objective of this study was to analyze surface soil moisture conditions to determine if circulations associated with soil moisture gradients could have been a factor in the post-landfall intensification of Hurricanes Fran (1996) and Danny (1997). In this study, structural changes in these two hurricanes that made landfall in NC were investigated. These two case studies show that, in the presence of soil moisture gradients, circulations can develop where air flows from wetter, cooler regions toward warmer, drier regions and enhance the vertical motion over drier regions.

These two case studies show that, in the presence of soil moisture gradients, circulations can develop where air flows from the wetter, cooler regions toward warmer drier regions and enhanced vertical motion over the drier regions. To determine if circulations associated with soil moisture distribution could have influenced the development of the convective cells associated with Hurricanes Fran and Danny, a model to estimate soil moisture was developed and tested. Model tests indicate that the model-estimated soil moisture values are reasonably representative of observed conditions.

Using the model developed in this study, plots of estimated soil moisture were generated for the region of the convective cell development. Model results indicate that the heaviest rainfall was located in areas where soil moisture gradients were present, and that the gradients were stronger prior to the convective development associated with Hurricane Fran than for Danny. This study was part of a M.S. thesis submitted to NCSU by Jennifer Kehoe in Fall 2000.

Enhancement of NC Agricultural Automated Weather Network and Development of Advanced Communication, Data Aquisition, and Dissemination Systems

Ameen Syed at Fletcher Station The AgNet is a weather network, which collects surface and subsurface meteorological data in North Carolina. Each AgNet weather station measures a variety of weather parameters such as air temperature, relative humidity, wind speed and direction, barometric pressure, solar radiation, photosynthetically active radiation, soil temperature, soil moisture and precipitation. The station summarizes the above parameters for every hour and stores them in its local memory. Currently the data collected over the entire day are then transferred to a central server through phone lines. The data collected at the central server are published on the Internet and disseminated by other means as well. Modernization of the AgNet weather network was accomplished over the last two years by making the network conform to standards, implementing a uniform sensor configuration and improving the methods of data acquisition, dissemination and display of weather data.

Since phone-based communication is not economical for real time data transfers other techniques such as Radio Frequency (RF) communication and satellite-based communication were evaluated. RF communication was the most promising communication technique. Since RF is limited by distance, a prototype combination of RF and Internet was designed. In this type of communication, data are transmitted from the weather station and received by a base station that is on the Internet. The received data are then forwarded to a central server at the State Climate Office where they are archived and disseminated. A successful test was conducted as proof of concept between Lake Wheeler road Field laboratory site, Raleigh and Varsity Laboratory, NC State University.

Since every system has inherent noise, data collected at each station have to go through different quality control algorithms to insure data quality. Different Quality Control (QC) algorithms were implemented. This report is part of a M.S. thesis submitted to NCSU by Vinayak Parameshwara in Summer 2000.

Details of this investigation are available on our website under EDUCATION AND RESEARCH.

Biosphere-Atmosphere Interactions Coupled with Carbon Dioxide and Soil Moisture Changes
by Devdutta S. Niyogi

Objectives of this research are to analyze coupled biosphere-atmosphere interactions with changes in soil moisture, CO2 availability and related environmental conditions. For this, a CO2 based Gas exchange Evapotranspiration Model (called GEM), with explicit photosynthesis based vegetation and soil moisture effects was developed. GEM was coupled to a prognostic hydrometeorological scheme, and a detailed PBL / atmospheric model. The coupled biosphere model (GEM) was validated through 11 different case studies with contrasting micrometeorological field conditions.

A statistical-dynamical study was performed using observations from a semi-arid tropical (HAPEX-Sahel), and a mid-latitudinal (FIFE) field experiment and simulated results from a land surface model: 'Simple SiB'. For the two cases, direct effects are similar, while higher order interactions are different. Also, for the water-stressed semi-arid tropical case, there was relatively very little interaction between the vegetation and the soil variables, suggesting instead of the 'effective surface' flux representation, the water-stressed arid tropical region will require explicit soil and vegetation flux estimation.

The effect of adopting photosynthesis-based vegetation schemes such as GEM in place of the traditional Jarvis-scheme in land surface models was also addressed. It appears uncertainties would be reduced with the use of the photosynthesis scheme as compared to the diagnostic Jarvis-type approach.

Additionally, it is shown that deposition velocities could be efficiently estimated for different gases (such as ozone, and nitrogen compounds) using a photosynthesis-based vegetation scheme. Another hypothesis tested the role of direct and interactive exchanges of the CO2 and soil moisture changes on transpiration, stomatal resistance, photosynthesis, and air temperature for different global biomes. Finally, a concept of differential vegetation characteristics (DVC) based sub-grid scale (SGS) heterogeneity was proposed, taking as an example co-existing C3 grasses and shrubs and C4 grass over a natural landscape. The errors were largest for biophysical variables such as photosynthesis, and transpiration, particularly for limiting resource conditions than for the doubling of CO2 scenarios. To address the issue of developing grid-averaged values under DVC-SGS, empirical relations were proposed for photosynthesis-based effects in the biosphere-atmosphere interactions for varying environmental conditions. This report summarizes a Ph.D. dissertation submitted to NCSU in Fall 2000.

Recent Precipitation and Temperature Conditions

Click on a map to view a larger image

Departure from 30-year average

Summer 2002 Precipitation Departures from Normal
Summer 2002

Autumn 2002 Precipitation Departures from Normal
Autumn 2002
Departure from 30-year average

Summer 2002 Temperature Departures from Normal
Summer 2002

Autumn 2002 Temperature Departures from Normal
Autumn 2002

Drought Outlook

Seasonal Drought Outlook

Outlook provided by the NOAA Climate Prediction Center ( http://www.cpc.noaa.gov )

Recent Activities

  • 50th N.C. Agriculture Research Station Annual Meeting, Morehead City, July 19-20, 2000
  • State Extension Advisory Council, August 24, 2000, Raleigh
  • Lecture to visiting Chinese Delegation, August 31, 2000, Raleigh
  • NC Emergency Management Hurricane Conference, October 30-31, 2000, McKimmon Center, NC State University, Raleigh
  • 2000 American Institute of Hydrologists International Conference, November 5-8, 2000, Research Triangle Park
  • Presentation to NC Geographic Information Coordinating Council, December 13, 2000, Raleigh
  • Presentation on Climate Change to Air & Waste Management Association, January 16, 20001, Research Triangle Park
  • Ground Hog Day Celebration, NC Museum of Natural Sciences, February 2, 2001, Raleigh
  • Post Storm Working Group Assessment Meeting, February 6, 2001
  • NC Flood Warning Working Group Meeting, February 13, 2001
  • NC Cooperating Technical State (CTS) Meeting, February 13, 2001
  • Presentation on Climate Change at Future Directions in Air Quality Research Conference, February 13, 2001, Research Triangle Park

« Back to Newsletters