James F. W. Purdom

Introducing GOES-I: The First of a New Generation of Geostationary Operational Environmental Satellites

Abstract In the spring of 1994, the first of the National Oceanic and Atmospheric Administrations (NOAAs) next generation of geostationary satellites, GOES-I, is scheduled for launch. The introduction of this major component of NOAAs modernization represents a significant advance in geostationary remote sensing. All major components of the GOES-1 system are new or greatly improved: 1) the satellite is earth oriented to improve instrument performance; 2) sounding and imaging operations are now performed by different and separate instruments; 3) a five-band multispectral radiometer with higher spatial resolution improves imaging capabilities; 4) a sounder with higher radiometric sensitivity enables operational temperature and moisture profile retrieval from geostationary altitude for the first time; 5) a different data format is used to retransmit raw data to direct receive users; and 6) a new ground data processing system handles the high data volume and distributes advanced products to a variety of use...

Satellite Analysis of Tropical Cyclones Using the Advanced Microwave Sounding Unit (AMSU)

The first Advanced Microwave Sounding Unit (AMSU) was launched aboard the NOAA-15 satellite on 13 May 1998. The AMSU is well suited for the observation of tropical cyclones because its measurements are not significantly affected by the ice clouds that cover tropical storms. In this paper, the following are presented: 1) upper-tropospheric thermal anomalies in tropical cyclones retrieved from AMSU data, 2) the correlation of maximum temperature anomalies with maximum wind speed and central pressure, 3) winds calculated from the temperature anomaly field, 4) comparison of AMSU data with GOES and AVHRR imagery, and 5) tropical cyclone rainfall potential. The AMSU data appear to offer substantial opportunities for improvement in tropical cyclone analysis and forecasting.

An Interesting Mesoscale Storm-Environment Interaction Observed Just Prior to Changes in Severe Storm Behavior

Abstract Satellite images are presented to illustrate an interesting interaction that occurred between a severe thunderstorm and a mesoscale feature that originated in its nearby environment. Immediately following that interaction, a series of tornadoes began, starting with a long-lived F5 tornado that produced major damage in Hesston, Kansas. Some speculation is presented regarding the physical processes that may have contributed to the observed changes in thunderstorm behavior.

High-Resolution GOES-8 Visible and Infrared Cloud Frequency Composites over Northern Florida during the Summers 1996–99

Abstract GOES-8 visible and infrared cloud frequency composites have been created from imagery collected during June, July, and August for the years 1996–99 over northern Florida. These cloud frequency composites are unique because they offer high-resolution coverage over a small area and have been tailored to address forecast needs. Both monthly and regime cloud frequency composites are presented. Nine regimes were designated to reflect the strength and development of the sea-breeze front under various synoptic winds and the resulting effect on convective development. The regimes were designated by mean boundary layer wind speed and direction over the region of interest. Results from four of the regimes are presented. A total of 222 days (60% of all possible days) were designated for the various wind regimes. Regime 4 (W to SW flow) occurred most frequently (24%) and had the most widespread distribution of higher cloud frequency, occurring both near the coast and inland. Regime 2, with contrasting E to N...

Observing Forest Fires with the GOES-8, 3.9-µm Imaging Channel

Abstract Blackbody radiation at 3.9 µm increases rapidly with temperature. This fact suggests a potential application by fire weather meteorologists of the 3.9-µm imagery data provided by the new GOES-8 weather satellite. The ability of the 3.9-µm channel to sense forest fires is briefly discussed and an example case study is presented. A simple radiation model is used to estimate the minimum detectable fire size for several types of wildfires.

Some Mesoscale Aspects of the 6 June 1990 Limon, Colorado, Tornado Case

Abstract During the late afternoon and early evening of 6 June 1990, a series of severe thunderstorms produced nine tornadoes and numerous incidents of large hail on the High Plains of eastern Colorado. While the morning synoptic data clearly indicated a severe threat over the entire eastern half of the state, the severe activity that did occur was much more localized. Significant events were confined to a relatively small geographical region east and southeast of Denver, Colorado, including the small town of Limon some 70 miles to its southeast. Satellite, radar, surface, and upper-air data are combined in this paper to study some of the mesoscale aspects of the severe storm environment. Results show that thunderstorm outflow from a large mesoscale convective system in Kansas and Nebraska played a crucial role in focusing the severe activity in eastern Colorado. Also, the evolution of convective development during the early part of the day suggested the presence of a sharp moisture gradient along the Fro...

Evolution of Satellite Observations in the United States and Their Use in Meteorology

In his keynote address celebrating the 25th anniversary of the launch of TIROS-1 at the Second International Satellite Direct Broadcast Services Users’ Conference in April 1985, G.O.P. Obasi, secretary-general of the World Meteorological Organization (WMO), remarked: We can marvel at the many significant technological developments which have taken place in meteorological satellites since 1 April 1960 … We need to express our gratitude that the countries now operating meteorological satellites recognized TIROS as only the first step and followed up, through generations of improved satellites, to the current global network. Every day, over 120 countries use information from this network of geostationary and polar-orbiting meteorological satellites. Never before has a technology developed so rapidly to become so essential to so many national weather services. The development of Automatic Picture Transmission (APT) was the prime catalyst in focusing the world’s attention on what satellites could do in improving meteorological services.

Use of VAS data to diagnose the mesoscale environment of convective storms

Abstract The utility of VISSR Atmospheric Sounder (VAS) retrieval datasets for mesoscale analysis is explored. A detailed mesoscale air mass analysis method is presented in which VAS soundings, satellite imagery, and conventional surface data are used to diagnose mesoscale differences in air mass character. Comparisons are made with radiosonde observations of the same air mass differences. A mesoscale air mass analysis is presented with a discussion of the role that the various air masses play in subsequent convective development. In a second technique, several VAS-derived thermodynamic parameters, such as positive and negative buoyant energy, are shown to be well suited to operational forecasting of convective storm development and evolution. The derivation of these parameters and their applications in forecasting are illustrated.

RAMSDIS Contributions to NOAA Satellite Data Utilization

Abstract The Regional and Mesoscale Meteorology (RAMM) Advanced Meteorological Satellite Demonstration and Interpretation System (RAMSDIS) was developed as part of an effort to get high quality digital satellite data to field forecasters prior to the deployment of the satellite component of the National Weather Service (NWS) Modernization Program. RAMSDIS was created by the National Oceanic and Atmospheric Administration (NOAA) National Environmental Satellite, Data and Information Service RAMM Team. RAMSDIS has made significant contributions to NOAAs satellite training and technology transfer program. The project has had a major impact on the utilization of digital satellite data, both nationally and internationally, providing the sole source for high–resolution digital satellite data at some NWS Forecast Offices (FOs) since 1993. In addition to its use in the FO, RAMSDIS has also provided data distribution and research capabilities on a common platform to several NOAA laboratories, allowing for more ef...

Clustering of satellite sounding radiances to enhance mesoscale meteorological retrievals

Abstract Clustering is used to enhance mesoscale meteorological detail in retrievals produced from satellite sounding measurements. By placing sounding fields-of-view (FOVs) into groups of similar measurements, mesoscale details are reinforced, compared to arbitrary grouping of FOVs into a fixed block size. Clustering takes advantage of similarity among the measurements to avoid smearing gradient information. A case study is presented showing the advantage of clustering as applied to the satellite sounding problem.