Paul Pellegrino

Monitoring the Mt. Pinatubo aerosol layer with NOAA/11 AVHRR data

The NOAA/NESDIS operational aerosol optical thickness product has provided an exceptional view of the development of the Mt. Pinatubo stratospheric aerosol layer. The product is derived from reflected solar radiation measurements of the Advanced Very High Resolution Radiometer onboard the NOAA/11 polar orbiting environmental satellite. The greater the optical thickness, the greater the amount of reflected solar radiation. Daily and weekly composites of aerosol optical thickness (AOT) at a wavelength of 0.5 micrometers have been analyzed to monitor the spatial and temporal variability of the aerosol layer and its optical thickness since the major eruption of Mt. Pinatubo on June 15, 1991. These analyses show that: the volcanic aerosol layer circled the Earth in 21 days; there are inhomogeneities in the layer that seem to remain after over two months of circling the Earth; using an AOT of 0.1 to define the layer, it covered about 42% of the Earths surface area after two months, over twice the area covered by the El Chichon aerosol layer two months after its eruption; the layer is confined to the latitude zone 20S to 30N, with occasional patches seen at somewhat higher latitudes; the largest mean optical thickness of the layer was 0.31, occurring on August 23rd; the mass of SO2 required to produce this aerosol optical thickness is 13.6 megatons; and, the globally averaged net radiation at the top of the atmosphere may be reduced by about 2.5 Wm−2 (cooling effect of at least 0.5°C) once the aerosol is distributed globally over the next two to four years.

Global distribution of cloud cover derived from NOAA/AVHRR operational satellite data

Abstract NOAA/NESDIS is developing an algorithm for the remote sensing of global cloud cover using multi-spectral radiance measurements from the Advanced Very High Resolution Radiometer (AVHRR) on-board NOAA polar orbiting satellites. The current (Phase 1) algorithm uses a sequence of “universal” threshold tests to classify all 2×2 pixel arrays of GAC (4 km) observations into clear, mixed and cloudy categories. A subsequent version of the algorithm (Phase II) will analyze the previous 9-day series of mapped ( 1 2 degree) “clear” array data to replace the “universal” thresholds with space and time specific values. This will provide more accurate estimates of cloud amount for each pixel. The current algorithm is being implemented into the operational data processing stream for testing and evaluation of experimental products. Eventually, it is intended for use operationally to support weather and climate diagnosis and forecasting programs, as well as to provide clear sky radiance data sets for other remote sensing parameters, e.g., vegetation index, aerosol optical thickness, and sea surface temperature.

NOAA operational hydrological products derived from the advanced microwave sounding unit

With the launch of the NOAA-15 satellite in May 1998, a new generation of passive microwave sounders was initiated. The Advanced Microwave Sounding Unit (AMSU), with 20 channels spanning the frequency range from 23-183 GHz, offers enhanced temperature and moisture sounding capability well beyond its predecessor, the Microwave Sounding Unit (MSU). In addition, by utilizing a number of window channels on the AMSU, the National Oceanic and Atmospheric Administration (NOAA) expanded the capability of the AMSU beyond this original purpose and developed a new suite of products that are generated through the Microwave Surface and Precipitation Products System (MSPPS). This includes precipitation rate, total precipitable water, land surface emissivity, and snow cover. Details on the current status of the retrieval algorithms (as of September 2004) are presented. These products are complimentary to similar products obtained from the Defense Meteorological Satellite Program Special Sensor Microwave/Imager (SSMI) and the Earth Observing Aqua Advanced Microwave Scanning Radiometer (AMSR-E). Due to the close orbital equatorial crossing time between NOAA-16 and the Aqua satellites, comparisons between several of the MSPPS products are made with AMSR-E. Finally, several application examples are presented that demonstrate their importance to weather forecasting and analysis, and climate monitoring.

The Nimbus-7 Global Cloud Climatology

A total of six years (April 1979 to March 1985) of continuous measurements from the Temperature Humidity Infrared Radiometer (THIR) and the Total Ozone Mapping Spectrometer (TOMS), both on the Nimbus-7 satellite, have been processed to form the Nimbus-7 Global Cloud Climatology (N7GCC). The cloud-estimation algorithms utilize THIR “11.5-micron” radiances, TOMS-derived “0.37-micron” reflectivities, climatological temperature lapse rates and concurrent surface temperatures, and snow-ice information. (The last two items are taken from the Air Force three-dimensional nephanalysis archive.) This cloud climatology gives, near local noon and midnight, the fractional area covered by high-level clouds middle-level clouds and low-altitude clouds, and the total fractional area covered by all clouds (total cloud). Statistics are also given for the special cloud types: cirrus, deep convective, and warm low-altitude clouds. The cloud and clear-sky radiances, together with correlative surface temperatures, are included....

The Tropical Rainfall Potential (TRaP) Technique. Part II: Validation

Abstract Satellite analysts at the Satellite Services Division (SSD) of the National Environmental, Satellite, Data, and Information Service (NESDIS) routinely generate 24-h rainfall potential for all tropical systems that are expected to make landfall within 24 to at most 36 h and are of tropical storm or greater strength (>65 km h−1). These estimates, known as the tropical rainfall potential (TRaP), are generated in an objective manner by taking instantaneous rainfall estimates from passive microwave sensors, advecting this rainfall pattern along the predicted storm track, and accumulating rainfall over the next 24 h. In this study, the TRaPs generated by SSD during the 2002 Atlantic hurricane season have been validated using National Centers for Environmental Prediction (NCEP) stage IV hourly rainfall estimates. An objective validation package was used to generate common statistics such as correlation, bias, root-mean-square error, etc. It was found that by changing the minimum rain-rate threshold, the...

The Improved AMSU Rain-Rate Algorithm and Its Evaluation for a Cool Season Event in the Western United States

Abstract Rain-rate retrievals from passive microwave sensors are useful for a number of applications related to weather forecasting. For example, in the United States, such estimates are useful for offshore rainfall systems approaching land and in regions where the Weather Surveillance Radar-1988 Doppler (WSR-88D) network is inadequate. Improvements have been made to the rain-rate retrieval from the Advanced Microwave Sounding Unit (AMSU) on board the National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POESs). The new features of the improved rain-rate algorithm include a two-stream correction of the satellite brightness temperatures at 89 and 150 GHz, cloud- and rain-type classification for better retrieval of rain rate, and removal of the two ad hoc thresholds in the ice water path (IWP) and effective diameter (De) retrieval where the scattering signals are very small. In this paper, the new algorithm has been compared to the previous NOAA operational algorith...

NOAA satellite‐derived hydrological products prove their worth

Satellite observations are particularly important for monitoring the global changes of atmospheric and surface features. For many parameters, satellite measurements are the only means of obtaining this information, particularly over the oceans and sparsely-populated land areas. For example, multi-spectral measurements from both geostationary and polar-orbiting satellites are key components of the Global Precipitation Climatology Project (GPCP) [Huffman et al., 1996], which has measured global rainfall for over 20 years. In addition, the longstanding National Oceanic and Atmospheric Administration (NOAA)-based Northern Hemispheric snow cover climatology has relied almost solely on satellite observations that are interpreted by satellite analysts [Robinson et al., 1993].

Synoptic-Scale Studies Using the Nimbus 6 Scanning Microwave Spectrometer

Abstract Several frontal systems over Europe in August 1975 and January and February 1976 are examined using scanning microwave spectrometer (SCAMS) data. Comparisons are made with thermal fields constructed from radiosonde temperatures. Because of the cloud penetrating property of microwave radiation, together with the high stability and sensitivity of the SCAMS instrument, many of the problems encountered with infrared remote sensing instruments are absent in the SCAMS measurements. Synoptic-scale features displayed by the SCAMS retrievals are comparable with radiosonde temperature analysts under both clear and cloudy conditions. Results from the synoptic-scale studies, confirm the theoretical expectations of standard error, which are 2.2, 2.3, 2.9 and 3.6 K at the 700, 500, 300 and 100 mb levels, respectively. These SCAMS results were obtained using “theoretical” temperature retrieval coefficients, which are based on the simulated SCAMS response to a historical sample of independent temperature statist...

Monitoring global surface temperature variations using cloud data sets

Abstract One of the by-products of cloud data sets such as that of the International Satellite Cloud Climatology Project (ISCCP) is global information on longwave window brightness temperatures for clear skies. These brightness temperatures depend mainly on the actual surface temperature with only a slight dependence on atmospheric water vapor. Thus, it may be possible to monitor long-term temperature variations using such data. The current methods for such monitoring depend on conventional surface observations and are subject to uncertainties due to inadequate spatial sampling. To test this idea monthly clear sky brightness temperatures from the six-year Nimbus-7 cloud data set are analyzed and compared to conventional estimates of surface temperature fluctuations.