ALBERT

Description: Seasonal snow cover in South America was examined in this study using passive microwave satellite data from the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-satellite and the Special Sensor Microwave Imagers (SSM/I) on board Defense Meteorological Satellite Program (DMSP) satellites. For the period from 1979-2003, both snow cover extent and snow depth (snow mass) were investigated during coldest months (May-September), primarily in the Patagonia area of Argentina and in Chile. Most of the seasonal snow in South America is in the Patagonia region of Argentina. Since winter temperatures in this region are often above freezing, the coldest winter month was found to be the month having the most extensive snow cover and also usually the month having the deepest snow cover as well. Sharp year-to-year differences were recorded using the passive microwave observations. The average snow cover extent for July, the month with the greatest average snow extent during the 25-year period of record, is 320,700 km(exp 2). In July of 1984, the average monthly snow cover was 701,250 km(exp 2) - the most extensive coverage observed between 1979 and 2003. However, in July of 1989, snow cover extent was only 120 km(exp 2). The 25-year period of record shows a sinusoidal like pattern, though there appears to be no obvious trend in either increasing or decreasing snow extent or snow mass between 1979 and 2003.

Description: Observations from the Microwave Limb Sounder (MLS) on NASA's new Aura satellite give an unprecedentedly detailed picture of the spring Antarctic polar vortex breakup throughout the stratosphere. HCl is a particularly valuable tracer in the lower stratosphere after chlorine deactivation. MLS HCl, N2O, H2O broke up in the upper stratosphere by early October, in the midstratosphere by early November, and in the lower stratosphere by late December. The subvortex broke up just a few days later than the lower stratospheric vortex. Vortex remnants persisted in the midstratosphere through December, but only through early January 2005 in the lower stratosphere. MLS N2O observations show diabatic descent continuing throughout November, with evidence of weak ascent after late October in the lower stratospheric vortex core.

Description: The Earth Observing System Microwave Limb Sounder measures several atmospheric chemical species (OH, HO2, H2O, O3, HCl, ClO, HOCl, BrO, HNO3, N2O, CO, HCN, CH3CN, volcanic SO2), cloud ice, temperature, and geopotential height to improve our understanding of stratospheric ozone chemistry, the interaction of composition and climate, and pollution in the upper troposphere. All measurements are made simultaneously and continuously, during both day and night. The instrument uses heterodyne radiometers that observe thermal emission from the atmospheric limb in broad spectral regions centered near 118, 190, 240, and 640 GHz, and 2.5 THz. It was launched July 15, 2004 on the National Aeronautics and Space Administration's Aura satellite and started full-up science operations on August 13, 2004. An atmospheric limb scan and radiometric calibration for all bands are performed routinely every 25 s. Vertical profiles are retrieved every 165 km along the suborbital track, covering 82 S to 82 N latitudes on each orbit. Instrument performance to date has been excellent; data have been made publicly available; and initial science results have been obtained.

Description: The technical innovations of precise numerical radiometry, spectral differentiation and seasonally repetitive monitoring, introduced by the Landsat series of satellites, created a new measurement approach for terrestrial monitoring. The Landsat 7 mission, successfully initiated on April 15, 1999, reflects significant progress in realizing the scientific potential of this measurement strategy. Substantial improvements in calibration procedures, both prior to launch and during normal operations, have been accomplished to insure long-term stability in the acquired spectral radiometry. For the first time, Landsat 7 will be operated with a long-term data acquisition plan that will insure, barring national emergencies, that substantially cloud-free, seasonal coverage will be recorded and archived in the US for all land areas of the globe. The expected outcome of these efforts is a rapid improvement in our understanding of the Earth system, as well as conceptual knowledge that will underpin commercial application of this technology. The Cape Town 2000 Symposium will take place approximately nine months after the Landsat 7 satellite and instrument completed its engineering checkout phase and was placed in its final orbit in late June, 1999. Thus, this presentation will provide a timely status report, in a significant international setting, regarding the early on-orbit performance of the Landsat 7 spacecraft, the ETM+ instrument, and the long-term data acquisition strategy that has been implemented. The latest data display and visualization techniques will be utilized to present this significant new source of Earth observation data.

Description: Since the launch of Landsat-1 28 years ago, remotely sensed data have been used to map features on the earth's surface. An increasing number of health studies have used remotely sensed data for monitoring, surveillance, or risk mapping, particularly of vector-borne diseases. Nearly all studies used data from Landsat, the French Systeme Pour l'Observation de la Terre, and the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer. New sensor systems are in orbit, or soon to be launched, whose data may prove useful for characterizing and monitoring the spatial and temporal patterns of infectious diseases. Increased computing power and spatial modeling capabilities of geographic information systems could extend the use of remote sensing beyond the research community into operational disease surveillance and control. This article illustrates how remotely sensed data have been used in health applications and assesses earth-observing satellites that could detect and map environmental variables related to the distribution of vector-borne and other diseases.

Description: The human health community has been slow to adopt remote sensing technology for research, surveillance, or control activities. This chapter presents a brief history of the National Aeronautics and Space Administration's experiences in the use of remotely sensed data for health applications, and explores some of the obstacles, both real and perceived, that have slowed the transfer of this technology to the health community. These obstacles include the lack of awareness, which must be overcome through outreach and proper training in remote sensing, and inadequate spatial, spectral and temporal data resolutions, which are being addressed as new sensor systems are launched and currently overlooked (and underutilized) sensors are newly discovered by the health community. A basic training outline is presented, along with general considerations for selecting training candidates. The chapter concludes with a brief discussion of some current and future sensors that show promise for health applications.

Description: A future hyperspectral resolution remote imaging and sounding system, called the GIFTS (Geostationary Imaging Fourier Transform Spectrometer), is described. An airborne system, which produces the type of hyperspectral resolution sounding data to be achieved with the GIFTS, has been flown on high altitude aircraft. Results from simulations and from the airborne measurements are presented to demonstrate the revolutionary remote sounding capabilities to be realized with future satellite hyperspectral remote imaging/sounding systems.

Description: This paper presents the performance and interference criteria for spaceborne active sensors, interference mitigation techniques, and allocation considerations for certain frequency bands for the upcoming WRC 2003.

Description: Land surface models (LSMs) are computer programs, similar to weather and climate prediction models, which simulate the storage and movement of water (including soil moisture, snow, evaporation, and runoff) after it falls to the ground as precipitation. It is not currently possible to measure all of the variables of interest everywhere on Earth with sufficient accuracy. Hence LSMs have been developed to integrate the available information, including satellite observations, using powerful computers, in order to track water storage and redistribution. The maps are used to improve weather forecasts, support water resources and agricultural applications, and study the Earth's water cycle and climate variability. Recently, the models have begun to simulate groundwater storage. In this paper, we compare several possible approaches, and examine the pitfalls associated with trying to estimate aquifer parameters (such as porosity) that are required by the models. We find that explicit representation of groundwater, as opposed to the addition of deeper soil layers, considerably decreases the sensitivity of modeled terrestrial water storage to aquifer parameter choices. We also show that approximate knowledge of parameter values is not sufficient to guarantee realistic model performance: because interaction among parameters is significant, they must be prescribed as a harmonious set.