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This paper summarizes recent studies of a variety of atmospheric phenomena in different parts of the world using the Penn State/NCAR mesoscale model. These phenomena include explosive cyclogenesis over the North Pacific and North Atlantic oceans, cyclogenesis over Europe and associated ozone transport during the ALPEX experiment, heavy rainfall and flash flood events over Pennsylvania and China, “Plateau” and “Southwest” vortices over China, severe storms over the United States, mesoscale convective complexes, elevated mixed layers and “lids,” an Australian Southerly Buster, low-level damming of cold air to the east of the United States Appalachian Mountains in winter, urban heat island effects, and regional acid deposition. This paper also reviews Observing System Simulation experiments (OSSEs), several sensitivity studies, the nesting of the mesoscale model in a global climate model for regional climate studies, and some recent real-time forecasting studies conducted by The Pennsylvania State University.
An important result of these and earlier studies is that a general mesoscale model with realistic treatment of surface conditions and physical processes, and initialized with good large-scale conditions is capable of simulating and predicting a large variety of synoptic and mesoscale phenomena in different parts of the world. The model simulations also provide high-resolution, dynamically consistent data sets which are useful in understanding the physical behavior of complex mesoscale systems.
This paper summarizes recent studies of a variety of atmospheric phenomena in different parts of the world using the Penn State/NCAR mesoscale model. These phenomena include explosive cyclogenesis over the North Pacific and North Atlantic oceans, cyclogenesis over Europe and associated ozone transport during the ALPEX experiment, heavy rainfall and flash flood events over Pennsylvania and China, “Plateau” and “Southwest” vortices over China, severe storms over the United States, mesoscale convective complexes, elevated mixed layers and “lids,” an Australian Southerly Buster, low-level damming of cold air to the east of the United States Appalachian Mountains in winter, urban heat island effects, and regional acid deposition. This paper also reviews Observing System Simulation experiments (OSSEs), several sensitivity studies, the nesting of the mesoscale model in a global climate model for regional climate studies, and some recent real-time forecasting studies conducted by The Pennsylvania State University.
An important result of these and earlier studies is that a general mesoscale model with realistic treatment of surface conditions and physical processes, and initialized with good large-scale conditions is capable of simulating and predicting a large variety of synoptic and mesoscale phenomena in different parts of the world. The model simulations also provide high-resolution, dynamically consistent data sets which are useful in understanding the physical behavior of complex mesoscale systems.
In operational numerical weather prediction systems, both observations and numerical models contribute to the skill of the forecast. A simple diagram representing the relative contributions of observations and models to the current level of forecast skill and to the ultimate predictability of atmospheric phenomena is interpreted in this note. The forecast skill of 500 mb heights and an estimate of the ultimate predictability of this variable are used in a quantitative illustration of the diagram.
In operational numerical weather prediction systems, both observations and numerical models contribute to the skill of the forecast. A simple diagram representing the relative contributions of observations and models to the current level of forecast skill and to the ultimate predictability of atmospheric phenomena is interpreted in this note. The forecast skill of 500 mb heights and an estimate of the ultimate predictability of this variable are used in a quantitative illustration of the diagram.
A few examples of scientific accomplishments in tropical meteorology and hurricane research are presented. Tropical field experiments such as GATE have greatly influenced observational studies of convection and tropical easterly waves. One application of the study of convection is the attempt to estimate precipitation from satellite platforms.
Research in tropical cyclones has further improved the definition of large-scale structure and the environment in which the hurricane grows. Radiation, convection, and air-sea interaction studies are directed at the forcing and possible feedback of the hurricane with its environment. With this improved physical understanding, numerical modeling of hurricanes can now produce position forecasts of reasonable accuracy that are becoming competitive with current statistical-dynamical methods. There is a continuing effort to attempt hurricane modification experiments in conjunction with an adequate measurement program.
A few examples of scientific accomplishments in tropical meteorology and hurricane research are presented. Tropical field experiments such as GATE have greatly influenced observational studies of convection and tropical easterly waves. One application of the study of convection is the attempt to estimate precipitation from satellite platforms.
Research in tropical cyclones has further improved the definition of large-scale structure and the environment in which the hurricane grows. Radiation, convection, and air-sea interaction studies are directed at the forcing and possible feedback of the hurricane with its environment. With this improved physical understanding, numerical modeling of hurricanes can now produce position forecasts of reasonable accuracy that are becoming competitive with current statistical-dynamical methods. There is a continuing effort to attempt hurricane modification experiments in conjunction with an adequate measurement program.
This article summarizes the activities of the past year's 40th anniversary celebration for the University Corporation for Atmospheric Research and the National Center for Atmospheric Research (NCAR). NCAR's High Altitude Observatory celebrated its 60th anniversary, and NCAR's sponsor, the National Science Foundation, celebrated their 50th. These anniversaries provided the opportunity to reflect on past accomplishments as well as look to the future. The article also relates the year-long community dialogue about issues important to the future of these organizations and the university community.
This article summarizes the activities of the past year's 40th anniversary celebration for the University Corporation for Atmospheric Research and the National Center for Atmospheric Research (NCAR). NCAR's High Altitude Observatory celebrated its 60th anniversary, and NCAR's sponsor, the National Science Foundation, celebrated their 50th. These anniversaries provided the opportunity to reflect on past accomplishments as well as look to the future. The article also relates the year-long community dialogue about issues important to the future of these organizations and the university community.
severe local storms
Papers presented to the U.S. House of Representatives Subcommittee on Environment and the Atmosphere at a special review session of the AMS Ninth Conference on Severe Local Storms, Norman, Okla., 23 October 1975
This paper provides an overview of applications of the Global Positioning System (GPS) for active measurement of the Earth's atmosphere. Microwave radio signals transmitted by GPS satellites are delayed (refracted) by the atmosphere as they propagate to Earth-based GPS receivers or GPS receivers carried on low Earth orbit satellites.
The delay in GPS signals reaching Earth-based receivers due to the presence of water vapor is nearly proportional to the quantity of water vapor integrated along the signal path. Measurement of atmospheric water vapor by Earth-based GPS receivers was demonstrated during the GPS/STORM field project to be comparable and in some respects superior to measurements by ground-based water vapor radiometers. Increased spatial and temporal resolution of the water vapor distribution provided by the GPS/STORM network proved useful in monitoring the moisture-flux convergence along a dryline and the decrease in integrated water vapor associated with the passage of a midtropospheric cold front, both of which triggered severe weather over the area during the course of the experiment.
Given the rapid growth in regional networks of continuously operating Earth-based GPS receivers currently being implemented, an opportunity exists to observe the distribution of water vapor with increased spatial and temporal coverage, which could prove valuable in a range of operational and research applications in the atmospheric sciences.
The first space-based GPS receiver designed for sensing the Earth's atmosphere was launched in April 1995. Phase measurements of GPS signals as they are occluded by the atmosphere provide refractivity profiles (see the companion article by Ware et al. on page 19 of this issue). Water vapor limits the accuracy of temperature recovery below the tropopause because of uncertainty in the water vapor distribution. The sensitivity of atmospheric refractivity to water vapor pressure, however, means that refractivity profiles can in principle yield information on the atmospheric humidity distribution given independent information on the temperature and pressure distribution from NWP models or independent observational data.
A discussion is provided of some of the research opportunities that exist to capitalize on the complementary nature of the methods of active atmospheric monitoring by GPS and other observation systems for use in weather and climate studies and in numerical weather prediction models.
This paper provides an overview of applications of the Global Positioning System (GPS) for active measurement of the Earth's atmosphere. Microwave radio signals transmitted by GPS satellites are delayed (refracted) by the atmosphere as they propagate to Earth-based GPS receivers or GPS receivers carried on low Earth orbit satellites.
The delay in GPS signals reaching Earth-based receivers due to the presence of water vapor is nearly proportional to the quantity of water vapor integrated along the signal path. Measurement of atmospheric water vapor by Earth-based GPS receivers was demonstrated during the GPS/STORM field project to be comparable and in some respects superior to measurements by ground-based water vapor radiometers. Increased spatial and temporal resolution of the water vapor distribution provided by the GPS/STORM network proved useful in monitoring the moisture-flux convergence along a dryline and the decrease in integrated water vapor associated with the passage of a midtropospheric cold front, both of which triggered severe weather over the area during the course of the experiment.
Given the rapid growth in regional networks of continuously operating Earth-based GPS receivers currently being implemented, an opportunity exists to observe the distribution of water vapor with increased spatial and temporal coverage, which could prove valuable in a range of operational and research applications in the atmospheric sciences.
The first space-based GPS receiver designed for sensing the Earth's atmosphere was launched in April 1995. Phase measurements of GPS signals as they are occluded by the atmosphere provide refractivity profiles (see the companion article by Ware et al. on page 19 of this issue). Water vapor limits the accuracy of temperature recovery below the tropopause because of uncertainty in the water vapor distribution. The sensitivity of atmospheric refractivity to water vapor pressure, however, means that refractivity profiles can in principle yield information on the atmospheric humidity distribution given independent information on the temperature and pressure distribution from NWP models or independent observational data.
A discussion is provided of some of the research opportunities that exist to capitalize on the complementary nature of the methods of active atmospheric monitoring by GPS and other observation systems for use in weather and climate studies and in numerical weather prediction models.
Abstract
Over a two-year period beginning in 2015, a panel of subject matter experts, the Space Platform Requirements Working Group (SPRWG), carried out an analysis and prioritization of different space-based observations supporting the National Oceanic and Atmospheric Administration (NOAA)’s operational services in the areas of weather, oceans, and space weather. NOAA leadership used the SPRWG analysis of space-based observational priorities in different mission areas, among other inputs, to inform the Multi-Attribute Utility Theory (MAUT)-based value model and the NOAA Satellite Observing Systems Architecture (NSOSA) study. The goal of the NSOSA study is to develop candidate satellite architectures for the era beginning in approximately 2030. The SPRWG analysis included a prioritized list of observational objectives together with the quantitative attributes of each objective at three levels of performance: a threshold level of minimal utility, an intermediate level that the community expects by 2030, and a maximum effective level, a level for which further improvements would not be cost effective. This process is believed to be unprecedented in the analysis of long-range plans for providing observations from space. This paper describes the process for developing the prioritized objectives and their attributes and how they were combined in the Environmental Data Record (EDR) Value Model (EVM). The EVM helped inform NOAA’s assessment of many potential architectures for its future observing system within the NSOSA study. However, neither the SPRWG nor its report represents official NOAA policy positions or decisions, and the responsibility for selecting and implementing the final architecture rests solely with NOAA senior leadership.
Abstract
Over a two-year period beginning in 2015, a panel of subject matter experts, the Space Platform Requirements Working Group (SPRWG), carried out an analysis and prioritization of different space-based observations supporting the National Oceanic and Atmospheric Administration (NOAA)’s operational services in the areas of weather, oceans, and space weather. NOAA leadership used the SPRWG analysis of space-based observational priorities in different mission areas, among other inputs, to inform the Multi-Attribute Utility Theory (MAUT)-based value model and the NOAA Satellite Observing Systems Architecture (NSOSA) study. The goal of the NSOSA study is to develop candidate satellite architectures for the era beginning in approximately 2030. The SPRWG analysis included a prioritized list of observational objectives together with the quantitative attributes of each objective at three levels of performance: a threshold level of minimal utility, an intermediate level that the community expects by 2030, and a maximum effective level, a level for which further improvements would not be cost effective. This process is believed to be unprecedented in the analysis of long-range plans for providing observations from space. This paper describes the process for developing the prioritized objectives and their attributes and how they were combined in the Environmental Data Record (EDR) Value Model (EVM). The EVM helped inform NOAA’s assessment of many potential architectures for its future observing system within the NSOSA study. However, neither the SPRWG nor its report represents official NOAA policy positions or decisions, and the responsibility for selecting and implementing the final architecture rests solely with NOAA senior leadership.
Abstract
Launched in 2006, the Formosa Satellite Mission 3–Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC) was the first constellation of microsatellites carrying global positioning system (GPS) radio occultation (RO) receivers. Radio occultation is an active remote sensing technique that provides valuable information on the vertical variations of electron density in the ionosphere, and temperature, pressure, and water vapor in the stratosphere and troposphere. COSMIC has demonstrated the great value of RO data in ionosphere, climate, and meteorological research and operational weather forecasting. However, there are still challenges using RO data, particularly in the moist lower troposphere and upper stratosphere. A COSMIC follow-on constellation, COSMIC-2, was launched into equatorial orbit in 2019. With increased signal-to-noise ratio (SNR) from improved receivers and digital beam steering antennas, COSMIC-2 will produce at least 5,000 high-quality RO profiles daily in the tropics and subtropics. In this paper, we summarize 1) recent (since 2011 when the last review was published) contributions of COSMIC and other RO observations to weather, climate, and space weather science; 2) the remaining challenges in RO applications; and 3) potential contributions to research and operations of COSMIC-2.
Abstract
Launched in 2006, the Formosa Satellite Mission 3–Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC) was the first constellation of microsatellites carrying global positioning system (GPS) radio occultation (RO) receivers. Radio occultation is an active remote sensing technique that provides valuable information on the vertical variations of electron density in the ionosphere, and temperature, pressure, and water vapor in the stratosphere and troposphere. COSMIC has demonstrated the great value of RO data in ionosphere, climate, and meteorological research and operational weather forecasting. However, there are still challenges using RO data, particularly in the moist lower troposphere and upper stratosphere. A COSMIC follow-on constellation, COSMIC-2, was launched into equatorial orbit in 2019. With increased signal-to-noise ratio (SNR) from improved receivers and digital beam steering antennas, COSMIC-2 will produce at least 5,000 high-quality RO profiles daily in the tropics and subtropics. In this paper, we summarize 1) recent (since 2011 when the last review was published) contributions of COSMIC and other RO observations to weather, climate, and space weather science; 2) the remaining challenges in RO applications; and 3) potential contributions to research and operations of COSMIC-2.
