Vadas S.L.,NorthWest Research Associates, Inc. |
Crowley G.,Atmospheric & Space Technology Research Associates, LLC
Journal of Geophysical Research: Space Physics
We model the gravity waves (GWs) excited by Tropical Storm (TS) Noel at 0432 UT on 30 October 2007. Using forward ray tracing, we calculate the body forces which result from the saturation and dissipation of these GWs. We then analyze the 59 traveling ionospheric disturbances (TIDs) observed by the TIDDBIT ionospheric sounder at 0400-1000 UT near Wallops Island. These TIDs were located at the bottomside of the F layer at z = 230-290 km, had periods of τr = 15 to 90 min, horizontal wavelengths of H = 100 to 3000 km, and horizontal phase speeds of cH = 140 to 650 m/s. 33 (∼60%) of the TIDs were propagating northwest(NW) and north(N)ward, from the direction of TS Noel 1700-2000 km away. We show that these TIDs were likely GWs. 40% of these GWs had phase speeds larger than 280m/s. This precluded a tropospheric source and suggested mesospheric and thermospheric sources instead. Using reverse ray tracing, we compare the GW locations with the regions of convective overshoot, mesospheric body forces, and thermospheric body forces. We identify 27 of the northwest/northward propagating GWs as likely being secondary GWs excited by thermospheric body forces. Three may have originated from mesospheric body forces, although this is much less likely. None are identified as primary GWs excited directly by TS Noel. 11 of these GWs with cH < 205 m/s likely reflected near the tropopause prior to detection. This secondary GW spectrum peaks at λH ∼ 100-300 km and cH ∼ 100-300 m/s. To our knowledge, this is the first identification and quantification of secondary GWs from thermospheric body forces. Copyright 2010 by the American Geophysical Union. Source
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase II | Award Amount: 750.00K | Year: 2014
ABSTRACT: The Air Force seeks to improve the accuracy of orbit specification and of 72-h orbit predictions beyond present capabilities. Thermospheric neutral density and satellite ballistic coefficient strongly impact satellite drag estimation, which is a leading source of error in orbit predictions in LEO. The goal of this Phase II project is to develop a satellite drag specification capability that will outperform the current JB08 and HASDM models. To address the proposal objectives, we propose to: a) Use full-physics models (TIMEGCM, CTIPe, and TIEGCM) to improve thermospheric density and wind forecasting to better capture storms and other anomalous conditions affecting satellite drag predictions. b) Use ensemble assimilation and dynamic tuning of model boundary conditions to produce best solutions of satellite drag and improved forecasting capability. c) Use state-of-the art forecast models, measurements, and indices for specifying solar, geomagnetic, and lower boundary conditions 72 hours in the future. d) Utilize multiple state of the art full-physics, independently assimilated, models in a super-ensemble framework to provide skill scores of drag and density predictions. Phase II deliverables include: (a) Comprehensive nowcast and forecast system for the thermosphere and satellite drag (Atmospheric Density Assimilation Model, or ADAM); (b) Model Evaluation and Validation Estimate (EVE). BENEFIT: At the end of the proposed Phase-II work, we will have a number of important accomplishments. In particular, we will have developed and validated a state-of-the-art atmospheric density and aerodynamic drag nowcast and forecast system based on three first-principles full-physics models and data assimilation techniques. The proposed ADAM framework will improve neutral density nowcast accuracy by 13-18% RMS over the Jacchia Bowman 2008 (JB08) model and 8%-12% over the High Accuracy Satellite Drag Model (HADSM) and will provide neutral density forecasts within 5% over a 72 hour period, a requirement not currently met with the present prediction models. The Phase II effort will bring together subject matter experts in atmospheric modeling, data assimilation, and satellite drag to develop an operational full-physics assimilative code for neutral density and satellite drag nowcast and forecast. The ADAM system will benefit commercial satellite operators for their own risk-mitigation exercises, including the reduction of the prediction errors of satellite positions. Primary areas for applications include satellite orbit determination, space hazard avoidance, SSA, and post-flight space-based science data analysis.
Agency: NSF | Branch: Standard Grant | Program: | Phase: AERONOMY | Award Amount: 40.00K | Year: 2014
This project supports the operation and maintenance of four Fabry-Perot Doppler Imagers, two at the Millstone Hill Observatory in Massachusetts and two at the Arecibo Observatory in Puerto Rico. These instruments provide data on the behavior of the neutral components of the Earth?s thermosphere, and contribute to studies of interactions among the Earth?s ionosphere and thermosphere in response to solar forcing as a system. This will address the distribution of energy and momentum throughout different latitudes and layers of the atmosphere. Data and operation will be centralized through a client-server architecture that allows for remote operation, data collection and automated analysis. Data will continue to be published to the web and Madrigal database daily, within hours of observation. The project will provide educational opportunities for undergraduate students through collaborations. SSI is pursuing non-traditional educational opportunities to educate the public about space science and optics in general.
The ASTRA team will use the Millstone Hill and Arecibo data to investigate the magnitude, occurrence rate and variability of the midnight temperature maximum (MTM), and the annual and semiannual variability of the upper thermosphere. These results will be compared with TIMEGCM model output. Thermospheric vertical winds will be measured at each location using two different techniques, a direct line-of-sight technique and the Burnside technique where vertical winds are inferred from the horizontal wind gradient. When available these vertical winds will be compared to vertical motion measured by the incoherent scatter radars at each location. These observations allow for the inter-comparison and verification of the veracity of different measurement techniques and will ultimately allow for a better understanding of the 3-d dynamics of the thermosphere.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 149.93K | Year: 2015
ABSTRACT:Overhead Persistent Infrared (OPIR) sensors are a key part of a developing mission area supported by the Air Force and the Intelligence Community to provide worldwide, persistent surveillance of missile launches and other operations. These sensors operate in the SWIR and MWIR spectral regions. While this spectral range has been valuable for decades to the meteorological community, it is always used in combination with visible, longwave IR, or thermal IR observations to characterize clouds. The meteorological community may benefit from the OPIR technology as it offers the potential to cover more of the globe and its higher temporal resolution may allow for better characterization of some environmental phenomena. In addition to these operational specifications, the addition of spectral information could augment the current suite of meteorological satellites. With a combined modeling and algorithm development effort, we propose to investigate the SWIR/MWIR region with the goal of identifying an optimal standalone OPIR channel set that maximizes the information content in support of cloud property retrievals. The spectral characteristics of the channels chosen for the proposed algorithm will become the starting point for the definition of the initial collection requirements for the OPIR sensor and the platform it is deployed on.BENEFIT:The US Government Accounting Office (GAO), in their latest High Risk Report titled Mitigating Gaps in Weather Satellite Data, says that the continuity in US weather-satellite data is at risk. The programs intended to replace aging satellite systems have had to reduce functionality and slip planned launch dates due, in part, to cost increases, missed milestones, technical problems, and management challenges. With concerns surrounding our weather and climatological observations, new technologies have an opportunity to make an impact. It has been shown many times through Observational System Simulation Experiment (OSSE) studies that improved cloud and water vapor retrievals dramatically improve the skill scores of weather forecasts. We anticipate, through the development of an accurate cloud retrieval algorithm applicable to OPIR data, the generation of improved inputs to forecasting models such as, CDFS-II. The real-time and persistent nature of the OPIR data stream will provide improved cloud products for forecasting models through OPIRs improved temporal resolution and wider global coverage. Commercial applications will come in the form of providing improved cloud observations to the meteorological community who use this environmental intelligence data in their forecasting models.
Agency: NSF | Branch: Standard Grant | Program: | Phase: Space Weather Research | Award Amount: 199.54K | Year: 2016
This is a short-term (less than one-year) effort to complete the construction, functional testing, and instrument calibration of a CubeSat with the capability to measure electric fields in the upper atmosphere. The DIME (Double-probe Instrumentation for Measuring Electric-fields) CubeSat concept builds on and further develops the NSF-funded Dynamic Ionosphere CubeSat Experiment (DICE) project aimed at measuring major space weather disturbances in the upper atmosphere. DICE was one of the first NSF CubeSat missions to be selected and flown. The DICE project consisted of two CubeSats weighing less than 2.2 kg each. They were launched into a low Earth orbit in October 2011 and collected data in space for two years. Each DICE satellite carried a suite of three scientific instruments. However, only two of them functioned successfully in space. Due to difficulties accurately controlling the spin of the spacecraft on orbit it was not possible to deploy the long wire booms that made up the electric field instruments. Thus, the DICE spacecraft could not provide measurements of the electric field. Fulfilling the need for continuous global measurements of this critical parameter in upper atmosphere dynamics remains a key goal and challenge for aeronomy and space weather research. The goal of the DIME project is to continue the development of an innovative approach to space-based measurement of the electric field. Leveraging the successes and lessons learned from the DICE mission DIME is envisioned as the next generation low cost, highly capable ionospheric sensor-sat observatory. New developments include improvements in the spin stabilization and control of the CubeSat, as well as improvements to the DICE electric field deployment mechanism. The DIME development so far has been funded under the Air Force SBIR program but falls short of delivering a fully equipped satellite that is ready to be launched and provide scientific data. Support for the purchase of the remaining parts and completion of the full flight assembly of the DIME CubeSat, and also for the completion of the satellite functional testing and calibration, while the present workforce and expertise is in place is the subject of this RAPID award. Delivery of a fully launch-ready DIME CubeSat, will enlist support from the Air Force for the launch and operation on orbit of the satellite. A newly graduated engineer, who worked as a student on the DICE project, in collaboration with a postdoctoral researcher, who with this project is offered a unique experimental research opportunity, will carry out most of the work under this effort. The project also continues to foster valuable collaboration between industry, academia, and government, involving ASTRA (a small business), the Air Force Research Laboratory, and Utah State University.
There are three fundamental drivers of global ionosphere-thermosphere (IT) behavior: solar UV/EUV radiation, high latitude forcing from solar wind-magnetosphere interaction and coupling to the ionosphere and thermosphere, and forcing by waves and tides from the lower atmosphere. While the principles of IT behavior are generally accepted, a complete understanding of the fully coupled ionosphere-thermosphere-magnetosphere system requires extensive measurements of environmental parameters that are not currently available. What are needed are simultaneous multipoint measurements of the electric field in the ionosphere. Focus here is on the high latitude forcing. While E-field measurements have been available from NSF-funded ground-based radars and the DMSP satellites, there is insufficient data to enable a comprehensive specification of the key high latitude potential pattern, electric fields, and their variability in space and time. The DIME sensor-sat has a unique potential to be a pathfinder that will pave the way for low-cost, very capable, next generation space weather CubeSat platforms from which to observe the system-driving electric field and other parameters in the Earth?s ionosphere. Future constellations of DIME platforms could provide networked, global measurements of the electric field. The DIME design additionally includes instrumentation to provide complementary magnetic field and plasma parameter measurements. In this way, DIME constitutes a key step in enabling large-return Geospace science missions using CubeSat technologies, targeting outstanding unanswered system-science and space weather questions.