MIT Haystack Research Articles

Characterizing Plasma Peak Density Thickness in the Ionosphere: A Single‐Site Multi‐Instrument Study

AbstractThis paper introduces the Peak Density Thickness (PDT) formalism, a novel approach to representing the F2 layer's vertical electron density profile in the ionosphere. It diverges from the conventional “pointed‐peak” model by suggesting a “broad‐peak” or “flat‐nose” profile where plasma density remains constant within an altitude interval χ. This theory is backed by independent observations, including a comprehensive data set from the Millstone Hill Incoherent Scatter Radar at the MIT Haystack observatory, spanning from 1993 to 2023, which illustrates the presence and diurnal variation of PDT. A single‐day intensive cross‐verification using Digisonde Portable Sounder DPS4D soundings of the sub‐peak ionosphere has shown remarkable agreement in the measurements of the lower boundary of the χ interval and the peak density. This study suggests incorporating the flat‐nose section χ into the F‐region profile formalism. Such a shift could improve the accuracy of topside specifications derived from ground‐based ionosonde measurements, enhancing our understanding of ionospheric plasma dynamics.

The Haystack Telescope as an Astronomical Instrument

The Haystack Telescope is an antenna with a diameter of 37 m and an elevation-dependent surface accuracy of ≤100μm that is capable of millimeter-wave observations. The radome-enclosed instrument serves as a radar sensor for space situational awareness, with about one-third of the time available for research by MIT Haystack Observatory. Ongoing testing with the K-band (18–26 GHz) and W-band receivers (currently 85–93 GHz) is preparing the inclusion of the telescope into the Event Horizon Telescope (EHT) array and the use as a single-dish research telescope. Given its geographic location, the addition of the Haystack Telescope to current and future versions of the EHT array would substantially improve the image quality.

Aspects related to variability of radiative cooling by NO in lower thermosphere, TEC and O/N2 correlation, and diffusion of NO into mesosphere during the Halloween storms

Nitric Oxide is a very important trace species which plays a significant role acting as a natural thermostat in Earth’s thermosphere during strong geomagnetic activity. In this paper, we present various aspects related to the variation in the NO Infrared radiative flux (IRF) exiting the thermosphere by utilizing the TIMED/SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/ Sounding of the Atmosphere using Broadband Emission Radiometry) observational data during the Halloween storm which occurred in late October 2003. The Halloween storm comprised of three intense-geomagnetic storms. The variability of NO infrared flux during these storm events and its connection to the strength of the geomagnetic storms were found to be different in contrast to similar super storms. The connection between the quantum of energy outflux from the upper atmosphere into space in terms of NO IRF and the duration of storms is established. The NO radiative cooling, and the closely correlated depletion in O/N2 ratio are controlled by the Joule heating intensity (proxied by AE-index). The collisional excitation rate of NO, calculated using the modelled datasets of WACCM-X (Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension), correlates well with the observed pattern of radiative emission by NO. Observational datasets from TIMED/GUVI (Global Ultra-Violet Imager) and MIT Haystack observatory madrigal GNSS (Global navigation satellite system) total electron content (TEC) database shows that the TEC and O/N2 enhancement in low-mid northern hemispheric latitudes are mainly controlled by the z-component of Interplanetary magnetic field (IMF-Bz). The penetration of eastward electric field during the storm events is found to be responsible for the overall enhancement of TEC. The contribution of enhanced day-side TEC in observed variation of O/N2 ratio by GUVI is also reported. It is also seen that during substorms related events the night-time polar region experiences more cooling due to NO than the daytime polar region. The connections between the mid- and low-latitude enhancement in NO IRF with the propagation of LSTIDs (Large-scale traveling ionospheric disturbances) in combination with the O/N2 variability, and the altitudinal variation in NO flux with the progression of the storm is also investigated. This study presents the evidence on the role of diffusion processes in the large scale enhancement of NO in the mesospheric altitudes.

A case study of the large-scale traveling ionospheric disturbances in the eastern Asian sector during the 2015 St. Patrick's Day geomagnetic storm

Abstract. This study presents a comprehensive observation of the large-scale traveling ionospheric disturbances (LSTIDs) in the eastern Asian sector during the 2015 St. Patrick's Day (17 March 2015) geomagnetic storm. For the first time, three dense networks of GPS receivers in China and Japan are combined together to obtain the two-dimensional (2-D) vertical total electron content (VTEC) perturbation maps in a wider longitudinal range than previous studies in this region. Results show that an LSTID spanning at least 60∘ in longitude (80–140∘ E) occurs as a result of possible atmospheric gravity waves (AGWs) propagating from high to lower latitudes at around 09:40–11:40 UT (universal time), and the crest of this LSTID shows a tendency of dissipation starting from the eastern side. The manifestation of the 2-D VTEC perturbation maps is in good agreement with the recordings from two high-frequency Doppler sounders and the iso-frequency lines from eight ionosondes. Then, the propagation parameters of the LSTIDs are estimated by applying least-square fitting methods to the distinct structures in the 2-D VTEC perturbation plots. In general, the propagation parameters are observably longitudinally dependent. For example, the propagation direction is almost due southward between 105 and 115∘ E, while it is slightly southwest and southeast in the western and eastern sides of this region. This feature is probably related to the regional geomagnetic declination. The mean values of the period, trough velocity (Vt), crest velocity (Vc), and wavelength of the LSTIDs in the studied longitudinal bands are 74.8±1.4 min, 578±16 m s−1, 617±23 m s−1, and 2691±80 km, respectively. Finally, using the VTEC map data from the Madrigal database of the MIT Haystack Observatory, the characteristics of the ionospheric disturbances over the European sector (30–70∘ N, 10–20∘ E) are also studied. The results are very different from those in the eastern Asian sector in parameters like the occurrence time, oscillation period, and propagation velocities.

Science, Society, and Software Engineering

column Share on Science, Society, and Software Engineering: Part 3 -- The Catch Author: Robert Schaefer MIT Haystack Observatory MIT Haystack ObservatoryView Profile Authors Info & Claims ACM SIGSOFT Software Engineering NotesVolume 42Issue 1March 2017 pp 4–6https://doi.org/10.1145/3041765.3041770Published:22 March 2017Publication History 0citation95DownloadsMetricsTotal Citations0Total Downloads95Last 12 Months1Last 6 weeks0 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

Ionospheric plasma disturbances generated by naturally occurring large-scale anomalous heat sources

We report the findings from our investigation on the possibility of large-scale anomalous thermal gradients to generate acoustic-gravity waves (AGWs) and traveling ionospheric disturbances (TIDs). In particular, here we consider the case of summer 2006 North American heat wave event as a concrete example of such large-scale natural thermal gradients. This special scenario of AGW/TID generation was formulated based on the results of our experiments at the Arecibo Observatory in July 2006, followed by a systematic monitoring/surveillance of total electron content (TEC) fluctuations over North America in 2005–2007 using the MIT Haystack Observatory's Madrigal database. The data from our Arecibo experiments indicate a continual occurrence of intense AGW/TID over the Caribbean on 21–24 July 2006, and the Madrigal TEC data analysis shows that the overall level of TID activity over North America had increased by ∼0.2 TECU during the summer 2006 heat wave event. Our proposed scenario is in agreement with these empirical observations, and is generally consistent with a number of past ionospheric HF heating experiments related to AGW/TID generation.

Statistical framework for estimating GNSS bias

Abstract. We present a statistical framework for estimating global navigation satellite system (GNSS) non-ionospheric differential time delay bias. The biases are estimated by examining differences of measured line-integrated electron densities (total electron content: TEC) that are scaled to equivalent vertical integrated densities. The spatiotemporal variability, instrumentation-dependent errors, and errors due to inaccurate ionospheric altitude profile assumptions are modeled as structure functions. These structure functions determine how the TEC differences are weighted in the linear least-squares minimization procedure, which is used to produce the bias estimates. A method for automatic detection and removal of outlier measurements that do not fit into a model of receiver bias is also described. The same statistical framework can be used for a single receiver station, but it also scales to a large global network of receivers. In addition to the Global Positioning System (GPS), the method is also applicable to other dual-frequency GNSS systems, such as GLONASS (Globalnaya Navigazionnaya Sputnikovaya Sistema). The use of the framework is demonstrated in practice through several examples. A specific implementation of the methods presented here is used to compute GPS receiver biases for measurements in the MIT Haystack Madrigal distributed database system. Results of the new algorithm are compared with the current MIT Haystack Observatory MAPGPS (MIT Automated Processing of GPS) bias determination algorithm. The new method is found to produce estimates of receiver bias that have reduced day-to-day variability and more consistent coincident vertical TEC values.

Dynamic provisioning of LightPath services for radio astronomy applications

A demonstration at iGRID 2005 used dynamic, deterministic, and dedicated LightPath network services to link radio telescopes from around the world with computational facilities at the MIT Haystack Observatory to create a single coherent instrument for real-time astronomical and geodetic research. The “electronic Very Long Baseline Interferometry” (e-VLBI) application provides ultra-high resolution images of very faint and very distant objects in the universe. The application-specific network topology carried 2 Gbps of VLBI data from radio telescopes in Europe, North America, and Japan to Haystack for real-time correlation processing. This paper describes the application, the network technologies employed for the demonstration, the results, challenges and future work.

관측 데이터의 고속기록을 위한 대용량 저장시스템

In this paper, we introduce the development of the large storage system in order to record the observed space radio signal in the Korean VLBI Network(KVN) with high-speed. The KVN is the Very Long Baseline Interferometery(VLBI) to observe the birth of star, the structure of space by constructing radio telescope with diameter 21m at the Seoul, Ulsan, Jeju from 2001 to 2007 years. To do this, Korea Astronomy Observatory joined the international consortium for developing the high-speed large storage system(Mark 5), which is developed by MIT Haystack observatory. The Mark 5 system based on hard disk has to record up to 1 Gbps the observed space radio signal. The main features of Mark 5 system are as follows; First it is able to directly record the input data to the hard disk without PC1(Peripheral Component Interconnect) internal bus, and the second, it has two hard disk banks, which are able to hot-swap ATA/IDE type very cheap up to 1 Gbps recording and playback. The third is that it follows the international VLBI standard interface hardware(VSI-H). Therefore it can be connect directly the VSI-H type system at the input/output. Finally it also supports e- VLBI(Electronic-VLBI) through the standard Gigabits Ethernet connection.

The Effectiveness of Internet-Controlled Astronomical Research Instrumentation for Education

Over the last decade, remote instruments have become widely used in astronomy. Educational applications are more recent. This paper describes a program to bring radio astronomy into the undergraduate classroom through the use of a remote research-grade radio telescope, the MIT Haystack Observatory 37 m telescope. We examine the effectiveness of such remote access in the classroom. The remote use of the large telescope has opened up a research facility for undergraduate students. The experience has been largely successful with over 150 students from about 20 colleges using the telescope every year. The student experiments have included classroom demonstrations by faculty, and short-term laboratory experiments and long-term research experiments performed by students. Although a visit to the site provided students with a sense of the scale of the antenna, operating on a purely remote basis still gave the students a rewarding research and learning experience. The effectiveness of the remote instrument is judged mainly by the student presentations and papers that have been generated, by the enthusiasm of the faculty to continue using the facility as part of their curricula, and through a survey of students and faculty.

The GPS ionospheric working group

The first GPS ionospheric working group workshop was held 10–11 November 2003 at the MIT Haystack observatory in Westford, MA. The purpose of this workshop was to foster an environment of collaboration on scientific projects, software development and long-range planning issues involving GPS. A prime motivation of this group is to integrate the use of GPS data more completely within the larger sphere of atmospheric research. For example, a primary goal is a closer coupling of GPS measurements with data from other atmospheric sensors, such as atmospheric imagers and the incoherent scatter radar observations. It is also desirable to make GPS data more accessible to atmospheric researchers. GPS is at the forefront of utilizing information from integrated ground-based atmospheric systems. By combining GPS data from the ground-based and space-based network of receivers, spatial and temporal changes in the global distribution of the total electron content (TEC) can be monitored, providing a new view of the large and meso-scale characteristics and dynamics of the plasmas of the extended ionosphere. GPS observations when processed this way are helping to increase the understanding of the driving forces between the coupled spheres of Earth’s upper atmosphere. The workshop drew participation from approximately 25 ionospheric researchers, including several from the international community. Topics discussed at the workshop included the development of new software receivers, the impact of ionospheric phenomena on operational systems, and GPS observations of ionospheric redistribution and implications for magnetospheric–ionospheric (MI) coupling. The format of this meeting was informal, and a workshop environment was adhered to. Workshop participants included representatives from MIT’s Haystack observatory, the Jet Propulsion Laboratory (JPL), Cornell University, Boston College, the University of Colorado, the Air Force Research Laboratory, the Naval Research Laboratory, and the University of Texas at Austin. International participants included representatives from the University of Calgary, the University of New Brunswick, the Institute for Research on Electromagnetics of the Italian National Research Council (IROE-CNR), the University of Bath, and the Technical University of Catalonia. The workshop began with each of the participants presenting a short summary of their current efforts. These efforts included numerous TEC and scintillation studies using GPS, studies of equatorial anomaly dynamics using multi-instruments, ionospheric storm modeling, ionospheric storm studies using GPS networks, ionospheric tomography, near-real time TEC map generation, ionospheric studies in support of WAAS, data assimilation, scintillation receiver development, Traveling Ionospheric Disturbances (TIDs) studies, data processing, software development, and the development of new receivers. Following the introductions, longer presentations were given. The first was given by Dr. Bruce Tsuratani of the JPL and he discussed the relationship of the ionosphere to interplanetary shock electric fields. He has been analyzing the 5–6 November 2001 interplanetary shock/electric field event using space-borne GPS receiver data and altimeter data from TOPEX/Poseidon. In particular he is interested in the magnetospheric convection electric fields and the convection of ionospheric plasmas by these electric fields. Much discussion ensued on the myriad of unusual effects. Dr. Brent Ledvina of Cornell University gave a brief presentation on Global Navigation Satellite System (GNSS) receivers, which include GPS and Galileo receivers. The Received: 16 March 2004 / Accepted: 26 March 2004 Published online: 14 July 2004 a Springer-Verlag 2004

Frequency‐and‐angular HF sounding and ISR diagnostics of TIDs

A single digisonde, used as a receiver for ionospheric high frequency signals from broadcast stations, was able to determine the wave characteristics of traveling ionospheric disturbances (TIDs) using frequency shift and arrival angle measurements. During a measurement campaign, aimed at recovering large‐scale wave‐like processes in the upper atmosphere, in March 2001 at the MIT Haystack Observatory (Millstone Hill, MA), a Digisonde Portable Sounder (DPS) made simultaneous observations with the incoherent scatter radar (ISR). The DPS was upgraded to include the frequency and angular sounding (FAS) technique previously developed at the Institute of Radio Astronomy in Kharkov, Ukraine, for TID diagnostics. The DPS with four spaced receive antennas received the radio signals at 3.33 MHz and 7.335 MHz from Radio CHU of the Canadian Time Service (Ottawa, Ontario). The FAS technique recovered the basic parameters of TIDs, i.e., amplitude, speed, and the direction of the propagation vector by modeling the ionosphere as a perfectly reflecting surface. For three days during the campaign the Millstone Hill ISR monitored the ionospheric midpoint using a triangulation mode to identify the direction of motion and speed of the wave‐like ionospheric disturbances. Comparison of the results from the two diagnostic techniques showed good agreement. The wave directions were within 10 to 15 degrees, and speed and wavelength were within 10 to 12%.

Rayleigh lidar observations of a mesospheric inversion layer during night and day

A narrow field of view Rayleigh lidar has been constructed at Millstone Hill / MIT Haystack Observatory (42.6°N, 71.5°W) for observations of middle atmospheric temperatures throughout the diurnal cycle. During a 31.5 h measurement on 19–21 March 2001 a mesospheric thermal inversion layer was observed in both the night and day. It developed near 60 km in altitude, progressed downward at 0.40±0.06 km/h, and had an overlying adiabatic lapse rate. The inversion amplitude correlated with the evolution of stratospheric gravity wave activity, although the mesospheric perturbations were too large to be due to conservative gravity‐wave growth alone. The 24 h mean temperature profile shows no evidence of a residual inversion layer.

Radio Astronomy: A Strong Link Between Undergraduate Education and Research

The program at the MIT Haystack Observatory has added a new opportunity for students as part of our overall national effort to encourage research by undergraduates. Radio astronomy complements other branches of astronomy, augments science education broadly, and serves to promote interdisciplinary research and education. In the past 2 years, we have conducted a successful pilot program to develop and test a program that facilitates the linking of undergraduate research and education through radio astronomy. As a result of this effort,