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Abstract.A latitudinal-distributed network of GPS receivers has been operating within Colombia, Peru and Chile with sufficient latitudinal span to measure the absolute total electron content (TEC) at both crests of the equatorial anomaly. The network also provides the latitudinal extension of GPS scintillations and TEC depletions. The GPS-based information has been supplemented with density profiles collected with the Jicamarca digisonde and JULIA power maps to investigate the background conditions of the nighttime ionosphere that prevail during the formation and the persistence of plasma depletions. This paper presents case-study events in which the latitudinal extension of GPS scintillations, the maximum latitude of TEC depletion detections, and the altitude extension of radar plumes are correlated with the location and extension of the equatorial anomaly. Then it shows the combined statistics of GPS scintillations, TEC depletions, TEC latitudinal profiles, and bottomside density profiles collected between September 2001 and June 2002. It is demonstrated that multiple sights of TEC depletions from different stations can be used to estimate the drift of the background plasma, the tilt of the plasma plumes, and in some cases even the approximate time and location of the depletion onset. This study corroborates the fact that TEC depletions and radar plumes coincide with intense levels of GPS scintillations. Bottomside radar traces do not seem to be associated with GPS scintillations. It is demonstrated that scintillations/depletions can occur when the TEC latitude profiles are symmetric, asymmetric or highly asymmetric; this is during the absence of one crest. Comparison of the location of the northern crest of the equatorial anomaly and the maximum latitude of scintillations reveals that for 90% of the days, scintillations are confined within the boundaries of the 50% decay limit of the anomaly crests. The crests of the anomaly are the regions where the most intense GPS scintillations and the deepest TEC depletions are encountered. In accord with early results, we observe that GPS scintillaCorrespondence to: C. E. Valladares (valladar@bc.edu) tions/TEC depletions mainly occur when the altitude of the magnetic equator F-region is above 500 km. Nevertheless, in many instances GPS scintillations and TEC depletions are observed to exist when the F-layer is well below 500 km or to persist when the F-layer undergoes its typical nighttime descent. Close inspection of the TEC profiles during scintillations/depletions events that occur when the equatorial F-layer peak is below 500 km altitude reveals that on these occasions the ratio of the crest-to-equator TEC is above 2, and the crests are displaced 10 • or more from the magnetic equator. When the equatorial F-layer is above 500 km, neither of the two requirements is needed, as the flux tube seems to be inherently unstable. We discuss these findings in terms of the RayleighTaylor instability (RTI) mechanism for flux-tube integrated quantities. We advance the idea that ...

[1] Orbit-averaged mass densities r and exospheric temperatures T 1 inferred from measurements by accelerometers on the Gravity Recovery and Climate Experiment (GRACE) satellites are used to investigate global energy E th and power P th inputs to the thermosphere during two complex magnetic storms. Measurements show r, T 1 , and E th rising from and returning to prevailing baselines as the magnetospheric electric field e VS and the Dst index wax and wane. Observed responses of E th and T 1 to e VS driving suggest that the storm time thermosphere evolves as a driven-but-dissipative thermodynamic system, described by a first-order differential equation that is identical in form to that governing the behavior of Dst. Coupling and relaxation coefficients of the E th , T 1 , and Dst equations are established empirically. Numerical solutions of the equations for T 1 and E th are shown to agree with GRACE data during large magnetic storms. Since T 1 and Dst have the same e VS driver, it is possible to combine their governing equations to obtain estimates of storm time thermospheric parameters, even when lacking information about interplanetary conditions. This approach has the potential for significantly improving the performance of operational models used to calculate trajectories of satellites and space debris and is also useful for developing forensic reconstructions of past magnetic storms. The essential correctness of the approach is supported by agreement between thermospheric power inputs calculated from both GRACE-based estimates of E th and the Weimer Poynting flux model originally derived from electric and magnetic field measurements acquired by the Dynamics Explorer 2 satellite.

Abstract. We have constructed latitudinal profiles of the total electron content (TEC) using measurements from six GPS receivers conducted during 1998. The TEC profiles have been divided into two groups: One corresponds to days when plumes or equatorial spread F (ESF) develops, and the second group portrays days of no-ESF condition.

[1] This paper describes new capabilities for operational geomagnetic Disturbance storm time (Dst) index forecasts. We present a data-driven, deterministic algorithm called Anemomilos for forecasting Dst out to a maximum of 6 days for large, medium, and small storms, depending upon transit time to the Earth. This capability is used for operational satellite management and debris avoidance in Low Earth Orbit (LEO). Anemomilos has a 15 min cadence, 1 h time granularity, 144 h prediction window (+6 days), and up to 1 h latency. A new finding is that nearly all flare events above a certain irradiance threshold, occurring within a defined solar longitude/latitude region and having sufficient estimated liftoff velocity of ejected material, will produce a geoeffective Dst perturbation. Three solar observables are used for operational Dst forecasting: flare magnitude, integrated flare irradiance through time, and event location. Magnitude is a proxy for ejecta quantity or mass and, combined with speed derived from the integrated flare irradiance, represents the kinetic energy. Speed is estimated as the line-of-sight velocity for events within 45°radial of solar disk center. Storms resulting from high-speed streams emanating from coronal holes are not modeled or predicted. A new result is that solar disk, not limb, observable features are used for predictive techniques. Comparisons between Anemomilos predicted and measured Dst for every hour over 25 months in three continuous time frames between 2001 (high solar activity), 2005 (low solar activity), and 2012 (rising solar activity) are shown. The Anemomilos operational algorithm was developed for a specific customer use related to thermospheric mass density forecasting. It is an operational space weather technology breakthrough using solar disk observables to predict geomagnetically effective Dst up to several days at 1 h time granularity. Real-time forecasts are presented at

[1] We explore the feasibility of using variations in the horizontal component (DB H ) of the Earth's magnetic field as measured by DMSP satellites while crossing the dip equator to estimate the provisional Dst index and the state of the thermosphere in near real time. Equatorial crossings are identified as locations where the vertical component of the main field measured by DMSP satellites vanishes. Local differences between measured and IGRF (epoch 2005) horizontal components (dB H ) were calculated for the years 2005 to 2009. Each year quiet time (0 ≥ Dst ≥ -7 nT) subsets of dB H were identified to establish offset baselines (dB H B ) as functions of longitude along the magnetic equator ( eq ) for each spacecraft. Year-to-year changes in dB H B reflect variations of the Earth's main field, indicating that baseline calculations must be updated at regular intervals for each spacecraft. Running-averaged values of DB H (t) = dB H ( eq , t) − dB H B ( eq , t) inferred from combined DMSP F16 and F17 data streams are shown to follow variations in Dst during the test interval. The method is also shown to apply during the magnetic superstorms of late 2003. Except during the late main phase, increases in globally averaged exospheric temperatures inferred from DB H and provisional Dst time series are in reasonable agreement with those inferred from measurements by accelerometers on the GRACE satellites.

[1] We compare thermospheric density (r) and exospheric temperature (T ∞ ) responses measured by the Gravity Recovery and Climate Experiment (GRACE) satellites with systematic characteristics of recurring high-speed streams (HSSs) in the solar wind observed by the Advanced Composition Explorer (ACE) at L 1 during the last four solar rotations of 2005. HSSs show remarkably similar features from one solar rotation to the next. Within corotating interaction regions (CIRs) at the leading edges of the HSSs plasma densities and magnetic fields steepen to excite low levels of geomagnetic and thermospheric activity. Consistent with origins in northern hemispheric coronal holes containing open, monopolar flux, interplanetary magnetic fields observed near L 1 had average B X and B Z with the same polarities and opposite to that of B Y . We show that a model used to estimate T ∞ changes during large magnetic storms overpredicts CIR-driven thermospheric heating. However, large-amplitude Alfvén waves in the interiors of HSSs generate regularly observed increases in T ∞ as well as the auroral electrojet index. The regularity of interplanetary driving and thermospheric responses suggests the possibility of developing reliable 27-day alerts about impending increases in thermospheric drag exerted on objects in low Earth orbits during solar minimum.

A compilation of the monthly and annual daily relative sunspot number is given for the years 1749 to 1957. Wolf's annual values are recompiled and given, back to 1700 from 1749. Tabular data include monthly, annual, and moving 11‐year means and totals. Times of cycle minima and maxima and appearances of first and last spots are indicated. Graphical presentations are given for the annual, 11‐ and 22‐year means, cycle means and cycle totals, and for some monthly and five‐monthly means. A check for continuation of a relationship of secular change to cycle length is made.