Monday, June 1, 2015
Severe solar storm serves as a reminder to always check the space weather forecast before doing any
GNSS surveying, precision agriculture, or GNSS-guided earthmoving work
The sun had a coronal mass ejection (CME) on June 18, 19, and 21 that we are experiencing as a series of geomagnetic storms. The NOAA Space Weather Prediction Center (SWPC) announced on Monday, June 22, that "the geomagnetic storm began as forecasted and quickly ramped up to severe (G4) levels."
On June 23, SWPC predicted the following over the June 23, 24, & 25 period:
The geomagnetic field is expected to remain agitated with G1-G2 (Minor - Moderate) possible early on day one (23 Jun) in continued response to the 21 Jun CME. Conditions are expected to continue to gradually taper off below G1 (Minor) over the next 12-18 hours back to quiet to active conditions. The 21 Jun CME is expected to arrive late on day two (24 Jun) to early on day three (25 Jun). The CME will likely enhance geomagnetic conditions to G1-G2 (Minor-Moderate) levels with the possibility for stronger conditions on day three (25 Jun).
On June 24, SWPC predicted the following over the June 24, 25, & 26 period:
G1 (Minor) geomagnetic storms are expected with waning effects from past CME. With the onset of the new CME, storming conditions up to G3 (Strong) are likely.
It is important to note that the SWPC reported the following in its June 23rd 3-Day Forecast, “No radio blackouts were observed over the past 24 hours.” Furthermore, SWPC predicted a 75% chance of minor-moderate (R1-R2) radio blackout levels for June 24, 25, and 26 and a 20% chance of a strong (R3 or greater) radio blackout over the 3-day period. SWPC explained, “R1-R2 (Minor-Moderate) or greater radio blackouts are expected, with a slight chance for R3 (Strong) radio blackouts on days one through three (24-26 Jun) due to flare potential from region 2371.”
How does space weather affect GNSS work? NASA provides the following response:
In calm conditions, single frequency GPS systems can provide position information with an accuracy of a meter or less. During a severe space weather storm, these errors can increase to tens of meters or more. Dual frequency GPS systems can provide position information accurate to a few centimeters. In this case the two different GPS signals are used to better characterize the ionosphere and remove its impact on the position calculation. But when the ionosphere becomes highly disturbed, the GPS receiver cannot lock on the satellite signal and position information becomes inaccurate.
Geomagnetic storms create large disturbances in the ionosphere. The currents and energy introduced by a geomagnetic storm enhance the ionosphere and increase the total height-integrated number of ionospheric electrons, or the Total Electron Count (TEC). GPS systems cannot correctly model this dynamic enhancement and errors are introduced into the position calculations. This usually occurs at high latitudes, though major storms can produce large TEC enhancements at mid-latitudes as well.
Therefore, it is advisable to not do any GNSS work over the next three days, if possible. As for work that was conducted during the geomagnetic storm’s most severe periods (2:00 pm – 5:00 pm EDT on June 22 and 11 pm EDT on June 22 to 2:00 am EDT on June 23) that work may need to be repeated.
Therefore, please always check the following SWPC webpages before doing any GNSS work:
Monday, June 1, 2015
NGS Releases New Beta Version of Transformational Tool
The National Geodetic Survey (NGS) is pleased to announce the Beta release of a new and improved transformation tool in the NGS geodetic toolkit. This redesigned version supports the transformation between geodetic coordinates and State Plane Coordinates (SPC), Universal Transverse Mercator (UTM) coordinates, Cartesian coordinates (XYZ), and U.S. National Grid (USNG) coordinates as a one-stop solution. It features transformation of single or multiple points, Web services, and software downloads. NGS encourages users to try the Beta Version and provide feedback to Krishna.Tadepalli@noaa.gov
so the final version may be improved prior to release as on official NGS product.
The update was in the development stage for several months, and it provides surveyors and geodesists with a more efficient and streamlined way of accessing frequently used NGS tools in the geodetic toolkit. The new interface allows one-page easy access to transformations that were previously available only on separate pages.
The Beta version is accessible at: http://beta.ngs.noaa.gov/gtkweb