Subj : Wx Terms (S)(6) To : All From : Daryl Stout Date : Thu Jul 20 2017 12:05 am SOI Southern Oscillation Index - a numerical index measuring the state of the Southern Oscillation. The SOI is based on the (atmospheric) pressure difference between Tahiti and Darwin, Australia. It is highly correlated with tropical sea surface temperature anomaly indices recorded in Ni¥o3. Soil Moisture Water contained in the upper part of the soil mantle. This moisture evaporates from the soil and is the used and transpired by vegetation. Solar Coordinates In solar-terrestrial terms, Central Meridian Distance (CMD). The angular distance in solar longitude measured from the central meridian. Solar Cycle In solar-terrestrial terms, the approximately 11-year quasi-periodic variation in frequency or number of solar active events. Solar Maximum In solar-terrestrial terms, the month(s) during the solar cycle when the 12-month mean of monthly average sunspot numbers reaches a maximum. Solar Minimum In solar-terrestrial terms, the month(s) during the solar cycle when the 12-month mean of monthly average sunspot numbers reaches a minimum. Solar Noon The time of day at which the sun is the highest in the sky. This time varies through the year due to the change in speed of the earth's orbit around the sun. Solar Sector Boundary (SSB) In solar-terrestrial terms, the apparent solar origin, or base, of the interplanetary sector boundary marked by the larger-scale polarity inversion lines. Solar Wind The outward flux of solar particles and magnetic fields from the sun. Typically, solar wind velocities are near 350 km/s. SOLN Solution SOLNS solutions Solstice Either of the two times per year when the sun is at its greatest angular distance from the celestial equator: about June 21 (the Northern Hemisphere summer solstice), when the sun reaches its northernmost point on the celestial sphere, or about December 22 (the Northern Hemisphere winter solstice), when it reaches its southernmost point. SOO Science and Operations Officer Sounding A set of data measuring the vertical structure of an atmospheric parameter (temperature, humidity, pressure, winds, etc.) at a given time. Southern Oscillation (SO) - a "see-saw" in surface pressure in the tropical Pacific characterized by simultaneously opposite sea level pressure anomalies at Tahiti, in the eastern tropical Pacific and Darwin, on the northwest coast of Australia. The SO was discovered by Sir Gilbert Walker in the early 1920's. Walker was among the first meteorologists to use the statistical techniques to analyze and predict meteorological phenomena. Later, the three-dimensional east-west circulation related to the SO was discovered and named the "Walker Circulation". The SO oscillates with a period of 2-5 years. During one phase, when the sea level pressure is low at Tahiti and High at Darwin, the El Ni¥o occurs. The cold phase of the SO, called "La Ni¥a" by some, is characterized by high pressure in the eastern equatorial Pacific, low in the west, and by anomalously cold sea surface temperature (SST) in the central and eastern Pacific. This is called El Ni¥o Southern Oscillation or ENSO. Southern Oscillation Index A numerical index measuring the state of the Southern Oscillation. The SOI is based on the (atmospheric) pressure difference between Tahiti and Darwin, Australia. It is highly correlated with tropical sea surface temperature anomaly indices recorded in Ni¥o3. Space Environment Center (SEC) - This center provides real-time monitoring and forecasting of solar and geophysical events, conducts research in solar-terrestrial physics, and develops techniques for forecasting solar and geophysical disturbances. SEC's parent organization is the National Oceanic and Atmospheric Administration (NOAA). SEC is one of NOAA's 12 Environmental Research Laboratories (ERL) and one of NOAA's 9 National Centers for Environmental Prediction (NCEP). SEC's Space Weather Operations is jointly operated by NOAA and the U.S. Air Force and is the national and world warning center for disturbances that can affect people and equipment working in the space environment. SPC Storm Prediction Center SPCLY Especially SPD 1) Speed 2) On a buoy report, ten-minute average wind speed values in m/s. Spearhead Echo A radar echo associated with a downburst with a pointed appendage extending toward the direction of the echo motion. The appendage moves much faster than the parent echo, which is drawn into the appendage. During its mature stage, the appendage turns into a major echo and the parent echo loses its identity. Special Avalanche Warning Issued by the National Weather Service when avalanches are imminent or occurring in the mountains. It is usually issued for a 24 hour period. Special Fire Weather Meteorological services uniquely required by user agencies which cannot be provided at an NWS office during normal working hours. Examples are on-site support, weather observer training, and participation in user agency training activities. Special Marine Warning (SMW) A warning product issued for potentially hazardous weather conditions usually of short duration (up to 2 hours) producing sustained marine thunderstorm winds or associated gusts of 34 knots or greater; and/or hail 3/4 inch or more in diameter; and/or waterspouts affecting areas included in a Coastal Waters Forecast, a Nearshore Marine Forecast, or an Great Lakes Open Lakes Forecast that is not adequately covered by existing marine warnings. Also used for short duration mesoscale events such as a strong cold front, gravity wave, squall line, etc., lasting less than 2 hours and producing winds or gusts of 34 knots or greater. Special Tropical Disturbance Statement This statement issued by the National Hurricane Center furnishes Information on strong and formative non-depression systems. This statement focuses on the major threat(s) of the disturbance, such as the potential for torrential rainfall on an island or inland area. The statement is coordinated with the appropriate forecast office(s). Specific Gravity The ratio of the density of any substance to the density of water. Specific Humidity In a system of moist air, the ratio of the mass of water vapor to the total mass of the system. Specific Yield In hydrologic terms, the ratio of the water which will drain freely from the material to the total volume of the aquifer formation. This value will always be less than the porosity. Spectral Density A radar term for the distribution of power by frequency. Spectral Wave Density On a buoy report, energy in (meter*meter)/Hz, for each frequency bin (typically from 0.03 Hz to 0.40 Hz). Spectral Wave Direction On a buoy report, mean wave direction, in degrees from true North, for each frequency bin. Spectrum Width This WSR-88D radar product depicts a full 360 degree sweep of spectrum width data indicating a measure of velocity dispersion within the radar sample volume. It is available for every elevation angle sampled, it provides a measure of the variability of the mean radial velocity estimates due to wind shear, turbulence, and/or the quality of the velocity samples. It is used to estimate turbulence associated with boundaries, thunderstorms, and mesocyclones; check the reliability of the velocity estimates; and locate boundaries (cold front, outflow, lake breeze, etc.). Spectrum Width Cross Section This WSR-88D radar product displays a vertical cross section of spectrum width on a grid with heights up to 70,000 feet on the vertical axis and distance up to 124 nm on the horizontal axis. Two end points to create cross section are radar operator selected along a radial or from one AZRAN to another AZRAN within 124 nm of the radar that are less than 124 nm apart. It is used to: 1) Verify features on the Reflectivity Cross Section (RCS) and Velocity Cross Section (VCS) and to evaluate the quality of the velocity data. 2) Estimate vertical extent of turbulence (aviation use). Speed Shear The component of wind shear which is due to a change in wind speed with height, e.g., southwesterly winds of 20 mph at 10,000 feet increasing to 50 mph at 20,000 feet. Speed shear is an important factor in severe weather development, especially in the middle and upper levels of the atmosphere. SPENES NESDIS Satellite Precipitation Estimates --- þ Synchronet þ The Thunderbolt BBS - wx1der.dyndns.org .