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# Topic: Geopotential height

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 Encyclopedia article: Geopotential height   (Site not responding. Last check: 2007-10-06) In the geosciences, geopotential height is a measure of geometric height that accounts for the dependence of gravity (A solemn and dignified feeling) on latitude and height. Geopotential height contours can be used to calculate the geostrophic wind (additional info and facts about geostrophic wind), which blows stronger where the contours are more closely spaced and tangential to the isolines. In atmospheric equations of motion, such as the primitive equations (additional info and facts about primitive equations), geopotential height is used to eliminate centrifugal force (The outward force on a body moving in a curved path around another body) and air density (The amount per unit size). www.absoluteastronomy.com /encyclopedia/g/ge/geopotential_height.htm   (194 words)

 Geopotential height - Wikipedia, the free encyclopedia Geopotential height is a vertical coordinate referenced to Earth's mean sea level - an adjustment to geometric height (elevation above mean sea level) using the variation of gravity with latitude and elevation. The geopotential thickness between pressure levels - difference of the 850 hPa and 1000 hPa geopotential heights for example - is proportional to mean virtual temperature in that layer. Geopotential height contours can be used to calculate the geostrophic wind, which is faster where the contours are more closely spaced and tangential to the geopotential height contours. en.wikipedia.org /wiki/Geopotential_height   (243 words)

 Geopotential Height: upper air station reports Geopotential Height approximates the actual height of a pressure surface above mean sea-level. Therefore, for the example given above, the height of the pressure surface on which the observation was taken is 5800 meters. When a collection of geopotential height reports are contoured on a given pressure surface, we are able to identify upper air troughs and ridges, which are very important influences on surface weather conditions. ww2010.atmos.uiuc.edu /(Gh)/guides/maps/upa/hght.rxml   (98 words)

 Geopotential height   (Site not responding. Last check: 2007-10-06) In the geosciences, geopotential height is a measure of geometric height that accountsfor the dependence of gravity on latitude and height. The result is that such a plot of geopotential height for a single level shows the midlatitude troughs and ridges, that is the Rossby wave pattern of cyclones and anticyclones, while the layer depth, between say, the 700hPa and 500 hPa geopotential heights is proportional to the temperature in that layer. Geopotential height contours can be usedto calculate the geostrophic wind, which blows stronger where thecontours are more closely spaced and tangential to the isolines. www.therfcc.org /geopotential-height-207210.html   (200 words)

 Geopotential height - collegetextbooks.net   (Site not responding. Last check: 2007-10-06) Geopotential is usually represented by the symbol F. Geopotential height is just the geopotential divided by g0, the standard value of gravity (i.e., the globally averaged value of gravity at Earth's surface). Thus, in this region of the atmosphere, the geopotential height Z is within 1% of the actual geometric height z throughout the lowest 100 km -- the troposphere and stratosphere -- of Earth's atmosphere. Geopotential height variations such as these have been observed intensively in the atmosphere since the International Geophysical Year in 1957, giving us a good, long-term record of their behavior and providing a useful record of atmospheric temperature changes. www.collegetextbook.net /sci_geopotential.shtml   (289 words)

 Notes and Problems The geopotential height of the surface level is not given in categories 2 to 4. The geopotential height of the surface report and the station elevation were supplied in the original sounding. Situations were frequently encountered in which the geopotential height at the surface was lower than the station elevation. nsidc.org /data/docs/daac/nsidc0008_hara/problems.html   (871 words)

 Geopotential Height: height of a given pressure The small numbers along the contours are labels which identify the value of a particular height contour (for example 5640 meters, 5580 meters, etc.). The height field is given in meters with an interval of 60 meters. Geopotential height is valuable for locating troughs and ridges which are the upper level counterparts of surface cyclones and anticyclones. ww2010.atmos.uiuc.edu /(Gh)/guides/mtr/cyc/upa/hght.rxml   (156 words)

 Parameter Information Page Geopotential is the potential energy acquired by unit mass on being raised through unit distance in a field of gravitational force of unit strength. The Geopotential meter is related to the Dynamic meter by the expression one geopotential meter=0.98 dynamic meter. Geopotential (from the dynamic point of view) is a better measure of height in the atmosphere than is geometric height since energy is in general lost or gained when air moves along a geometrically level surface but not when it moves along an equigeopotential surface. daac.gsfc.nasa.gov /PIP/shtml/geopotential_height.shtml   (209 words)

 A.Frolov, R.Hudson: CORRELATION OF NORTHERN HEMISPHERE TOTAL OZONE AND GEOPOTENTIAL HEIGHT FIELD.   (Site not responding. Last check: 2007-10-06) The study of the daily geopotential height fields at the level 200 mb and 300 mb from NMC analysis together with the daily total ozone TOMS and SBUV images reveal a strong correlation between total ozone and the geopotential fields for the Northern Hemisphere. The daily geopotential height fields at the level 200 mb and 300 mb from NMC analysis, together with the daily total ozone TOMS and SBUV/2 images reveal a strong correlation between total ozone and the geopotential fields for the Northern Hemisphere [A.M.Shalamyansky and K.I.Romashkina], [A.J.Miller and R.Nagatani]. The Northern Hemisphere geopotential height field at the 200 mb level for June 4, 1990 (12 h GMT) is shown on figure 7. www.atmos.umd.edu /~frolov/paper.html   (1668 words)

 GEOPOTENTIAL HEIGHT   (Site not responding. Last check: 2007-10-06) The height of a given point in the atmosphere in units proportional to the potential energy of unit mass (geopotential) at this height, relative to sea level. The relation, in the cgs system, between the geopotential height H and the geometric height Z is where g is the acceleration of gravity, so that the two heights are numerically interchangeable for most meteorological purposes. At the present time, the geopotential height unit is used for all aerological reports, by convention of the World Meteorological Organization. www.websters-online-dictionary.org /definition/GEOPOTENTIAL+HEIGHT   (206 words)

 USMM Runs The geopotential height field at 100 hPa on day 0 is unchanged and the field is interpolated linearly between days 0 and 4. The geopotential height field at 100 hPa on day 0 is unchanged and the field is interpolated linearly between days 0 and 2. The geopotential height field at 100 hPa on day 0 is unchanged and the field is interpolated linearly between days 0 and 6. www.met.rdg.ac.uk /~wal/usmm.html   (1113 words)

 Aerospace Science and Technology Dictionary G Page The potential energy of a unit mass relative to sea level, numerically equal to the work that would be done in lifting the unit mass from sea level to the height at which the mass is located; commonly expressed in terms of dynamic height or geopotential height. A unit of length used in measuring geopotential height; 1 geopotential meter is equal to 0.98 dynamic meter. Since the earth is rotating, the force observed as gravity is the resultant of the force of gravitation and the centrifugal force arising from this rotation and the use of an earthbound rotating frame of reference. www.hq.nasa.gov /office/hqlibrary/aerospacedictionary/508/g.html   (10020 words)

 Richardson Calculator The change in geopotential height usually determines the stability of the air. If the change in geopotential height is small, the flow is dynamically unstable and turbulent. Geopotential height at the lower geopotential height (z2) www.shodor.org /os411/courses/_master/tools/calculators/richardson   (225 words)

 Encyclopedia: Geopotential height   (Site not responding. Last check: 2007-10-06) Which is just as well, because you wouldn't want to park your car. The density of air, ρ (Greek: rho) (air density), is the mass per volume of Earths atmosphere, and is a useful value in aeronautics. Therefore, a geopotential height observation represents the height of the pressure surface on which the observation was taken. www.nationmaster.com /encyclopedia/Geopotential-height   (535 words)

 Restless Sailor Weather Info   (Site not responding. Last check: 2007-10-06) Black contours indicate the geopotential height of the 500 millibar surface, in tens of meters. Low geopotential height (compared to other locations at the same latitude) indicates the presence of a storm or trough at mid-troposphere levels. Positive (counterclockwise rotation) vorticity at 500 millibars is associated with cyclones or storms at upper levels, and will tend to coincide with troughs in the geopotential height field. restless.to /weather/cola3.htm   (500 words)

 Data Compilation Initial frequency histograms of geopotential height, temperature, wind direction and wind speed were compiled for each layer and for each season in 1987. It was found to be inappropriate for geopotential height; however, due to the logarithmic decay of pressure with increasing elevation. To check the geopotential heights, we made use of this logarithmic relationship: Taking the log of pressure at the bottom (P1) and top (P2) of the layer in which the observed pressure (P) fell, a weight W was calculated: nsidc.org /data/docs/daac/nsidc0008_hara/process.html   (960 words)

 [No title] As a very close approximation: h = H + N where h = ellipsoid height H = orthometric height N = geoid height In theory this equation is not exact because the ellipsoid height is normal to the ellipsoid, orthometric height is normal to the geoid, and these two surfaces are not necessarily parallel. Dynamic heights were computed from geopotential heights (geopotential numbers) which were obtained for all bench marks in the general adjustment of the North American Vertical Datum of 1988 (NAVD88). A related unit for measuring geopotential is the geopotential number (C), which was adopted by the IAG in 1955. ngs.ky.gov /Documents/dsdata.txt   (4071 words)

 MTP Altitude Discussion Allthough pressure altitude is a type of geopotential height, I discuss it separately because of it's importance in atmospheric research. Historically, the motivation for introducing the concept of geopotential height was to come up with a scheme by which the pressure, temperature, and relative humidity measured by radiosondes around the world could be compared on a common altitude scale. In fact, this expression is often used as the definition of the geopotential height. mtp.jpl.nasa.gov /notes/altitude/altitude.html#Zh   (2857 words)

 SVS Animation 3207 - Global 300 hPa Geopotential Height during Hurricane Frances (WMS) This animation shows the altitude above sea level (the geopotential height) of the 300 hectopascal (hPa) pressure surface for the whole globe from September 1, 2004, through September 5, 2004, during the period of Hurricane Frances in the western Atlantic Ocean and Typhoon Songda in the western Pacific Ocean. At this region, air is trying to flow from the equator towards the poles to reduce the slope, but the rotation of the Earth forces the flow to divert to the east, forming the strong west-to-east jet stream flows in these regions. Global 300 hPa geopotential height from the 0.25 degree resolution fvGCM atmospheric model for the period 9/1/2005 through 9/5/2005. svs.gsfc.nasa.gov /vis/a000000/a003200/a003207   (290 words)

 Overland et al. -- Recent Temperature Changes in the Western Arctic during Spring Spatial correlations are summarized in Table 2 between pairs of monthly mean anomaly distributions for March and April for the four years in the 1980s and in the 1990s selected in section 5. The second and third sets of correlations in Table 2, which involve the 850-hPa temperature with the 200-hPa geopotential height and temperature, respectively, are used to indicate the consistency in the nature of the influence of the lower stratosphere on the lower-tropospheric temperature. Our results are consistent with the idea that the principal low-frequency geopotential height anomalies in the Arctic occur in the stratosphere and they are also expressed below in the troposphere, but that tropospheric temperature anomalies result largely from anomalous horizontal temperature advection. www.pmel.noaa.gov /pubs/outstand/over2348/variations.shtml   (801 words)

 NWD Tornado Study   (Site not responding. Last check: 2007-10-06) The (geopotential) heights east of 150W are generally zonal as they move onshore with a broad 300 mb ridge tilted negatively back across Colorado into Idaho. The 500 mb (geopotential) height and temperature axes are located along the Idaho-Oregon border in both Figures 18a and 18b. The 300 mb height pattern for days 3, 2, 1, and 0 days prior to the onset of the CRIT pattern is analyzed in Figure 20. www.nwas.org /ej/pih   (3884 words)

 Help for standard name product_of_eastward_wind_and_geopotential_height   (Site not responding. Last check: 2007-10-06) Y" means X*Y. Geopotential is sum of the specific gravitational potential energy relative to the geoid and the specific centripetal potential energy. Geopotential height is the geopotential divided by the standard acceleration due to gravity. It is numerically similar to the altitude (or geometric height) and not to the quantity with standard name www.cgd.ucar.edu /cgi-bin/eaton/CFStdNameTable/stdnamehelp?product_of_eastward_wind_and_geopotential_height   (88 words)

 Tropical Cyclones Algorithms for determining the temperature, geopotential height and balanced wind fields of tropical cyclones using data from the Advanced Microwave Sounder Unit (AMSU) are being developed. The geopotential heights are determined from the hydrostatic equation, where an NCEP analysis is used for boundary conditions. Hamsu6.gif: Geopotential height field at 400 hPa determined from AMSU data and from NCEP operational analysis for an upper-level trough at 0400 UTC on 6/24/99. www.cira.colostate.edu /RAMM/IN-HOUSE/3qtr99/tropica3.htm   (1323 words)

 50mb Geopotential Height Figure 4.7 shows the first two principal components of Trial A at the 50mb geopotential height. The structure is simpler than that at the 500mb geopotential height. The angular distribution, shown in figure 4.10, has a similar structure as that in the 500mb geopotential height. www.eos.ubc.ca /~psih/library/node13.html   (343 words)

 MADIS Radiosonde Quality Control Moving a layer at a time up from the surface, the height at the top level of the layer is estimated from reported pressure and temperature, then compared against the reported height. The height residual is then tested against a threshold that allows a margin of error based on the depth of the layer, which can span one missing mandatory level. In that event, both the height and temperature at the suspect level are failed by the QC, and the check is not applied to data higher up in the sounding. www-sdd.fsl.noaa.gov /MADIS/madis_raob_qc.html   (1233 words)

 m300l4   (Site not responding. Last check: 2007-10-06) The geopotential is the work that must be done against Earth's gravity in order to raise a 1 kg mass from sea level to altitude z. We can define the geopotential height as the geopotential divided by the acceleration due to gravity at the surface. Usually we consider the scale height, H, to be equal to 7 km. www.ems.psu.edu /~brune/m300f99/m300l4.html   (241 words)

 Homework # 5 Solutions If this station plot is taken from a 250 mb chart, what is the geopotential height at that level (in meters)? If this were taken from a 250 mb chart, we would have to take the height given (069) and decode it by multiplying the value by ten and then adding 10,000. Height (in feet): (There are 3.28 feet in one meter) weather.ou.edu /~metr1111/hw5sol.html   (659 words)

 700hPa Geopotential Height Figure 3 shows a graph of the proportion of correctly classified test patterns against values of k ranging from 1 to 100, for k-nearest neighbour classifiers used to reproduce the Grosswetterlagen catalogue on the basis of the first 18 principal components of the 700hPa geopotential height field. Figure 2: Graph of the proportion of correctly classified patterns against kfor k-nearest neighbour classifiers reproducing the Grosswetterlagen catalogue on the basis of the first 18 principal components of the 700hPa geopotential height field. Table 2 shows a confusion matrix for the optimal 1-nearest neighbour classifier, again using a leave-one-out cross validation approach to estimate the true generalisation performance. theoval.cmp.uea.ac.uk /~gcc/projects/accord/experiments/experiment4a/node4.html   (173 words)

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