CrossSection Analysis metr 2413 April 2 2004 CrossSection

Cross-Section Analysis metr 2413 April 2, 2004

Cross-Section Analysis l Illustrates the vertical structure of the atmosphere (2 D vs 1 D) l Compliments horizontal analyses to help diagnose three-dimensional structure l Helps to determine the location of jets, fronts and other stable layers

Analysis of soundings l From a horizontal chart, identify the features you want to analyze (fronts, jet stream, etc. ) l Determine a “line” of radiosonde stations which is perpendicular to this feature.

Identification of stable layers l The second step is to locate the stable layers and tropopause in each of the soundings. If some of the stable layers represent fronts and can be identified on two or more adjacent soundings, they should be connected. The tropopause should be connected where it is behaving as a material surface. Cross-section analysis l On the cross-section chart, perform scalar analysis of temperature, potential temperature, winds, mixing ratio and others

Thermal Wind Relationship in Isentropic Coordinates l Isentropic surfaces have a steep slope in regions of fronts. Flat isentropes indicate more unstable conditions and little/no change of the wind with height. l Frontal zones are characterized by sloping isentropic surfaces which are vertically compacted (indicating strong static stability). l In the stratosphere the static stability increases by about one order of magnitude.

Isentropic Mean Meridional Cross Section

Isentropes near Frontal Zones

Surface Map for 12 UTC 30 December 1990

Cross Section Taken Normal to Arctic Frontal Zone: 12 UTC 30 December 1990

Surface Map for 00 UTC 27 November 2001 DTX DDC

Sample Cross section for 00 UTC 27 November 2001

Lab Assignment 11 l Using upper air soundings, construct your own cross-section from Brownsville, TX (BRO) to Aberdeen, SD (ABR) using the following location for data: ¡ ¡ ¡ ¡ l l l Brownsville, TX (BRO) Corpus Christi, TX (CRP) Dallas/Ft. Worth, TX (FWD) Norman, OK (OUN) Topeka, KS (TOP) Omaha, NE (OAX) Aberdeen, SD (ABR) Data should be from 12 Z April 2, 2004 Vertical coordinate should be pressure Plot potential temperature and mixing ratio

310 K @ 600 mb 305 K @ 700 mb 297 K @ 800 mb 290 K @ 900 mb

300 K @ 600 mb 297 K @ 700 mb 289 K @ 800 mb 285 K @ 900 mb

309 K @ 600 mb 303 K @ 700 mb 297 K @ 800 mb 285 K @ 900 mb

Additional Notes l On your chart, identify the location of the tropopause and any fronts that may be present l The lab assignment and all relevant soundings are located at weather. ou. edu/~metr 2413 l Office Hours: Tuesday/Thursday 1: 30 -2: 30 SEC 1370