HR: 1340h
AN: A13A-0903    [Abstracts]
TI: AGCM simulated Great Plains Low-level Jet and its mechanisms
AU: * Jiang, X
EM: xianan.jiang@noaa.gov
AF: AOS Program, Princeton University/GFDL, 201 Forrestal Rd,PO BOX 308, Princeton, NJ 08542
AU: Lau, N
EM: gabriel.lau@noaa.gov
AF: AOS Program, Princeton University/GFDL, 201 Forrestal Rd,PO BOX 308, Princeton, NJ 08542
AU: Held, I M
EM: isaac.held@noaa.gov
AF: AOS Program, Princeton University/GFDL, 201 Forrestal Rd,PO BOX 308, Princeton, NJ 08542
AB: As one of the key components of the summertime climate system over North America, the nocturnal Great Plains low-level jet (GPLLJ) simulated by the GFDL AGCM have been analyzed. Results show that the most important observed features of the GPLLJ are well simulated by the AGCM, including the diurnal phase, amplitude and location. Hence, based on the AGCM output, physical mechanisms for the formation of this nocturnal low-level jet are re-evaluated in the context of two main existing theories, i.e., the alternate heating and cooling of the slopes of the Rockies (Holton 1967) and the inertial oscillation due to frictional decoupling (Blackadar 1957). Results indicate that the observed phase and amplitude of the GPLLJ are largely ascribed to the combination of these two mechanisms. While both of the mechanisms contribute to the amplitude of the GPLLJ, the diurnal peak of the low-level jet resulting from either Holton's or Blackadar's mechanism alone tends to display an unrealistic meridional phase shift. It is also found that terrain induced meridional pressure gradient distribution could be important in determining the location of the GPLLJ center.
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 3337 Global climate models (1626, 4928)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005