Study Guide (lecture # 16)

Book pages: 177-204, 210-217

Review:

• zonal variations observed in: Radiation, T, V
• Sections: 5.1, 5.2, 5.3, 6.2.3.1,

Today's topics:

• zonal variations of: P, moisture, momentum flux, heat flux, storm tracks, Asian monsoon
• Sections: 5.4, 5.5, 5.6, 5.7, 5.9 (skip 5.8)

Jargon:

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Non Zonal Fields:

- Organize interpretation around these regions that keep being mentioned:

1. near the east coasts of continents (land/sea contrast)
2. near subtropical west coasts (land/sea contrast) (includes deserts)
3. tropical land masses (land/sea contrast)
4. major mountainous areas
5. along midlatitude frontal cyclone tracks (differs from 1. in S. Hemisphere)

• at surface: H & L over land/sea & the seasonal change;
  • subtropical Highs and Hadley cell; ICZ & lowest pressure --> strongest convection;
  • "semi-permanent" (subtropical) highs and (high latitude) lows.
• at upper levels: show time mean long waves -> related to T via thickness; (Region 1)
• time variance map: proxy for storm track. (Region 5)
  • larger on east side of long wave trough
  • broader zonal extent in SH: from S. Atlantic to Australia

• time mean cloud distribution: ICZ snapshot vs time average;
  • relative max in clouds along ICZ with strong preference for land (Region 3)
  • persistent clouds in the eastern subtropical oceans (Region 2)
  • double max in January: Amazonia & Indian ocean vs other areas.
  • rather uniform bands of clouds in midlatitudes along to storm tracks
  • subtropical cloudbands: SPCZ, NPCB, also Atlantic; more prominent in January.
  • cloud amount by cloud top; Region 3 (high), region 2 (low), regions 1 & 5 (middle)
• water mass (specific humidity):
  • strong decrease with latitude
  • moisture convergence over tropical lands (Region 1)
• precipitation: has small scale;
  • compare to zonal mean (triple max);
  • like clouds, enhanced over tropical land masses (Region 1)
  • west side of continents: dry in subtropics (Region 2), wet poleward (east end of region 5)

• transient and stationary waves comparable peak values in NH
• transient eddiss tilts:
  • varies as eddy traverses the long wave (Region 1)
  • NH: poleward then equatorward along the track (Region 5)
  • NH: creates momentum convergence (just poleward of jet) which is K_E to K_Z energy conversion
  • SH: no stationary long waves so flux poleward at most longitudes (required for [M] balance)

• meridional flux: down gradient of T for transient eddies: implies A_Z to A_E (middle of Region 5)
  • dipole pattern for steady eddies (east end of Region 5)
• vertical flux: locations similar as transient eddy meridional flux
  • recall from QG theory: related to A_E to K_E conversion.
  • tends to be positive most places

• preferred development regions (3 categories of regions)
  • WBC's (Region 1);
    • east coasts of N. America and Asia (2 places)
  • other areas of large SST.gradients (i.e. S.W. Indian Ocean)
    • areas of S.H. roughly lined up along dot-dashed line in fig. 5.19c (5 places)
  • lee side of major mountain ranges (region 4);
    • downstream of Rockies and Alps (2 places)
• typical tracks: Highs move equatorward, Lows poleward; as each moves east
  • N. Atlantic track has greater poleward direction than N. Pacific track (on long term average)
• decay regions: Antarctic coast (SH); "semipermanent" lows (NH)

• tropical easterly jet where upper Hadley circulation is equatorward (Arabian sea)
• ‘Walker’ circulation implies mid-ocean upper level troughs
  • mid-ocean troughs transport M to compensate for weak Hadley cell in summer