Geoscience Reference
In-Depth Information
Figures of atmospheric variables in this chapter, and subsequent chapters,
use the NCEP/NCAR and ERA-Interim reanalyses described in the following
references:
Kistler, R., E. Kalnay, W. Collins, and co-authors, 2001: The NCEP-NCAR
50-year Reanalysis: Monthly Means CD-ROM and Documentation.
Bulletin of the American Meteorology Society, 82, 247-268.
Dee, D. P., S. M. Uppala, A. J. Simmons, and co-authors, 2011. The ERA-Interim
Reanalysis: Configuration and performance of the data assimilation system.
Quarterly Journal of the Royal Meteorological Society, 137, 553-597.
Observations of the ocean are plotted from the World Ocean Atlas:
Conkright, M. E., S. Levitus, T. O'Brien, and co-authors, 1998: World
Ocean Database (1998) Documentation and Quality Control. National
Oceanographic Data Center, Silver Spring, MD.
2.7 EXERCISES
2.1. Calculate the following values:
(a) The lapse rate in the troposphere in middle latitudes (say, between 40˚N
and 60˚N) of the Northern Hemisphere.
(b) The zonal mean meridional temperature gradient between 40
º
N and
60
º
N near the surface of the earth.
Express your answers in K/km, and note the relative size of the two
temperature gradients.
2.2 The atmosphere is thin.
(a) A typical horizontal space scale for weather systems in midlatitudes is
1000 km. Assuming that weather systems occupy the full depth of the
troposphere, what is the ratio of the horizontal and vertical space scales
typical of these systems?
(b) How does the magnitude of the meridional temperature gradient in the
atmosphere compare with the magnitude of the lapse rate?
2.3 Wind-driven ocean currents.
Compare the magnitudes and directions of ocean surface currents with
the magnitudes and directions of surface winds. Generalize. Roughly, by
what factor do the low-level wind and the surface current magnitudes
differ? Where do their directions generally agree, and where do they differ?
2.4 Plot vertical profiles of specific humidity at the equator and at 50ºN using
pressure as a vertical coordinate.
2.5 On average for the globe, what is the ratio of the mean evaporation rate
from a unit surface area of ocean to the mean evaporation rate from a unit
surface area of land? What, do you think, is the most important reason for
the difference? (
Note
: The surface of the earth is about 71% ocean.)
