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---
layout: default
title: Report Series
---
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta name="Author" content="Anna McCravy">
<meta name="GENERATOR" content="Mozilla/4.51 [en] (WinNT; U) [Netscape]">
<title>rpt26</title>
</head>
<body text="#000000" bgcolor="#FFFFFF" link="#0000FF" vlink="#0000FF" alink="#FF0000">
<h1>Report 26: Uncertainties in Global
Ocean Surface Heat Flux Climatologies Derived from Ship Observations</h1>
<ul><b>Gleckler,</b> Peter J. and Bryan C. Weare
<br>August 1995, 40 pp.
<hr>A methodology to define uncertainties associated with ocean surface
heat flux calculations has been developed and applied to a revised version
of the Oberhuber (1988) global climatology, which utilizes a summary of
the COADS surface observations. Systematic and random uncertainties in
the net oceanic heat flux and each of its four components at individual
grid points and for zonal averages have been estimated for each calendar
month and the annual mean.
<p>The most important uncertainties of the 2° x 2° grid cell values
of each of the heat fluxes are described. Annual mean net shortwave flux
random uncertainties associated with errors in estimating cloud cover in
the tropics yield total uncertainties which are greater than 25 W m^-2.
In the northern latitudes, where the large number of observations substantially
reduce the influence of these random errors, the systematic uncertainties
in the utilized parameterization are largely responsible for total uncertainties
in the shortwave fluxes which usually remain greater than 10 W m^-2. Systematic
uncertainties dominate in the zonal means because spatial averaging has
led to a further reduction of the random errors. The situation for the
annual mean latent heat flux is somewhat different in that even for grid
point values the contributions of the systematic uncertainties tend to
be larger than those of the random uncertainties at most all latitudes.
Latent heat flux uncertainties are greater than 20 W m^-2 nearly everywhere
south of 40°N , and in excess of 30 W m^-2 over broad areas of the
subtropics, even those with large numbers of observations. Resulting zonal
mean latent heat uncertainties are largest (~30 W m^-2) in the middle latitudes
and subtropics and smallest (~10-25 W m^-2) near the equator and over the
northernmost regions.
<p>Preliminary comparison of zonal average fluxes suggest that most atmospheric
general circulation models produce excessively large ocean surface fluxes
of net solar heating and evaporative cooling when forced with realistic
sea surface temperatures. It is expected that the method introduced here
will be refined to produce increasingly reliable estimates of uncertainties
in surface flux atlases derived from ship observations. <a href="pdf/rep26.pdf">(pdf
file)</a>
</ul>
<p><font size=-1>UCRL-MI-123395</font></p>