Data support activities for the Marine Weather Service Program are outlined. Forecasts, cover anomolous water levels, including sea and swell, surface and breakers, and storm surge. Advisories are also provided for sea ice on the Great Lake and Cook inlet in winter, and in the Bering, Chukchi, and Beaufort Seas in summer. Attempts were made to deal with ocean currents in the Gulf Stream, areas of upwelling, and thermal structure at least down through the mixed layer

Mccaslin, R. W.

Mull, M.

Travers, J.

English

NASA Technical Reports Server

Data Requirements in Support of the Marine Weather Service Program 13
I. Introduction
J. Travers, R. McCaslin, and M. Mull
NOAA/National Weather Service ._ .
Silver Spring, Maryland 20910 _ N 7 S" I 5 8 8 2
The National Weather Service (NWS) furnishes weather and river fore-
casts and warnings to the public, and provides specialized services
concerned with marine, aviation, agricultural and forestry operations
and air pollution control.
Historically, marine weather support was a principal basis for the
development of a government weather service, beginning with a Congres-
sional Resolution in 1870. In 1891 the newly established Weather Bureau
took over the weather services, and finally, just a year ago with the
formation of NOAA we became the National Weather Service, with a con-
stantly growing awareness of, and interest in, serving mariners, boat-
men, and all others who work or relax in the marine environment.
Much of the work within the National Weather Service has to do with the
description and prediction of weather patterns over most of the globe,
and the closely related sea and swell patterns in ocean areas. The
operating program is widespread. Its personnel are found at approximately
400 facilities within the 50 states, at 15 overseas stations, 7 ocean sta-
tions, and 20 moving ships. To meet our responsibilities for the provision
of forecasts and warnings over wide areas of the globe, rapid receipt and
processing of global data are required on a continuing and regular basis.
Data must be gathered in real-time, within one to three hours or so, from
international organized networks covering the land and ocean areas, and
extending up through the atmosphere. The inter-relations of the fluid
envelope are such that these data are required even for forecasting the
state of the ocean.
In order to satisfactorily predict future conditions of the atmosphere and
the ocean, it is necessary that we have a running account of these condi-
tions delivered to the forecasters at regular intervals and as soon after
the observations as is possible. Any data delayed in delivery may be use-
ful for climatological purposes or for hind-casting, but it simply does
not exist as far as the forecaster is concerned. As high-speed communica-
tions improve, so our operational weather data base improves. We reached
the point about 15 years ago where high-speed computers became necessary
to assimilate the vast amount of data. Computers at the National Meteoro-
logical Center, aided by human judgment and prompting, calculate the broad-
scale weather analyses and predictions, and the results are immediately
relayed by teletypewriters and facsimile machine to "the field."
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https://ntrs.nasa.gov/search.jsp?R=19730006655 2020-03-17T07:40:57+00:00Z
Our field forecast offices use the hroadscale predicted patterns and
statements as guidance in preparing forecasts for their respective areas
of responsibility, and these forecasts in turn are further refined for
local use by Weather Service Offices (WSOs)scattered in communities
throughout the country. These forecasts include, as applicable, informa-
tion on wind, waves, weather, air temperature, and visibility. At coast-
al locations the Weather Service Offices makeavailable the astronomical
tide predictions and in somecases also the "surf" temperature. In addi-
tion to the general public services, we provide more specialized services
to agriculture, aviation and other weather-sensitive endeavors, including,
of course, marine interests on the high seas, in coastal waters, and on
the Great Lakes. Becauseof the special threats presented by severe local
stGrms and by hurricanes, expertise and communications necessary to deal
_ith these phenomenaare concentrated at a few key locations. The
National Severe Storms Forecast Center at Kansas City rides herd on tor-
nadoes, severe thunderstorms and the llke, while the wild ocean storms
are handled by the National Hurricane Center, Miami, and our forecast of-
fices at San Francisco and Honolulu. Storm surge and high waves are fore-
cast, along with atmospheric phenomena.
Very briefly, the marine service program is concerned with furnishing
information on the present state of the marine environment, predictions
of future developments, and Warnings of expected hazardous conditions.
Timely warnings of severe storms, hurricanes, andother marine environ-
mental hazards contribute substantially to the safety and efficiency of
marine operations. Ships on the high seas use regularly broadcast warn-
ings and forecasts to navigate around severe storms, to select time-_avlng
routes, and to schedule shipboard operations.
Our present program includes information about anomolouswater levels, in-
cluding sea and swell, surf and breakers, and storm surge. Advisories
concerning sea ice on the Great Lakes and Cook Inlet in winter, and in
the Bering, Chukchi, and Beaufort Seas in summer, are a part of our exist-
ing program. In _the future we hope to do more. Wethink we can deal with
ocean currents such as the Gulf Stream, with areas of upwelling, with the
thermal structure at least downthrough the mixed layer, and with the day
to day anomolies in the tide height and tidal currents. To gather data
necessary for this ambitious program we will look to various methods,
including in sltu measurementsand surface-based remote sensing as well
as to satellites.
The NWSis working very closely with the National Data Buoy Project people
and otherNOAA componentsin marine instrumentation. Although the NWSis
involved in somesensor development, our principal efforts lie in helping
to devise methods for rapid data relay, in improving forecast techniques,
and in finding ways toreach the people who need our service products.
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iII. Present Data and Problems
At the present time we have, in addition to observations from coastline
points and islands, regularly scheduled observations from seven "sta-
tionary" ships in the Atlantic and Eastern Pacific, from 20 moving ships
that carry NWS personnel, and from a great many moving ships that have
NWS instrumentation. The reports are collected each six hours, averaging
about 560 reports _ each collection period. Unfortunately, only about three-
fourths of these arrive at the National Meteorological Center (NMC) in
time to be included in the working analyses. In addition to observed
weather phenomena and the barometric pressure, the reports include wind
speed and direction, wave and swell height, period, and direction, air
temperature and dew point, ice information, and sea surface temperature.
Unfortunately, these ship reports come almost entirely from ships on well-
traveled regular trade routes, leaving very large areas of the oceans
unreported.
In addition there are reports from shore stations and a limited number of
reports from airlines over the ocean, and while these aircraft reports
do not speak directly to surface conditions, we can make large scale
inferences from their altimetry and wind calculations. From satellites
we already have a limited subjective ocean roughness parameter, in that
the sun glint from the ocean surface has different characteristics and
brightness with different surface conditions.
ii We hope to enroll additional ships into the internationally sponsored
cooperative ship program, to at least make our data base mere dense ever
the trade routes. Furthermore, these ships and those already in the pro-
gram provide potential platforms for obtaining bathythermograph data as
well as additional ocean surface data. We have some hope for this new
data now because of our cooperation, along with other NOAA elements and
other government agencies, in the Integrated Global Ocean Stations Systems
(IGOSS), a joint effort of the Intergovernmental Oceanographic Commission
and the World Meteorological Organization. The first phase of the IGOSS
° will be to Obtain and distribute bathythermograph data in real time. The
target date for commencing this new data distribution is January 1972.
!_ Satellite observations of sea surface temperature, already available , will
be incorporated with those from ships, for a complete analysis of this
/i parameter.
III. Needs For Sea Surface Data
_i_ The National Weather Service has agreed in principle to common DOC-DOD
requirements for sea state data in the Federal Plan for Meteorological
Data from Satellites. As stated in that document they are:
_3-3
Waves (sea and swell) (global and local)
Frequency of observation 4 obs per day
'i'ii:_ Timeliness (receipt after obs) 3 hours
Grid spacing i00 n.m. (over open ocean:
i
ii
Vertical resolution
closer near shores)
2 ft. intervals 0-10 ft.
5 ft. intervals 10-30 ft.
i0 ft. intervals above 30 ft.
The Federal Plan also states a common requirement for location accuracy of
one nautical mile. However, it seems that a location accuracy of 4 or
5 n.m. will meet National Weather Service needs for a few years.
The above requirements are for data over the high seas in the Northern
Hemisphere, and will be used to furnish a base line for our numerical
wave prediction model. They should be looked on as goals for satellite
observation capabilities in the next 5 years or more.
The principal requirement of NWS is for information concerning wave height.
In addition, some measure of wave direction and of length or period would
be useful. If these requirements cannotbe met, it would still be useful
to have an indication of roughness or some other parameter that can be re-
lated to wave energy, which in turn can be related to wave heights.
Other anomalous water levels are also of interest, such as storm surge,
and lesser deviations from astronomical tide calculations, changes in
Great Lake levels due to wind set-up or seiche, and surf and breakers
along the coast. The above requirements represent the more urgent opera-
tional concerns of the Marine Weather Service Program of _4S.
As the satellite's capability to provide more quantitative data grows, we
expect to use such data as direct input to the numerical wave prediction
model. The availability of such data should result in increased accuracy
of sea state predictions. In terms of safety of life and property on the
high seas, sea state is one of the most important parameters.
Tide gage observations of wave height are desired to an accuracy of one
foot or 10%. However, from the point of view of remote sensors, let us
assume that this represents a future research need which might become an
operational need several years from now.
Numerical weather analysis programs at the National Meteorological Center
are capable of handling input weather data in many forms. Objective
13-4
analysis schemes used on the computer to prepare input for numerical
weather forecast models can be designed to weight various forms of input
data according to accuracy and timeliness. Thus, the derived surface
wind speeds in the range from about 5 to 30 knots said to be possible
from radar scatterometry data could be integrated into the forecast sys-
tem. The speed information merged with wind speed and direction observa-
tions from ships and islands would be helpful over the broad ocean areas
for wind, weather and sea state forecasts.
IV. Summary
One of the greatest responsibilities of the NWS is to provide forecasts
of atmospheric and ocean surface conditions over vast areas where data is
usually scarce and sometimes unreliable. An improvement in our services
would represent a considerable improvement in the safety and efficiency
of shipping and fishing industries, and in the safety of the growing
population of those who find recreation on the oceans and Great Lakes.
Our efforts toward improved services are considerably hampered by lack of
information concerning those parameters we hope to forecast. We have tra-
ditionally depended largely on our prime users, the ships at sea, for our
data. It is a little ironic that the better we get in forecasting, the
less data we have from storm areas, rough sea areas, and ice areas. Fur-
thermore, there are large parts of the oceans not usually populated with
ships in normal commerce. Therefore our requirements for additional data
are immediate and will be of long standing, and hopefully can be met in
part by observations from satellites.
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Data requirements in support of the marine weather service program

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