Date:    February 19, 1976

Reply to Attn of::      W522xl

Subject:     Transmittal Memorandum for Operations Manual Issuance 76-5

To:    All Holders of Operations Manual

1.    Material Transmitted:

Chapter B-40, Upper Air Stations.

2.    Summary:

This chapter describes the upper air data acquisition programs of the National Weather Service, including types of stations, observational elements, and management policies.

3.    Effect on Other Instructions:

OML 73-16, issued July 6, 1973, now filed with Chapter B-40 should be refiled with Chapter B-99.

George P. Cressman
Director, National Weather Service

Issue Date    Org. Code     NATIONAL WEATHER SERVICE         Part     Chap.
2-19-76        W522x1             Operations Manual                                    B         40

Table of Contents:

1.    Purpose

2.    Upper Air Observational Network

        2. l    National Weather Service Stations
        2.2    NWS Cooperative Stations
        2.3    Other Types of Stations
        2.4    Type of Observations
                2.4.1     Rawinsonde
                2.4.2     Low-Level
                2.4.3     High Altitude
                2.4.4     Pilot Balloon (Pibal)
                2.4.5     Scheduled Observations
                2.4.6     Special Observations

3.     Specifications of Upper Air Data Reported in Observations

3.1    Pressure
3.2    Geopotential Height
3.3    Temperature
3.4    Dew Point Depression
3.5    Wind Direction
3.6    Wind Speed
3.7    Wind Shear
3.8    Low-Level Mean Winds
3.9    Stability Index
3.10    Other Information

4.     Establishment of NWS Upper Air Stations

4.1    Network Criteria
4.2    Station Criteria

5.    Management of the NWS Upper Air Program

5.1     Observational Instructions
        5.1.1    Minicomputer Computation
        5.1.2    Commercial Time-Shared Computer Computation
        5.1.3    Manual Computation
        5.1.4    ADAS Computation
        5.1.5    LO-CATE System Computation
                5.1.6     Coding Instructions
    5.2    Authority for Setting or Altering NWS Upper Air Standards and Procedures
    5.3    Forms Used At NWS Upper Air Stations for Recording and Computing Soundings
    5.4    Required Publications at NWS Upper Air Sites
    5.5    Transmission of Data
    5.6    Priority of Observations
    5.7    Release Procedures at Airports
    5.8    Miscellaneous Station Requirements
            5.8.1     General Theodolite Test
            5.8.2     Rawin-Theodolite Comparison
            5.8.3     Civil Defense Fallout Winds
            5.8.4     Limiting Angle Zone
            5.8.5     Receipt of Instructions
   5.9    Procedures in the Event of Minicomputer Malfunction
    5.10    Quality Control of NWS Upper Air Program
                5.10.1     NWS Field Stations
                5.10.2     Weather Service Forecast Office (WSFO)
                5.10.3     Regional Headquarters
                5.10.4     Weather Service Headquarters (WSH)
                5.10.5     National Climatic Center (NCC)
    5.11    Equipment and Supplies
                5.11.1     Station Maintenance
                5.11.2     Defective Supplies
                5.11.3     Ordering Supplies
                5.11.4     Shortages

1.     Purpose. This chapter describes the upper air data acquisition programs managed by the National Weather Service (NWS). The goal of these programs is to provide accurate and timely data on the vertical and horizontal distributions  of temperature, wind, pressure (Geopotential height), and water vapor. These data, together with simultaneous surface, satellite and radar observations, provide forecasters with a complete three-dimensional picture of the atmosphere.

2.     Upper Air Observational Network. The upper air observational network consists of three categories of stations. These stations are responsible for taking a variety of upper air observations.

2.1     National Weather Service Stations. Included in this category are all land stations taking any kind of upper air sounding and which use NWS-supplied equipment and NWS personnel  (salaries paid by NWS).  Also included are the five Trust Territory stations where the staff, while not NWS are funded from NWS congressional appropriations.

2.2     NWS Cooperative Stations. This category comprises stations located in foreign lands, using standard NWS supplied equipment, but employing native personnel (salaries paid by the native government).

2.3    Other Type of Stations. Other types of upper air stations include those using equipment supplied by an agency  other than the NWS, but employing NWS personnel, and the  NWS ocean ship station.

2.4     Types of Observations. The types of observations taken at upper air stations serve many purposes and are dependent upon the data required or requested.

2.4.1     Rawinsonde. The standard rawinsonde observation serves as the major data source for the upper air program. Data from these observations are used for weather prediction and analysis, for meteorological research, and are exchanged internationally. These data provide a three-dimensional picture of the distribution of pressure, temperature, water vapor, and wind. The rawinsonde consists of sending aloft a balloon-borne instrument, the radiosonde, which telemeters temperature, pressure, and humidity data back to the ground station. Winds aloft are obtained by electronically tracking the radiosonde with precision radio-direction-finding equipment at the ground station. The standard times of observation are 0000 and 1200 GMT. Special observations are taken to provide additiona1 data to Federal and non-Federal agencies conducting meteorological research or as a further aid to forecasters. The rawinsonde observation is made in accordance with Federal Meteorological Handbook (FMH) No. 3, Radiosonde Observations; FMH No. 5, Winds Aloft Observations; and Instruction Manual, NWS Computer System (Upper Air). Coding of the elements observed into the upper air messages is done in accordance with FMH No. 4, Radiosonde Code; FMH No. 6 Upper Wind Code; and Instruction Manual, NWS Computer System (Upper Air).  The messages are collected and transmitted throughout the United States primarily by means of the Service C teletypewriter circuits.

2.4.2     Low-Level. The low-level observation is a sounding which normally terminates at the 700 mb level. It provides a vertical profile of wind, temperature, and relative humidity primarily for the purpose of observing and predicting the capacity of the atmosphere to transport and dilute air pollution. Taken within urban areas using visually tracked, slow ascent balloons for lift (the winds aloft observation when visually tracking the radiosonde is termed a "rabal"), the low-level sounding provides highly resolved and accurate data for the lower atmosphere. Scheduling of low-level soundings is flexible; generally, one or two observations are taken daily, near sunrise and/or in early afternoon. Special observations may be requested. Low-level soundings are made in accordance with FMH No. 3 and FMH No. 5 and encoded in accordance with FMH No. 6.  Stations with minicomputers will also follow instructions contained in Instruction Manual. NWS Computer System (Upper Air).  Dissemination of the coded messages is accomplished by means of the Service C teletypewriter circuits. In addition, the data are employed by local forecasters and may also be required for research projects (i.e., air pollution studies).

2.4.3     High Altitude. The high altitude observation provides rawinsonde data regularly to 100,000 feet. At strategically located stations, special high altitude balloons are used to obtain the required rawinsonde data. High altitude soundings are normally taken only once daily, at 1200 GMT.  Other than the use of a different type balloon to achieve a reliable, high bursting altitude, the high altitude sounding is identical to the standard rawinsonde observation (see 2.4.1).

2.4.4     Pilot Balloon (Pibal). Pibal observations provide low-level (below 20,000 feet) winds aloft information to supplement that obtained from the rawinsonde.  Briefly, the pibal involves visually tracking a small, gas-filled balloon by means of an optical theodolite.  Angular bearings are used in conjunction with an assumed ascent rate of the balloon to compute direction and speed of the winds aloft.  At those stations taking pibals, the standard times of observation are 0600 and/or 1800 GMT. An on-call pibal capability is maintained by stations which have discontinued the routine pibal program.  Special pibals may be requested. Pibal observations are made in accordance with FMH No. 5 and encoded in accordance with FMH No. 6.  Pibal data are transmitted on the Service C teletypewriter circuits.  At stations where the pibal program has been reduced to an on-call capability, it is the responsibility of the MIC/OIC to keep the observers proficient in taking the pibal observation. The MIC/OIC will also be responsible for ensuring that all pibal equipment is in good working order and in sufficient quantity.

2.4.5     Scheduled Observations. By far, the overwhelming mass of upper air data results from the routine, regularly scheduled, daily observations taken by all stations in the NWS upper air network. Depending upon the type of observation taken, the standard times of observation are 0000, 0600, 1200, and 1800 GMT.  The actual times of observation (release times) will be scheduled as close as possible to 2330, 0530, 1130, and 1730 GMT.  Except where authorized, releases will not be scheduled more than 15 minutes earlier nor more than 30 minutes later than the above release times. Releases may be made after the standard times of observation, but in no case later than 1 hour after these times.  Special observations may be made at times other than the standard hours of observation. The data are transmitted throughout the United States, in particular to the National Meteorological Center (NMC) in time to meet the deadlines for NMC analyses.

2.4.6     Special Observations. Certain conditions warrant additional soundings (other than the regularly scheduled flights) to be taken.  These include severe weather situations (i.e. tornadoes, hurricanes and typhoons, blizzards, floods, air pollution, etc.), training, calibration of instruments, and special research projects of agencies outside of the NWS.  NWS units may request special observations on an ad hoc basis, with notification of actions taken sent to their regional headquarters. Specific instructions for requesting special soundings are explained in WSOM Chapter B-90. Flights may also be taken for an outside agency, in almost all cases at that agency's expense. The flights paid for by an outside agency, referred to as "reimbursable" observations, must be approved in advance at both the regional headquarters and the Weather Service Headquarters levels. Depending upon the nature of the request, approval may be granted for an individual sounding or a series of soundings spread out over weeks or months duration.

3.     Specifications of Upper Air Data Reported in Observations. Each of the elements reported in the coded message (radiosonde and upper wind codes) will now be briefly discussed. Details concerning the coded messages are given in FMH No. 4, Radiosonde Code, and FMH No. 6, Upper Wind Code.

3.1     Pressure.  Pressure is reported to the nearest whole millibar (up to and including 100 mb) or to tenths of a millibar (above 100 mb) for the following levels of the sounding:

    a.     surface

    b.     tropopause

    c.     maximum wind

    d.     significant levels with respect to temperature and/or humidity

    e.     extrapolated termination.

3.2     Geopotential Height. Geopotential height is reported in whole meters for levels up to 500 mb and in tens of meters for levels at 500 mb and higher.  It's reported for each mandatory pressure level (standard isobaric surface) of the sounding and for an extrapolated termination level.

3.3     Temperature. For the following levels of the sounding, air temperature is reported in degrees and tenths Celsius:

    a.     surface

    b.     all mandatory levels

    c.     all significant levels with respect to temperature and/or humidity

    d.     tropopause.

3.4     Dew Point Depression. The measure of humidity is reported in the coded message as dew point depression, defined as the result of subtraction of the dew point temperature from the ambient air temperature. It's reported in whole degrees or degrees and tenths Celsius, depending Upon the magnitude of the depression. At temperatures below -40^o C, dew point depression isn't reported, since there is no acceptable capability to measure it with reasonable accuracy.  At relative humidities less than 20 percent, a single dew point depression (30.0) is assigned, since an accurate assessment of water content is difficult to obtain at the lower humidities.   Dew point depression is reported for the levels in 3.3.

3.5     Wind Direction. The wind direction is reported to the nearest 5 degrees for the following levels:

    a.     surface

    b.     all mandatory pressure levels

    c.     tropopause

    d.     maximum wind

    e.     regional and significant levels for wind.

3.6     Wind Speed. Wind speed is reported to the nearest whole knot for the levels in 3.5.

3.7     Wind Shear. The vector differences in the winds 3,000 feet above and below the level of maximum wind are calculated and reported.

3.8     Low-Level Mean Winds. Mean winds for the layer from the surface to 5,000 feet (msl) and from 5,000 feet to 10,000 feet (msl) are calculated and reported (at stations within the contiguous U.S.).

3.9     Stability Index. The stability index is a measure of the degree of stability of the layer of air extending from a level near the surface of the earth to the 500 mb surface.  Positive values denote stable conditions, and negative values unstable conditions. The degree of stability or instability is indicated by the magnitude of the index.  Alaskan stations will make the stability index computation from May 1to  September 30, inclusive.

3.10    Other Information. Also reported are station identification data and data describing irregularities or difficulties in the sounding.

4.     Establishment of NWS Upper Air Stations. Upper air stations are established to meet specific operational and scientific needs for data.  Certain network criteria must be met before a station may be established.  Once a decision is made to establish a station, its actual location is based on station establishment criteria.

4.1     Network Criteria. Ideally, the optimum upper air network for forecasting would be one such that the spacing of stations could resolve all of the different scales of atmospheric motion.  In actuality, however, this isn't possible due to the complex nature of interactions between certain atmospheric phenomena. The maximum density of stations for general forecasting purposes is limited by:

    a.     predictability limits of the atmosphere with large-scale models

    b.     capacity of available or anticipated computers

    c.     budgetary and other economic constraints

    d.     observationa1 technology

With the current state of the art, "optimum" spacing of stations over the contiguous United States is approximately 400 km. In the Pacific, spacing is largely determined by the distribution of islands. To a lesser extent geography also dictates station spacing in the Alaska Region.

4.2     Station Criteria. Site selection for an upper air station shall be a Joint effort by the regional Data Acquisition and Engineering Divisions, in coordination with their counterparts at Weather Service Headquarters. Items of importance to consider when selecting the site are:

    a.     satisfaction of network criteria (see 4.1)

    b.     altitudes of obstructions

    c.     condition of launching area terrain

    d.     availability of areas for placement of tracking equipment, inflation shelter, office space, etc.

    e.     expected costs

    f.     possible encroachment on other interests, environmental impact, etc.

    g.     future plans for the area.

The site of the observing equipment shall be selected in an effort to reduce to a minimum the probability of loss of data due to fixed obstructions.  Altitudes of obstructions should be less than that of the tracking antenna, since an obstruction may seriously affect the ability of the antenna to track the radiosonde whenever the angular altitude of the radiosonde approaches that of the obstruction. The launching area should be flat, smooth, and free of any obstructions which might hinder personnel while releasing the balloon.  Considerable room should be available for observers to maneuver during launches performed under adverse weather conditions.

Angular altitudes of obstructions around theodolites (with the exception of small masts or pipes) shouldn't exceed 6 above the horizontal plane. Avoid installation of the theodolite in close proximity to chimneys so as to eliminate the possibility of smoke obscuring the balloon. Alternate theodolite sites may be established for use under varying wind conditions if a single suitable site isn't available.

5.     Management of the NWS Upper Air Program.

5.1     Observational Instructions. Upper air observations are taken (launch and preparation for launch) and recorded in accordance with instructions contained in FMH No. 3 and FMH No. 5. Instructions in this regard which are peculiar to the LO-CATE system are contained in separate publications (see 5.1.5). Specific instructions for computation and coding of the sounding are contained in the following documents:

5.1.1     Minicomputer Computation. Computation of a sounding by minicomputer will he made in accordance with instructions contained in the Instruction.   Manual for NWS Computer System (Upper Air), No. 9-501.

5.1.2     Commercial Time-Shared Computer Computation. Computation of a sounding by time-shared computer will be made in accordance with instructions contained FMH No. 3 and supplemented by specific computer instructions.

5.1.3 Manual Computation. Manual computation of a sounding will be made in accordance with instructions contained in FMH  No.3 and FMH No.5).

5.1.4     ADAS Computation. Sounding computation using the ADAS (Automatic Data Automatic)n System) will be made in accordance with appropriate instructions prepared by Weather Service Headquarters.

5.1.5     LO-CATE System Computation. Computation of a sounding using the LO-CATE (WL-3 and W-3N) system will be made in accordance with instructions contained in the appropriate manual as prepared by Beukers Laboratories, Inc.

5.1.6     Coding Instructions. Instructions for coding are contained in FMH No. 4 and FMH No. 6. Specific coding instructions for the time-shared computer and minicomputer are found in FMH No. 3 and in Instruction Manual for NWS Computer System (Upper Air), respectively. Particulars for ADAS coding are contained in the specific system operating instructions.

5.2     Authority for Setting or Altering NWS Upper Air Standards and Procedures.  On the national level, Weather Service Headquarters has the sole authority to set or alter standards and procedures for the upper air program. Any regional headquarters may alter or establish regional procedures as long as such changes don't alter or conflict with national policy.  Similarly, supervisors at NWS field stations may alter or establish local procedures as long as such changes don't alter or conflict with either national and/or regional operating policy.

Field stations and regional offices may propose modifications to established national operating policies by means of thorough coordination and discussion with Weather Service Headquarters. Field offices shall first refer any proposed modifications to their regional headquarters.

5.3     Forms Used at NWS Upper Air Stations for Recording and Computing Soundings. Depending upon the method employed to evaluate the sounding, the following forms shall be used by NWS stations taking upper air observations:

a.    minicomputer and ADAS - WS Form B-62 (Rawinsonde Minicomputer Data)

b.    time-shared computer - WS Form B-6 (Rawinsonde Computer Data) and WS Form B-7 (Rawinsonde Computer Data)

c.    manual - MF3-31A, AA, B, and C (Adiabatic Chart), MF5-20 and 21 (Winds Aloft Computation Sheet), and D-31 (Adiabatic Chart D-31, Low-Level Sounding).

5.4     Required Publications at NWS Upper Air Sites. WSOM Chapter A-15 contains a list of publications recommended for the station library of all NWS observing stations.  Included in A-15 is an explanation of the correct procedure to use when ordering these publications. The following publications should be on hand at those NWS stations taking upper air observations, in addition to the publications listed in A-15:

a. FMH No. 3, Radiosonde Observations

b. FMH No. 4, Radiosonde Code

c. FMH No. 5, Winds Aloft Observations

d. FMH No. 6, Upper Wind Code

e. Instruction Manual for NWS Computer System  Upper Air), No. 9-501 through 9-505

f. Radiosonde Tables

g. Pibal Computation Tables.

These publications may be obtained from the Central Logistics Supply Center, Kansas City, Missouri.  It's the responsibility of the MIC or OIC to establish and maintain the publications library.

5.5     Transmission of Data. Maximum effort must be made to meet the scheduled time for transmission of upper air data. The timely receipt of accurate data is not only essential to NWS operations, it's necessary for compliance with national and international data exchange agreements. The deadlines for rawinsonde data receipt currently in effect at the National Meteorological Center (NMC) are:

	NMC Deadline
Type of Data	0000Z Reports	1200Z Reports
Early Transmission	0115Z	1315Z
Part A	0200Z	1400Z
Part B	0255Z	1455Z
Part C	0930Z	2130
Part D	0930Z	2130Z

To ensure receipt of data at NMC, the following methods of communication will be used (in priority order):

    a.     Service C or A-C-O circuits

    b.     RAWARC

    c.     Telephone.

Methods b and c are for contiguous U.S. stations only.  The telephone should be used only as a LAST resort to meet NMC dead1ines.  Although it may be impossible at times to transmit reports on schedule, data communicated late will be used by NMC provided they are received within 10 hours after observation time.  In any event, data should be transmitted at the earliest opportunity to meet established communications schedules.  If complete reports are not available at the scheduled time, partial reports shou1d be communicated and followed by complete reports when ready.  Under no circumstances should one type of report (e.g., TTBB) be communicated at a time specifically scheduled for transmission of another part (e.g., TTAA).  If this mistake is made, loss of the report may result.

5.6     Priority of Observations. Where station personnel have the responsibility of taking both surface and upper air observations, the surface observations shall have priority over the upper air observations.  If balloon release should conflict with the time of a surface observation, the release wi1l be delayed until completion of the surface observation.

5. 7     Release Procedures at Airports.  It's vitally important that correct launch procedures be strictly adhered to whenever radiosondes are released near or at airports.  Where possible, a "Notice to Airmen" (NOTAM) will be filed at least 30 minutes before the radiosonde is released (FMH No. 3 contains instructions for filing NOTAMS).  At or near airports having an operative control tower, observers will inform the tower 30 minutes prior to release, and arrange for clearance from the tower personnel by telephone or visual signal at the actual time of release.  Before the release may be attempted, a visual check to determine if the radiosonde f light train poses a threat to aircraft traffic is required at stations located at or near airports that don't have an operative control tower.

5.8     Miscellaneous Station Requirements.

5.8.1     General Theodolite Test.  All stations capable of taking pibal or rabal observations will perform the general theodolite test, according to instructions contained in FMH No. 5, upon receipt of the theodolite and quarterly thereafter.  A record of each test will be entered in the station log or maintenance record for the theodolite, on WS Form B-29, and on MF5-20 f or the next succeeding pibal or rabal observation in the space above "Reason for Termination." Due to the uncertainty of the time of the next observation, stations taking pibals on an "oncall" basis only aren' t required to note the theodolite test on the MF5-20.

5.8.2     Rawin-Theodolite Comparison.  As soon as possible after the rawin equipment is installed, and at roughly monthly intervals thereafter, each station will take simultaneous rawin and theodolite observations for comparison purposes.   Instructions for taking the comparison are found in FMH No. 5. If possible, the comparative observations should coincide with, and serve the purpose of, a regularly scheduled observation.  If it is impossible to take a comparative during a given month, a continuous angle recording trace may be substituted for a maximum of two consecutive months. Instructions for evaluating the continuous angle recording trace are contained in FMH No. 5.  A duplicate of the time-share or minicomputer data inputs will be provided along with a duplicate WS Form B-17 (if a continuous angle trace is used, the recorder trace is substituted for WS Form B-17) as submissions to regional headquarters.

5.8.3     Civil Defense Fallout Winds.  All rawinsonde stations must maintain the capability for computation of  fallout winds on an on-call basis.   One practice computation must be made at least once every 3 months.  FMH No. 5 and WSOM Chapter I-04 contain detailed instructions.

5.8.4     Limiting Angle Zone. The limiting angle zone for tracking and receiving equipment is regarded as extending 6^o  in elevation above the horizon or above any object (except trees) on the horizon.   For azimuth, the zone extends  from each side of an object.  Wind data will not be computed from elevation angle readings which fall into the limiting angle zone.  Computations using slant range instead of elevation angle will be acceptable even though the signal from the radiosonde is passing through the 1imiting angle zone.  Each station shall prepare a table and diagram of  the horizon seen by the antenna, revising and updating as conditions warrant.  Procedures for the preparation, alteration, and disposition of the table and diagram are explained in FMH No. 5.

5.8.5     Receipt of Instructions.  Receipt of any instructions pertaining to upper air observations shall be acknowledged on the first scheduled observation after their receipt.  Automated stations will make notation of instruction receipt in the "Remarks" column of WS Form B-47, Rawinsonde Monthly Transmittal.  Manual stations  will do  the same under "Remarks" on MF3-31A or AA.

5.9     Procedures in the Event of  Minicomputer Malfunction. (See Interim Change No. 4, Instruction Manual NWS Computer System - Upper Air.)  When the minicomputer is down for operational use (according to the criteria in Interim Change No. 4), commercial time-share backup will be used.  In the unlikely event both the minicomputer and time- share systems are inoperable, scheduled observations will not be taken.  For stations without time-share backup capability, and which. are no longer required to maintain manual proficiency, the scheduled observations will not be made. The station shall not resort  to manual computation of  the sounding after the requirement to maintain manual proficiency has been dropped.  However, the observer must be able to manually code the data messages in order to check the computer's coded message, and in case time-.share backup is used (coded messages are not produced automatically with the time-share system.)

5.10     Quality Control of  NWS Upper Air Program. Quality control of the upper Air program is performed to varying degrees by:

    a.     each upper air unit

    b.     Weather Service Forecast Office (WSFO)

    c.     regional headquarters

    d.     Weather Service Headquarters (WSH)

    e.     National Climatic Center (NCC).

Problem areas are identified and the necessary corrective action is instituted as a result of the monitoring activities of the above offices.  Various reports are prepared and submitted at regular intervals evaluating or documenting station performance and the quality of data and equipment.   A short description of the quality control responsibilities of the units involved will now follow.

5.10.1     NWS Field Stations. NWS field stations are responsible for the initial phases of quality control. Observers are responsible for checking various aspects of the sounding where human error may become a factor (i.e., the correct selection of  levels on the recorder record).  The MIC/OIC must continually keep abreast of his station's performance and institute corrective action when and where it's required.   In addition, each upper air unit is required to prepare and submit a number of reports, some of which deal with:

    a.     performance of radiosondes, batteries, balloons, and ground equipment

    b.     log of the time-shared computers

    c.     inventory of  radiosondes, batteries, balloons, parachutes, and gas cylinders.

Instructions for completing and mailing these reports are contained in FMH No. 3.

5.10.2     Weather Service Forecast Office (WSFO). Each WSFO has on its staff a Weather Service Evaluations Officer (WSEO), among whose duties are station visitations. The visitations are designed to augment the regional headquarters visitation programs. With regard to upper air observations, the WSEO is mainly concerned with the timely dissemination of observational data. WSOM Chapter A-63 describes the WSEO's duties and responsibilities.

5.10.3     Regional Headquarters.  Quality control at the regional level is handled by the Regional Upper Air Specialist. Among his duties are the periodic inspection of the upper air units in his region, followed by the preparation of a complete station inspection report.  He's required to furnish reports to the rawinsonde offices in his region concerning flight performance and error rating. Each station is rated according to the numbers and types of errors committed by observers taking observations. Consistently poor ratings will necessitate corrective measures to be taken by the field station.

5.10.4     Weather Service Headquarters (WSH). Weather Service Headquarters receives copies of the various reports prepared by the other units performing quality control,  and if  it deems necessary, recommends or institutes corrective action.  As a result of quality control input to WSH, the implementation or change of  NWS policy may be required.  WSH performs the function of   focal point for all matters relating to the NWS upper air program and is the final authority on such matters.  Through the Regional Upper Air Specialist,  WSH is kept abreast of conditions in the field that require attention.  A constant dialogue is maintained between WSH and the regional headquarters.  WSH (Office of Technical Services) is also responsible (in conjunction with NMC) for the real-time quality control advisory service.  At specified times each day, the rawinsonde reports are decoded and examined.  Real-time quality control advisories, which indicate non-receipt or errors in the data are produced and transmitted to the appropriate field station so that corrections may be made prior to the NMC analysis deadlines.

5.10.5     National Climatic Center (NCC). Forms and records of soundings are examined by NCC for possible errors.  Error letters are forwarded by NCC to the appropriate station (with copies to the regional headquarters) where the observers responsible will review and initial all the indicated errors.  Error summaries are prepared on all upper air stations and sent to the various supervisory offices.

5.11     Equipment and Supplies.

5.11.1     Station Maintenance. Except as authorized by the electronics technician or other appropriate authority, and specified in FMH No. 3, station personnel are limited to relatively simple, basic maintenance of equipment.  It's important, nevertheless, that station personnel have a good feel for understanding the nature of the symptoms of possible equipment breakdown or malfunction.  The MIC/OIC should make certain that his personnel are knowledgeable in this regard, and with any corrective actions they are authorized to perform.  The MIC/OIC is also responsible for the upkeep of station facilities not directly involved with upper air observations.

5.11.2     Defective Supplies. FMH No. 3 details actions to be taken in the event of the receipt of defective items.

5.11.3 Ordering Supplies. Details on requisitioning supplies are contained in FMH No. 3 and FMH No. 5.

5.11.4     Shortages. Normally, stations should have a sufficient supply of necessary items to continue operations for no less than 20 days beyond the time when new supplies are expected to arrive. In the event that a critical shortage is expected to occur and that omission of observations is likely, and all normal procedures for obtaining supplies have been exhausted, regional headquarters shall be notified at least 7 days before observations are discontinued.

WSOM Issuance
76-5    2-19-76