Date of Issue:    February 14, l 985            Effective Date:    January1,1985

In Reply Refer To:    W/OTS21x1            File With:   B-60

Subject:     Quality Control of  Surface Observations

Reference(s):     WSOM Chapter B-60, dated February 25, 1983, TM 83-1

Cancels: OML 1-84 dated January 23, 1984, filed with B-60.

Purpose. This OML establishes standard indexes for error rates throughout the National Weather Service (NWS).

Types of Surface Observation Errors:

Operational (OPR). Errors on Meteorological Form MF1-l0A, "Surface Weather Observations," discovered by the National Climatic Data Center (NCDC).

Documentary (DOC). Errors on Form MF1-l0B discovered by NCDC.

Local Climatological Data (LCD). Errors on Form F-6, "Preliminary Local Climatological Data," discovered by NCDC.

Redlining (RL). Errors on Form MF1-l0A, discovered on-station and marked in red after either local or linguine dissemination. (See Federal Meteorological Handbook No.1 (FMC #1), chapter A3, paragraph 1.3.1.2.). The practice of redlining is optional; the decision to do so rests with the Regional Director. Redlining will only be done in instances where there are sufficient positions and available staff time to accomplish it.

NWS Standard Index (Non-Weighted). The Standard Index is applicable to NWS stations and Weather Service Contract Meteorological Observatories (WSCMO) whose contracts are effective after January 1, 1983.

Surface Observations Checked by NCDC. Surface observations checked by NCDC to obtain error data for the preparation of the monthly and yearly quality control evaluation of surface observations include:

Processing of Error Data and Preparation of NCDC Quality Control Evaluation of Surface Observations. On January 1, 1983, NCDC quality control evaluation of surface observations began applying a weighting factor of one for OPR, DOC, and LCD errors. The numerical rating of a station is based on the total number of hourly observations minus the total number of OPR, DOC, and LCD errors divided by the total number of hourly observations multiplied by 100; e.g.,

720-1 x 100 = 99.86 numerical rating.
720

The error data are processed by NCDC and sent to National Headquarters, regional, and central offices. At the end of 1984, the Data Systems Division, Office of Technical Services, updated the NWS Standard Index using a frequency distribution applied to the 1984 data.

NWS Standard Index. Based on the numerical rating of observations for 1 year:

Less than       -	97.64	Well below average
97.64            -	98.76	Below average
98.77            -	99.84	Average
99.85            -	99.94	Above average
Greater than -	99.94	Well above average

All WSCMO's that begin operating under contract after January 1, 1983, will be evaluated using the NWS Standard Index.

NWS Weighted Indexes. WSCMO's that are operating under contract prior to January 1, 1983, will be evaluated using the Weighted Indexes until their respective contracts expire. Upon renewal of the contract, the WSCMO will automatically be evaluated using the Standard Index.

Surface Observations Checked by NCDC. Surface observations checked by NCDC to obtain error data for the preparation of the monthly and yearly quality control evaluation of surface observations include:

Processing of Error Data and Preparation of NCDC Quality Control Evaluation of Surface Observations. NCDC quality control evaluation of surface observations will apply weighted factors of 5 for OPR, 2 for DOC, and 1 for LCD errors. Redline errors are reported but no weight is given; they are not used in determining the numerical rating.

The numerical rating of a station is based on the total weighted errors multiplied by 100 and divided by the number of observations checked by NCDC, e.g., 3 x 100 = 1.10 index
                                                                                        272

The error data are processed by NCDC and sent to National Headquarters, regional, and central offices. At the end of 1982, the Data Systems Division, Office of Technical Services, updated the NWS Weighted Indexes using the gamma distribution function applied to 4 years of data.

NWS Weighted Indexes. Based on the gamma distribution of data from 1978 through 1981:

.00 - .33	Well above average
.34 - .83	Above average
.84 - 2.22	Average
2.23 - 3.83	Below average
Greater than 3.83	Well below average

When opportunities for quality control are limited, priorities for station visits should be given to those stations falling into the "well below" and "below average" categories.

Richard E. Hallgren
Assistant Administrator
    for Weather Services

Date of Issue:     January 1, 1985                  Effective Date:    January 1, 1985

In Reply Refer To:    W/OTS21x1B60        File With:    B-60

Subject:     Microcomputer-Aided Paperless Surface Observations

Reference(s):     WSOM Chapter B-60, dated February 25, 1983, TM 83-1

Purpose. This OML provides National Weather Service (NWS) policy with respect to the Microcomputer-Aided Paperless Surface Observations (MAPSO) program.

Definitions:

Backup. A procedure, technique, or hardware intended to be used in an emergency to help recover lost or destroyed data or to help keep a system running.

Hardware. Physical equipment, as opposed to the computer program or method of use, e.g., mechanical, magnetic, electrical, or electronic devices.

Software. A set of computer programs, procedures, and possibly associated documentations concerned with the operation of a data processing system.

Equipment Approval:

All hardware or equipment used in the MAPSO program must be approved by Data Systems Division (DSD), Office of Technical Services (OTS), and the AFOS Configuration Management Board, prior to implementation.

Software Control:

MAPSO program software will be provided and controlled by NWS Headquarters. Any changes or alterations to the software must be approved by DSD and Engineering Software Analysis Branch, OTS, prior to implementation.

Electronic Data Transfer:

The method employed for electronic transfer at any MAPSO program site must be one of those described in Part B of Federal Meteorological Handbook No. 1 (FMH #1).

System Failure:

Backup procedures employed in the event of system failure must be in accordance with instructions filed in Part B of FMH #1.

Richard E. Hallgren
Assistant Administrator
   for Weather Services