NCMRWF Weekly Data Monitoring Report 26/11/2007 to 02/12/2007 Data Processing and Monitoring Group Permission to quote from this report Should be obtained from Head, NCMRWF NATIONAL CENTRE FOR MEDIUM RANGE WEATHER FORECASTING (MINISTRY OF EARTH SCIENCES) A-50, Institutional Area, Phase-II, Sector-62, NOIDA (U.P.) – 201307 INDIA
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NCMRWF Weekly Data Monitoring Report
26/11/2007 to 02/12/2007
Data Processing and Monitoring Group
Permission to quote from this report Should be obtained from Head, NCMRWF
NATIONAL CENTRE FOR MEDIUM RANGE WEATHER FORECASTING
(MINISTRY OF EARTH SCIENCES) A-50, Institutional Area,
As a weekly publication, the NCMRWF Data Monitoring Report presents a general view of the data availability for the whole month as well as its quality. Data produced by the Global Observing System, transmitted by the Global Telecommunication System and received by the India meteorological Department at New Delhi is relayed to the NCMRWF data processing system. This report consists of the results of quantity monitoring of all the data received at the NCMRWF including delayed data upto a period of three days. It may however be mentioned that data which goes into the analysis-forecast system is likely to be less because of the cut-off time. Besides quantity monitoring, the report also presents results of quality monitoring for the Indian subcontinent (blocks 42 and 43) data only. For quality monitoring only those data, which are received at the NCMRWF within the cut-off time are used.
The zone of responsibility of the RTH New Delhi as far as the collection
(through the main telecommunication network) and processing of observational data is concerned includes India, Pakistan, Bangladesh, Nepal, Bhutan, Sri Lanka, Maldives, Burma and adjoining sea and ocean areas. Objective monitoring of the quality of the data ( for block 42 and 43 only) is undertaken by the NCMRWF as a weekly activity. Tables are prepared following the Commission for Basic System (CBS) recommended format so that the monitoring results can be immediately compared with those from other meteorological centers. This is an important task, because frequent comparisons of this kind are absolutely necessary for improvement of the quality of tropical data.
Following the establishment procedure at other major weather forecasting
centers the model first guess has been used in determining data quality. This approach assumes a very accurate first guess, which is not necessarily valid in data sparse regions like the tropics and also due to model systematic errors. As a result the quality monitoring of tropical data is a difficult task, and any judgment has to be arrived at carefully.
This report is an outcome of the combined effort of the Data Processing
and Monitoring Group of the NCMRWF. Cooperation of the other groups at the NCMRWF as well as that of the Computer Maintenance Corporation is acknowledged. Comments and suggestions are welcome and should be sent to :
Head, NCMRWF Attn: Data Processing and Monitoring Group NCMRWF, A-50, Institutional Area, Phase-II, Sector-62 NOIDA (U.P.) – 201307 INDIA
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2. NCMRWF MONITORING STATISTICS
Availability (global) and data quality (for WMO blocks 42 and 43 only) are presented in figures and tables of which only very brief descriptions are given below. Complete explanations are given at the end of this report.
Data Availability (Global observations, weekly average)
Figs. 1.1 – 1.7 are global charts for all seven types of observations, received at the NCMRWF. Each number is the average for 24 hours, over all observations of the particular type received in a 5-degree box. Fig Observation Type Parameter Level/Layer 1.1 SYNOP / SHIP MSL Pressure Surface 1.2 TEMP Geo-potential 500 hPa 1.3 TEMP / PILOT Wind 300 hPa 1.4 AIREP Wind 300 – 150 hPa 1.6 (a) SATOB Wind 400 – 150 hPa 1.6 (b) SATOB Wind 1000 – 700 hPa 1.7 BUOY MSL Pressure Surface
Data Availability (Number of daily reports)
Figs. 2.1 – 2.7 are histograms for all seven types of reports received at the NCMRWF. Each figure represents number of reports of the particular type for each day of the month.
Fig Observation Type Parameter 2.1 SYNOP / SHIP MSL Pressure 2.2 TEMP Geo-potential / Wind 2.3 PILOT Wind 2.4 AIREP Wind 2.6 SATOB Wind 2.7 BUOY MSL Pressure
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TABLE 1 RESULTS OF COMPLEX QUALITY CONTROL OF RADIOSONDE
MANDATORY LEVEL HEIGHTS AND TEMPERATURES FOR 26 11 2007 TO 2 12 2007
The material presented in this report is based on the data that is received by the India Meteorological department and relayed to the NCMRWF in a delayed mode. Half hourly data are received 48 times a day, with an average delay of almost 20 minutes from the real time, from 01 April 1997. Analysis is performed for all the four synoptic hours, and therefore the assimilation cycle is run continuously to produce the first-guess (six-hour forecast) for the analysis step. The five-day forecast however, is started only from the 00Z initial conditions.
Data Availability
The average number of reports of each type received per day in a 5-degree
square box and rounded off to the nearest integer is indicated for the whole globe (Fig. 1.1 – 1.7). Four such numbers are actually displayed inside a 10-degree box for convenience. The integer 0 means that the average number of observations in the smaller box was less than 0.5. If no observation was received at all in the smaller box, then no number is printed for that smaller box.
Histograms for the number of daily reports of a particular type received at the
NCMRWF are shown (Fig. 2.1 – 2.7). This is important in monitoring the steadiness of the reception rate. It can be seen that on some days the number of reports received fall off drastically. In most of the cases they are traced to computer problems at the data reception centre.
Monitoring of quality and quantity of Global Radiosonde Reports (land) by
Complex Quality Control (CQC). Table 1 presents the total number of land radiosonde reports received for the
month (by WMO Blocks), the number of hydrostatic errors detected in these reports by the CQC and the percent of corrections performed that are confident corrections.
Indian data frequency
Table 2 shows the number of times an upper air station within WMO block 42
or 43 reported in this month. The lists of stations are in accordance with the latest WMO directory. The numbers for 00Z, 06Z, 12Z and 18Z are listed in separate columns. All stations that are expected to report are listed including those stations, which did not report even once during the whole month. It is seen that there are variations in reporting frequencies.
Indian data Quality
Tables 3-6 represent the results of quality monitoring statistics carried out at
the NCMRWF for the upper air stations under the WMO blocks 42 and 43 only. The conventional procedure is followed, which is that of first computing the normalized magnitude of the observation minus, first guess interpolated to the observation point ( the ‘residual’) and then comparing this value against a preset limit as well checking the consistency of this value against similar values in the neighborhood. The rationale of this approach is based on the work of A. Hollingsworth et. al., Weekly Weather Review, Vol.114, No.5, May 1986 where the authors demonstrated the ability of modern data
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assimilation system to monitor the quality of an observational network. However, in the tropics these results have to be accepted with caution for two reasons:
(1) As mentioned before, the above procedure assumes high quality first guess,
which is not guaranteed in a data sparse area like the tropics.
(2) Since small scale features like convection play a dominant role in the tropical atmosphere, sometimes there might be a mismatch between this scale and that of the first guess which is determined by the forecast model.
Tables 3a and 3b present the number of observations received, rejection by the
analysis (in percentage), total bias, standard deviation and root mean square for the 100 hPa geo-potential heights, for 00Z and 12Z respectively in units of meters. Tables 4a and 4b are similar tables for 500 hPa geo-potential heights. Tables 5a and 5b present similar results for 100 hPa dry temperatures and tables 6a and 6b present similar results for 500 hPa dry temperatures. Tables 7a and 7b show similar results for 100 hPa zonal winds, and tables 8a and 8b similar results for 500 hPa zonal winds. Tables 9a and 9b show similar results for 100 hPa meridional winds and tables 10a and 10b present similar results for 500 hPa meridional winds.
SYNOP - Number of Reports For 26/11 to 02/12, 2007
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
1 2 3 4 5 6 7
Fig. 2.1
-- R
epor
ts --
>
TEMP - Number of Reports For 26/11 to 02/12, 2007
1060
1080
1100
1120
1140
1160
1180
1200
1220
1240
1 2 3 4 5 6 7
Fig. 2.2
-- R
epor
ts --
>
PILOT - Number of Reports For 26/11 to 02/12, 2007
0
100
200
300
400
500
600
700
800
900
1 2 3 4 5 6 7
Fig. 2.3
-- R
epor
ts --
>
AIREP - Number of Reports For 26/11 to 02/12, 2007
0
20000
40000
60000
80000
100000
120000
140000
160000
1 2 3 4 5 6 7
Fig. 2.4
-- R
epor
ts --
>
SATOB - Number of Reports For 26/11 to 02/12, 2007