VALENCIA ANCHOR STATION

Reference Meteorological Station for Remote Sensing data and products and Climate Change studies


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Quality Control of the Valencia Anchor Station data
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Quality of the Valencia Anchor Station data

To carry out scientific studies with long temporary meteorological data series it's required to employ fiable measurements. That is the main point to use a Quality Control in the data base. Quality Control is a procedure to provide information about the kindness of the analyzed measurements.

Quality Control implanted in Valencia Anchor Station (VAS) is based on code developed by Baseline Surface Radiation Network (BSRN) http://bsrn.ethz.ch/. At the moment, it's only applied to measured radiation parameters in the station (Downwelling and Upwelling Long wave radiation, Incident and Reflected Short wave radiation), but it is pretended a next ampliance for new meteorological parameters.



Flagging the data throught automated procedures

Quality Control run five analysis procedures for each data, every time more rigorous control operations to obtain an optimal result. When they get through every one of these controls are analyzed and labeled with a different control flag based on the result of this study. The result of these five flags digits give information about Quality Control realized. The quality codes together with the respective five quality control procedures are listed in the table below:



Last two procedures do not work yet, because of we have not physic model to run 4º procedure and 5º procedure is not yet defined.



Physic procedures of Quality Control

In this section we are going to specify the incoming parameters in Quality Control, as well as the procedures used for each one of these parameters.

The meaning of employed expressions on interval definitions can be seen in Anex. 1

- 1º Procedure: Physically possible limits
- 2º Procedure: Extremely rare limits
- 3º Procedure: Comparisons between magnitudes

1º Procedure: Physically possible limits

GLOBAL SW (DIRECT + DIFFUSE RADIATION)

Min: -4 Wm-2

Max: Sa x 1.5 x µ01.2 + 100 Wm-2

 

REFLECTED UPWELLING SW RADIATION

Min: -4 Wm-2

Max: Sa x 1.2 x µ01.2 + 50 Wm-2

 

DOWNWELLING LW RADIATION

Min: 40 Wm-2

Max: 700 Wm-2

 

UPWELLING EMITTED LW RADIATION

Min: 40 Wm-2

Max: 900 Wm-2



2º Procedure: Extremely rare limits

GLOBAL SW (DIRECT + DIFFUSE RADIATION)

Min: -2 Wm-2

Max: Sa x 1.2 x µ01.2 + 50 Wm-2

 

REFLECTED UPWELLING SW RADIATION

Min: -2 Wm-2

Max: Sa x µ01.2 + 50 Wm-2

 

DOWNWELLING LW RADIATION

Min: 60 Wm-2

Max: 500 Wm-2

 

UPWELLING EMITTED LW RADIATION

Min: 60 Wm-2

Max: 700 Wm-2



3º Procedure: Comparisons between magnitudes

COMPARISON BETWEEN LWdown AND AIR TEMPERATURE (2m)

0.4 x sTa  <  LWdown  <  sTa + 25

 

COMPARISON BETWEEN LWup AND AIR TEMPERATURE (2m)

s(Ta – 15 K)4  <  LWup  <  s(Ta + 25 K)4

 

COMPARISON BETWEEN DOWNWELLING AND UPWELLING LW

LWdown  <  Lwup + 25 Wm-2

LWdown  >  Lwup - 300 Wm-2

 

ANEX 1.

 

SZA = Solar Zenith Angle

µ0 = cos(SZA)

S0 = Solar constant at mean Earth-Sun distance, S0= 1368 Wm-2

AU = Earht-Sun distance in Astronomical Units, 1 AU = Mean T-S distance

Sa = S0/AU2 = Solar constant adjusted for Earht-Sun distance

s = Stephan-Boltzman constant = 5.67 x 10-8 Wm-2 K-4

Ta = Air temperature (2m) in Kelvin

Global SW: Incident SW mesured by unshaded pyranometer

Reflected SW radiation: Reflected SW mesured by unshaded pyranometer

LWdown: Downwelling LW mesured by pirgeometer

LWup: Upwelling LW mesured by pirgeometer

Result visualization

The results of Quality Control are available with the station data download. Here are attached four archive images for the visualization of the obtained results, one for each parameter studied.

There are two types of results: monthly and annual summaries, depending on the downloaded data. An example of a monthly/annual report can be seen here.

MONTHLY QUICK VIEW REPORT



On the picture we can observe the result for a individual month, after the aplication of Quality Control. Evaluated parameter and the month name appears in the top of this picture, on the vertical axis are the five procedures processed, and finally, in graph legend the different colors show the five chosen intervals:

·       0-2.5 %  error data

·       2.5-5 %  error data

·       5-7.5 %  error data

·       7.5-10 %  error data

·       >10 %  error data

·       No data – Without information, no processed data.

ANNUAL QUICK VIEW REPORT



In the figure we can see the result for a complete year after the aplication of Quality Control. In the top of image appear the evaluated parameter, on vertical axis are the five procedures processed, on the abcisa axis we can find the twelve analyzed months, and the graph legend is at bottom, analogous to the legend of the mounthly quick view summary.