The Concept of Quality of Meteorological Data

Inclusion of Remote Sensing?

Tor Håkon Sivertsen

The Norwegian Crop Research Institute

What is Quality of Data?

(a)The properties, conditions and value of the data, including

completeness and representativeness

(b) The identity (social system) producing the data (giving the

data authority)(c) The availabilty of the data

(d) The presentation of the data including the context of the

presentation

An Interpretation of the Hypothetico-Deductive

Principle

A Documentation System for Parameters (a) Measured

(b) In Models

• Name of the parameter

• Unit

• Defintion

• Method(s) for measurement

• Representative-ness for certain phernomena

• Connection to measuring system

• Name of the parameter

• Unit• Definition• Representative-

ness of phenomena in model cosidered

• Representative-ness for phenomena in other models

• Connection to modelling system

Phenomena and the Concept of

Precipitation• Different parameters connected to

different models ( different spatial and temporal scales)

• Different parameters connected to different ways of making measurements

• Rain gauge measurements and spatialisation of rain gauge measurements

• Weather radar measurements • Combination of these types of

measuring systems

Precipitation from rain gauge RR

• Name of the parameter:Accumulated hourly value of the precipitation measured by some gauge placed between 1.5 m above the ground and the ground.  

• Unit: mm (m3/ m2) x 1000

• Definition:RR is defined as accumulated precipitation of an hour measured at the ground level or between ground level and the height of 1.5 m.

Precipitation from rain gauge RR

• Measurement procedures:For the measurement of precipitation as rain only, tipping bucket systems are used. The resolution is 0.1 mm. For measuring snow and hail the system consists of a bucket for catching the precipitation, suspended in strings, and the change in the weight of the bucket is the physical entity recorded. The resolution is 0.1 mm. Small negative and positive values of precipitation may occur because of wind movements.

Precipitation from weather radar RRRAD

• Name of the parameter:Accumulated hourly value of the precipitation at a specified area 2x 2 km measured by the sensing equipment of one single weather radar 

• Unit: mm• Definition:RRRAD is defined as

accumulated precipitation of an hour measured by a weather radar system less than 240 km from the site and the pixel area covers a specific site.

Precipitation from weather radar RRAD

• Measurement procedure: The measuring system is measurement of radar reflectivity factor transformed into the standard Z-R relationship with coefficients a=200 and b=1.6. The sampling interval is 15 minutes.The correctness of using this standard conversion is partially known.

Representativeness RR and RRAD

• Representativeness for certain phenomena (models): Here we must invoke the hypthetico-deductive principle by using some sort testing for the different models. The phenomena are quantitatively expressed by attributes called parameters

• Examples of such parameters/ attributes are: Hourly precipitation, daily precipitation, monthly precipitation, at a certain site, or averaged over some specified area.

Combining information, rain gauge and weather

radar

• We have got two independently measured parameters of the same site of practically the same thing:

  RR measured by gauge and RRRAD measured by radar

• These are two independent documented  parameters

• We then may include qualitative and quantitative information from other sources systematically in our system and create and document new parameters concerning the same situation, if that is possible.

Including additional information

• (1.1)         Time of the year• (1.2)         Description of the type

of weather situation (shower or stable precipitation etc)

• (1.3)         Influence of the actual weather situation (1.4)         Description of the site of the gauge

• (1.5)         Description of the topography around the site

• (1.6)         Knowledge of other measured parameters at the site

Including Additional Information

Including additional information

• (1.7)         Knowledge of the functioning of the measuring devices ( controlling the systems)

• (1.8)         Historical knowledge of the correlation between the measurements of RR and RRRAD

• (1.9)         Knowledge of numerical prognosis

  One ought to be allowed to do this

operationally by very close cooperation between the observers, forecasting people and researchers.

Including Additional Information