Precipitation Measurements Studying the modification of the freezing layer in precipitation

The freezing layer is the region in the atmosphere where frozen particles melt into rain. This region is commonly referred to as the "bright band" as it gives a stronger (brighter) radar reflection than the regions of frozen particles above and rain below.

The Micro Rain Radar, a vertical pointing radar with a maximum range up to 6 km, is increasingly used to study the affects of  precipitation on this bright band as well as increasing the knowledge of Drop Size Distributions (DSD) evolution at various heights.

To see more about this application please see: www.biral.com/met/microrainradar/brightband.htm.

More information on the new Micro Rain Radar web pages

Even if you are already aware of the Micro Rain Radar you might like to see our newly extended information and application examples at: www.biral.com/met/microrainradar.

Precipitation Measurements A low cost disdrometer - the Laser Precipitation Monitor

The Laser Precipitation Monitor (LPM) provides an unrivalled amount of in-situ precipitation information for those applications where the Micro Rain Radar's remote sensing technology is not needed.

The LPM uses a thin ribbon of transmitted light to detect particles passing though the sample volume and can measure particles as small as 0.16 mm diameter.

In addition to outputting over 400 class bins for drop size distribution, the LPM allows the user to change the modes of the disdrometer so that a new data telegram will be produced for each and every drop that passes through the sample volume. The LPM can also be used as a METAR observational tool and provides present weather in several international formats such as SYNOP, SPECI, METAR, NWS, WMO table 4680 and others!

A nice feature are the two relay contacts which can be used completely autonomously from the previous outputs. These relays could, for example, be set to switch monitoring equipment when there is a start/stop of precipitation and to provide an adjustable pulse level output similar to that of a tipping bucket (but without the problems associated with conventional tipping bucket rain gauges such as blockages from leaves).

The LPM provides more detailed precipitation information at a single point in space than the Micro Rain Radar (MRR), whereas the MRR provides drop size distributions over a larger spatial area and allows precipitation profiling at a very attractive price. Between them, these two instruments completely cover one difficult to measure but very prevalent parameter.

For more information on the Laser Precipitation Monitor please visit: www.biral.com/met/precipitation/lpm.htm

Precipitation Measurements Popular rain event sensors

We have a range of sensors to detect the beginning and end of precipitation of which the sensor manufactured by Thies Clima (model 5.4103.10.000) and the sensor manufactured by Eigenbrodt (model RS85) are the most popular.

The Thies sensor (top photo) is a small horseshoe shaped monitor with a 25 cm² sensor surface area which is used for controlling closure settings (on windows, awnings and blinds etc), for collection apparatus and for status monitoring. This is a good all rounder providing accurate information and because it has no moving parts it has very low maintenance requirements and does not require calibrating. The sensor works by looking at breaks in the infra red signal and adjusts a relay appropriately.

However, if your application requires far greater accuracy or the sensor is to be used in harsh climatic conditions and snow the Eigenbrodt instrument (bottom photo) may be more suitable. The Eigenbrodt sensor has a larger sensing surface area of 60 cm² which is gold plated for best response, 2 levels of heating (the Thies model has one level) and selectable sensitivity. Snow pins are also incorporated to ensure proper measurements in frozen precipitation.

To see more on both sensors please visit: www.biral.com/met/precipitation/presence.htm

Met Events and Visits Event and visit programme for the next few months

Events :

• May 26 - 30 :  British Columbia, Canada
  CMOS 2008 Congress (Canadian Meteorological and Oceanographic Society).

  We will be supporting ATS, our Canadian distributor, on their booth.
  On display: - HSS visibility sensors and ultrasonic anemometers
      
  Exhibition Link:  www.cmos2008.ca

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• June 9 - 30 :  Stockholm, Sweden  
  18th Symposium on Boundary Layers and Turbulence
  
  If you are attending this event Richard McKay hopes to meet up with you there.
    
  Exhibition Link:  www.ametsoc.org/meet/fainst/200818BLT.html
  
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• July 14 - 16 :  Guildford, UK
  Wind Engineering Society Conference - Guildford, UK
  
  We hope to see you there.
  
  Exhibition Link: www.ukwes.bham.ac.uk

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For a full list of met events please visit www.biral.com/eventsmet.htm

Customer visits :

Richard McKay, our meteorological applications expert, will be visiting French and Swiss customers in May and US customers in June.

If you would like him to drop by to discuss your requirements please contact him at rmckay@biral.com.

In the next issue  The new smaller more portable   SODAR for wind profiling . . .

The new SODAR for profiling wind vertically up to 500 m will be featured in the next meteorology enews in July. This SODAR PCS16 is an ideal tool for research and wind park site feasibility studies and has excellent data resolution.

This enews will be sent to customers registered with an interest in wind measurements. However, you can access all topics in our enews archive at:

www.biral.com/enews/archive.htm