Mountain - barometers of climate change, but so far science has no answers to the simplest questions about them. How much snow on the top and slopes? As the snow cover varies from year to year?

These and other questions is designed to meet the new international program.

For two years the project "Experiment intercomparison of solid precipitation" (Solid Precipitation Intercomparison Experiment, SPICE), led by the world meteorological organization (WMO), will deploy an array of the most modern sensors 15 geographically and climatically different locations around the world at altitudes up to 4 318 m above sea level. The objective is the precise measurement of the thickness of the snow cover and snowfall, the most fragile kinds of precipitation, which can avoid the attentions of simple devices of collection or smother them. The results will help to improve climate models and help forecast the stability of permafrost, changes in ecosystems and the availability of water resources in the coming decades.

"Snowfall is an important part of the hydrologic cycle, " explains Roger Atkinson, acting head of the programme WMO instruments and methods of observations. - If we fail to accurately measure the amount of snow, we are not destined to see how much water we have now and how the situation will change in the future."

Snowfall is also partly determines the glacier to grow or recede, said Zhang Insan of the research Institute of the Tibetan plateau of China (PRC), not taking part in the project. "The debate about the fate of Himalayan glaciers are very long, but we do not understand even the basics", - says the expert.

Many parameters of climate can be assessed today with great accuracy: temperature, pressure, wind speed, air humidity. Snowfall is not in this list. Snowflake light, they often takes the wind, and how much snow will fall in measuring cylinders, can affect different weather conditions, reminds us Rodica Nitu of the canadian Department for environmental protection, who heads the project. And at the temperature about zero of wet snow, as a rule, stick to the edges of the container, forming a cap, which does not allow to collect snow on.

"The shortage is a serious problem," agrees Roy Rasmussen from the U.S. National center for atmospheric research. This sin and automatic sensors that collect sometimes only 20% of snow. While unreliable data lead to one of the largest uncertainties in the work of the climate models, which are unable to predict the situation with water resources and hazardous processes in the mountains, says Mr. Rasmussen. Moreover, the amount of precipitation (snow and including) will grow as further heating of the planet. It is necessary to know, whether it compensates intensifying melting of glaciers.

The last major international project on measuring the snow cover was carried out over 20 years ago, and all this time science and technology is not standing still. One of the goals of the new program will be a check recently developed instruments and enclosures. For example, field observations show that the screens that reduce horizontal wind speed above the sensor, greatly enhance the collection. "This is the most important factor for accurate measurements", - said Mr. Rasmussen.

New methods of heating devices will also help to solve the problem of blockages without evaporation of snow or enhance air turbulence, causing the snow is blown away. There is a transition to an automated Toolkit that allows continuous measurements on large areas in the remote areas.

Alas, SPICE will cover not the entire world. For example, the Himalayas are covered by the project, but Mr. Zhang and his colleagues at the beginning of next year will fill the gap, organizing station on the Tibetan plateau at altitudes up to 6 000 m

In any case, ground-based measurements is not enough to never. Therefore, the results SPICE useful for calibration of satellite sensors that using microwave radiation, radars and lasers will cover a much larger area.