Calculation of icing. Intensity icing. Conditions of icing aircraft

The icing is called ice deposition on the streamlined parts of aircraft and helicopters, as well as on power plants and external parts of special equipment when flying in clouds, fog or wet snow. The icing occurs if there are supercooled drops in the air at the air height, and the surface of the aircraft has a negative temperature.

The following processes may result in icing of aircraft: - direct settlement of ice, snow or hail on the surface of the aircraft; - freezing of clouds or rain drops when contact with the surface of the aircraft; - Sublimation of water vapor on the surface of the aircraft. To predict icing in practice, several sufficiently simple and efficient ways are used. The main ones are as follows:

The weather forecast method. This method lies in the fact that the caseins present materials are determined by layers in which cloudy and negative air temperatures are observed.

The layers with possible icing are determined by the aerological chart, and the procedure for processing the chart to you, dear reader, is well known. Additionally, we can once again say that the most dangerous icing is observed in a layer where the air temperature ranges from 0 to -20 ° C, and for the occurrence of strong or moderate icing, the temperature difference from 0 to -12 ° C is the most dangerous. This method is simple enough, does not require considerable time to perform the calculations and gives good results. Other explanations for its use are inappropriate. Method of enclosure.

This Czech physicist proposed to determine the magnitude of TN. - The saturation temperature is possible ice by the formula: tn.l. \u003d -8d \u003d -8 (T - TD), (2) where: D is a dew point deficiency at a level. If it turned out that the saturation temperature is necessary ice above the ambient temperature, then at this level should be expected to find. Forecast of icing on this method is also given with the help of an aerological chart. If according to sensing data, it turns out that the enclosure in some layer is the right of the stratification curve, then the icing should be predicted in this layer. Enjoying is recommended to use its forecast of icing forecasts only to a height of 2000 m.

As additional information, the following established dependence can be used as an additional information. If in the temperature range from 0 to - 12 ° C, the dew point deficiency is greater than 2 ° C, in the temperature range from-8 to - 15 ° C, the dew point deficiency is greater than 3 ° C, and at temperatures below - 16 ° C dew point deficiency more 4 ° C, then with a probability of more than 80% icing under such conditions there will be no observed. Well, naturally, an important help for the synoptic in the forecast of icing (and not only it) is the information transmitted to the land by flying crews, or crews by tuting and boarding.

according to icing courts on the waters of the Far Eastern seas

Vladivostok - 2011.

Preface

In the cold season on the seas, the most dangerous for ships is recognized as icing. Dozens and hundreds of courts suffer daily from icing. Obeling makes it difficult and violates production activities, leads to injury to sailors and often to disastrous consequences.

The phenomenon of icing of vessels refer to the category of hazardous and especially dangerous (OA) or natural hydrometeorological phenomena (NMA). For navigators, appropriate instructions of behavioral behavior have been developed, while the basic means of combating icing are: a ship maneuver that reduces ice growth; ice window crew forces; Exit from the icing zone. When planning work in the sea, it is necessary to know the conditions and factors contributing to icing, among which are: technical (vessel type, rigging, loading, coating, and so on); Subjective (ship maneuver) and hydrometeorological. The total impact of all these factors does not allow to consider this phenomenon as a natural and characterize it only from the hydrometeorological side. Therefore, all the conclusions obtained in the study of icing as natural phenomenon, have a recommendatory, probabilistic nature.

The atlas consists of three parts characterizing the conditions of icing in the Bering, Okhotsk and the Japanese seas. Each part consists of administration and two sections.

In the introduction, the characteristics of icing conditions and explanations to the table material are given.

The first section contains a tabular material characterizing the initial data, characteristics of the icing icing parameters, the interdependence of the icing parameters from hydrometeorological elements and weather conditions For a particular sea.

The second section contains card icing cards for three gradations of intensity: slow icing, fast and very fast - calculated on temperature and wind gradations.

Atlas is designed for captains and navigations of various departments, employees of research and design organizations, organs of the hydrometeorological service.

The atlas is designed in the "dvnigmi" stat. Scientific Sotr., k. G. N., A. G. Petrov and ML. Scientific Sot. E. I. Stasyuk.

The materials presented in the Atlace are based on a large number of source data. The paper uses more than 2 million ship observations over the hydrometeorological elements made on the waters of the Far Eastern seas, of which more than 35 thousand cases recorded the icing of courts. The time period covers a period of time from 1961 to 2005. The existing material of observation is an inhomogeneous array of information in which there are often no other hydrometeorological parameters and, above all, the parameters characterizing the icing of ships. As a result of this, the tables presented in the Atlace there is a mismatch of the mutual number of icing parameters. Under these conditions, the criterot of existing information on the allocation of cases of icing cases was carried out, first of all, on the basis of accounting for the possibility of icing on physical laws.

For the first time, the results of the joint analysis of the icing parameters of directly fixed cases of icing and hydrometeorological observations characterizing the temperature-wind mode are presented. It was noted that the icing of courts according to the data of the observed cases of icing is recorded for most of the waters under consideration from October to June. The most favorable conditions for the occurrence of all types of icing are developing during intensive ice formation: from January to March. More than 2 thousand synoptic processes over the waters of the Far Eastern seas are viewed to determine the synoptic conditions.

The above icing characteristics are used for approximate calculations of the icing of vessels with displacement within 500 tons. With 80% probability, the nature of the splashes of such vessels is the same with splashing of courts with large displacement, which allows interpreting the submitted materials and on ships with high water displacement. The greatest danger icing presents for ships with a limited maneuver of movement (for example, when towing another vessel), as well as when the vessel is moving at an angle of 15-30º to the wave, which causes best conditions for splashing it sea water. Under these conditions, even with minor negative air temperatures and a small wind speed, strong icing is possible, aggravated by the uneven distribution of ice on the vessel surface, which can lead to disastrous consequences. With slow icing, the rate of ice deposits on the deck and superstructure of the vessel with a displacement of 300-500 T can reach 1.5 t / h, with rapid icing - 1.5-4 t / h, with very fast - more than 4 t / h.

The calculation of the intensity of possible icing (for the construction of cards) was made in accordance with the recommendations developed in "Methodical guidelines to prevent the threat of icing of courts" and used in the prognostic divisions of Roshydromet, based on the following hydrometeorological complexes:

Slow icing

• air temperature from -1 to -3 ºС, any speed of wind, splashing or one of the phenomena - atmospheric precipitation, fog, sea care;
• air temperature -4 ºС and below, wind speed up to 9 m / s, splashing, or one of the phenomena - atmospheric precipitation, fog, sea care.

Fast icing

• air temperature from -4 ºС to -8 ºС and wind speed from 10 to 15 m / s;

Very fast icing

• air temperature -4 ºС and below, wind speed 16 m / s or more;
• air temperature -9 ºС and below, wind speed 10 - 15 m / s.

Reference material characterizing the icing parameters and the hydrometeorological elements associated with them are presented in the first section in the form of tables, drawings and graphs.

Card icing of ships for months is presented in the second section. Here are the probability maps of possible icing on three gradations of intensity: slow, fast, very fast, calculated on the temperature and wind complexes by month.

Card construction was based on the results of calculating the repeatability of the corresponding temperature and wind complexes. To do this, all available information about air temperature and wind speed in the sea According to ship observations, 1º squares were grouped by month. The calculation of the repeatability of icing characteristics was produced for each square. Given the greater heterogeneity of the obtained values \u200b\u200bof the repeatability, on the maps shows the insulance of repeatability of more than 5%, with the dotted line the extreme boundary of possible icing is applied. Maps are constructed separately for each type of icing intensity (slow, fast, very fast). Here are the zones of the presence of ice in the various winter type: soft, medium and harsh. In addition to these information on the maps, zones are highlighted in which there is a lack of source data, both in their total quantity and the sufficiency of their climatic generalization for each square. The minimum number of source data was chosen based on the calculation of the first Quarterly with the statistical processing of the entire data array for the month. On average, it turned out to be equal to 10 observations for all months. The minimum amount of data for climatic generalization was made - three (in line with methodical recommendations). Zones are highlighted with hatching.

Brief description of the icing of ships on the waters of the Far Eastern seas in January

(fragment analysis of the characteristics of the icing of ships for months)

In January, about 1347 cases of icing were recorded in the Bering Water area, about 1347 cases of icing, of which 647 cases of slow and 152 cases of rapid icing of vessels are recorded, which is about 28% of all cases of slow icing and about 16% of the rapid. The icing is likely throughout the water area of \u200b\u200bthe sea, while the probability of slow icing on wind-temperature conditions reaches 60%, evenly increasing from the south to the north to the coasts of Asia and America. The probability of rapid icing is characterized by 5 - 10% almost throughout the water area of \u200b\u200bthe sea, and very quickly reaches 20-25%.

In the Sea of \u200b\u200bOkhotsk, over 4300 cases of icing are registered. Of these, 1900 are slow and 483 rapid icing. According to the calculated data, icing may be observed throughout the water area of \u200b\u200bthe sea, while the probability of slow icing is in the range of 40 - 60%, fast - 10-30%, and very fast - 10-15%.

In the Japanese Sea registered over 2160 cases of icing. Of these, more than 1180 are slow and about 100 cases of fast icing. According to the calculated data, the probability of icing is high for most of the water area of \u200b\u200bthe sea. Thus, the probability of slow icing on temperature and wind conditions is evenly increasing from the south to north from 5 to 60% or more. Fast icing is characteristic of the central part of the sea with values \u200b\u200bfrom 5 to 15% and a decrease in the top of the Tatar Strait to 5%. The probability of very rapid icing increases from the south to the rover of the Tatar strait from 5 to 30%.

Such a brief analysis of court icing is presented for all seas for all months in which there is a probability of icing of courts.

Table 1 provides information on the number and repeatability of hydrometeorological observations, including cases of direct registration of the icing of vessels, which were used in the analysis of the causes and nature of the icing of courts. Figures 1-3 present examples of the spatial location of fixed cases of icing of ships in the Far Eastern seas.

Figure 4 shows an example of graphic information, namely, the characteristic of fixed cases of icing of courts due to both the nature of icing.

Figures 5-8 present the charts of the dependence of spray icing from hydrometeorological elements: water and air temperature, wind speed and wave height) for all three seas.

Table 1 - Quantity and repeatability (%) data of hydrometeorological observations by months, including information about direct registration of court icing

1 - the total number of ship meteleomarities;

3 - the total number of reported cases of icing;

5 - the number of cases of slow icing;

7 is the number of cases of fast icing.

Figure 1 - Coordinates of cases of all types of icing

Figure 2 - Coordinates of cases of slow icing

Figure 3 - Coordinates of rapid icing cases

Figure 4 - Repeatability of icing depending on causes and character

Figure 5 - repeatability of spray icing depending on the temperature of the water

Figure 6 - repeatability of splashes icing depending on the distribution of ice thickness

Figure 7 - Repeatability of spray icing depending on the height of the wave

Figure 8 - repeatability of spray icing depending on the temperature distribution of air temperature

An example of the probability of icing calculated on the temperature and wind complexes (a fragment from the Atlas of the probability of icing in the Bering Sea in January)

As a result of the processing of data on the temperature and wind regime, the repeatability of icing characteristics (slow, fast, very fast) in one months per month were calculated on the waters of the Far Eastern seas.

The calculation was made on the basis of the interrelations of air temperature and wind speed with the nature of the icing of vessels used in the prognostic organizations.

Thus, in Figure 9, an example of cartographic information for calculating the probability of icing of courts in the Bering Sea of \u200b\u200btemperature and wind conditions in January is presented. In the picture, the darkening areas mean the position of the ice cover in January in various types of winters: soft, medium and harsh. A red hatching zones in which an insufficient amount of data is noted for statistically reliable calculation of the probability of icing.

Figure 9 - An example of cartographic information for calculating the probability of icing of vessels in the Bering Sea by temperature and wind conditions in January

METHOD OF FORDOCK OF THE ZONS OF POSSIBLE ORGINATION OF AERS

General

In accordance with the test plan for 2009, operational tests of the method of forecasting zones of possible icing of aircraft (Sun) on the models of melting and NCEP from April 1 to December 31, 2009 were carried out in GU "Hydromet Center of Russia". part of Special phenomena card calculation technologies (SIGNIFICANT WEATHER AT THE MIDDLE LEVELS - SWM) for aviation. The technology was developed in the Department of Aviation Meteorology (OAM) in 2008 as part of the topic of NIR 1.4.1 for the introduction of zonal forecasts in the laboratory. The method also applies to predict icing at the lower levels of the atmosphere. Development of the method of calculating the predictive Card Ia at the lower levels (Significant Weather AT The Low Levels - SWL) is scheduled for 2010

The icing of aircraft may be observed with the required condition consisting in the precess of the cloud drops in the desired quantity. This condition is not sufficient. Sensitivity of various types of aircraft and helicopters to icing Nonodynakov. It depends on both the characteristics of the cloud and the flight speed and the aerodynamic characteristics of the aircraft. Therefore, only the "possible" icing in the layers is preparing, where its prerequisite. Such a forecast should be accurate, ideally, from the prediction of the presence of clouds, their water, temperature, as well as the phase state of cloud elements.

In the early stages of the development of settlement methods for finding icing, their algorithms relied on the temperature forecast and dew point, the synoptic cloud forecast and statistical data on the microphysics of clouds and the recipes of icing Sun. Experience has shown that such a forecast was ineffective at that time.

However, afterwards, up to the present, even the best numerical world-class models did not provide a reliable forecast of the presence of clouds, their water and phase. Therefore, the forecast of icing in world centers (for building cards of the OA; we do not touch the super-shit forecast and scooter here, the state of which is characterized by c) is still based on the temperature and humidity of the air, as well as, if possible, the simplest characteristics of the cloudiness ( layered, convective). The success of such a forecast, however, turns out to be practically significant, since the accuracy of the pre-election of temperature and humidity of air has increased greatly compared with the state corresponding to the writing time.

The main algorithms of modern methods of finding icing are presented. For the purposes of building SWM and SWL cards, we selected those of them that are applicable to our conditions, i.e. are based only on the weekend products of numerical models. Algorithms for calculating the "icing potential", combining model and real data in the scooting mode, in this context are not applicable.

Development of the forecast method

As samples of data on the icing of aircraft used to assess the comparative success of the algorithms listed in, as well as those previously known (including the famous formula, Verb) were taken:
1) TAMDAR system data installed on aircraft flying over the territory of the United States within the lower 20 thousand feet,
2) Base of air sensing data over the territory of the USSR in the 60s. The twentieth century, created in 2007 in the OAM in the framework of the topic 1.1.1.2.

Unlike the AMDAR system, the TAMDAR system includes icing sensors and dew points. Tamdar's data managed to collect for the period from August to October 2005, all of 2006 and January 2007 from the site http: \\\\ amdar.noaa.gov . From February 2007, data access was closed for all users, except for US government organizations. The data were collected by OAM employees and are presented in the form of a base suitable for computer processing, by manual sample with the following information mentioned above: Time, geographic coordinates, GPS height, temperature and humidity, pressure, wind, icing and turbulence.

Let us in briefly focus on the features of the TAMDAR system, compatible with the international AMDAR system and promptly working on US Civil Aviation Airplanes Since December 2004, the system is developed in accordance with the requirements of WMO, as well as NASA and NOAA USA. Sensor counts are made through the predetermined pressure intervals (10 GPa) on the height and reduction dial modes and at a given time intervals (1 min) on the horizontal flight mode. The system includes a multifunctional sensor installed on the front edge of the aircraft wing, and the microprocessor, processing signals and transmitting them to the processing and data distribution point located on Earth (AIRDAT system). An integral part is also a satellite GPS system operating in real time and providing spatial data bindings.

Bearing in mind the further analysis of the TAMDAR data is connected with the data of OA and the numerical forecast, we were limited to the voiding data only in the neighborhood of ± 1 h from the timelines 00 and 12 VV. The data array assembled in this way includes 718417 separate samples (490 dates), including 18633 references with the presence of icing. Almost all of them belong to the term of 12 VV. The data was grouped along the squares of the latitude-long net size of 1.25x1.25 degrees and height in the vicinity of standard isobaric surfaces 925, 850, 700 and 500 GPa. The surroundings were considered layers 300 - 3000, 3000 - 7000, 7000 - 14000 and 14000 - 21000 f., Respectively. The sample contains 86185, 168565, 231393, 232274 samples (cases) in the vicinity of 500, 700, 850 and 925 GPa, respectively.

To analyze TAMDAR data on icing, it is necessary to take into account their next feature. The icing sensor captures the presence of ice layer at least 0.5 mm. Since the appearance of ice and until the moment of its complete disappearance (i.e., during the entire period of icing), temperature and humidity sensors do not work. The dynamics of deposits (rapid speed) in this data is not reflected. Thus, not only there is no data on the intensity of icing, but there is no data on temperature and humidity over the icing period, which predetermines the need to analyze TAMDAR data in conjunction with independent data on the specified values. As such, OA data from the Base of the GU "Hydromet Center of Russia" on the temperature of the VRRsduha and relative humidity. A sample including TAMDAR data about the predictant (icing) and OA data on predictors (temperature and relative humidity) will be designated in this report as a Tamdar-OA sample.

In the sample of aircraft sensing data (CZ) over the territory of the USSR, all counts containing information on the presence of either the absence of icing, as well as about the temperature and humidity, regardless of the presence of clouds. Since at our disposal there is no data of reanalysis for the period 1961-1965, it did not make sense to be limited to the surroundings of terms 00 and 12 mSV or the surroundings of standard isobaric surfaces. The air probing data, thus, were used directly as measuring in situ. The SZ data sample included more than 53 thousand counts.

As predictors from these numerical forecasts, the prognostic fields of geopotential, air temperature (T) and relative humidity (RH) were used with 24 h long models in terms of global models: semi-migrant (in the nodes of the mesh 1.25x1.25 °) and the NCEP model (in the nodes of the mesh 1x1 ° ) For periods of collecting information and comparing models in April, July and October 2008 (from 1 to 10th of the month).

Results having methodical and scientific importance

1 . The temperature and humidity of the air (relative humidity or the temperature of the dew point) are significant predictors of the zones of possible icing of the Sun, provided that these predictors are measured in situ (Fig. 1). All experienced algorithms, including the ENEIS formula, at the sample of air sensing data, showed quite practically significant successfulness of the sections of the presence and lack of icing. However, in the case of TAMDAR data on icing, supplemented by objective analysis of temperature and relative humidity, the success of separation is reduced, especially at levels of 500 and 700 GPa (Fig. 2-5), due to the fact that the predictors are averaged in space (within the square Mesh 1.25x1.25 °) and can be sent vertically and in time from the moment of observation by 1 km and 1 hour, respectively; Moreover, the accuracy of objective analysis of relative humidity is significantly reduced with a height.

2 . Although the icing of the aircraft may be observed in a wide range of negative temperatures, its probability is maximum in comparatively narrow temperature and relative humidity intervals (-5 ... -10 ° C and\u003e 85%, respectively). Outside of these intervals, the probability of icing is quickly reduced. At the same time, dependence on relative humidity seems stronger: it is, with Rh\u003e 70%, 90.6% of all cases of icing were observed. These conclusions are obtained at the sample of air probing data; They find a complete qualitative confirmation on TAMDAR-OA. The fact of the good agreement of the results of the analysis of two samples of data obtained by various methods in highly different geographic conditions and at different periods of time shows the representativeness of both samples used to characterize the physical conditions of aircraft icing.

3 . Based on the results of the testing of various algorithms for calculating the icing zones and taking into account the available data on the dependence of the intensity of icing from air temperature, the most reliable algorithm has been selected and recommended to practical use, which has previously proven itself in international practice (algorithm developed in NCEP). This algorithm turned out to be the most successful (the values \u200b\u200bof the quality criterion of Piercy-Obukhov accounted for 0.54 at the sample of air probing data and 0.42 on the TAMDAR-OA data sample). In accordance with this algorithm, the forecast of the zones of possible icing of aircraft is the diagnosis of the specified zones according to prognostic fields of temperature, T ° C, and relative humidity, Rh%, on isobaric surfaces 500, 700, 850, 925 (900) GPA in the nodes of the model mesh .

Natures of grids belonging to the zone of possible icing of aircraft, the nodes in which the following conditions are followed:

Inequalities (1) were obtained in the NCEP under the RAP (Research Application ProgramE) program on a large sample of measurement data using insolent icing sensors, temperature, humidity and applied in practice to calculate the prognostic cards of special phenomena for aviation. It is shown that the repeatability of the icing of aircraft in the zones of performing inequality (1) is an order of magnitude higher than outside these zones.

Specificity of operational test methods

The program of operational testing of the method of forecasting areas of possible icing of aircraft using (1) has certain features that distinguish it from standard test programs for new and improved forecast methods. First of all, the algorithm is not the original development of the GU "Hydromet Center of Russia". It is sufficiently tested and evaluated on different samples of data, see.

Further, the success of the separation of cases of availability and lack of icing Sun can not be in this case the object of operational tests, due to the impossibility of obtaining operational data on the icing of Sun. Single, irregular reports of pilots entering the MC AUWD cannot at the foreseeable time to compile a representative data sample. There are no objective data from Tamdar over the territory of Russia. It is impossible to obtain such data and over the territory of the United States, because on the site from which we received the data made by Tamdar-OA, icing information is now closed for all users, except US state organizations.

However, given that the decisive rule (1) was obtained on a large data archive and introduced into the NCEP practice, and its success is repeatedly confirmed on independent data (including within the framework of the topic 1.4.1 at the samples of the SZ and TAMDAR-OA), It is assumed that in the diagnostic plan, the statistical relationship between the probability of icing and the implementation of conditions (1) is quite close and rather reliably appreciated for practical application.

The question remains unexplained how correctly in the numerical forecast of the provisions zone (1) allocated according to objective analysis.

In other words, the test object should be a numerical forecast of the zones in which conditions are satisfied (1). That is, if in the diagnostic plan, the decisive rule (1) is effective, then it is necessary to assess the success of the forecast of this rule with numerical models.

Copyrights under the framework of the topic 1.4.1 showed that the melting model successfully predicts the zones of possible icing of the Sun, determined through conditions (1), but is inferior in this regard the NCEP model. Since now the operational data of the NCEP models come to the GU "Hydromet Center of Russia", it is fairly early, it can be assumed that, subject to a significant advantage in terms of the forecast accuracy, it is advisable to use this data to calculate the CAP cards. Therefore, it was considered appropriate, to assess the success of the prognosis of conditions for the fulfillment of conditions (1) both according to the melting model and the NCEP model. In principle, it would be necessary to include in the program and the spectral model T169L31. However, serious flaws of the forecast of the humidity field do not allow us to consider this model promising to predict icing.

Methods for assessing forecasts

The database recorded fields of calculations on each of the four indicated isobaric surfaces in dichotomic variables: 0 means failure to comply with conditions (1), 1 - execution. In parallel, similar fields were calculated according to objective analysis. To estimate the precision of the forecast, it is necessary to compare the results of the calculation (1) in the nodes of the grid according to the prognostic fields and in the fields of objective analysis on each isobaric surface.

The results of calculations of relations (1) according to objective analysis were used as actual data on the zones of possible icing. In relation to the layer model, these results of calculations (1) in the mesh nodes in 1.25 degrees, as applied to the NCEP model - in the mesh nodes in 1 degrees; In both cases, the calculation is made on the isobaric surfaces of 500, 700, 850, 925 GPa.

Forecasts were evaluated in the framework of the evaluation technology for dichotomic variables. Estimates were performed and analyzed in the laboratory of testing and evaluating methods for forecasts of GU "Hydromet Center of Russia".

To determine the success of the forecasts of zones of possible icing of aircraft, the following characteristics were calculated: justifying forecasts for the presence of a phenomenon, lack of phenomenon, the overall justifies, prevention of the presence and absence of a phenomenon, the quality criterion of Piercy-Wit and the reliability criterion of Hyidke-Bagrova. Estimates were performed for each isobaric surface (500, 700, 850, 925 GPa) and separately for forecasts starting at 00 and 12 VV.

Results of operational tests

Test results are presented in Table 1 for the three forecast areas: for the Northern Hemisphere, for the territory of Russia and its European territory (ETP) in the advance of the forecast of 24 hours.

It can be seen from the table that repeatability of icing on the objective analysis of both models is close, and it is maximum on the surface of 700 GPa, minimal on the surface of 400 GPa. When calculating the hemispheres in the second place in the repeatability of icing, the surface is 500 GPa, then 700 GPa, which is obviously explained by the large contribution of deep convection in the tropics. When calculating in Russia and ETP in second place in the repeatability of icing there is a surface of 850 GPa, and on the surface 500 GPa, the repetition of icing is already twice as much. All characteristics of justifying forecasts were high. Although the indicators of the success of the melting model are somewhat inferior to the NCEP models, however, they are quite practically significant. At levels where the repeatability of icing is high and where it represents the greatest danger for the aircraft, the success indicators should be recognized very high. They are noticeably declining on the surface of 400 GPa, especially in the case of a melting model, remaining significant (Piercy criterion on the northern hemisphere is reduced to 0.493, in Russia - up to 0.563). According to ETP, the test results at the level of 400 GPa are not given in view of the fact that cases of icing at this level were extremely small (37 nodes of the NCEP model for the entire period), and the result of assessing the success of the forecast is stable insignificant. At the remaining levels of the atmosphere, the results obtained by ETR and Russia are very close.

conclusions

Thus, operational tests have shown that the developed method of forecasting zones of possible icing Sun, implementing the NCEP algorithm, provides a sufficiently high success of the forecast, including on the weekend of the global model of the melting, which is currently the main prognostic model. By the decision of the Central Methodological Commission on the Hydrometeorological and Heliogeophysical Principles of Roshydromet dated December 1, 2009, the method is recommended for the implementation of the Laboratory of Zonal Forecasts of the GU "Hydromet Center of Russia" to build cards of special phenomena for aviation.

Bibliography

1. Technical regulations. Volume 2. WMO-№49, 2004. Meteorological maintenance of international air navigation
2. Report on the Nir: 1.1.1.2: Development of a project technology for the preparation of a prognostic map of special weather phenomena for aviation flights at the lower levels (final). № state. Registration 01.2.007 06153, M., 2007, 112 p.
3. REPORT ON NIR: 1.1.1.7: Improving methods and technologies of forecasts for airfield and on air tracks (final). № state. registration 01.02.007 06153, M., 2007, 97 p.
4. Baranov A.M., Mazurin N.I., Solonin S.V., Yankovsky I.A., 1966: Aviation meteorology. L., hydrometeoisdat, 281 c.
5. Zverev F.S., 1977: Synoptic meteorology. L., hydrometeoisdate, 711 s.
6. Otkin J. A., Greenwald T. J., 2008: COMPARISONS OF WRF Model-Simulated and Modis-Derived Cloud Data. MON. Weather Rev., V. 136, No. 6, pp. 1957-1970.
7. Menzel W. P., Frei R. A., Zhang H., et al., 2008: Modis Global Cloud-Top Pressure and Amount Estimation: Algorithm Description and Results. Weather and forecasting, ISS. 2, pp. 1175 - 1198.
8. Guide to predicting meteorological conditions for aviation (ed. Abramovich K.G., Vasilyev A.A.), 1985, L., Hydrometeoisdat, 301 p.
9. BERNSTEIN B.C., MCDONOUGH F., POLITOVICH M.K., BROWN B.G., RATVASKY T.P., MILLER D.R .., WOLFF C.A., CUNNING G., 2005: CURRENT ICING POTENTIAL: ALGORITHM Description and Comparison with Aircraft Observations. J. Appl. Meteorol., V. 44, pp. 969-986.
10. Le Bot C., 2004: Sigma: System of Icing Geographic Identification in Meteorology for Aviation. 11 th conf. ON AVIATION, RANGE, AND AEROSPACE, HYANNIS, MASS., 4-8 OCT 2004, AMER. Meteorol. SOC. (BOSTON).
11. Minnis P., Smith WL, Young DF, Nguyen L., Rapp AD, Heck PW, Sun-Mack S., Trepte Q., Chen Y., 2001: A Near Real- Time Method for Deriving Cloud and Radiation Properties From Satellites for Weather and Climate Studies. Proc. AMS 11th conf. Satellite Meteorology and Oceanography, Madison, Wi, 15-18 Oct, PP. 477-480.
12. Thompson G., Bruintjes R.T., Brown B.G., Hage F., 1997: Intercomparison of in-Flight Icing Algorithms. Part 1: Wisp94 Real-Time Icing Prediction and Evaluation Program. Weather and forecasting, v. 12, pp. 848-889.
13. Ivanova A. R., 2009: Experience to verify numerical forecasts of humidity and assessment of their suitability for the forecast of casting areas of aircraft. Meteorology and hydrology, 2009, No. 6, p. 33 - 46.
14. Shakina N. P., Skripthunova E. N., Ivanova A. R., Gorlach I. A., 2009: Assessment of the mechanisms for generating vertical movements in global models and their initial fields due to the numerical precipitation forecast. Meteorology and hydrology, 2009, No. 7, p. 14 - 32.

Intensity icing The aircraft in the flight (I, mm / min) is estimated by the rate of ice increase on the front edge of the wing - the thickness of the deposition of ice per unit of time. In intensity distinguishes weak icing - I less than 0.5 mm / min; moderate icing - I from 0.5 to 1.0 mm / min; Strong icing - I more than 1.0 mm / min.

When assessing the risk of icing, the concept of the degree of icing can be used. The degree of icing is the total deposition of ice over the time stay of the aircraft in the icon of icing.

For theoretical assessment of factors affecting the intensity of icing, the formula is used:

where I is the intensity of icing; V- air velocity speed; ω - water clouds; E - integral capture coefficient; β is the coefficient of alteration; ρ is the density of the growing ice, which fluctuates in the range - from 0.6 g / cm 3 (white ice) to 1.0 g / cm 3 (transparent ice).

The intensity of icing of aircraft increases with an increase in the water content of the clouds. The values \u200b\u200bof water water change vary widely - from thousands of thousands of up to several grams of 1 m3 of air. When water, the clouds are 1 g / m 3 or more is the most strong icing.

Capture and intentions - dimensionless values \u200b\u200bthat are almost difficult to determine. The integral seizure coefficient is the ratio of the water mass in the profile on the profile of water to the mass, which would be assisted in the absence of curvature of the trajectories of water drops. This ratio depends on the size of the droplets, the thickness of the wing profile and air velocity aircraft: the larger the drops, thinner the wing profile and more air speed, the greater the integral capture coefficient. The coefficient of altitude is the ratio of the mass of ice that has grown on the surface of the aircraft, to the mass of water, settled during the same time on the same surface.

Mandatory condition for icing aircraft in flight is the negative temperature of their surface. The ambient air temperature at which the icing of aircraft was marked, varies widely - from 5 to -50 ° C. The probability of icing increases at air temperature from -0 to -20 ° C in supercooled clouds and precipitation.

With an increase in air velocity, the intensity of icing increases, as can be seen from the formula. However, at large air speeds, the kinetic heating of aircraft preventing icing. Kinetic heating arises due to the inhibition of air flow, which leads to the compression of the air and the increase in its temperature and surface temperature of the aircraft. Due to the effect of kinetic heating, the icing of aircraft occurs most often with air speeds less than 600 km / h. Air ships are usually underdended when takeoff, height, decrease, and go for landing, when speed is small.

When flying in the areas of atmospheric fronts, the icing of aircraft is observed 2.5 times more often than when flying in homogeneous air masses. This is due to the fact that the front cloudiness is, as a rule, more powerful vertically and more extended horizontally than intramass clouds. Strong icing in homogeneous air masses is observed in isolated cases.

The intensity of icing aircraft during flights in the clouds of various forms is different.

In cue-rain and powerful cumulative clouds With a negative temperature of the air, it is almost always possible to strong icing of aircraft. These clouds contain large drops with a diameter of 100 μm and more. Water content in the clouds increases with a height.

It is installed on the edge of the roofs, in the drains and gutters, in the places of the possible accumulation of snow and ice. When the heating cable is operation, melting water is freely passing through all elements of the drainage system to the Earth. The freezing and destruction of the elements of the roof, the facade of the building and the drain system itself does not occur in this case.

For proper operation of the system, it is necessary:

• Determine the most problematic areas on the roof and in the drainage system;
• Make the correct calculation of the power of the heating system;
• Use a special heating cable of the required power and length (for outdoor installation, resistant to ultraviolet radiation);
• Select fastening elements depending on the material and construction of the roof and the drain system;
• Choose the necessary heating control equipment.

Installing the anti-icing system on the roofs.

When calculating the required power of the snow staining system and the roof ice, it is important to take into account the type, roof design and local weather conditions.

Conditionally roofs can be divided into three types:

1. "Cold roof". Roof with good insulation and low heat loss through its surface. On such a roof, the flapping is usually formed only when the snow melts in the sun, while the minimum temperature of melting is not lower than -5 ° C. When calculating the required power of the anti-change system for such roofs, the minimum power of the heating cable will be sufficient (250 - 350 W / m² for the roof and 30-40 W / m for drainage).

2. "Warm roof." Roof with poor insulation. On such roofs the snow melts with enough low temperatures air, then water flows down to the cold edge and to the drainage, where it freezes. The minimum temperature of melting is not lower than -10 ° C. This type includes most of the roofs of administrative buildings with a attic. When calculating the anti-change system for "warm roofs", it is necessary to increase the power of the heating cable on the roof edge and in the gutters. This will ensure the efficiency of the system even at low temperatures. (Fig.1).

3. Hot roof. The roof with poor thermal insulation, which attic is often used for technical purposes or as a living area. On such roofs, snow melts and at low air temperatures (below -10 ° C). For hot roofs, in addition to using a heating cable with high power, it is desirable to use a weather station or a thermostat to reduce the cost of electricity.

If the cable is placed on the roof with a soft coating (for example, rubberoid), the maximum power of the heating cable should not exceed 20 W / m.

Installing an anti-icing system in gutter and drainage.

When calculating the anti-icing system, it is necessary to consider:

1. Diameter of the drain pipe and gutter. When the diameter of the vertical drainage pipe is less than 10 cm, it is recommended to install one line of heating cable.
2. The material from which the drainage is made. (See Table).

In most cases, the heating cable is placed in two lines: in the gutters using special plates, in the drains with a pigtail (cable with special fasteners fixing the cable). Mounts provide reliable fixation and do not allow crossing the lines of the heating cable.

If there is a chance of clogging of gutters or drainage foliage, needles, etc. It is recommended to use a self-regulating heating cable. Since the usual resistive heating cable in places of clogging can overheat and eventually fail.

Vertical drainage pipes are most susceptible to freezing in winter time. In long pipes (15 m or more) due to air convection, the lower part of the pipe is possible. To avoid freezing, additional heating cable lines are installed (power increases) at the bottom of the pipe at a length of 0.5 - 1 m (Fig. 2).

It is necessary to eliminate the formation of icicles and forehead on the edge of the roof and prevent the drainage system freezing. The length of the roof edge is 10 m, thermal insulation does not provide a complete elimination of heat loss (warm roof). The length of the gutter is 10 m, two drains have a length of 6 m. The chute and the drainage are made of plastic, the diameter of the drainage of 10 cm, the width of the gutter 20 cm.

Decision:

In this case, an option is optimally suitable with a separate heating of the roof edge (Fig. 3) and the drain system.

Fig. 3.

Calculation of the heating system for the roof:

1. On the table, we determine the power required for heating the edge of the "warm roof" per square meter – 300 - 400 W.
2. We determine the total heating area ( S.): (Heating must be carried out along the entire length of the roof (10 m), depending on the inclination of the roof, we determine the width of the heating section, in our case - 50 cm). S. = 10m × 0,5m \u003d 5 m²
3. Select the heating cable, the power and length of which will meet the requirements specified above. The minimum cable power will be:

5 m² × 300 W \u003d 1500 W.

Option 1. Heating cable Nexans TXLP / 1, 28W / M, 1800 W, 64.2M.

In this case, the power (W) per m² will be:

where boulder. - Full power of heating cable, S - Number of heated square meters.

(This value satisfies the conditions of the table)

The laying step (N) of the cable will be:

whereS. - Heating area,L.- length of cable.

(For convenience, when installing it is possible to accommodate the heating cable with a step of 8 cm, and the small residue of the cable can be mounted on the free area of \u200b\u200bthe roof.)

Option 2: Heating cable Hemstedtt DAS 55 (1650 W, 55 m). By the formulas specified above, we define the necessary parameters.

(Power per 1 m² \u003d 330 W, laying step \u003d 9 cm)

Option 3: EXCONE heating cable ELIT 2-23, 1630 W, 70 m

(Power per 1 m² \u003d 326 W, laying step \u003d 7 cm)

Approx. In addition, it is possible to use self-regulating cables and cutting resistive cables.

Calculation of the heating system for drains:

1. On the table, we determine the required power for the drain:

W. \u003d 40 - 50 W / m

1. Determine the desired length of the heating cable based on the condition specified above.

Since the diameter of the drain is 10 cm, the heating cable must be mounted in one living L.in. \u003d 6 + 6 \u003d 12 m

For a gutter width of 20 cm, the cable is selected with the calculation of laying in two veins.

L.g. \u003d 10 × 2 \u003d 20 m.

Option 1: Self-regulating heating cable.

For each drainage, we use 6 meters of a power cable with a power of 40 W / m, and in a 20 m cable chute with a power of 20 W / m, with an attachment every 40 cm by mounting plates.

Option 2: Hemstedt DAS 20 heating cable (for styling in a chute in two veins) and 6 M Self-regulating cable 40 W / m (for laying in each drainage.)

A task: It is necessary to prevent the freezing of melt water in the drain.(The length of the drain is 15 m, the material is metal, diameter - 20 cm, the drain of water occurs from the "cold roof")

In addition to heating the vertical pipe, it is necessary to ensure heating horizontal drainage (Fig. 4), which flows melt and rainwater from the drain and from the platform with paving slabs, in which it is located. The length of the runoff is 6.5 m, width 15 cm.

Decision:

1. Based on the parameters specified in the Correction, we determine the required power to 1 mp. W \u003d 30 - 40 W / m.
2. Determine the length of the heating cable. (For the diameter of the drain and drainage of the specified in the condition, laying of the heating cable in 2 lines is necessary)L \u003d (15 + 6.5) × 2 \u003d 43 meters.
3. Select the heating cable of the corresponding length and power.

Option 1: Nexans TXLP / 1 1280 W, 45.7m. The cable is placed in two lines with a pigtail and connects in a convenient place (to the thermostat or to the meteorological station). The rest of the cable (2.7 meters) is possible to be put into the drain neck of the drain, or extend the heating section at the end of the drainage.

Option 2: Exxon elite 23, 995 W, 43.6 m.

Option 3: NEXANS DEFROST SNOW TXLP / 2R 1270W, 45.4 m.

Option 4: self-regulating or cutting resistive heating cables.