1、 Recommendation ITU-R P.835-6 (12/2017) Reference standard atmospheres P Series Radiowave propagation ii Rec. ITU-R P.835-6 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication
2、services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunica
3、tion Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations
4、 by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu
5、.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propaga
6、tion RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissi
7、ons V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2017 ITU 2017 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written
8、permission of ITU. Rec. ITU-R P.835-6 1 RECOMMENDATION ITU-R P.835-6 Reference standard atmospheres (Question ITU-R 201/3) (1992-1994-1997-1999-2005-2012-2017) Scope Recommendation ITU-R P.835 provides expressions and data for reference standard atmospheres required for the calculation of gaseous at
9、tenuation on Earth-space paths. The ITU Radiocommunication Assembly, considering a) the necessity for a reference standard atmosphere for use in calculating gaseous attenuation along an Earth-space path, recommends 1 that the standard atmospheres in Annex 1 be used to determine temperature, pressure
10、 and water-vapour pressure as a function of altitude, for calculating gaseous attenuation when more reliable local data are not available; 2 that the experimental data in Annexes 2 and 3 be used for the locations of interest when seasonal and monthly variations are concerned. Annex 1 1 Mean annual g
11、lobal reference atmosphere The following mean annual global reference atmosphere reflects the mean annual temperature and pressure profiles vs. height when averaged across the globe. 1.1 Temperature and pressure The mean annual global reference atmosphere approximates the U.S. Standard Atmosphere, 1
12、976 with insignificant relative error. The atmospheric temperature and pressure profiles are defined in two height1 regimes: 1) geopotential heights from 0 km to 84.852 km, and 2) geometric heights from 86 km to 100 km. The conversions between geopotential height, h (km), and geometric height, h (km
13、), are: = 6356.7666356.766+ (1a) and = 6356.7666356.766 (1b) 1 km are units of geopotential height, and km are units of geometric height. 2 Rec. ITU-R P.835-6 where a geopotential height of 84.852 km corresponds to a geometric height of 86 km. Since various P-series Recommendations (e.g. Recommendat
14、ion ITU-R P.676 Annex 1) use geometric height, the temperature and pressure at a geometric height h .dat, where WMO_code is the code name of the site according to the World Meteorological Organization (e.g.: 03496.dat, 03496 is the WMO station code for Hemsby-in-Norfolk). An example of one profile i
15、s given in Table 2. The list of locations is contained in an ASCII file (using the comma separated value file, CSV, file format) called dst_std_lst.csv. Each record of this file contains the following field: WMO_CODE, Station Name, Country, Latitude, Longitude, Altitude above sea level. An example o
16、f such a record is given in Table 3. Above the maximum altitude, extrapolation can be performed by using the reference profiles given in Annex 1. To translate the relative humidity into absolute values of water-vapour density, the formulae contained in Recommendation ITU-R P.453 should be used. TABL
17、E 2 DST.STD data format Example of month average profile (station 10410) YYMMDDHH NL 99 199 0 33 Press (hPa) Z (km) Temp (K) RH (%/100) 1 016.905 0.00 273.62 0.864E+00 956.686 0.50 273.33 0.830E+00 898.555 1.00 271.74 0.754E+00 844.014 1.50 269.59 0.665E+00 791.860 2.00 267.15 0.591E+00 742.661 2.50
18、 264.56 0.518E+00 696.285 3.00 261.89 0.470E+00 651.977 3.50 258.94 0.458E+00 610.086 4.00 255.88 0.448E+00 570.467 4.50 252.69 0.445E+00 533.076 5.00 249.33 0.451E+00 497.767 5.50 245.90 0.453E+00 464.123 6.00 242.32 0.450E+00 432.441 6.50 238.75 0.450E+00 402.414 7.00 235.16 0.443E+00 374.177 7.50
19、 231.59 0.437E+00 347.236 8.00 228.12 0.433E+00 322.281 8.50 224.88 0.427E+00 8 Rec. ITU-R P.835-6 TABLE 2 (end) YYMMDDHH NL 99 199 0 33 298.474 9.00 221.89 0.421E+00 276.492 9.50 219.27 0.416E+00 255.527 10.00 217.08 0.411E+00 236.297 10.50 215.62 0.402E+00 218.415 11.00 214.79 0.393E+00 201.366 11
20、.50 214.14 0.348E+00 186.214 12.00 214.02 0.205E+00 172.093 12.50 214.24 0.104E+00 158.709 13.00 214.66 0.368E-01 146.492 13.50 214.94 0.351E-02 135.813 14.00 214.88 0.120E-02 125.690 14.50 214.50 0.117E-02 116.027 15.00 214.01 0.113E-02 106.798 15.50 213.56 0.110E-02 98.291 16.00 213.26 0.107E-02 L
21、egend to Table 2: YY = Year (99 for mean monthly profiles) MM = Month (1 = January, 2 = February, .) DD = Day of the month (99 for mean monthly profiles) HH = Hour of the day (UTC) NL = Number of vertical levels (NL = 33 for STD.DST) Press (hPa) = Atmospheric total pressure Z (km) = Height above the
22、 Earths surface Temp (K) = Air temperature RH (%/100) = Relative humidity (as a fraction) NOTE 1 The level values of Temp and Press may be set to zero if unrecorded. TABLE 3 DST_STD_LST.CSV station information file Example of record structure WMO code Station name Country Latitude (degrees) Longitud
23、e (degrees) Asl (m) 10 410 ESSEN DL 51.4 6.967 153 NOTE Latitude and longitude values are in decimal degrees (i.e. 51.4 = 51 24). Rec. ITU-R P.835-6 9 Annex 3 1 Numerical weather prediction data of atmospheric vertical profiles Monthly averages, conditioned to the hour of the day, of vertical profil
24、es of temperature, pressure and water-vapour density were calculated using the ECMWF 15-year data set (ERA15) from the re-analysis project. This data set contains the mean monthly vertical profiles at 00:00, 06:00, 12:00 and 18:00 UTC of total air pressure, air temperature and water-vapour density a
25、t 32 height levels from a reference height located around the local Earths surface up to about 30 km above the Earths surface. The data are from 0 to 360 in longitude and from +90 to 90 in latitude, with a resolution of 1.5 in both latitude and longitude. All the data are stored in files using the I
26、EEE floating point single precision standard (4 bytes, 32 bits) in a Big-Endian format. The data set and the associated Matlab files to access the data are an integral part of this Recommendation and are available in the Supplement file R-REC-P.835-6-201712-I!ZIP-E. The mean monthly profiles of each
27、 meteorological parameter are contained in binary files _.bin, where param is the name of the meteorological parameter (pres = total air pressure (hPa), temp = air temperature (K), vapd = water-vapour density (g/m3) and hh is the hour of the day (i.e. 00, 06, 12 and 18 (UTC). The associated heights
28、of the profile levels are contained in the binary file hght.bin. An example profile for Latitude = 45 N, Longitude = 9 E, July, and 12:00 UTC is given in Table 4. TABLE 4 Example Profile Z (m) Press (hPa) Temp (K) Vapd (g/m3) 665.488 939.255 298.373 9.823 698.823 935.673 298.125 9.617 816.585 923.09
29、2 296.598 9.302 1 026.379 900.957 294.292 8.811 1 309.298 871.693 291.459 8.099 1 650.689 837.298 288.287 6.992 2 039.463 799.373 285.107 5.706 2 467.391 759.191 282.116 4.555 2 928.467 717.723 279.045 3.641 3 418.375 675.691 275.934 2.692 3 934.342 633.633 272.913 1.855 4 474.659 591.936 269.707 1.
30、286 5 038.169 550.876 266.183 0.911 5 624.303 510.656 262.354 0.636 6 232.944 471.427 258.213 0.428 6 864.291 433.307 253.687 0.277 7 518.708 396.390 248.780 0.173 8 196.752 360.767 243.521 0.103 8 898.985 326.527 237.971 0.058 9 626.211 293.764 232.319 0.034 10 380.050 262.580 226.984 0.019 11 164.
31、590 233.064 222.845 0.009 10 Rec. ITU-R P.835-6 TABLE 4 (end) Z (m) Press (hPa) Temp (K) Vapd (g/m3) 11 988.097 205.263 220.483 0.003 12 861.558 179.195 219.279 0.001 13 796.578 154.827 218.154 0.001 14 809.705 132.043 217.057 0.001 15 931.961 110.604 216.026 0.000 17 225.900 90.110 215.674 0.000 18 818.316 70.037 216.262 0.000 20 961.771 50.038 219.300 0.000 24 267.900 30.039 223.166 0.000 31 427.936 10.320 232.854 0.000 Legend to Table 4: Z (m) = Height with respect to sea level Press (hPa) = Atmospheric total pressure Temp (K) = Air temperature Vapd (g/m3) = Water-vapour density _
