Beginning with the December issue, No. 24 of this series, polar plots of the prediction maps will be included for every even hour universal time. These are plotted on the same scale as the former polar plots, but extend only to 40° latitude. The contours of the rectangular world maps are now cut off at 80° latitude. Occasional slight discrepancies between the contours of the rectangular maps and those of the polar maps are due to the different computer programs used to derive the two sets of contours from the table of numeri¬ cal coefficients. These discrepancies are well within the accuracy of the predictions. 
These polar maps are being published on a trial basis for six months. They will be discontinued after six months unless there is a positive indication of their usefulness from a substantial proportion of users of these predictions. Therefore, if you wish these to continue, it is necessary to send us your comments in writing as soon as possible. 

The CRPL Ionospheric Predictions are issued monthly as an aid in determining the best sky-wave frequencies over any transmission path, at any time of day, for average conditions for the month. Issued three months in advance, each issue provides tables of numerical coefficients that define the functions describing the predicted worldwide distribution of foF2 and M(3000)F2 and maps for each even hour of uni¬ versal time of MUF(Zero)F2 and MUF(4000) F2. 
Note: Department of Defense personnel see back cover. 
U3e of funds for printing this publication approved by the Director of the Bureau of the Budget (June 19, 1961). 
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402. Price 25 cents. 
Annual subscription (12 issues) $2.50 (75 cents additional for foreign mailing). 

National Bureau of Standards

The functions of the National Bureau of Standards are set forth in an Act of Congress, March 3, 1901, as amended. These include the development and mainte¬ nance of the national standards of measurement and the provision of means and methods for making meas¬ urements consistent with these standards; the deter¬ mination of physical constants and properties of ma¬ terials; the development of methods and instruments for testing materials, devices, and structures; advisory services to government agencies on scientific and tech¬ nical problems; invention and development of devices to serve special needs of the Government; and the de¬ velopment of standard practices, codes, and specifica¬ tions. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services, and various consulta¬ tion and information services. The Bureau also serves as the Federal technical research center in a number of specialized fields. 

Central Radio Propagation Laboratory

The Central Radio Propagation Laboratory at Boulder, Colorado, is the central agency of the Federal Government for the collection, analysis, and dissemina¬ tion of information on propagation of radio waves at all frequencies along the surface of the earth, in the at¬ mosphere, and in space, and performs scientific studies looking toward new techniques for the efficient use and conservation of the radio spectrum. To carry out this responsibility, the CRPL-1. Acts as the central agency for the conduct of basic research on the nature of radio waves, the pertinent properties of the media through which radio waves are transmitted, the interaction of radio waves with those media, and on the nature of radio noise and interference effects. This includes compilation of re¬ ports by other foreign and domestic agencies conduct¬ ing research in this field and furnishing advice to government and nongovernment groups conducting propagation research. 
2. Performs studies of specific radio propagation mechanisms and performs scientific studies looking toward the development of techniques for efficient use and conservation of the radiofrequency spectrum as part of its regular program or as requested by other government agencies. In an advisory capacity, coor¬ dinates studies in this area undertaken by other gov¬ ernment agencies. 
3. Furnishes advisory and consultative service on radio wave propagation, on radiofrequency utilization, and on radio systems problems to other organizations within the United States, public and private. 
4. Prepares and issues predictions of radio wave propagation and noise conditions and warnings of dis¬ turbances in these conditions. 
5. Acts as a central repository for data, reports, and information in the field of radio wave propagation. 
6. Performs scientific liaison and exchanges data and information with other countries to advance knowl¬ edge of radio wave propagation and interference phenomena and spectrum conservation techniques, in¬ cluding that liaison required by international respon¬ sibilities and agreements. 

Introduction

The "Central Radio Propagation Laboratory Ionospheric Predictions" is the successor to the former "Basic Radio Propagation Predictions," CRPL Series D. To make effective use of these predictions, National Bureau of Standards Handbook 90, "Handbook for CRPL Ionospheric Predictions Based on Numerical Methods of Map¬ ping," available from Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402, price 40 cents. This Handbook includes required additional data, nomographs and graphical aids, as well as meth¬ ods for use of the predictions. The Handbook supersedes the obsolete NBS Circular 465. 
The basic prediction appears in tables 1 and 2, presenting predicted coefficients for foF2 and M(3000)F2 defin¬ ing the numerical map functions desci'ibing the predicted worldwide variation of these characteristics. With addi¬ tional auxiliary information, these coefficients may be used as input data for electronic computer programs solving specific high-frequency propagation problems. Basic equations, their interpretation, and methods of using numer¬ ical maps are described in papers by W. B. Jones and R. M. Gallet, "The Representation of Diurnal and Geo¬ graphic Variations of Ionospheric Data by Numerical Methods," Vol. 66D, No. 4, July-Aug. 1962, pages 419-438, and "Methods for Applying Numerical Maps of Ionospheric Characteristics," Vol. 66D, No. 6, Nov.-Dee. 1962, pages 649-662, both in the Journal of Research of the National Bureau of Standards, Section D. Radio Pi-opagation. The predicted numerical map coefficients of tables 1 and 2 may be purchased in the form of a tested set of punched cards. Write to Prediction Services Section, Central Radio Propagation Laboratory, National Bureau of Standards, Boulder, Colo., to arrange for purchase of a set of punched cards, and for information and assistance in the application of computer methods and numerical prediction maps to specific propagation problems. 
The graphical prediction maps, derived from the basic prediction, are provided for those unable to make use of an electronic computer. Information concerning the theory of radio wave propagation and such important problems as absorption, field intensity, lowest useful high frequencies, etc., is given in National Bureau of Standards Circular 462, "Iono¬ spheric Radio Pi'opagation." A revised work is in preparation which will be announced in the Ionospheric Predic¬ tion series when available. Additional information about radio noise may be found in C.C.I.R. Report Number 322, "Revision of Atmospheric Noise Data," International Telecommunication Union, Geneva, 1964. Reports to this Laboratory of experience with these predictions would be appreciated. Correspondence should be addressed to the Prediction Services Section, Central Radio Propagation Laboratory, National. Bureau of Stand¬ ards, Boulder, Colorado. NOTE: The MUF (ZERO)F2 values of fibres 1A through 12A were derived by adding one-half the gyrofrequency to the foF2 calculated by use of the predicted coefficients in table 1. The error introduced by this approximation is generally not important compared to other uncertainties in the predictions, and is significant only when the foF2 is near or below the gyrofrequency. If more precise values of predicted fxF2 are desired, the theoretical relationships should be applied to the foF2 values calculated by the coefficients in table 1. 
(»lHO®l/'INf'Jl9>f <\i in © © © >r a IT IA O N N T h >C 4-o^«4'0©ir'r'-4m©onj -*®mi*"44nj©®m©©«- ^OffNN^ONHHfflOA IAT^-IM-ONHMATO-M«T(VIA®-H|ATT®IN 1 1 1 1 1 1 1 1 1 1 1 1 1 Nojhho-00-<t^ht-.h--hnh-.-nO^'--' OOOOOOOOOOOOOOOOOOOOOOOOOO 1,1,1 OJ ujluluujujujujujuiujuj ®C'T'-r'®lA®r'J®lAP'(TI7'N ,j- ® ,y O N O O •f 0'fO'OIAAJ®MATOMNJ'T-lAJlA-iff'-<®ON®HH T N ^ T ON H A®0-CA®®ON®IA -O fA IA O <A (A IA THo®N'faoTT^ocr-<o •j^(siiA7i(r®f*®0'® N>->J'-TTN®0®(rO®N®®AO'TOfA®CAN®<AA ff®mNNC'®0(A0®IA0TN ^TT«0'NiA®®AN AT®OONN(MTTONHiAA-i®'f ^ho>»iAhhT 7 7 i o o o o o o 1 1 1 1 1 1 a-o ® m ® © © © © A-rg o 4 in ® © m o fg © ® © A-in ® 4 m o 4 in 4 O © 4 O' njmnjC44-«©mN-( ( 1 1 1 1 1 1 1 1 1 III 4- nj UA 1 1 ^-<HOOOO-<^>--lNNN-iNAJN*<fVNNHHHN ® eg « rsj ® -4 rvj OOOOOOOOOOOOO 1 1 1 UJUJUiUJUJUJUJUIUJUJUJUJUJ inMMVCMJ'H^IN(TO':f>r UJUJUJUJLUU/UJUJUJUJUJIUUJUIUJUJUJUJUJUJLUUJUJUJUJUJ 00®9lIAH^f*N(A(AOIf>'»lA®0'^lANONA®'<lA ^N'ON-<®c'"^o^fN'Tfr'®®'Ocro(AtA®r'^'roC' o o o o o o o 1 1 1 1 1 1 1 Ui LU UJ UJ UJ ID UJ eg © a~ o © © <v O O © © (M © ® ® Of-fTPO'IAmMAO-tOlA NOAiBfOtMO^H^lANN -*.-«in44>r**«n®<-»-«^N-m 0®mCOIAH«NMAHO N-4 A-«rf^O-N®OOOOHTN®N-OOH^«IA ><NNNNNNTH ® (A O fA ® N ® ^NOlAfAififAeiAIA ®lPinrgl'-0©®©0©fN©in4m©®0®<M®©®'0© ^MAO-*IA'riATN®AJNO'N®^®OlArAlA>fT(\Aj HO-<A(AN N A O <A O A ■# ®00®-*®4 4 ® fM N-© © -^ ®mmi^-«m4'©®'0®fMfM ii II II <m 4 4 n a ^fM^-4--incgrsifninfMiMfn-a-®-* 1 1 1 l till till ®B-HAN® IIII -fM-*rsi-^-i OOOOOOOOOOOOO 1 1 LUUIUJUJUJUJIULLIUJIUUJUJUJ h NlA ^ ® f> 4 0'HfflOMN (NNNONhOOTOOTA|hh-iN-*iON-'OONO oooooooooooooooooooooooooo III II ujujujujijjujujujujujiuujujujujujujujujujujujujujujuj ®®lAMNOAJN®A(A<AO-*MMO'-MNAI<l,OlAAJNA -i^OaONO'BNTONIAAJIAOO'O^O'flAOO-'f OOOOOOOOOOOOOO 1 1 1 1 1 1 1 1 1 1 1 1 1 1 UJLULUUJUJUJUJUJUJUJUJUJUJUJ ©4-<a~©o©oa-®o©©® 0'#AJ4®«fOOiN®0'NAA <n f9IA(*W9IAl^a-f'®lAOCA C'«riAO--<,NM<MTIIf'f9N rsl®Cg©<M4<NIO -<M © eg © ^ONfAMAOMCNANO (MT'-NIT-tf fAWP-O-f- Jj^iA'fAOlAlA^TVAMANO TO'OOO'aNNfflO'IO^H-iONlANOONO'NNN HOT®ffl®NHA®IT'-A®^NOlAT(?0'0®'<'fH OfflNOffl--'JfflO'TN-HO®NAO(fN#N®OT ®-^hA(J'NNOMANNN J-CD-*-<®®®®®-«fM4'®4 ©00®©4inm©0©©min -f-*®4©44-'©®A^44in (MO'(M-icgin®©.-<r'--ifM® III II II ® in 4 ® © h-<-• ®in<-*-*rg-<•-rg®r^©rg(M4'-4-<© I 1 1 1 1 | 1 l l 1 1 1 1 <M -m©m©<Mr^©4fM-*fM4 III III »--*'M(M-jfM-<'-i OOOOOOOOOOOOO 1 1 QD r\j IN ® *0 O' © O © 4 4 © -• NNOOrtO--rfO'--<-<-'fM(\|NHMHAJrtl\i-rfp- OOOOOOOOOOOOOOOOOOOOOOOOOO III ^ UUJUJUJUJUJUJUJIUUJIUUJUJUJ NNtn-'OO-'OOhhhO OOOOOOOOOOOOOO 1 1 1 1 1 1 III ®r^r--o®<M®^ip®.o®(MiP .-«®^r*-®®Of'-©<M®®in lAHO-^ (T®NNNNN®0 f».-«4-<®©in-*©iM4m® ^aoo'®r~-r-'0000-'®f»> ©iP4®4r~-®04r-o-•© (AO'O'OfAAIMAO'A'J-r ^ffMA'O^O'AfNNMA®^ ®®T®CMAN(TNNO''®®'ff'IN'TlAlA®-AJ^O'(T N lA fA ® O ® 4 ®®-HAON ^®(MA(A(ArAMA 'll ® O A ^f»f.f~5'HO'J<A-I^-'®-T'A7'f~IAOlA'OlA-<®fAlA r<T < >o o -o >r m o o n n ® iaia n.® ia ® ia a n a n ^ -iVNTHMA<J'lANlAN^-0®'-5'Nff®A0lA0-f 'f-AAH® O'HAff'OOff'O' ®in4<M©4©44m®pgmm ® O' -* «M ®0 0«AO'N44-' ®®--0'--r^®^®r-®®®® O® ®fM®«M-*'-'fM0'0'fM®«-' 0J » m®^^miAO'^«-
■ -i CD © O O f-© ® -T'ON-'OCTCDfM'TN-4 ® O 4 -u 4 -• ® ANANAAmOBA-T ©inin©0m00®©0^-0©© ^A®MAJNANA-''OAOAI^^fflAO'AAJ®4-AJAA OfgAB'TOU'BAMABNATON'A'OffllAOO'B'f- HIAANAO®NBA®(?'fA'OHNOa'A®HIAATCr ^H^NOOIA^'J1 T-O-lTOOO'AAJANNlAJO'H -4-<C>*-iOO00O'-*0OO«-J OOOOOOOOOOOOOO 1 1 1 -JAMNAO'AOAN'-®'*® ■o <j~ <x> -r -• d cr\ r-■j-*f-o\r\0'r- 4-® -4-n-■ 4' -g ® r-® 4--c t*\ ®OON®#IAhB®OIA^(T N®n®N< (A-OH® NO- <M®®C'®®r-®®"0®(7'^'M ®®-*®®-»®m--r-^®in® - ^,_,_,®^rMrg4®4rg -f- 1 II II 1 O-iO-■-*fMfM(M<M<Mrg<M'-< OOOOOOOOOOOOO ® © -< in -< 4 a-o ® --f aj o IN 190 -19 -r N -f O « B IN O ©®r~©in®®©oo4in® 44inin©4©®®mr-*-ir'- MTifilAOIAOBONOOO -•44r'-N-4(M-'4r-o©r^ ®f'4'OMfAlAAJ®MOH(A fM®-J®^ -^'-'r'-^H®4<M©rg©®'-'fMA-'M-<©'M©4 1 1 1 1 till 1 1 1 1 _.,_4_«0^00-JfM-<>-*<M<M<M.-<®®»MfM®®fM-*fN(M<M OOOOOOOOOOOOOOOOOOOOOOOOOO III uiujujujuiuiujujujujujujujuj -fflNNN'I-'AMAff'TAMANtf^MA'JOON-fA IAIA"<NlA®IAO--,®'T^®®A®'^®lAffl®0'ArAO® 4 >m in ® in ® a-■ in ^-.ONNCAMaN aatnaaca 0N®®®'rA\001ArgT®TAj-NCMNNN0NNCMA OAAA®0'J®N'AAN'TT'A<NOfA(T®^'TAJOON •^AlO'lNfN-iNN'fA ©-*N-»*mm©©N--Omin<M®in<M® AHAfA^NNfA® BNOCOBOOT-OXIH-'OO® NIAIA®0'-«'4;N^ IIII IIII fMIM-^-•>-*-•O^O*-'-'■-'O OOOOOOOOOOOOO ®0'®®400'®4-'-®'M4 ®®®4,OCMCf4' 4 4' ® O' (M ® O' AO'®»'Oaj^AhO A^A4N®-i4NB®®0 ®BOA.0OA4ONA®h ®-*pjino®®0'®<M®®r- cg4m<M® --i®Cgm<M-© II II II 1 T T* T | "■' f'-a-'fiii iiii i rUOOlNNN -(M-.-g<M®-H O o OOOOOOOOOOOOO m^ONO^H o-Iaoit N®®MT-*(Atr-HTHOO rv-^Cf-j-<mmfAHO'C'(r' fMIAIA>Cf'fT®'0®f'J®®r''0 r~ ^OO'O'T-MAIAIAIAHIA MOH^o-f o-airmciAB 0®A'TOO'OHIAN®MT OOOOOOOOOOOOOOOOOOOOOOOOOO in®®®®® in © cror^N-®®®!-fNjnjooTT-'fNJt^r^ ©0®04©m®4 ®0®4l"-in4»*®®Oinin»H®®in nj®m © © o o -• 4 44©®®®o-*m©©®f\icgcg<M® O' ® 4 'MOO' © ® © IP O' in-* © •-< ip -* ip © ® rg -u ® ip --f>- ® ® © © ® -■< ®®A(M®-«®vTO' © O fM 4 © •-J © f\J lp_.fM®0'®0'^~r®^-N-^o0'<Mo-jN->?-®®®n.®r~ o AJ -f 400©0lP0©r»®®®®4-«r-®40-'©r-r- -<M O -* <M -O o o o o o o o II III f~or~®®®^- r» r~ r-® >o m ® N JO--4NN OOAIflN® N-OO-Cf AN H» O 4 -O O O' O ® ® -f-m ip O' M»W<IH®MSa'NN II II II 1 N-#N't^N-<®H#A®AN«JNNlMHNHrtrfN® III IIII IIII | -i ® -i ® -• l i l o c o t 0^(Nm-|'in^P*®0'0-fN AN®C7'O^AJ®J1AAN®(?'O^I\T4'1A<1^OD ^ ^ ^ ^ ^ ^ ^ <M<M«M«NOJ(MfMiM<M<M®®®®®®®®® O' O « (M ® •TAANfflJO'*N ^4'4-4'4'4-4'4'44'4'ininm E o X *-« a 0 O' O 4 O O' IAOO hi WNCO Of < h H il 4^ O' fM < o o o o o (M CD CD -O O' ® O O 00 O -■ CT ^ eo fsi nj in o CO 4 AJ © o O O O O C ® © O O' • O' © O' O - O O IT O I O'ilNfff O' oo eo r-«M O <M © nj o 4 in 4 4 m BON o o o o o •roifiHP NCH1VIHVA "IVDIHdVd9039 ii_ © a f J I 5 -2 NOliViyVA ~IV0IHdVa9039 PREDICTED COEFFICIENTS DSK DEFINING THE FUNCTION T( A,0,t) FOR MONTHLY MEDIAN f0 F2 (Mc/s) TIME VARIATION C T3 5 o c * % Vi ■O o o -Q • c 3 I ! s i o 5 45 c 5 ~ o 4> a T3 ffi (/) .Q -'O a. W £ o I o g> _ in .1 ? T3 O 2 </> g s T3 m- .T= ■ © -^ u - >s TD * s s 0> § & .2 E



  Figures 1 to 12 present world maps of MUF (Zero) F2 and MUF(4000)F2 for each even hour of universal time. Figures 13 to 24 present the same predictions for even hours 00 through 22 universal time for the North and South Polar areas. Handbook 90 describes methods for including regular E-Fl propaga¬ tion. Figure A is a graph of predicted and observed Zurich sunspot numbers which shows the recent trend of solar activity. Table A lists observed and predicted Zurich smoothed relative sunspot numbers and includes the sunspot number used for the current prediction. Members of U.S. Army, Navy, or Air Force desiring the Handbook and the Ionospheric Predictions should send requests to the proper service address; for Navy: The Director, Naval Communications, Department of the Navy, Washington, D.C., 20350; for Air Force: Directorate of Command Control and Communications, Headquar¬ ters, United States Air Force, Washington, D.C., 20330. Attention: AFOCCAA. Army personnel should refer to the Handbook as TM-11-499 and to monthly predictions as TB ll-499-( ), predictions for the month of March 1965 being distributed in December 1964 and designated TB ll-499-(24), and should requisition these through normal publication channels. 




  UJ UJ UJ UJ -H®oinN-®©44®-«oin<Mip©<M-<--'©in©0'M0f'-in®©®®m-T4m*~IHAJ0H-f-H'JA-(90®'AlA-tr-r' $®iA®N'H^'j,®®(r'®m-f^ 4'-r-o<M©©-'©©© -<r»©®r'-r-®©in<\Jin4in®ip®©©®4©©m®®© c s s it ia o 4®4in©r-r-r-®o~<©fM--®©<M©©fM IP O' -< -«4®in®®f'g©O0r~®<N0®®'*H 




  -'4'O'-''J''J,AI®(A-f0''<lAN(AlA-<r-OO® A®NAjO'TNOO'N'jr'HMN®®aOU'NMANN^N «A<3(?H0'O'0ANT®^IJ'HAN®'0N'f-i'TO-O 4(Min©0(M©m®'M'M4<Mr-©in©®®®4-'©©a-• AJlTHNAHlTAA <TAI'0^lAN®®Tff'(ANCAJ®®'-1 O ® A-U'BHHNNNfflO'AAWAONANN'IHOAO ®r*-®®f«--i-<®-<®0' 




  FIG. I A. PREDICTED MEDIAN MUF(ZERO) F2 (Mc/s) 




  FIG. 12A. PREDICTED MEDIAN MUF(ZERO) F2 (Mc/s) 


Table A

 A Observed and Predicted Zurich Smoothed Relative 


					Sunspot Numbers					
	Month Jan. Feb. Mar. Apr. May	June July Aug.	Sept. Oct. Nov. Dec.
	6	6	4	3	4	4	5	7	8	8	10	12
	(14)	(12)	(ID (10) (10)	(9)	(8)	(8)	(8)	(10)	(10)	(ID
	14	16	20	23	29	35	40	46	55	64	73	81
	(12)	(14)	(14)	(13)	(16)	(18)	(22)	(27)	(30)	(31)	(35)	(42)
	89	98	109	119	127	137	146	150	151	156	160	164
	(48)	(53)	(60)	(68)	(77)	(89)	(95) (105) (119) (135) (147) (150)
	170	172	174	181	186	188	191	194	197	200	201	200
	(150) (150) (150) (150) (150) (150) (150) (150) (150) (150) (150) (150)
	199	201	201	197	191	187	185	185	184	182	181	180
	(150) (150) (150) (150) (150) (150) (150) (150) (150) (150) (150) (150)
	179	177	174	169	165	161	156	151	146	141	137	132
	(150) (150) (150) (150) (146) (143) (141) (142) (141) (139) (137) (137)
	129	125	122	120	117	114	109	102	98	93	88	84
	(136) (135) (133) (130) (125) (120) (118) (115) (110) (108) (105) (100)
	80	75	69	64	60	56	53	52	52	51	50	49
	(100)	(90)	(90)	(90)	(85)	(85)	(80)	(75)	(70)	(70)	(65)	(60)
	45	42	40	39	39	38	37	35	33	31	30	30
	(60)	(50)	(48)	(45)	(42)	(37)	(34)	(31)	(29)	(28)	(27)	(34)
	29	30	30	29	29	28	28	27	27	26	23	21
	(31)	(28)	(26)	(25)	(25)	(25)	(23)	(21)	(20)	(18)	(18)	(17)
	19	17	15									
	(17)	(17)	(17)	(17)	(17)	(17)	(17)	(17) (17.5)(17.3)(17.0) (17.0)
	(15.0)(16.0) (16.0)*									

Note: Final numbers are listed through June 1963, the succeeding values being based on provisional data.The predicted numbers are in parentheses.* Number used for predictions in this issue.