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: http://www.naic.edu/~phil/tecdoc.html
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NAME: tec0intro - Intro to using the atm tec routines. The tec (Total Electron Cnt) data is recorded from a receiver at the lidar lab. It receives a dual frequency beacon from a number of satellites and converts this info to tec. Data is processed and stored once a second for each satellite pass. Routines are used to move this data to an idl archive where it can be extracted and plotted with the tec idl routines. Each pass of a satellite will last a few hundred seconds. The processed data is stored in an idl structure at 1 second intervals. This data structure contains the data from the processed file (the interpretation of some of the elements is still waiting on hien). help,tar,/st JD DOUBLE 2454161.7 ; julian date for sample to 1 sec resolution TEC FLOAT 0.686000 ; slant relative tec for this second. SAT INT 6 ; satellite code (see tecsatnm(code) for name) PH INT 20 ; phase flag ?? UHF INT 0 ; uhf flag VHF INT 4 ; vhf flag PASSNUM LONG 18 ; unique number for each pass of a satellite AZ FLOAT 318.140 ; azimuth of satellite from ao EL FLOAT 19.5100 ; elevation of the satellite from ao. FLAT FLOAT 23.4100 ; lattitude where ao-sat pierces fregion FLON FLOAT -71.9000 ; longitude where ao-sat pierces fregion ELAT FLOAT 20.0500 ; lattitude where ao-sat pierces eregion ELON FLOAT -68.5100 ; longitude where ao-sat pierces eregion ========================= Notes on the dataset: ========================= - The data set started on 20dec06. - It looks like the tec data has not been range corrected. - There has been no data quality filtering. There are a bunch of elevations < 0. ========================= Using the tec idl routines: ========================= - starting idl: idl @phil @tecinit - inputting a range of tec data (say 28jan07 thru 31jan07); yymmdd1=070128 yymmdd2=070131 npnts=tecget(yymmdd1,yymmdd2,tar) - converting from slant tec to vertical tec for 300 km: hght=300. tecV=tecver(tar,hght)k - plotting: - the tecvalue plot,tar.tec - the tec value by date: xtickf=tecbydate() plot,tar.jd,tar.tec,xtickf=xtickf - tec value by ast hour hr=tecasthr(tar) ; convert to ast hr plot,hr,tar.tec,psym=1 ; put a cross at each point - help explain,tecdoc .. list tec routines explain,tec0intro .. list this help explain,tecget .. list tecget doc
(See /pkg/rsi/local/libao/phil/tec/tec0intro.pro)
NAME: tecasthr - return ast hr of day for each point SYNTAX: hr=tecasthr(tar) ARGS: tar[n]: {} structure holding tec info returned by tecget() RETURNS: hr[n] : double ast hr for each point. DESCRIPTION: Convert the julian date of each point to AST hr from midnite.
(See /pkg/rsi/local/libao/phil/tec/tecasthr.pro)
NAME: tecbydate - setup for plotting by date SYNTAX: xtickf=tecbydate(formatCodes) ARGS: formatCode: string format codes to use on x axis. The default is: dayMonYr. see idl routine label_date() for a list of the codes to use. %M month name %N month number (2 digits) %D day number of month (2 digits) %Y year (4 digits) %Z year (2 digits) %H hour (2 digits) %I minutes (2 digits) RETURNS: xtickf: string variable to pass to xtickformat=xtickf keyword when calling plot: EXAMPLE: ; suppose we want the xaxis to be labeled as: yymmdd:hh formatcodes='%Z%N%D:%H' xtickf=tecbydate(formatCodes) plot,tar.jd,tar.tec,xtickf=xtickf
(See /pkg/rsi/local/libao/phil/tec/tecbydate.pro)
NAME: tecchk - return indices of good data SYNTAX: ngood=tecchk(tar,indgood,elmin=elmin) ARGS: tar[]: {} array of tec structures KEYWORDS: elMin: float minimum elevation to allow. Default is 0. RETURNS: ngood : long number of good points in indgood indgood[ngood]: long indices into tar for the good points. DESCRIPTION: Check the data quality. A good point must have: 1. tar.el between minEl and 90 deg 2. tar.flat between -10 and 50 3. tar.vhf lt 49.5 (seems to saturate at vhf=50??)
(See /pkg/rsi/local/libao/phil/tec/tecchk.pro)
NAME: tecget - get tec data from the archive SYNTAX: npnts=tecget(yymmdd1,yymmdd2,tecAr) ARGS: yymmdd1: long first day to get yymmdd2: long last day to include RETURNS: npnts : long number of points found. tecAr[npnts]: {} tecAr holding all data samples in the requested range DESCRIPTION: Return all of the tec info between the specified dates. A sample is included if the ast time of the first point in the satellite pass falls within the date range (including the last day).
(See /pkg/rsi/local/libao/phil/tec/tecget.pro)
NAME: tecplttecel - plot tec and elevation vs hour SYNTAX: tecplttecel,tecAr,tecv=tecv,lsat=lsat,ldate=ldate,title=title, cs=cs ARGS: tecAr[n]: {} array of tec strucutures from tecget(); KEYWORDS: tecv: if set then call tecver() to convert to "vertical" tec.. lsat : if set then include satellite name in the title ldate : if set then include the AST start time in the title title : string title to include in first plot of each page. cs : float characiter size for the labels (as passed to plot). DESCRIPTION: Plot tec vs hour and overplot elevation vs hour for each pass in the array tecAr. The elevation is overplotted in red with the elevation axis plotted on the right side of each plot. You can add the satellite name and date/time for start of the pass with the keywords /lsat and /ldate (all times are AST). The horizontal scale should be set to autoscaling (use hor). The vertical scale can be left to autoscale or you could set a fixed value for the tec plots using ver (the elevation scale is always 0 to 90). You can place multiple plots on the page using !p.multi= system variable. EXAMPLE: plot all of the passes between 23mar07 and 25mar07. Place two plots per page. yymmdd1=070323 yymmdd2=070325 npnts=tecget(yymmdd1,yymmdd2,tar) ; throw out bad elevations.. ngood=tecchk(tar,indgood) tar=tar[indgood] !p.multi=[0,1,2] ; 1 column, 2 rows per page cs=1. ; default scale for labels ver,0,20 ; limit tec range to 0,20 ; make the plots tecplttecel,tar,/lsat,/ldate,title='23-25mar07',cs=cs
(See /pkg/rsi/local/libao/phil/tec/tecplttecel.pro)
NAME: tecsatlist - return list of all tec satellite names SYNTAX: satNmAr=tecsatlist() RETURNS: satNmAr[]: strarr array of all satellite names DESCRIPTION: return list of all satellite names we know about. To map from a tec.sat to these names use: satNm=satNmAr[tec[i].sat -1] .. (the codes start counting from 1).
(See /pkg/rsi/local/libao/phil/tec/tecsatlist.pro)
NAME: tecsatnm - map satellite code to satellite name SYNTAX: istat=tecsatnm(satCode,satNm,satList=satList) ARGS: satCode: int satellite code stored in tecAr.sat RETURNS: istat: int 1 found satellite name 0 illegal satCode satList[]: strarr array holding all of the satellite names we know of.
(See /pkg/rsi/local/libao/phil/tec/tecsatnm.pro)
NAME: tecsatnmtocode - map satellite name to satellite code SYNTAX: satcode=tecsatnmtocode(satNam) ARGS: satNam: string satellite name (as defined in the data files). RETURNS: satcode: int satellite code number for satNam 0 if there if this sat name is not in the list
(See /pkg/rsi/local/libao/phil/tec/tecsatnmtocode.pro)
NAME: tecver - convert from slant to vertical tec SYNTAX: tecv=tecver(tAr,Hght,oblAng=oblang,freg=freg,ereg=ereg); ARGS: tar[n]: {} array of tec structures from tecget hght : float the height in the atmosphere for the vertical measure (units are kilometers). KEYWORDS: freg : if set, ignore altitude, use hght of 350 km. ereg : if set, ignore altitude, use hght of 110 km. RETURNS; tecv[n] : float the vertical tec oblAng[n]: float the obliquity angle for each tec value used for the correction. DESCRIPTION: Compute the obliquity angle: oblAng=(Re + Hght) / (sqrt((Re + Hght)^2 - (Re*cos(el))^2) where: Re is the radius of the earth : 6376.5 meters (from tempo). Hght is the atmospheric height passed in (in km). el is the elevation of the satellite from ao for each sample. The corrected tec is then tecV= tecS/oblAng
(See /pkg/rsi/local/libao/phil/tec/tecver.pro)