Using the HydroEstimator in McIDAS

1
Using the Hydro-Estimator in McIDAS

• Bob Kuligowski
• NOAA/NESDIS Center for Satellite Applications and
  Research (STAR)

2
Outline

• Brief McIDAS Background
• Hydro-Estimator Basics
• Running the Hydro-Estimator
• Preparing the data fields
• Running the algorithm
• Examining the results
• Appendix Basic McIDAS Commands

3
Brief McIDAS Background

• Man-computer Interactive Data Access Systemused
  to display and analyze satellite data (GEO and
  LEO)
• Supports both line commands and a programming
  language similar to FORTRAN 77
• Information and online documentation
  http//www.ssec.wisc.edu/mcidas/
• To run, just type mcidas from a terminal window.
  A command screen and display screen should
  appear.

4
McIDAS Programs

• McIDAS has a programming language that is
  virtually identical to FORTRAN 77.
• Programs are kept in the mcidas/src directory and
  have a .pgm suffix instead of .f or .for.
• Special subroutines and library functions are
  used to read and write McIDAS data files, but
  ASCII and binary file formats are also supported
• Programs are compiled using the command
  fx program l vendor which compiles
  program.pgm and places an executable program.k in
  the mcidas/bin directory.

5
Outline

• Brief McIDAS Background
• Hydro-Estimator Basics
• Running the Hydro-Estimator
• Preparing the data fields
• Running the algorithm
• Examining the results
• Appendix Basic McIDAS Commands

6
Hydro-Estimator Basics

• Manual techniques for estimating rainfall from
  satellite cloud-top temperatures have existed for
  gt30 years
• The Auto-Estimator was the first-generation
  automated technique at NESDIS the
  Hydro-Estimator (HE) replaced it in 2002.
• Both techniques related rainfall rate to
  cloud-top temperature as estimated in 10.7-µm
  GOES imagery
• Colder clouds are raining heavily
• Warmer clouds are raining lightly or not at all.

7
Illustration of the IR signal from different
rainfall intensities
Tb200 K
Tb212 K
Tb224 K
Tb230 K
200
250
290
T (K)
8
Exceptions to the Rule...
Cirrus Tb205 K
Cumulonimbus Tb200 K
Nimbostratus Tb240 K
290
200
250
T (K)
9
Hydro-Estimator Basics

• Simple use of 10.7-µm brightness temperatures
  leads to missing of warm, stratiform rain and
  incorrect designation of cold cirrus as raining
  cloudsa major problem with the original
  Auto-Estimator
• The HE considers the temperature relative to the
  surrounding pixels using the relationship
  Z(µ-T)/ s
• µ is the mean temperature of the nearby cloudy
  pixels
• s is the standard deviation of the temperature of
  the nearby cloudy pixels
• Pixels colder than their surroundings (positive
  Z) are assumed to be convective updrafts and
  hence producing rainfall
• Pixels as warm as or warmer than their
  surroundings (negative Z) are presumed to be
  convectively inactive

10
Tb lt Tb Rain
Tb Tb No Rain
Tb lt Tb Rain
Tb Tb No Rain
290
200
250
T (K)
Illustration of the HE Rain-No Rain
Differentiation
11
Hydro-Estimator Basics

• Satellite imagery alone does not contain all the
  information needed for evaluating rainfall.
  Numerous processes occur below the clouds,
  including
• Evaporation of raindrops
• Enhancement or reduction of rainfall by
  terrain-induced upslope / downslope
• Numerical Weather Prediction (NWP) model forecast
  fields are used to derive correction factors
• Precipitable water enhance rain rates in high-PW
  areas reduce in low-PW areas
• Relative humidity reduce rain rates in dry
  (low-RH) areas
• Convective equilibrium level temperature regions
  with values above 213 K have their rain rates
  enhanced
• 850-hPa winds interfaced with digital topography
  enhance rain rates in upslope regions and reduce
  them in downslope regions

12
Rain rate as a function of brightness temperature
and precipitable water in the Hydro-Estimator
Convective Core rainfall
Non-core rainfall
PW (mm)
PW (mm)
13
Reduction in rain rate as a function of relative
humidity in the Hydro-Estimator
14
GOES T10.7
Eta TEL
ORO
Eta PW
GOES T10.7
Eta TEL
N
TadjT10.7
Preliminary EL, ORO, PW Adjustments (T10.7?Tpre)
TELlt270 K?
Y
TELadjmin(TELmin(T(Z110), T10.7))/2, Tmin)
N
Tpre235 K?
RR0
Done
Y
TEL-min(T(Z11.0), T10.7)lt10 K?
Find Tmin in surrounding 101x101 box
N
Y
r1250-Tmin 30r150 r215
Tadj0.9(213 - TELadj
Tadj0.6(213-TELadj)
ORO
Compute µ, s for r1 and r2
Tadjgt210?
Tadjmax(Tadj-ORO/2,210)
Replace Tpre with Tadj
TadjTadj-ORO
Eta PW
Zi(µ-Tadj)/ s for r1, r2
Y
Y
PWgt1.5?
PWgt2.0?
DPW2(2-PW)
N
Zigt0?
RRi0
i1,2
N
N
Y
DPW1.5-PW
DPW2.5(1-PW)
RRiRRcZ2RRn(1.5-Z)2/Z2(1.5-Z)2
Tadjmax(TadjDPW, 210)
Tadjgt210?
Y
N
Y
N
RR1gt0?
RRSQRT(RR12RR22)
RRRR2
RR25.4(1-DPW/10)
RHRH-0.01SQRT(RR-10)
Eta RH
Compute core RRc via function fit (RRc_at_210KRR
in/hr RRc_at_240K0.5 in/hr)
RRRR-25(0.85-RH)-0.35(0.6-RH)-0.5(0.4-RH) (only
negative components are used)
Compute non-core RRn with 12 mm/h
cap RRnmin(RR(250-Tadj)/5,RRc/5)
Done
15
Outline

• Brief McIDAS Background
• Hydro-Estimator Basics
• Running the Hydro-Estimator
• Preparing the data fields
• Running the algorithm
• Examining the results
• Appendix Basic McIDAS Commands

16
Sample Hydro-Estimator Run

• Different from operational HE in that we will use
  pre-made adjustment files
• Necessary inputs
• Current GOES band 4
• NAM EQL (convective equilibrium level in K)
• NAM precipitable water (PW in hundredths of
  inches)
• NAM mean relative humidity (percent) from the
  lower third of the NAM vertical domain
• Orographic correction (ORO NAM 850-hPa winds
  interfaced with digital topography)
• Dummy file with all values100

17
Sample Hydro-Estimator Run

• Necessary Programs (again, a reduced set)
• zenitcor.pgm Corrects for limb cooling at high
  satellite zenith angles
• zenitcor IN OUT
• parcormercir.pgm Corrects for parallax
• parcormercir IN OUT
• rainsplitiso.pgm Produces rain rate estimates
• rainsplitiso GOES OUT PW RH EQL RH ORO DUM

18
Getting StartedGet the Files

• Create a local directory for yourself and cd to
  it
• Access ftp.orbit.nesdis.noaa.gov via anonymous
  ftp
• cd /aftp/pub/smcd/emb/bobk/HE
• ls (directory listing)
• prompt
• binary
• mget (download the files into your local
  directory)
• bye (to exit), and then uncompress the files
  (uncompress .Z)

19
Getting StartedData Files

• Copy the following files into mcidas/data,
  assigning your own set of AREA numbers to the new
  files
• goes12.2006.171.17mm.Z (pick 1 of the 3) GOES
  Imager band 4 for 17mm UTC 20 June 2006 (Julian
  day 171)
• 0606201200EQL.Z NAM-derived convective
  equilibrium level temperature for 1200 UTC 20
  June 2006
• 0606201700PW_.Z NAM PW for 1700 UTC 20 June 2006
• 0606201700RH_.Z NAM RH for 1700 UTC 20 June 2006
• 0606201200ORG.Z NAM-derived orographic
  correction for 1200 UTC 20 June 2006
• DUM.Z a dummy file used to fill an unused slot
• Use the standard copy command e.g.,
• cp goes12.2006.171.1701.Z mcidas/data/AREA5001.Z

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Getting StartedData Files

• From your McIDAS command line, first reproject
  each of your AREA files onto a common grid using
  the IMGREMAP command. The grid projection,
  coverage, resolution, etc. do not matter as long
  as you are consistent. A suggestion
• IMGREMAP LA.1001 LA.2001 LAT40 95 PROMERC RES4
  SIZALL
• Make sure you use different destination AREA
  numbers for each one! You may want to write them
  down for reference.
• Display a few images to see the difference before
  and after remapping.

21
Getting StartedSource Code

• Copy the following files into mcidas/data
• latitudeerror
• zenitherror
• Copy the following programs into mcidas/src
• zenitcor.pgm Corrects for limb cooling at high
  satellite zenith angles
• parcormercir.pgm Corrects for parallax
• rainsplitiso.pgm Produces rain rate estimates
• Compile each program using fx name l vendor,
  where name does NOT have the .pgm suffix.

22
HEZenith Angle Correction

• To correct for limb darkening of the GOES
  imagery, use ZENITCOR sarea darea
• sarea is the source AREA file number (your
  remapped GOES band 4 file)
• darea is the destination AREA file number
• Display the image and compare it to the original
  it should appear slightly warmer, especially in
  northern portions of the image

23
HEParallax Correction

• To correct for parallax in the GOES imagery, use
  PARCORMERCIR sarea darea
• sarea is the source AREA file number (your
  limb-corrected GOES band 4 file)
• darea is the destination AREA file number
• Display the image and compare it to the original
  the clouds should have shifted to the east
  (toward 75 W) and south (toward the equator)

24
HERain Rate Estimation

• To create the rain rate images, use RAINSPLITISO
  goes darea pw eql rh oro dum
• goes is the AREA file number of your limb- and
  parallax-corrected GOES band 4 file
• darea is the destination (output) AREA file
  number
• pw is the reprojected PW AREA file number
• eql is the reprojected EQL AREA file number
• rh is the reprojected RH AREA file number
• oro is the reprojected ORO AREA file number
• dum is the reprojected dummy AREA file number
• Run it and look at the output, using the WSI.ET
  enhancement table (see next page).

25
HEAdding a Color Bar

• Copy the files WSI.ET and WSI75.ST to mcidas/data
• On the same frame where the HE is displayed, type
  BAR SUWSI750 ORIHOR RAN0 75 LIN5
• This will add a color bar to your display. Note
  that EG will not get rid of it you have to use
  ERASE.

26
HEExperimentation

• One more useful command is IMGOPER, which can be
  used to make additive or multiplicative
  adjustments to the values in IMAGE files
• IMGOPER sdataset1 . . sdatasetn ddataset
  keywords
• sdataset1n are the input datasets
• ddataset is the destination dataset
• Keywords
• ACOc adds a constant c to all data
• ADD adds the corresponding pixels in each
  dataset to subtract, include COEF-1
• MULT multiplies the corresponding pixels to
  divide, include POW-1 to multiply by different
  factors, use POWa b c d, etc. where ad are
  multiplication factors.
• MCOd multiplies all data by a constant d
• Try IMGOPER on a file and use IMGPROBE to examine
  the results. Then try those new files as HE
  inputs to see what happens!

27
Appendix Basic McIDAS Commands
28
McIDAS Command Line Basics

• McIDAS displays in ALL CAPS when the Caps Lock
  is OFF and vice versa
• Arrow keys scroll the screen up and down, but
• Only the current command is visible use
  ltshift-7gt () to recall previous commands
• Use the arrow keys to move across the command
  line to edit it
• Default is to replace text
• Toggle ltInsertgt to insert intead of replace

29
McIDAS CommandsDSINFO

• Lists data on local and remote servers
• DSINFO type group
• type type of data (GRID, IMAGE, NAV, POINT, or
  TEXT)
• group group name
• DATALOC LIST lists all of the available groups
  and their IP addresses
• DSINFO ALL displays all of the available data
  sets
• DSINFO ALL group displays all available data sets
  in a particular group

30
McIDAS CommandsIMGCOPY

• Copies image data from one dataset to another.
• IMGCOPY sdataset ddataset keywords
• sdataset source dataset group and position
• sdataset destination dataset group and position
• Typically one copies into the local data
  directory, where sdataset is given as LOC/AREA.
  (or just LA.), where is a number up to 9999.
• These files can be also be viewed outside of
  McIDAS in the mcidas/data directory.
• Try IMGCOPY GER/GENHEM04I4 LA. SIZEALL.

31
McIDAS CommandsIMGCOPY

• Important IMGCOPY keywords
• LATlat lon, where lat and lon are the latitude
  and longitude (degrees, with west longitude as a
  POSITIVE value) of the region of interest,
  specified either as
• PLAULEFT lat lon is the upper left of the
  region
• PLACENTER lat lon is the center of the region
  (DEFAULT)
• SIZline ele, where the height (line) and width
  (ele) are given in pixels
• NOTE the DEFAULT value is 480 640
• SIZALL will copy the entire image

32
McIDAS CommandsIMGLIST

• Lists the properties of the image
• IMGLIST dataset epos keywords
• dataset is the same as before (e.g., LA.)
• If using local data, you can use epos to specify
  the top end of range of data files to be listed
  (e.g., IMGLIST LOC/AREA.7670 7679)
• The keyword FORMEXP gives a detailed listing
• Try IMGLIST LA. FORMEXP on the image you copied
  earlier.

33
McIDAS CommandsIMGDISP

• Graphically displays a McIDAS data file
• IMGDISP dataset frame keywords
• dataset is the same format as before
• frame is the McIDAS graphic frame number. McIDAS
  can hold displays in multiple frames at once for
  making loops, etc. The default value is the
  frame you are currently displaying, which should
  be frame 1.
• You can either display a file on the server or a
  file in your local directory.
• Display the file you just copied using
  IMGDISP LA.

34
McIDAS CommandsIMGDISP

• Some keywords of interest
• LATlat lon, where lat and lon are the latitude
  and longitude (degrees, with west longitude as a
  POSITIVE value) of the region of interest,
  specified either as
• PLAULEFT lat lon is the upper left of the
  region
• PLACENTER lat lon is the center of the region
• MAGlmag emag, where lmag is the magnification in
  the line (y) direction, and emag is the
  magnification factor in the element (x)
  direction. Both values should be integers, with
  positive values blowing up the image and negative
  values blowing down the image

35
McIDAS CommandsEU

• Enhancement Utility (color enhancements)
• EU LIST lists all of the color enhancement tables
  that are available along with their directory
  locations
• EU REST name bframe eframe applies enhancement
  table name.ET to frames bframe through eframe.
• Note that the .ET suffix is optional.
• Note that bframe and eframe are optional default
  is the frame currently being displayed.
• Look at the available enhancement tables and
  apply one or more to your displayed image.

36
McIDAS CommandsMAP

• Display a map background and/or lat/lon lines
• MAP map color1 LALO color2 keywords
• mapmap background. Options include
• NANorth Americas coastal boundaries
• HNorth Americas political boundaries
• LWorlds coastal boundaries
• POLIWorlds political boundaries
• Note MUST include the keyword DOMYES to make
  the map match the image projection!
• LALO option draws lat/lon lines instead
• INTlat lon option specifies lat/lon line spacing
• Examples MAP H 1 DOMYES
• MAP LALO 5 INT5 5

37
McIDAS CommandsCleanup

• EG m n erases graphics (map overlays, etc.) in
  frames m through n.
• ERASE G m n does the same thing.
• EG I m n erases the image (but NOT the graphics)
  in frames m through n.
• ERASE I m n does the same thing.
• ERASE F m n erases everything from frames m
  through n.

38
McIDAS CommandsLoops

• It is possible to load a series of images into
  consecutive frames and then loop through them.
• Manual loop use ltALT-Agt to advance the display
  by one frame use ltALT-Bgt to go back by one
  frame. You can also just type A or B and hit
  ltEntergt.
• Toggle ltALT-Lgt to turn looping through the frames
  on and off, or just type L and hit ltEntergt.
• To set boundaries on the frames through which
  ltALT-Lgt will loop, use LB m n, where m is the
  first frame and n is the last.
• Type F and hit ltEntergt to see your current frame
  configuration.

39
McIDAS CommandsIMGPROBE

• IMGPROBE will cause McIDAS to return information
  about any grid point which you right-click on
  using the mouse and cursor. Use ltALT-Qgt to turn
  it off.
• You can also use ltALT-Dgt to get a similar display
  for the point beneath the cursor.

40
McIDAS CommandsIMGREMAP

• Remaps the image into a different map projection
• IMGREMAP sdataset ddataset keywords
• sdataset and ddataset are the source and
  destination datasets, as before
• Selected keywords
• LATclat clon (center lat/lon of area to remap)
• PRODEST (same projection as ddataset if theres
  something already in there)
• PROLAMB slat1 slat2 slon (Lambert conformal
  projection with standard latitudes slat1 and
  slat2 and standard longitude slon
• PROMERC (Mercator projection)
• PROPS slat slon (Polar stereographic projection)
• RES resolution in km
• SIZline ele (size of destination image)

41
McIDAS CommandsGRDCOPY

• Copies grid dataanalogous to IMGCOPY
• GRDCOPY sdataset ddataset keywords
• sdataset source dataset group and position
• sdataset destination dataset group and position
• Typically one copies into the local data
  directory, where sdataset is given as LOC/GRID.
  (or just LG.), where is a number up to 9999.
• These files can be also be viewed outside of
  McIDAS in the mcidas/data directory.
• Try IMGCOPY MOD/GFS LG. NUM250

42
McIDAS CommandsGRDCOPY

• Important GRDCOPY keywords
• LEVlev, which can be either SFC or a pressure
  surface (e.g., 850MB) or a height surface
  (e.g., 5000M).
• PARpar, which are the model parameters,
  including T (temperature), Z (height), RH
  (relative humidity), PWAT (precipitable water)
• NUMnum, which is the number of grids meeting the
  criteria which are to be copied (default is 1the
  first grid only)
• FHOfho, which is the forecast lead time in hours
• FTIft, which is the forecast time in hours
• GRIgri, which is the grid number (from GRDLIST)

43
McIDAS CommandsGRDLIST

• Lists the properties of the image
• GRDLIST dataset keywords
• dataset is the same as before
• Keywords are largely the same as GRDCOPY

44
McIDAS CommandsGRDDISP

• Plots grid data
• GRDDISP dataset frame keywords
• dataset and frame are same as previously
• Keywords are the same as for GRDLIST, plus
• LATlat1 lat2 for the latitude range
• LONlon1 lon2 for the longitude range
• COLgraphics color
• OUTCON (contour plot) or OUTPLOT (plots the
  numbers, but theyre usually hard to read unless
  its a small area)

45
McIDAS CommandsGRDIMG

• Converts a portion of a GRID file to an AREA file
• GRDIMG sdataset ddataset keywords
• sdataset and ddataset are same as previously
• Keywords are the same as for GRDLIST, but you
  will only copy the FIRST grid that meets the
  specifications given. So be sure to use GRDLIST
  (which gives only the first grid meeting those
  specifications) to be sure that you get what you
  want!
• Try converting your local GRID file to an AREA
  file and then displaying it using IMGDISP.
  Overlay the GRID file on top of the AREA file to
  see if you did it correctly.