Transcript McIDAS Basics and an Introduction to the Hydro

Using the Hydro-Estimator
in McIDAS
Bob Kuligowski
NOAA/NESDIS Center for Satellite Applications and
Research (STAR)
Outline
I. Brief McIDAS Background
II. Hydro-Estimator Basics
III. Running the Hydro-Estimator
A. Preparing the data fields
B. Running the algorithm
C. Examining the results
Appendix: Basic McIDAS Commands
Brief McIDAS Background
• Man-computer Interactive Data Access
System—used 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.
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.
Outline
I. Brief McIDAS Background
II. Hydro-Estimator Basics
III. Running the Hydro-Estimator
A. Preparing the data fields
B. Running the algorithm
C. Examining the results
Appendix: Basic McIDAS Commands
Hydro-Estimator Basics
• Manual techniques for estimating rainfall from
satellite cloud-top temperatures have existed for
>30 years
• The Auto-Estimator was the first-generation
automated technique at NESDIS; the HydroEstimator (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.
Illustration of the IR signal from different rainfall intensities
Tb=200
K
Tb=212
K
Tb=224 K
Tb=230 K
200
250
T (K)
290
Exceptions to the Rule...
Cirrus
Tb=205 K
Cumulonimbus
Tb=200 K
Nimbostratus
Tb=240 K
200
250
T (K)
290
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 clouds—a major
problem with the original Auto-Estimator
• The HE considers the temperature relative to the
surrounding pixels using the relationship Z=(µ-T)/ σ
– µ is the mean temperature of the nearby cloudy pixels
– σ 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
200
250
Tb < Tb
Tb ≥ T b
Rain
No Rain
Tb < Tb Tb ≥ Tb
Rain
No Rain
290
T (K)
Illustration of the HE Rain-No Rain Differentiation
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
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)
Reduction in rain rate as a function of relative humidity in the
Hydro-Estimator
GOES T10.7
Eta TEL
ORO
Eta PW
GOES T10.7
Eta TEL
N
Tadj=T10.7
TEL<270 K?
Preliminary EL, ORO, PW
Adjustments (T10.7Tpre)
Y
TELadj=min(TEL+min(T(Z1=10), T10.7))/2, Tmin)
Tpre≤235 K?
N
RR=0
Done
Y
TEL-min(T(Z1=1.0), T10.7)<10 K?
Find Tmin in surrounding 101x101 box
r1=250-Tmin; 30≤r1≤50
r2=15
Y
N
Tadj=0.9*(213 - TELadj
Tadj=0.6*(213-TELadj)
ORO
Compute μ, σ for r1 and r2
Tadj>210?
Replace Tpre with Tadj
Tadj=max(Tadj-ORO/2,210)
Tadj=Tadj-ORO
Eta PW
Zi=(μ-Tadj)/ σ for r1, r2
Y
Y
PW>1.5?
PW>2.0?
DPW=2*(2-PW)
N
i=1,2
Zi>0?
RRi=0
Y
N
N
DPW=2.5*(1-PW)
DPW=1.5-PW
RRi=[RRc*Z2+RRn*(1.5-Z)2]/[Z2+(1.5-Z)2
Tadj>210?
N
RR=RR2
Y
RR1>0?
RR=SQRT(RR12+RR22)
Y
Tadj=max(Tadj+DPW, 210)
N
RR’=25.4*(1-DPW/10)
Eta RH
RH=RH-0.01*SQRT(RR-10)
RR=RR-25*(0.85-RH)-0.35(0.6-RH)-0.5(0.4-RH)
(only negative components are used)
Done
Compute “core” RRc via function fit
(RRc@210K=RR’ in/hr; RRc@240K=0.5 in/hr)
Compute “non-core” RRn with 12 mm/h cap:
RRn=min(RR’*(250-Tadj)/5,RRc/5)
Outline
I. Brief McIDAS Background
II. Hydro-Estimator Basics
III. Running the Hydro-Estimator
A. Preparing the data fields
B. Running the algorithm
C. Examining the results
Appendix: Basic McIDAS Commands
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 values=100
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
Getting Started—Get 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)
Getting Started—Data 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
Getting Started—Data 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 LAT=40 95 PRO=MERC RES=4
SIZ=ALL
•
•
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.
Getting Started—Source 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.
HE—Zenith 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
HE—Parallax Correction
• To correct for parallax in the GOES imagery, use
PARCORMERCIR sarea darea
– sarea is the source AREA file number (your limbcorrected 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)
HE—Rain 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).
HE—Adding 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 SU=WSI750 ORI=HOR RAN=0 75
LIN=5
• This will add a color bar to your display. Note
that EG will not get rid of it; you have to use
ERASE.
HE—Experimentation
• 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]
– sdataset1…n are the input datasets
– ddataset is the destination dataset
– Keywords:
• ACO=c 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 POW=a b c d, etc. where a…d
are multiplication factors.
• MCO=d 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!
Appendix: Basic McIDAS
Commands
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 <shift7> (&) to recall previous commands
• Use the arrow keys to move across the
command line to edit it
– Default is to replace text
– Toggle <Insert> to insert intead of replace
McIDAS Commands—DSINFO
• 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
McIDAS Commands—IMGCOPY
• 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.#
SIZE=ALL.
McIDAS Commands—IMGCOPY
• Important IMGCOPY keywords:
– LAT=lat 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
• PLA=ULEFT: lat lon is the upper left of the region;
• PLA=CENTER: lat lon is the center of the region (DEFAULT)
– SIZ=line ele, where the height (line) and width
(ele) are given in pixels
• NOTE: the DEFAULT value is 480 640
• SIZ=ALL will copy the entire image
McIDAS Commands—IMGLIST
• 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 FORM=EXP gives a detailed listing
• Try IMGLIST LA.# FORM=EXP on the image
you copied earlier.
McIDAS Commands—IMGDISP
• 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.#
McIDAS Commands—IMGDISP
• Some keywords of interest:
– LAT=lat 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
• PLA=ULEFT: lat lon is the upper left of the region;
• PLA=CENTER: lat lon is the center of the region
– MAG=lmag 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
McIDAS Commands—EU
• 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.
McIDAS Commands—MAP
• Display a map background and/or lat/lon lines
• MAP map color1 LALO color2 [keywords]
– map=map background. Options include:
•
•
•
•
•
NA=North America’s coastal boundaries
H=North America’s political boundaries
L=World’s coastal boundaries
POLI=World’s political boundaries
Note: MUST include the keyword DOM=YES to make the map match
the image projection!
• LALO option draws lat/lon lines instead
– INT=lat lon option specifies lat/lon line spacing
• Examples: MAP H 1 DOM=YES
MAP LALO 5 INT=5 5
McIDAS Commands—Cleanup
• 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.
McIDAS Commands—Loops
• It is possible to load a series of images into consecutive
frames and then loop through them.
• Manual loop: use <ALT-A> to advance the display by
one frame; use <ALT-B> to go back by one frame. You
can also just type A or B and hit <Enter>.
• Toggle <ALT-L> to turn looping through the frames on
and off, or just type L and hit <Enter>.
• To set boundaries on the frames through which <ALT-L>
will loop, use LB m n, where m is the first frame and n is
the last.
• Type F and hit <Enter> to see your current frame
configuration.
McIDAS Commands—IMGPROBE
• IMGPROBE will cause McIDAS to return information
about any grid point which you right-click on using the
mouse and cursor. Use <ALT-Q> to turn it off.
• You can also use <ALT-D> to get a similar display for the
point beneath the cursor.
McIDAS Commands—IMGREMAP
• 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:
– LAT=clat clon (center lat/lon of area to remap)
– PRO=DEST (same projection as ddataset if there’s something
already in there)
– PRO=LAMB slat1 slat2 slon (Lambert conformal projection
with standard latitudes slat1 and slat2 and standard
longitude slon
– PRO=MERC (Mercator projection)
– PRO=PS slat slon (Polar stereographic projection)
– RES= resolution in km
– SIZ=line ele (size of destination image)
McIDAS Commands—GRDCOPY
• Copies grid data–analogous 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.# NUM=250
McIDAS Commands—GRDCOPY
• Important GRDCOPY keywords:
– LEV=lev, which can be either SFC or a pressure
surface (e.g., 850[MB]) or a height surface (e.g.,
5000[M]).
– PAR=par, which are the model parameters, including
T (temperature), Z (height), RH (relative humidity),
PWAT (precipitable water)
– NUM=num, which is the number of grids meeting the
criteria which are to be copied (default is 1—the first
grid only)
– FHO=fho, which is the forecast lead time in hours
– FTI=ft, which is the forecast time in hours
– GRI=gri, which is the grid number (from GRDLIST)
McIDAS Commands—GRDLIST
• Lists the properties of the image
• GRDLIST dataset [keywords]
– dataset is the same as before
• Keywords are largely the same as GRDCOPY
McIDAS Commands—GRDDISP
• Plots grid data
• GRDDISP dataset frame [keywords]
– dataset and frame are same as previously
• Keywords are the same as for GRDLIST, plus:
–
–
–
–
LAT=lat1 lat2 for the latitude range
LON=lon1 lon2 for the longitude range
COL=graphics color
OUT=CON (contour plot) or OUT=PLOT (plots the
numbers, but they’re usually hard to read unless it’s a
small area)
McIDAS Commands—GRDIMG
• 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.