Contour Ilugc Demo Presentation

Arulalan.T

Final Year MCA

Saveetha Engg College

Project Title

Contour Analysis And Visualization

Guide

Mr.Thyagarajan Shanmugham

Thanks To . . .

Mr.Charles Doutriaux CDAT Developer

Dr. Krishna AchutaRao Center for Atmospheric Science

IIT Delhi

CDAT Climate Data Analysis Tool

Installation

Working in Cdat

Edit Cdat Map

Isolines

NetCDF

Demo on creating current isotherm lines over on India map

System requirement

Hardware

* Dual Core Intel 2 Ghz Processor Machine * Decent Broadband Connection

Software

* A linux distro in my case Ubuntu 9.10 * CDAT

* Dependencies of CDAT

Dependencies :

# bison *# byacc *# flex *# gawk *# g++# gfortran (for contrib packages)# libxtdev# libx11dev# tcsh (just highly recomended)# xorgdev (also called xserverxorgdev)#libpng (1.1 or later ) and freetype (1.4 or later)

Installation :

export CC=gccexport FC=gfortranexport CXX=g++

svn export http://wwwpcmdi.llnl.gov/svn/repository/cdat/tags/5.2 cdat5.2src

./configure prefix=/usr/local/cdat5.2/ withexternals=/usr/local/cdat5.2/cdat_ext.

sudo make

Cdat Working Directory :

# You can now start CDAT with the command

$ cd /usr/local/cdat5.2/bin

$ ./cdat

Cdat Working Directory :

# You can now start CDAT with the command

$ cd /usr/local/cdat5.2/bin

$ ./cdat

Example Program

#sample.py

import vcs, cdms2, cdutil, time, os, sysimport time

v = vcs.init()

filepath = os.path.join(sys.prefix,'sample_data/clt.nc')cdmsfile = cdms2.open( filepath )

cf_asd = v.getboxfill( 'ASD' )cf_asd.datawc(1e20,1e20,1e20,1e20) cf_asd.level_1=1e20 cf_asd.level_2=1e20 cf_asd.color_1=240 cf_asd.color_2=240

data = cdmsfile('clt', longitude=(180, 180), latitude = (180., 180.))

#data = cdmsfile('clt', longitude=(60, 100), latitude = (5., 40.)) # For India

v.plot( data,cf_asd )

Cdat World Map Outline

Cdat India Map Outline

#sample1.py


v = vcs.init()




#data = cdmsfile('clt', longitude=(60, 100), latitude = (5., 40.)) # For Indiav.plot( data,cf_asd , continents=4 )

Cdat World Map Continents

Cdat India Map Continents

How To Edit Cdat Map

Our Indian Political Map wrongly depicted in CDAT as below

1) Correcting the Pakistan part , which belongs to India

2) Correcting the part of the land which is occupied by the Chinese in the state of jammu and kashmir

While asking help from Mr.Charles Doutriaux [ CDAT Developer ] regarding edit map in cdat, he gave the source data of cdat world map in .shp binary file.

#make_world_coordinates.py

import vcsaddons

v = vcs.init()

world_continents = vcsaddons.continents.Guc(x=v)

data = world_continents.load_shapefile('/home/arul/Desktop/WORLD_COUNTRIES.shp')

#wrting the data into out.txt file

fileiter=open("/home/arul/Desktop/out.txt","w")print >> fileiter, data[:]fileiter.close()

200 1 59.790276 83.623596 72.830238 12.204896 60.238045 43.12388660.174297 43.10916960.110275 43.08666260.082497 43.12444360.019024 43.14041959.989437 43.19347059.992493 43.23889260.023605 43.33111659.972763 43.35889459.928326 43.39583259.903320 43.50194559.954636 43.48825859.914711 43.57277759.947212 43.72471659.877213 43.65388559.804436 43.84972459.790276 43.90222259.811661 44.00695059.800545 44.06194359.813538 44.109722

There are more than one lakh lines like this.

These are x,y coordinate points.

Simply says, these are Latitude and Longitude values of the whole [real] world.

out.txt

My Hacks On Cdat Map

Over World

Over India

My Construction On Cdat India Map

Finally

Our India

Now we have to save as the modified out.txt file i.e WorldContinent.shp's text file in the name of “data_continent_other7” in the path “/home/arul/PCMDI_GRAPHICS/”

v.plot( data,cf_asd , continents=6 )

#sample2.py


v = vcs.init()



#data = cdmsfile('clt', longitude=(180, 180), latitude = (180., 180.)) # For the world


v.plot( data,cf_asd, continents=6 )

Corrected India Map in Cdat

Corrected India region in CdatWorld Map

Isolines

Isolines Contour Isotherm Isobar

What is Contour ?

Contour is line drawn on a map connecting points of equal height .

Contour lines (also isolines) connect a series of points of equal elevation and are used to illustrate topography, or relief on a map.

They show the height of ground above Mean Sea Level (M.S.L.) in either feet or meters and can be drawn at any desired interval.

What is Isotherm ?

An isotherm ( meaning 'heat') is a line that connects points on a map that have the same temperature.

Therefore, all points through which an isotherm passes have the same temperatures at the time indicated.

http://en.wikipedia.org/wiki/Temperature

http://en.wikipedia.org/wiki/Temperature

What is Isobar ?

A line of constant pressure. Isobars are found ONLY on surface charts.

They most commonly connect lines of equal pressure in the units of millibars.

High pressure isobars generally occurs with isobars above 1010 mb while low pressure isobars occur with lower than 1010 millibars.

What are the Uses of Isotherm ?

Isotherms are used to find regions with

* Warm air advection * Cold air advection

* Short waves* Fronts* Temperature gradient boundaries and * Instability zones.

They are most commonly used at pressure surfaces below 500 millibars and on surface charts.

Isolines in Cdat

Iso Lines Over India Map

CDAT User :

How can a user create their own Isolines on cdat map?

CDAT User :

Generally we can't create our own isolines in cdat map.

We can set only levels on isolines.

levels = [10,20,30]

Reason is . . .

NetCDF file

What is NetCDF File ?

NetCDF (network Common Data Form)

is a set of software libraries and machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data.

Purpose of NetCDF (.nc)File

The main purpose of netCDF is to protect the user from having to know the details of how the data is stored in the netCDF file.

Cdat have clt.nc file which is reason to create isolines on map.

My Project

is going to create our own isolines on cdat map.

How to read/write NetCDF (clt.nc) file ?

$ sudo apt-get install netcdf-bin

To convert .nc binary into editable text $ ncdump clt.nc > clt.cdl

To generate clt.nc from edited clt.cdl file$ ncgen -b clt.cdl

What is My Project ?

My Project going to create the isotherm lines, which will be plot on India Cdat Map.

We have 4 processes to do this . . ..

Process 1:

1.1 WebScrape the current temperature and barometer (millibar) of all over cities in India and its surroundings countries from the Internet.

1.2 Store the city name, temperature, millibar into the file.

Process 2:

2.1 Combine the temperature and mb values with latitude and longitude of corresponding cities, which is already collected info file.

2.2 Make decision and covert lat into 4 intervals & lon into 5 intervals

Process 3:

3.1 Create the binary iso.nc file which contains

current temperature values along with lat & lon.

3.2 Move the “iso.nc” to the cdat location in our system.

Process 4:

4.1 Run the “isotherm.py” to create our isolines on

cdat India Map.

4.2 EMail to us with the attachment of the output image, which is created by “isotherm.py”

To automate all the 4 processes we may use “crontab”

to get isotherm update on India for every one hour or . . .

Web Scraping Program

Isothermal Lines On Cdat Map

Google Temperature Values

Store the GoogleTemperature Valuesinto the File

Draw Isothermal Lines from the File Values

Data Flow Diagram For Generating Isothermal Lines From Google Temperature

Before going to Demo . . .

On 12 th Mar 2010 isothermlines on India from

1 pm to 11 pm

1 pm

4 pm

5 pm

6 pm

7 pm

8 pm

9 pm

10 pm

11 pm

12 am

Demo . . . !

Coding . . .

Applications :

By the visualization of Isothermal lines on map, we can analyses and obtain the temperature and pressure values.

Using this we can analysis/predict the climate changes.

Applications :

.

Advection The horizontal transfer of heat

Forecaster Someone who makes

predictions of the future

Applications of isolines : By Meteorologist Jeff Haby

Q1. What is meteorologically significant about isobars or isohypses being closely spaced?

Answer: A forecaster can determine the amount of thermal advection (temperature advection). Closely spaced contours indicate stronger wind.

Source : http://www.theweatherprediction.com/basic/isopleths/


Q2. Negative thickness advection is lower values of thickness moving toward a fixed point. How can this be determined by examining a thickness chart?

Answer: If height contours or isobars are overlaid on the thickness field, a forecaster can determine the speed and direction cold air will have. If the lower thicknesses are advected by the height contours or isobars toward a fixed point, that fixed point will experience a cooling of weather.



Q3. In feet and meters, what is the average height of the 850, 700, 500 and 300 mb surfaces?

Answer:

850 mb (1,500 meters, 5,000 feet)700 mb (3,100 meters, 10,000 feet)500 mb (5,500 meters, 18,000 feet)300 mb (9,300 meters. 30,000 feet)


Applications :

Isallobar / Height change contours

A line of equal pressure change. They are used to forecast the propagation of low and high pressure systems


Q4. How are isallobars significant to weather forecasting?

Answer: They give the indication of pressure change. Lows tend to move toward the region with the greatest height falls. Values tell a forecaster if a low or high is increase or decreasing in intensity..


THANK YOU

Education

Contour Ilugc Demo Presentation