Thursday, October 30, 2008

facebook notes about metoce

gradsc code for wind vector

'open data/ctl/ugrd850.prs '
'open data/ctl/vgrd850.prs 0.2'
'set lat 0 30'
'set lon 40 100'
'set gxout vector'
'd ugrd;vgrd.2'
'printim output/wv850.jpg white'

Click here for more GRADS Codes

Monday, October 13, 2008

Walker Circulation

Walker Circulation is the closed circulation cells in the zonal-vertical plane with pronounced vertical upward and downward motion and favorable zonal motions at lower and upper troposphere in opposite directions.

South east Asian monsoon walker Circulation has its ascending limb over Eastern India, Bangladesh, and Burma while its descending limb lies over Pakistan and adjoining desert region

Equatorial Pacific Walker Circulation has its ascending limb over west equatorial Pacific near Indonesia and descending limb over central and east pacific dry zone.

Dr T. N. Krishnamurti (in1979) studied about walker circulation on the basis of 3 month average 200mb flow pattern

Upper tropospheric divergence outflow

Northern summer

1. Asian summer monso0on region
2. Pacific coast of south Mexico

Southern Summer

1. Central Africa
2. Indonesia
3. North west part of south America

Sinking Regions

Northern summer

1. Mid-Pacific Trough
2. Mid-Atlantic Trough
3. North africa

Southern Summer

1. Mid-Pacific Trade Belt
2. Mid-Atlantic Trade Belt

Page 11.17,Chapter 11, Volume 3 , Tropical Meteorology by G. C. Asnani

Friday, October 3, 2008

Madden-Julian Oscillation

The Madden-Julian Oscillation (MJO) is an equatorial traveling pattern of anomalous rainfall that is planetary in scale. The mechanism and cause of the MJO is as yet not well-understood and is a subject of ongoing study.

The MJO is characterized by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean. The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific. This pattern of tropical rainfall then generally becomes very nondescript as it moves over the cooler ocean waters of the eastern Pacific but reappears over the tropical Atlantic and Indian Ocean. The wet phase of enhanced convection and precipitation is followed by a dry phase where convection is suppressed. Each cycle lasts approximately 30-60 days.

The MJO is also known as the 30-60 day oscillation, 30-60 day wave, or intraseasonal oscillation.

* 1 Atmospheric patterns
* 2 North American winter effects
o 2.1 Pineapple Express events
* 3 Boreal Summer Effects
* 4 Tropical cyclone influence