Hi Sushant,
I modified my joint script with Kumar to meet your requirement and the script is attached here as llj.gs. Please note the changes in the sorting arrangment (as the values are not increasing linearly) and the altered details in the string functions (due to your different extent of latitudes and longitudes). The output is as follows:-
Pressure Magnitude
level(hPa) maximum wind(m/s) for defined area: 20S-40N & 30-100E
.............. .............................. at 18Z31JAN2008
1000 15.7547
925 21.0772
850 20.7338
700 25.1241
largest maximum wind magnitude = 25.1241 m/s
corresponding pressure level : 700 hPa
at grid points : 27.5 deg N and 45 deg E
I am not sure whether this is the correct way to identify the low level jet. As you are aware, wind magnitude usually increases from 850 hPa upwards, reaching a maximum around 200 hPa before decreasing again. It appears that your low level jet tends to occur around 925 hPa. By confining it to the lowest 3 levels may be the right choice. Anyway, I hope the script helps.
Regards.
Ooi
--- On Fri, 26/3/10, sushant puranik <sushantpuranik at gmail.com> wrote:
From: sushant puranik <sushantpuranik at gmail.com>
Subject: Re: [gradsusr] Help in showing the example of using fndlvl(), max() and maxloc()
To: "See Hai Ooi" <axl419 at yahoo.com>
Date: Friday, 26 March, 2010, 8:52 PM
Hello Ooi
I have attached my modified script.
i) Yes LLJ covers between 1000 to 700 hPa over the region 30-100deg E and 20degS-40degN.
I will try to modify the script by keepin levels upto 700.
ii) i am also using NCEP/NCAR reanalysis dataset. Yes in my case components are u and v . Levels available in my dataset are
l.1=1000, l.2=925, l.3=850, l.4=700, l.5=600, l.6=500, l.7=400, l.8=300, l.9=250, l.10=200, l.11=150, l.12=100, l.13=70, l.14=50, l.15=30, l.16=20, l.17=10
Thank you for suggestions. I will modify the script and again check it what the results it producing.
Thanking you
On Fri, Mar 26, 2010 at 11:26 AM, See Hai Ooi <axl419 at yahoo.com> wrote:
Hi Sushant,
Can you show me your modified script ? However, you may wish to consider the following points/notes in your intended work :-
(i) It depends on how you define your low level jet. I guess it hovers between 1000 hPa and 850 hPa over your specific area. If that is the case, you merely reduce the number of vertical pressure levels to 3, viz. 1000, 925 and 850 hPa levels.
(ii) I use NCEP/NCAR Reanalysis data. The u- and v-components are uwnd and vwnd respectively. In your case, it could be u and v. Also, what are the levels available in your data set (u2008.nc, ... ) ? Delete/amend those not available in my joint script with Mr. Kumar. Just query your file to find more information about it.
Hope this helps.
Ooi
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