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[IDV #ZEC-697467]: METAR decoding problem in the IDV
- Subject: [IDV #ZEC-697467]: METAR decoding problem in the IDV
- Date: Tue, 26 Jan 2010 08:13:04 -0700
Hi Steve-
This is Don Murray.
> Full Name: Steve Nesbitt
> Email Address: address@hidden
> Organization: Department of Atmospheric Sciences, University of Illinois
> Package Version: 2.8 build date:2010-01-15 20:48 UTC
> Operating System: Mac OS X
> Hardware: Java: home:
> /System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home version:
> 1.6.0_17 j3d:1.3.1
> Description of problem: Hello,
>
> I am having students make surface maps from METAR data in IDV. We are
> noticing that cloud cover (fields CC1 and CC2) are often missing in the data
> even though cloud cover is being reported in the raw METAR reports. I have
> attached an example screen capture showing that little cloud cover is being
> plotted (only a few stations), and the plot for Champaign showing CC1 and CC2
> are missing. Note the associated raw METAR report below, which indeed reports
> a cloud cover of OVC. This issue precludes making complete surface maps in
> IDV.
>
> KCMI 211753Z 06016KT 2SM -RA BR OVC005 01/M01 A2964 RMK AO2 SFC VIS 2 1/2
> UPB37E39RAB39 CIG 003V008 SLP045 P0001 60001 T00061006 10011 20000 58022
The CC1, CC2 and CIG values in the METAR datasets are not the WMO cloud
coverage values one might think. They are McIDAS representations of the
ceiling, and other cloud levels. The values range from 0-3 for CLR, SCT, BKN,
OVC and 5 for FEW. In this case, there is only one level and it is a ceiling,
so the CIGC is 3 and the others are missing. For the example:
KHSP 261440Z AUTO 25013G23KT 10SM SCT018 BKN047 OVC065 M04/M06
A2966 RMK AO2=
we have:
Date ID CC1 ZCL1 CC2 ZCL2 CIGC
CIGH
Tue, Jan 26 2010 14:00 GMT KHSP 1 1800 3 6500 2
4700
So, the ceiling is the BKN (2) layer, the SCT (1)layer is CC1, and the other
non-ceiling cloud group (CC2) is the OVC (3) layer.
The synoptic and ship reports have a CA group which is the WMO cloud coverage
value. We are going to look at fabricating a CA group for the METARs based on
CC1, CC2 and CIGC. The problem is that some information has been lost (like
thin layers), so the mapping might not be exact, but at least would be better.
Hope that explanation helps.
Don
Ticket Details
===================
Ticket ID: ZEC-697467
Department: Support IDV
Priority: Normal
Status: Open