Category Archives: work

Difference between Radar precipitation data stage 2 and stage 4

Zhuotong Nan ([email protected])

Stage II

Be produced directly from the real-time gauge and WSR-88D radar data received at NCEP.

raingauges:

  • from ~1450 ASOS sites from near-real time METAR file
  • and from ~5500 HADS automated gauge reports via the GEOS data Collection Platform.

Radar:

  • Hourly real-time Digital Precipitation Arrays (DPAs) from 140 ConUS WSR-88D radar sites.

The primary input to the ETA/EDAS precipitation assimilation before 2003.

Stage IV

A mosaic of regional multi-sensor analysis produced by NWS River Forecast Centers (RFCs) and benefits from the RFCs’ manual quality control step

mosaicked from the regional multi-sensor 1h and 6h analyses produced by the 12 ConUS RFCs.

The primary input to the ETA/EDAS precipitation assimilation after 2003. Stage II is only used when Stage IV is unavailable.

In summary,

Since Stage IV benefits from manual QC at the local RFCs, it is generally better than Stage II, which has no manual QC. There are a number of other issues for your consideration:

1. Coverage period: Stage II began to be archived at NCAR on 1 May 1996. Stage IV did not began to be archived until 1 Jan 2002. (NOTE: we have data from 1997 on for OHIO river basin. I guess this statement is for entire continuous continental, rather than for an individual RFC. -Zhuotong)

2. Do you need hourly or 6-hourly analysis? For 6-hourlies, Stage IV is the one to use (if you don’t need the pre-2002 data). Stage IV hourlies have some coverage problem since we do not receive the local analyses from all the RFCs for all hours.

3. How soon do you need the analysis to be available? Stage II hourly analysis is made at 35 minutes after the top of the hour, then re-made twice at 6 hours and 18 hours later. Stage VI runs each hour at approximately 35 minutes past the top of the hour.

4. If I choose Stage II, which type should I use? We recommend the multi-sensor analysis with the exception of early spring – early Aug 2000, when the radar coverage was bad. You might want to use the gauge-only analysis for that time period.

Validation examples:

clip_image004 clip_image006

figure 1 24 hour precipitation accumulative amount on OCT 10, 2004, Stage II (left) and Stage IV (right).

clip_image008clip_image010

figure 2 Left: Stage II; Right: Stage VI. On Jun 28 2005. Here we can see the variance between them.

References:

1. http://www.emc.ncep.noaa.gov/mmb/ylin/pcpanl/refs/stage2-4.19hydro.pdf
2. http://www.emc.ncep.noaa.gov/mmb/ylin/pcpanl/QandA/
3. http://www.emc.ncep.noaa.gov/mmb/ylin/pcpverif/daily/

最近研究一下了HDF

因为需要对modis数据进行处理,研究了一下hdf和hdf eos两个类库
hdf是个好东西,不过有点太复杂,而且api尽管很强大,但工具还是相对不多,可以windows下使用的则更少
 

卸载网筝NK800 v2

南卓铜([email protected])

西部数据中心目前提供的网筝驱动程序v2(20060927)安装后不能正常卸载。我们已经向软件提供商反映此问题。这些提供了一个临时的解决方案。

1. 在开始菜单,找到“卸载网筝NK-800”,点击“属性”,copy目标里的内容。

image

2. 找到从westdc上下载来的驱动文件,如果是压缩包,请解压缩到一个目录,比如c:tempnk800目录下。这个路径以下有用。

3. 打开command窗口(开始->运行,键入cmd),将步骤1里目标内容,粘贴到命令行下(右键,粘贴),如下:

image

移动鼠标,更改

“C:Program FilesIn
stallShield Installation Information{9147E0F5-074A-4D73-B8EA-63FDE7C70330}Setu
p.exe” (注意,{}内的可能不一样)

为步骤2找到的位置(该目录下应该有原始的Setup.exe等文件)。我这里是,

“c:tempnk800Setup.exe”

现在完整命令如下所示,

C:WINDOWSsystem32RunDll32.exe C:PROGRA
~1COMMON~1INSTAL~1engine6INTEL3~1Ctor.dll,LaunchSetup “c:tempnk800Setu
p.exe”  -uninst  -f

4. 运行。按照出现的图形界面提示,完成卸载。

Group meeting有关multifractal云里雾里的

在Group meeting上给大家演示用multifractal+wavelet的方法做time-space downscaling。讲的稀里糊涂,听的也是云里雾里。其实在看的时候就有好多问题发现,但没有时间进一步去看相关文献。L老师提的问题又太过涉及公式本身。
不过这个paper proposed的方法估计本身也有问题,尽管结论说downscale还不错。但作者在此文发表后的后续工作又重新time和space分开来做downscaling了,估计也是意识到time和space结合在一起很难找到完美的方法。

ISO 19115 editor

一直在关注ISO 19115元数据有关的一些进展。
它的editor比较有名的包括:
– GeoNetwork OpenSource Desktop
– DISY Preludio
– ISO Metadata Editor (IME)
– CatMDEdit
– M3Cat
– MetaD
– ArcCatalog ISO Wizard
另外,OGC catalogue service也是比较有意思的一个东西。大家感兴趣可以从Google搜索以上产品。

这个鬼网络,所里远程登录基本不能用

本想更新一下Asian G-WADI,远程登陆到westdc服务器,足足折腾了1个半小时,慢的跟比蜗牛还慢,一个简单的操作要半小时那边才反应过来。终于彻底失去耐性了。这事情以后甭找我干了。
访问美国这儿的网站都能很快反应过来,就国内的网站不知道怎么回事,也都号称是挺快的骨干网上,就是死活慢的离谱的。
刚才试着westdc服务器上从download.microsoft.com下载一个40来m的东西,发现速度在1KB不到,估计所网又在闹病毒全堵塞了,彻底晕倒。

完成了一个雷达数据到水文模型时间序列的转换程序包

这边的一个韩国同事前面写了一个Python版本的,在Linux下可以运行。我在Windows下对它进行了改进,并做了一些优化。结果在正式计算的时候,发现Ohio流域的一个子流域(2560个HRAP网格)10年逐小时估计要花上233天以上,同时需要空间也达100G以上。所以尽管该Python可用,但基本上对于大流域属于不实用的。为了完成工作,与梁讨论了以后,决定结合GIS和自己写代码,大概Coding了两周吧,现在终于完成了好几个小工具。在性能上进行了大量的优化(前一版本在转换到一半的时候出现内存不够,所以调试要花十分多的时间)。
我写了一个Instruction,大概从原始下载过来的XMRG二进制文件到可用的水文模型(如VIC)的时间序列大概要经过近10个步骤。不过实现了一个有意思的内插方法(与前Python算法相同),从HRAP网格到1/8度的转换时,由于每个1/8度网格覆盖多个HRAP格子,这个算法使用了面积加权来计算1/8度网格的平均降水。
现在完成上述任务大概需要2天。大家就可以在自己的桌面机器上用了,而不必一定要使用服务器(有大内存)。
没有时间做多线程或者并行优化,估计那样异步或并行处理性能会得到更好的提升。