Changes in the metastability of the Southern Hemisphere 500-hPa circulation are examined using both cluster analysis techniques and split-flow blocking indices. The cluster methodology is a purely data-driven approach for parameterization whereby a multiscale approximation to nonstationary dynamical processes is achieved through optimal sequences of locally stationary fast vector autoregressive factor (VARX) processes and some slow (or persistent) hidden process switching between them. Comparison is made with blocking indices commonly used in weather forecasting and climate analysis to identify dynamically relevant metastable regimes in the 500-hPa circulation in both reanalysis and Atmospheric Model Intercomparison Project (AMIP) datasets. The analysis characterizes the metastable regime in both reanalysis and model datasets prior to 1978 as positive and negative phases of a hemispheric midlatitude blocking state with the southern annular mode (SAM) associated with a transition state. Post-1978, the SAM emerges as a true metastable state replacing the negative phase of the hemispheric blocking pattern. The hidden state frequency of occurrences exhibits strong trends. The blocking pattern dominates in the early 1980s, and then gradually decreases. There is a corresponding increase in the SAM frequency of occurrence. This trend is largely evident in the reanalysis summer and spring but was not evident in the AMIP dataset. Further comparison with the split-flow blocking indices reveals a superficial correspondence between the cluster hidden state frequency of occurrences and split-flow indices. Examination of composite states shows that the blocking indices capture splitting of the zonal flow whereas the cluster composites reflect coherent block formation. Differences in blocking climatologies from the respective methods are discussed.
The author of the recent
about 50 more than just engaged in or have been engaged in 1-2 SEOER made a small investigation, including many candidates, in real work can analysis to log SEOER proportion is very small, the access log has played in the role of SEO in question, many SEOER shook his head, or just know some fur did not personally operation, the main reason is the platform in the company did not have the opportunity to practice, the author to share their original site access log:
what is access log
web access log is a document that records the various raw information such as the web server, the receive processing request, and the runtime error. It should be the server log, to be exact,.Log. Its role is to make our SEOER can clearly know the user in what IP, what time, what, what, what the browser operating system resolution display access without which the pages of your website, whether successful visit.
when do we need to analyze the log and journal features
will we analyze the journal every day? No, because log analysis is boring. It is usually analyzed once a month or half a month. This kind of analysis is a routine analysis. If your site is always normal, you can analyze it once a month, or you can analyze it easily.
in fact, the log is more unusual when the site, will observe half a log, focus on the analysis of spider movements. For example, analysis is not the site 404, robots set the exception or caused by spider horse disappeared, one son to find solution to the problem.
here is an access record from the Journal of our daily analysis:
22.214.171.124 – [10/Apr/2012:00:04:54 +0800] " GET /bbjk/index.html HTTP/1.0" 20025269 " -" " Sogou web spider/4.0 (+http://s.sogou.com/docs/help/webmasters.htm#07) "
126.96.36.199 access ip
10/Apr/2012:00:04:54 +0800 for access date – time zone
GET /bbjk/index.html HTTP/1.0 crawls under the HTTP/1.1 protocol (domain name) /bbjk/index.html this page (GET indicates server action >