Absolute TEC Map (Beta Ver.)
Total Electron Content (TEC) map is produced using the data of the observatories over Thailand sector.
Total electron content (TEC)
The slant TEC (STEC), absolute TEC values are computed from the dualfrequency GNSS receiver. Each color represents the calculated TEC values from different satellites.
Bangkok (KMI6) 
Vientiane (NUO2) 
Chumphon (CPN1) 
Nakhon Ratchasima (RUTI) 
Chaingmai (CHMA) 
Cambodia (CADT) 
Rate Of TEC change Index (ROTI) map
CPN Ionogram
This quicklook ionogram is provided by FM/CW ionosonde at CPN station which is administrated by the research cooperation between SEALION project, Japan, and KMITL, Thailand.
The peak frequency of Elayer (foE)
The peak frequency of the Elayer is called foE. The echo frequencies are received at FMCW ionosonde at CPN station by the reflection of radio waves with the ionospheric Elayer. The graph shows the statistics of median values of the foE against the universal time (0023 hour) and months (JanuaryDecember).
Critical Frequency of F2 layer (foF2)
The critical frequency of the F2 region (foF2) is the maximum frequency which can be vertically refracted by the F2 layer. The graphs below show examples of the foF2 plots vs. local time from the FM/CW ionosonde observatory at Chiang Mai (18.8 N – 98.9 E), north of Thailand, Chumphon (10.72 N – 99.4 E), south of Thailand and Kototabang (0.2 N – 100.3 E) in Indonesia. The observations are compared with the foF2 results of a global prediction model (the IRI2016 model).
The monitoring of foF2 at Chumphon station
This monitoring exhibits the median value of foF2 as the graph with a red square, the blue graph is an observed foF2 value and the black color bar represents the equatorial spreadF (ESF). The realtime observation is coming soon…
 Ionospheric condition: Quiet
 ESF condition: 5.0 hours
 Historical foF2 plot (under construction)
The foF2 2D map using the data from the IRI2016 model
The foF2 2D map is produced by utilizing the foF2 predicted data from the IRI2016 model. This 2D foF2 map covers the latitudes (0 – 25E) and the longitudes (95 – 110N) over Thailand and nearby regions.
Spread F Statistics
The spread F is an important parameter obtained from the spread of F trace on ionograms. Spread F occurrence at the equatorial region is typically due to instability of the bottom side of F2 layer after sunset. Various types of spread F include (1) frequency spread F (FSF), (2) range spread F (RSF), mixed spread F (MSF) and strong spread F (SSF), respectively. The spread F impacts the high frequency (HF) communications and navigation systems such as Global Navigation Satellite Systems (GNSS). Examples of spread F statistics at Chumphon station are shown below.

Chiangmai (CMU): 2004
The ESF statistics and the virtual height of F layer (h’F) are observed by the FMCW ionosonde at Chiangmai and Chumphon stations in 2004. Where blue bar represents the monthly percentage of ESF occurrences and the red graph represents the h’F against the local time (UTC +7).
Chumphon (CPN): 2004
Chumphon (CPN): 2014
 The statistical percentages are measured by FMCW ionosonde at Chumphon station from 2014 to 2015. Where blue bar, orange bar, and brown bar represent each different type of ESFs including FSF, RSF, and SSF, respectively.
Chumphon (CPN): 2015
Chumphon (CPN): September, 2019
S4 Index
S4 index is used to measure the severity of scintillation (fluctuation) on GNSS or GPS signals.
S4 Index (Chumphon station, CPN)