Ali K. Saleh’s scientific contributions

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Publications (2)


Fig. 5. Empirical probability density function (EPDF) of collected SST data (2001-2019) in Kuwait Bay.
Fig. 6. Decomposition plot of monthly average SST (2001-2019) over Kuwait Bay in degrees Celsius. The grey bars on the right are magnitude guides-each bar represents the same magnitude.
Remote sea-surface temperature variations (2001–2019) in Kuwait Bay: Time series analysis in frequency and time domains
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December 2021

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101 Reads

Kuwait Journal of Science

Ali K. Saleh

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There is a recognized need to analyze the temporal changes of sea surface temperature in various water bodies, especially the semi-enclosed ones, because of the direct link between sea temperature and aquatic biodiversity. There has been substantial research undertaken on the role of time series analysis as a powerful technique for studying the characteristics of long-term SST changes at regular time intervals. The present paper aimed to study the monthly-averaged MODIS SST data (2001–2019) over Kuwait Bay, i.e., the northwestern corner of the Arabian Gulf. Because different approaches can yield different results, the analysis of the SST time series was conducted using time and frequency domains. The preliminary analysis of the time series reported a significant SST peak in August 2010 that reached nearly 34.2 °C (SD = 0.17 °C) due to the moderate intensity El Niño event in 2010. However, in the preceding year, we observed a cool SST anomaly in the range of –0.5 °C to –2.4 °C. From the SMK trend test, we found that monthly climatological SST in September exhibited a significant upward trend (𝑆9 = 103, 𝜏 = 0.6, 𝑃 = 0.0004). Pettitt’s change-point test indicated a significant change in the central tendency of SST data after April 2012. The annual periodicity of the SST in Kuwait Bay was constant over the 19 years. Furthermore, a very weak periodicity of 6-month has been barely noticed. Our present results provide large-scale guidance that affirms the importance of highlighting the severe SST fluctuations in Kuwait’s water in order to understand and improve its marine environmental status.

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Statistical validation of MODIS-based sea surface temperature 2 in shallow semi-enclosed marginal sea: A comparison between 3 direct matchup and triple collocation

April 2021

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84 Reads

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11 Citations

Water

Validating remotely sensed sea surface temperature (SST) is a fundamental step in establishing reliable biological/physical models that can be used in different marine applications. Mapping SST using accurate models would assess in understanding critical mechanisms of marine and coastal zones, such as water circulations and biotic activities. This study set out to validate MODIS SSTs with a spatial resolution of 1-km in the Arabian Gulf (24–30° N, 48–57° E) and to assess how well direct comparison of dual matchups and triple collocation analyses perform. For the matchup process, three data sets, MODIS-Aqua, MODIS-Terra, and iQuam, were co-located and extracted for 1-pixel box centered at each actual in situ measurement location with a time difference window restricted to a maximum of ±3 h of the satellite overpass. Over the period July 2002 to May 2020, the MODIS SSTs (N = 3786 triplets) exhibited a slight cool night-time bias compared to iQuam SSTs, with a mean ± SD of −0.36 ± 0.77 °C for Aqua and −0.27 ± 0.83 °C for Terra. Daytime MODIS SST observations (N = 5186 triplets) had a lower negative bias for both Aqua (Bias = −0.052 °C, SD = 0.93 °C) and Terra (Bias = −0.24 °C, SD = 0.90 °C). Using extended triple collocation analysis, the statistical validation of system- and model-based products against in situ-based product indicated the highest ETC-based determination coefficients (ρt,X2 ≥ 0.98) with the lowest error variances (σε2 ≤ 0.32), whereas direct comparison underestimated the determination coefficients and overestimated the error estimates for all MODIS algorithms. The ETC-based error variances for MODIS Aqua/Terra NLSSTs were 0.25/0.19 and 0.26/0.32 in daytime and night-time, respectively. In addition, MODIS-Aqua was relatively more sensitive to the SST signal than MODIS-Terra at night and vice versa as seen in the unbiased signal-to-noise ratios for all observation types.

Citations (1)


... The MODIS Terra sensor captures images twice a day, with quality flags ranging from 0 (best quality, cloud-free) to 4 (worst quality, failure or masked) [39,40]. However, several studies have validated this dataset, indicating the good accuracy of MODIS SST through comparisons with independent measurements from ship-borne infrared spectroradiometers and drifting buoys [41,42]. Saleh et al. (2021) [42] demonstrated a strong correlation between MODIS SST and measurements from drifting buoys, showing consistent accuracy compared to traditional in situ measurements. ...

Reference:

Impact of Sea Surface Temperature on City Temperature near Warm and Cold Ocean Currents in Summer Season for Northern Hemisphere
Statistical validation of MODIS-based sea surface temperature 2 in shallow semi-enclosed marginal sea: A comparison between 3 direct matchup and triple collocation

Water