Dayanandan et al. (2025) Systematic Spatio-Temporal Analysis of Long Term Trends and Surface Warming Thresholds Over Oman

Identification

• Journal: Earth Systems and Environment
• Year: 2025
• Date: 2025-10-17
• Authors: Baiju Dayanandan, Alim Abbas, Ajay Parottil, V. Vinoj, Soumyajyoti Jana, Ahmed Al‐Harrasi, Mohammed Safi Al Kalbani, Rahma Al Nadhairi, Humaid AlBadi
• DOI: 10.1007/s41748-025-00874-x

Research Groups

• Natural and Medical Sciences Research Centre, University of Nizwa, Birkat Al Mawz, Oman
• Atmospheric Chemistry Observations & Modelling, NSF, National Centre for Atmospheric Research (NCAR), CO, USA
• Indian Institute of Technology Bhubaneswar, Bhubaneswar, India
• Indian Institute of Tropical Meteorology, Maharashtra, India
• Oman Environment Authority, Muscat, Oman
• Oman Civil Aviation Authority, Muscat, Oman

Short Summary

This study presents a comprehensive assessment of long-term surface air temperature trends over Oman using ground measurements and ERA5 from 1981 to 2020. Results reveal significant nationwide non-uniform warming, with average, maximum, and minimum temperatures rising by 0.23–0.25 °C per decade, making Oman a vulnerable climate hotspot.

Objective

• Validate the performance of the ERA5 reanalysis dataset against ground observations and compare it with MERRA-2, CRU, and NCEP/NCAR to identify the most reliable product for climate analysis over Oman.
• Examine long-term trends in average (T avg ), maximum (T max ), and minimum (T min ) temperatures at national, regional, and seasonal scales using the Mann–Kendall test and Sen’s slope estimator.
• Quantify decadal variability, with a special focus on the accelerated warming period post-2000.
• Analyze the spatio-temporal frequency of extreme temperature thresholds (T avg >36 °C, T max >45 °C, T min >30 °C) to assess growing heat stress.
• Contextualize Oman’s warming rate by comparing it with global and Arabian Peninsula averages.
• Synthesize these findings to assess Oman’s status as a regional climate hotspot and discuss the implications for climate adaptation and policymaking.

Study Configuration

• Spatial Scale: Oman (approximately 309,500 km²), with regional segmentation into North, Central, and South Oman.
• Temporal Scale: 1981 to 2020 (40 years), analyzed on decadal and seasonal scales.

Methodology and Data

• Models used: Mann-Kendall (MK) test, Sen’s slope estimator for trend analysis. Python and ArcGIS for spatial explicit trend maps and threshold-exceedance frequency plots.
• Data sources:
  • ERA5 reanalysis dataset (hourly, ~31 km spatial resolution) as the primary dataset.
  • Ground measurements from 14 observation stations across Oman (Oman Civil Aviation Authority) for validation.
  • MERRA-2, NCEP/NCAR Reanalysis-2, and CRU TS 4.08 datasets for comparative evaluation.

Main Results

• Oman experienced significant nationwide non-uniform warming from 1981 to 2020. Average (T avg ), maximum (T max ), and minimum (T min ) temperatures increased by 0.23 ± 0.16 °C decade⁻¹, 0.25 ± 0.16 °C decade⁻¹, and 0.23 ± 0.20 °C decade⁻¹, respectively.
• Seasonal trends show spring (MAM) warming as the most rapid, followed by autumn (SON). Summer (JJA) exhibits consistent increases, while winter (DJF) displays the slowest warming.
• A pronounced acceleration in warming is evident post-2000, with the 2011–2020 decade ranking as the warmest on record.
• The frequency and extent of extreme temperature days have increased sharply. Central Oman records over 110 days annually with T avg >36 °C, while days with T max >45 °C and tropical nights (T min >30 °C) have more than tripled.
• Regionally, northern Oman shows the most pronounced and persistent warming, central Oman exhibits notable warming with more variability, and southern Oman displays relatively weaker and more variable trends.
• Oman's warming rate is 1.2–2.3 times faster than the global average but slightly slower than the broader Arabian Peninsula.
• ERA5 reanalysis data was validated as highly accurate for climate analysis over Oman, outperforming other tested datasets (MERRA-2, NCEP/NCAR, CRU).

Contributions

• Provides the first comprehensive four-decade (1981–2020) validation of high-resolution ERA5 reanalysis data against ground observations in Oman, confirming its high accuracy for climate analysis in a data-scarce region.
• Offers a detailed spatio-temporal assessment of long-term temperature trends and surface warming thresholds across Oman, addressing a critical gap in regional climate research.
• Quantifies region-specific warming rates and the increasing frequency of extreme heat events, establishing a robust baseline for future hypothesis-driven studies.
• Contextualizes Oman's warming rate by comparing it with global and Arabian Peninsula averages, highlighting its status as an intermediate yet vulnerable climate hotspot.
• Informs the development of region-specific climate adaptation strategies for critical sectors such as water resource management, public health, agriculture, and energy planning.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Citation

@article{Dayanandan2025Systematic,
  author = {Dayanandan, Baiju and Abbas, Alim and Parottil, Ajay and Vinoj, V. and Jana, Soumyajyoti and Al‐Harrasi, Ahmed and Kalbani, Mohammed Safi Al and Nadhairi, Rahma Al and AlBadi, Humaid},
  title = {Systematic Spatio-Temporal Analysis of Long Term Trends and Surface Warming Thresholds Over Oman},
  journal = {Earth Systems and Environment},
  year = {2025},
  doi = {10.1007/s41748-025-00874-x},
  url = {https://doi.org/10.1007/s41748-025-00874-x}
}