A comparison of the warm-season wind regimes of the Beaufort/Chukchi Seas Coasts using observations and the North American Regional Reanalysis
Abstract
In recent years several reanalysis datasets have been developed and released to the public. One common use of this data is climatic studies. Such datasets have proven extremely useful for conducting climate studies in data sparse regions (Bromwich and Fogt, 2004). High latitude regions, such as the Beaufort and Chukchi Sea Coasts, are examples of such regions. The North American Regional Reanalysis (NARR) is a high-resolution reanalysis data set that is well suited to climatic studies over the North American region, due to both its high spatial resolution (32-km) and number of variables available for study. Reanalysis data have been used in several studies in the Arctic to better understand the near surface and upper air wind regimes, primarily in the ice-free, warm season months. However, efforts to directly compare reanalysis output to direct observations over the Beaufort/Chukchi region have been minimal. Due to increasing economic activity in this region related to resource extraction and shipping and evidence of a rapidly changing climate, understanding the reality of wind regimes is important for both economic development and environmental protection (Serreze and Francis, 2006). In this study, several long-term observational sites along the Beaufort and Chukchi Sea coasts were chosen and compared with the nearest neighbor grid cell from NARR for the warm-season months (May, June, July, August, and September) from 1979-2009. Both surface station observations and 850 hPa level radiosonde data were used in compiling the observational data sets. Monthly climatologies were developed for temperature, wind speed, and wind direction for both observational and NARR datasets over the 31-year period. Time series analyses were also performed on the data to look for statistically significant temporal trends in temperature, wind speed, and wind direction. Several key differences were noted between the observations and NARR in the analyzed variables. These included both positive and negative biases in temperature and wind speed, and wind direction in the NARR when compared to observations. The sign of the bias was generally dependent on the stations proximity to the coast and month. This suggests that NARR has difficulty in areas with complex terrain, as well as arctic coastal environments. Rapid seasonal change during the months of May and September may have contributed to the differences seen in these months. Statistically significant temporal trends were also noted in both observational and NARR data at several sites over the time period analyzed, with trends in surface temperature and 10-m wind speed being significant (α ≤ 0.05) at several locations over the 31-year period. Evidence of mesoscale phenomena, such as a warm-season sea breeze, were also present in both observations and NARR. An understanding of the differences between observations and reanalysis output will further aid research in this data sparse region. Planned future work that will be aided by this comparison includes a quantitative evaluation of the warm-season sea breeze for the Beaufort/Chukchi coasts.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMGC51F1084B
- Keywords:
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- 1616 GLOBAL CHANGE / Climate variability;
- 3309 ATMOSPHERIC PROCESSES / Climatology;
- 3349 ATMOSPHERIC PROCESSES / Polar meteorology;
- 3364 ATMOSPHERIC PROCESSES / Synoptic-scale meteorology