Volume 5,Issue 2
Fall 204
Anomalous wind circulation over Taipei, Taiwan during the northern winter seasons of 2004 and 2005- A case study
This research reports, for the first time, an anomalous wind circulation over Taipei (Latitude 25.030N, Longitude 121.510E), Taiwan during the northern hemisphere winter season (December, January, and February) of years 2004 and 2005. The anomalous wind circulation of meridional winds, which showed southward directions during the winter seasons of 2004 and 2005 instead of northward winds, is noticed from one kilometer altitude range (lower troposphere) and that trend continued till around 20 km altitude range (lower stratosphere). To ascertain whether such a disturbed nature of wind pattern existed over nearby locations to Taipei, we have analyzed radiosonde-measured meridional and zonal winds over four nearby stations station to Taipei including, Roig, Xiamen, Minami and Fuzhou. Surprisingly, no anomalous wind behavior is seen except over Taipei during the northern winter seasons of 2004 and 2005. On the other hand, the European Centre for Medium-Range Weather Forecasts (ECMWF) model-predicted winds do not show any anomalous wind patterns over Taipei and other nearby stations, possibly due to the large averaging of internal variabilities of reanalysis databases. The plausible physical mechanisms of these disturbed meridional wind patterns are not understood at this juncture, but it is believed that local winds and atmospheric pollutants might have created an amicable environment as to provide such a disturbed meridional wind pattern over Taipei, Taiwan in the winter season of 2004 and 2005.
1. Trenberth KE, Stepaniak DP, Caron JM. The global monsoon as seen through the divergent atmospheric circulation. Journal of Climate 2000; 13: 3969–3993.
2. Lu J, Deser C, Reichler T. Cause of the widening of the tropical belt since 1958. Geophysical Research Letters 2009; 36, L03803.
3. Garfinkel CI, Waugh DW, Polvani LM. Recent Hadley cell expansion: The role of internal atmospheric variability in reconciling modeled and observed trends. Geophysical Research Letters 2015; 42: 10824–10831.
4. Polvani LM, Waugh DW, Correa GJP, et al. Stratospheric ozone depletion: The main driver of twentieth-century atmospheric circulation changes in the Southern Hemisphere. Journal of Climate 2011; 24: 795–812.
5. Staten PW, Rutz JJ, Reichler T, et al. Breaking down the tropospheric circulation response by forcing. Climate Dynamics 2012; 39: 2361–2375.
6. Hu YY, Tao LJ, Liu JP. Poleward expansion of the Hadley circulation in CMIP5 simulations. Advacens in Atmospheric Sciences 2013; 30: 790–795.
7. Quan XW, Diaz HF, Hoerling MP. Change in the tropical Hadley cell since 1950. In: Diaz HF, Bradley RS (eds) The Hadley circulation: past, present, and future. Cambridge University Press, New York 2004;
8. Allen RJ, Norris JR, Kovilakim M, et al. Influence of anthropogenic aerosols and the Pacific decadal oscillation on tropical belt width. Natural Geosciences 2014; 7: 270–274.
9. Schneider DP, Deser C, Fan T. Comparing the Impacts of Tropical SST Variability and Polar Stratospheric Ozone Loss on the Southern Ocean Westerly Winds. Journal of Climate 2015; 28: 9350–9372.
10. Allen RJ, Sherwood SC, Norris SC, et al. Recent Northern Hemisphere tropical expansion primarily driven by black carbon and tropospheric Ozone. Nature 2012; 485: 350–354.
11. Kovilakam M, and Mahajan S. Black carbon aerosol-induced Northern Hemisphere tropical expansion. Geophysical Research Letters 2015; 42: 4964–4972.
12. Oort AH, Rasmusson EM. On the annual variation of the monthly mean meridional circulation. Monthly Weather Review 1970; 98: 423– 442.
13. Oort AH, Yienger JJ. Observed interannual variability in the Hadley Circulation and its connection to ENSO. Journal of Climate 1996; 9: 2751–2767.
14. Seidel DJ, Randel RJ. Recent widening of the tropical belt: Evidence from tropopause observations. Journal of Geophysical Research 2007; 112: D20113.
15. Mathew SS, Kumar KK, Subrahmanyam KV. Hadley cell dynamics in Japanese Reanalysis-55 dataset: Evaluation using other reanalysis datasets and global radiosonde network observations. Climate Dynamics 2016; 47: 3917–3930.
16. Tanaka HL, Ishizaki N, Kitoh A. Trend and interannual variability of Walker, monsoon and Hadley circulations defined by velocity potential in the upper troposphere. Tellus 2004; 56: 250–269.
17. Mitas C M, Clement A. Recent behavior of the Hadley cell and tropical thermodynamics in climate models and reanalyses. Geophysical Research Letters 2006; 33: L01810.
18. Jagannadha Rao VVM, NarendraBabu A, et al. Anomalous wind circulation observed during 1997/98 El Nin˜o using Indian MST radar. Journal of Applied Meteorology and Climatoogy 2007; 46: 112–119.
19. Roja Raman M, Jagannadha Rao VVM, Venkat Ratnam M, et al. Atmospheric circulation during active and break phases of Indian summer monsoon: A study using MST radar at Gadanki (13.50 N, 79.20 E). Journal of Geophysical Research 2008; 113: D20124.
20. Dee DP, Uppala SM, Simmons AJ, et al. The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quartely Journal of Royal Meteorological Society 2011; 137: 553–597.
21. Ladstädter F, Steiner AK, Schwärz M, et al. Climate intercomparison of GPS radio occultation, RS90/92 radiosondes and GRUAN from 2002 to 2013. Atmospheric Measurement Techniques 2015; 8: 1819–1834.
22. Moradi I, Buehler SA, John VO, et al. Comparing upper tropospheric humidity data from microwave satellite instruments and tropical radiosondes. Journal of Geophysical Research 2010; 115: D24310.
23. Brahmanandam PS, Chu YH, Liu J. Observations of equatorial Kelvin wave modes in FORMOSAT-3/COSMIC GPS RO temperature profiles. Terrestrail Atmospheric, Oceanic Sciences 2010; 21: 829–840.
24. Anisetty SKAV Prasad Rao, Brahmanandam PS, Uma G, et al. Planetary-scale wave structures of the earth's atmosphere revealed from the COSMIC observations. Journal of Meteorological Research 2014; 28: 281–295.
25. Kottayil A, Mohanakumar K, Samson T, et al. Validation of 205 MHz wind profiler radar located at Cochin, India, using radiosonde wind measurements. Radio Science 2016; 51: 106–117.
26. Birner T, Sean MD, Seidel DJ, et al. The changing width of Earth’s tropical belt. Physics Today 2014; 67: 38–44.
27. Trenberth KE, Guillemot CJ. Evaluation of the atmospheric moisture and hydrological cycle in the NCEP/NCAR reanalyses. Climate Dynamics 1998; 14: 213–231.
28. Berbery EH. Intraseasonal interactions between the tropics and extratropics in the southern hemisphere. Journal of Atmospheric Science 1993; 50: 1950–1965.
29. Simmons AS, Uppala S, Dee D, et al. ERA-Interim: New ECMWF reanalysis products from 1989 onwards. ECMWF Newsletter, ECMWF, Reading, United Kingdom 2007a; 110: 25–35.
30. Simmons AS, Uppala S, Dee D. Update on ERA-Interim. ECMWF Newsletter, No. 111, ECMWF, Reading, United Kingdom 2007b; 111: 5.
31. Uppala S, Dee D, Kobayashi S, et al. Towards a climate data assimilation system: Status update of ERA-Interim. ECMWF Newsletter, ECMWF, Reading, United Kingdom 2008; 115: 12–18.
32. Uppala S, et al. The ERA-40 Re-Analysis. Quartely Journal of Royal Meteorological Society 2005; 131: 2961–3012.
33. Koteswaram P. The Asian summer monsoon and the general circulation over the tropics. In Proceedings of the Symposium on Monsoons of the World, India Meteorological Department (eds). India Meteorological Department: New Delhi 1960; 105–110.
34. Bjerknes J. A possible response of the atmospheric Hadley circulation to equatorial anomalies of ocean temperature. Tellus 1966; 18: 820–829.
35. Hou AY. Hadley circulation as a modulator of the extratropical climate. Journal of Atmospheric Sciences 1998; 55: 2437–2457.
36. Ramanathan V, et al. Atmospheric brown clouds: Impacts on South Asian climate and hydrological cycle. Proceedings of National Academy of Science, U. S. A 2005; 102: 5326–5333.
37. Wild M, et al. From dimming to brightening: decadal changes in surface solar radiation. Science 2005; 308: 847–850.
38. Padma Kumari B, Londhe AL, Daniel S, et al. Observational evidence of solar dimming: offsetting surface warming over India. Geophysical Research Letters 2007; 34: L21810.