Periodicity of Downward Longwave Radiation at an Equatorial Location

Authors

1 Ph.D. Graduated, Department of Physics, University of Lagos, Akoka, Lagos State, Nigeria

2 Professor, Department of Physics, University of Lagos, Akoka, Lagos State, Nigeria

3 Professor, Department of Physics, University of Calabar, Calabar, Cross River State, Nigeria

Abstract

A good understanding of the diverse mechanisms in the atmosphere is required in modelling the climate. In this study, the diurnal and seasonal patterns of all-sky downward longwave radiation (DLR) at Ilorin (8o 32l N, 4o 34l E), Nigeria were investigated alongside relative humidity (RH) and temperature. The average diurnal pattern of DLR gives an arc that begins by increasing gradually with some inherent fluctuations from 01:00 hour to a maximum at 14:00 hour local time, and then gradually decreases to a minimum at 00:00 hour. However, sometimes erratic and double peak arc diurnal DLR patterns occur around the mid and the end of the year periods respectively. The seasonal, diurnal peak of temperature and the minimum of relative humidity (RH) occur approximately two hours after the peak of DLR. Besides, the seasonal trends of both DLR and RH match each other, except sometimes in June, which could be due to the midyear DLR erratic diurnal effect. Possibly, the mechanisms of the inter-tropical discontinuity (ITD) influence the particular diurnal patterns of DLR at the midyear and year-end periods.  Moreover, monthly dispersion of DLR is high during known months of high atmospheric aerosols, and annual maximum temperature occurs after the Harmattan season. Hence, variations in DLR are influenced mostly by mineral dust in the atmosphere, mechanisms of ITD and changes in the sun-earth distance, which reflects on the different seasons in Ilorin.

Keywords

Main Subjects

References

Adedokun, J. A., Emofurieta, W. O. and Adedeji, O. A., 1989, Physical, mineralogical and chemical properties of Harmattan dust at Ile-Ife, Nigeria. Theor. Appl. Climatol., 40, 161–169.
Adejuwon, J. O., 2012, Rainfall seasonality in the Niger Delta Belt, Nigeria. J. Geogr. Region. Plann. 5, 51–60.
Allan, R. P., 2006, Variation in clear-sky longwave radiative cooling of the atmosphere. Journal of Geophysical Research, 111, D22105. DOI: 10.1029/2016JD007304.
Anuforom, A. C., Akeh, L. E., Okeke, P. N. and Opara, F. E., 2007, Inter-annual variability and long-term trend of UV-absorbing aerosols during Harmattan season in sub-Saharan West Africa. Atmos. Environ., 41, 1550–1559.
Babatunde, E. B., Akoshile, C. O., Falaiye, O. A., Willoughby, A. A., Ajibola, T. B., Adimula, A. and Aro, T. O., 2009, Observation bio-effect of SW-global solar radiation in Ilorin in the tropics.  Adv. Space Res., 43, 990–994.
Beer, J., Mende, W. and Stellmacher, R., 2000, The role of the sun in climate forcing. Quat. Sci. Rev., 19, 403–415.
Catalanotti, S., Cuomo, V., Piro, G., Ruggi, D., Silvertrini, V. and Troise, G., 1975, The radiative cooling of selective surfaces. Sol. Energy, 17, 83–89.
Culf, A. D. and Gash, J. H. C., 1993, Longwave radiations from clear skies in Niger; a comparison of observation with simple formulae. J. Appl. Meteorol., 32, 539–547.
Dickinson, R. E., 1975, Meteorology of the upper atmosphere. Rev. Geophy., 13, 771–790.
Dufresne, J.-L. Gantier, C., Ricchiazzi, P. and Fouquart, Y., 2002, Longwave scattering effects of mineral aerosols. J. Atmos. Sci., 59, 1959–1966.
Goudie, A. S. and Middleton, N. J., 1992, The changing frequency of dust storms through time. Climate Change, 20, 197–225.
Harris, I. and Priester, W., 1962, Time-dependent structure of the upper atmosphere. J. Atmos. Sci., 19, 287–301.
Hartmann, D. L., Moy, L. A. and Fu, Q., 2001, Tropical convection and the energy balance at the top of the atmosphere. J. Climate, 14, 4495–4511.
Hoch, S. W., Calanca, P., Philipona, R. and Ohmura, A., 2007, Year-round observation of longwave radiation flux divergence in Greenland. J. Appl. Meteorol., 46, 1469–1479.
Igbal, M., 1983, An introduction to solar radiation. Academic Press, New York.
Ilesanmi, O. O., 1971, An empirical formulation of an ITD rainfall model for the tropics: a case study of Nigeria. J. Appl. Meteorol., 10, 882– 891.
Iziomon, M. G., Mayerb, H. and Matzarakisb, A., 2003, Downward atmospheric longwave irradiance under clear and cloudy skies: measurement and parameterisation. J. Atmos. Terr. Phys., 65, 1107–1116.
Jonsson, P., Eliasson, I., Holmer, B. and Grimmond, C. S. B., 2006, Longwave incoming radiation in the tropics: results from fieldwork in three African cities. Theor. Appl. Climatol., 85, 185–201.
Jordan, D. N. and Smith, W. K., 1994, Energy balance analysis of night-time leaf temperatures and frost formation in a subalpine environment. Agric. For. Meteorol., 71, 359–372.
Kesseler, A. and Jaeger, L., 2003, Analysis of long time series of long-wave radiation fluxes above a pine forest. Theor. Appl. Climatol., 74, 179–189.
Konig-Langlo, G. and Sieger, R., 2013, Report of the working group BSRN-Baseline surface radiation network. AIP Conf. Proc. 1531, 668– 671.
L’homme, J. P. and Guilioni, L., 2004, A simple model for minimum crop temperature forecasting during nocturnal cooling. Agric. For. Meteorol., 123, 55–68.
Mallet, M., Tulet, P., Serc, D., Solmon, F., Dubovik, O., Pelon, J., Pont, V. and Thouron, O., 2009, Impact of dust aerosols on the radiative budget, surface heat fluxes, heating rate profiles and convective activity over West Africa during March 2006. Atmos. Chem. Phys., 9, 7143–7160.
Marty, Ch., Philipona, R., Frӧhlich, C. and Ohmura, A., 2002, Elevation dependence of surface radiation fluxes and cloud forcing in the Alps: results from the alpine surface radiation network. Theor. Appl. Climatol., 72, 135–155.
Martzke, J. and Scott, J. R., 1999, Convective mixing and the thermohaline circulation. J. Phys. Oceanogr., 29, 2962–2970.
Miskolczi, F., Aro, T. O., Iziomon, M. and Pinker, R. T., 1997, Surface radiative fluxes in sub-Sahel Africa. J. Appl. Meteorol., 36, 521–530.
Morcrette, J.-J., 2002, The surface downward longwave radiation in the ECMWF forecast system. J. Climate, 15, 1875–1872.
Naud, C., Chen, Y., Rangwala, I. and Miller, J.R., 2013, Sensitivity of downward longwave surface radiation to moisture and cloud changes in a high-elevation region. J. Geophys. Res., 118, 10072–81.
Niemelä, S., Räisäneu, P. and Savijärvi, H., 2001, Comparison of surface radiative flux parameterizations Part 1: longwave radiation. Atmos. Res., 58, 1–18.
Obot, N. I., 2015, New clear skies empirical models and neural networks estimations of downward longwave radiation in Nigerian environment. Ph.D. Thesis, University of Lagos, Nigeria.
Obot, N. I. and Chendo, M. A., 2014, Diurnal downward longwave radiation at an equatorial location. BSRN conference in September Bologna, Italy.
Obot, N. I., Chendo, M. A. C. and Oyeyemi E.O., 2018, Downward longwave radiation categories in Nigeria. Dynam. Atmos. Ocean, 83, 122–134.
Ohmura, A., 2001, Physical basis for temperature based melt-index method. J. Appl. Meteorol. 40, 753–761.
Ohmura, A. Dutton, E. G., Forgan, B., Frohlich, C., Gilgen, H., Hegner, H., Heimo, A., Konig-Langlo G., McArthur, B., Muller, G., Philipona, R., Pinker, R., Whitlock, C.H., Dehne, K. and Wild, M., 1998, Baseline surface radiation network (BSRN/WCRP): new precision radiometry for climate research. Bull. Amer. Meteor. Soc. 79, 2115–2136.
Philipona, R., Fröhlich, C. and Betz, C., 1995, Characterization of pyrgeometer and the accuracy of atmospheric long-wave radiation measurements. Appl. Opt., 34, 1598–1605
Philipona, R., Dutton, E., Stoffel, T., Michalsky, J., Reda, I., Stifter, A., Wendling, P., Wood, N., Clough, S. A., Mlawer, E. J., Anderson, G., Revercomb, H. E. and Shippert, T. R., 2001, Atmospheric longwave irradiance uncertainty: pyrgeometers compared to an absolute sky-scanning radiometer, atmospheric emitted radiance interferometer, and radiative transfer model calculations. J. Geophys. Res. Atmos., 106, 2812–28141.
Priester, W. and Cattani, D., 1962, On the semiannual variation of geomagnetic activity and relation to solar corpuscular radiation. J. Atmos. Sci., 19, 121–126.
Ramanathan, V., Crutzen, P. J., Kiehl, J. T. and Rosenfeld, D., 2001, Aerosols, climate, and the hydrological cycle. Science, 7, 2119 – 2124.
Seefeldt, M. W., Hopson, T. M. and Warner, T.T., 2012, A characterisation of the variation in relative humidity across West Africa during the dry season. J. Appl. Meteorol., 51, 2077–2089.
Sellers, W. D., 1965, Physical Climatology. University of Chicago Press. Chicago.
Schlegel, K., Diendorfer, G., Thern, S. and Schmidt, M., 2001, Thunderstorms, lightning and solar activity – Middle Europe, J. Atmos. Solar-Terr Phys., 63, 1705–1713.
Schwanghart, W. and Schutt, B., 2008, Meteorological causes of Harmattan dust in West Africa. Geomorphology, 95, 412-428.
Sicart, J. E., Pomeroy, J. W., Essery, R. L. H. and Bewley, D., 2006, Incoming longwave radiation to melting snow: observations, sensitivity and estimation of northern environments. Hydrol. Process, 20, 3697–3708.
Soares, J., Oliveira, A. P., Boznar, M. Z., Mlakar, P., Escobedo, J. A. and Machado, A. J. 2004, Modelling hourly diffuse solar-radiation in the city of Sao Paulo using neural-network technique. Appl. Energ., 79, 201–214.
Stanhill, G., Hofstede, G. J. and Kalma, J. D., 1966, Radiation balance and natural and agricultural vegetation. Q. J. R. Meteorol. Soc. 92, 128–140.
Stephens, G.L, Wild, M., Stackhouse, J.P.W., Ecuyer, T. L., Kato, S.and Henderson, D. S., 2012, The global character of the flux of downward longwave radiation. J. Climate, 25, 2329–2340
Tang, Q., Oki, T., Kanae, S. and Hu, H., 2007, The influence of precipitation variability and partial irrigation within grid cells on a hydrological simulation. J. Hydrometeorol., 8, 499–512.
Udo, S. O., 2004, Characteristics of diurnal pattern of downward infrared radiation at Ilorin, Nigeria. Nig. J.  Phys., 16, 126–130.
Udo, S. O., 2003, Modelling of infrared radiation for all skies from easy-to-measure meteorological parameters at tropical location: Ilorin, Nigeria. Turk. J. Phys., 27, 61–68.
 
 
 
Udo, S. O., 2000, Quantification of solar heating of the dome of a pyrgeometer for a tropical station: Ilorin, Nigeria. J. Atmos. Oceanic Tech., 17, 995–1000.
Udo, S. O. and Aro, T. O., 2000, New empirical relationships for determining global PAR from measurements of global solar radiation, infrared radiation or sunshine duration. Int. J. Climatol., 20, 1265–1274.
Udo, S. O. and Aro, T. O., 1999, Measurement of global solar global photosynthetically active and downward infrared radiations at Ilorin, Nigeria. Renew. Energy, 17, 113–122.
Wang, K. and Liang, S., 2009, Global atmospheric downward longwave radiation overland surface under all-sky conditions from 1973 to 2008. J. Geophy. Res., 114 doi: 10.1029/2009JDO11800.
Wild, M., Folini, D., Schär, C., Loeb, N., Dutton, E. G. and König-Langlo, G., 2013, The global energy balance from a surface perspective. Clim. Dynam., 40, 3107–3014.
Wild, M., Ohmura, A., Gilgen, H. and Rosenfeld, D., 2004, On the consistency of trends in radiation and temperature records and implications for the global hydrological cycle. Geophy. Res. Lett., 31 doi: 10.1029/2003GL019188
Wild, M., Ohmura, A., Gilden, H., Morcrette, J.-J. and Slingo, A., 2001, Evaluation of downward longwave radiation in the general circulation models. J. Climate, 14, 3227–3239.
Zhao, C., Liu, X., Leung, L.R. and Hagos, S., 2011, Atmospheric Chemistry and Physics Radiative impact of mineral dust on monsoon precipitation variability over West Africa. Atmos. Chem. Phys., 11, 1879–1893.
Journal of the Earth and Space Physics
Volume 44, Issue 4
January 2019
Pages 165-177

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