Title Diurnal variations of humidity and ice water content in the tropical upper troposphere
Author Eriksson, P.; Rydberg, B.; Johnston, M.; Murtagh, D.P.; Struthers, H.; Ferrachat, S.; Lohmann, U.
Author Affil Eriksson, P., Chalmers University of Technology, Department of Earth and Space Sciences, Gothenburg, Sweden. Other: Stockholm University, Sweden; Eidgenössiche Technische Hochschule Zürich, Switzerland
Source Atmospheric Chemistry and Physics, 10(23), p.11519-11533, . Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680-7316
Publication Date 2010
Notes In English. Published in Atmospheric Chemistry and Physics Discussions: 3 May 2010, http://www.atmos-chem-phys- discuss.net/10/11711/2010/acpd-10-11711-2010. html; accessed in June, 2011. 59 refs. GeoRef Acc. No: 309975
Index Terms atmospheric circulation; climate; diurnal variations; humidity; ice; models; remote sensing; statistical analysis; water; water vapor; Bolivia; Brazil; Africa--Central Africa; India; Indian Ocean; Malay Archipelago; Far East--Malay Peninsula; Pacific Ocean--North Pacific; Africa; Asia; boreal environment; CAM3; Central Africa; EC- EARTH; ECHAM; equatorial region; Far East; geostatistics; greenhouse gases; Indian Peninsula; Malay Peninsula; North Pacific; Pacific Ocean; satellite methods; South America; terrestrial environment; troposphere
Abstract Observational results of diurnal variations of humidity from Odin-SMR and AURA- MLS, and cloud ice mass from Odin-SMR and CloudSat are presented for the first time. Comparisons show that the retrievals of humidity and cloud ice from these two satellite combinations are in good agreement. The retrieved data are combined from four almost evenly distributed times of the day allowing mean values, amplitudes and phases of the diurnal variations around 200 hpa to be estimated. This analysis is applied to six climatologically distinct regions, five located in the tropics and one over the subtropical northern Pacific Ocean. The strongest diurnal cycles are found over tropical land regions, where the amplitude is ~7 RHi for humidity and ~50% for ice mass. The greatest ice mass for these regions is found during the afternoon, and the humidity maximum is observed to lag this peak by ~6 h. Over tropical ocean regions the variations are smaller and the maxima in both ice mass and humidity are found during the early morning. Observed results are compared with output from three climate models (ECHAM, EC- EARTH and CAM3). Direct measurement-model comparisons were not possible because the measured and modelled cloud ice masses represent different quantities. To make a meaningful comparison, the amount of snow had to be estimated from diagnostic parameters of the models. There is a high probability that the models underestimate the average ice mass (outside the 1-sigma uncertainty). The models also show clear deficiencies when it comes to amplitude and phase of the regional variations, but to varying degrees.
URL http://www.atmos-chem-phys.net/10/11519/2010/acp-10-11519-2010.pdf
Publication Type journal article
Record ID 65006877