Microwave and Physical Electronics

Contains reports on seven research projects

Analysis of sources and sinks of atmospheric nitrous oxide (N 2

Here I use a simple model to place constraints on the relative sizes of N2O sources in the northern and southern hemispheres (NH and SH). Using measurements of the rate of temporal increase of atmospheric nitrous oxide (N2O) concentrations and observations of their cross-equator differences, I calculate the total sources of N2O for the (NH and SH). The NH source ΦN must exceed the SH source ΦS; their ratio R = (ΦN/ΦS) is between 1.7 and 2.4 for the case where the NH concentration is 1 ppb higher than that in the SH. When the NH concentration is 0.75 ppb higher, R is between 1.5 and 1.9. -from Autho

Physical Electronics

Contains reports on four research projects

Microwave and Physical Electronics

Contains reports on six research projects

Microwave and Physical Electronics

Contains reports on seven research projects

The Coupled Model Intercomparison Project (CMIP)

The Coupled Model Intercomparison Project (CMIP) was established to study and intercompare climate simulations made with coupled ocean-atmosphere-cryosphere-land GCMs. There are two main phases (CMIP1 and CMIP2), which study, respectively, 1) the ability of models to simulate current climate, and 2) model simulations of climate change due to an idealized change in forcing (a 1% per year CO2 increase). Results from a number of CMIP projects were reported at the first CMIP Workshop held in Melbourne, Australia, in October 1998. Some recent advances in global coupled modeling related to CMIP were also reported. Presentations were based on preliminary unpublished results. Key outcomes from the workshop were that 1) many observed aspects of climate variability are simulated in global coupled models including the North Atlantic oscillation and its linkages to North Atlantic SSTs, El Niño-like events, and monsoon interannual variability; 2) the amplitude of both high- and low-frequency global mean surface temperature variability in many global coupled models is less than that observed, with the former due in part to simulated ENSO in the models being generally weaker than observed, and the latter likely to be at least partially due to the uncertainty in the estimates of past radiative forcing; 3) an El Niño-like pattern in the mean SST response with greater surface warming in the eastern equatorial Pacific than the western equatorial Pacific is found by a number of models in global warming climate change experiments, but other models have a more spatially uniform or even a La Niña-like, response; 4) flux adjustment, by definition, improves the simulation of mean present-day climate over oceans, does not guarantee a drift-free climate, but can produce a stable base state in some models to enable very long term (1000 yr and longer) integrations-in these models it does not appear to have a major effect on model processes or model responses to increasing CO2; and 5) recent multicentury integrations show that a stable surface climate can be attained without flux adjustment (though still with some systematic simulation errors)

Radon 222 and tropospheric vertical transport

Radon 222 is an inert gas whose loss is due only to radioactive decay with a half life of 3. 83 days (5. 51-day 'exponential' lifetime). It is a very useful tracer of continental air because only ground level continental sources are significant. Previously published measured **2**2**2Rn profiles are analyzed here by averaging for the summer, winter, and spring-fall seasons. The analysis shows that in summer, about 55% of the **2**2**2Rn is transported above the planetary boundary layer, considerably more than during the other seasons. Similarly, in summer, about 20% rises to over 5. 5 km (500 mbar). The average profiles have been used to derive vertical eddy diffusion coefficients with maximum values of 5-7 multiplied by 10**5 cm**2 s** minus **1 in the midtroposphere and 8 multiplied by 10**3 to 5 multiplied by 10**4 cm**2 s** minus **1 near the surface