Poster Summaries
607
somewhat different precipitation pattern than today's and a similar planetary albedo, except
for the polar regions (that lack a permanent ice sheet).
Development of reliable models for microwave emission and scattering from terrain, i.e. soil,
vegetation, snow, forest, etc., is one of the important problems of microwave remote sensing.
The simple case of scattering by a thin dielectric strip was examined by Arslan. Extinction
cross sections were conducted for certain dielectric constants and strip dimensions corresponding
to the parameters of vegetation elements.
Schroder and Hense applied inverse modelling, concerning different parameterizations of the
horizontal energy transports in atmosphere and ocean, to validate simple Energy Balance Models. Up to now two different diffusive approaches for the transports and one including some
transport velocity were examined by estimating coarse patterns of the free parameters of each
parameterization from net radiation data at the top of the atmosphere. First results suggest
the parameterizations (models) are of similar quality.
Models can be used to interpret remote sensing images. In the case study by Li et aI., the
two-layer finite depth model is used to simulate the oceanic internal wave propagation over
the continental shelf of United States imaged by Airborne High Resolution Synthetic Aperture
Radar in 1991. The results agree well with coincident oceanographic in-situ measurements.
Today a big effort is devoted to calibrate models with available measured data or to use models
to help explain processes in the atmosphere-ocean-cryosphere.
Pereira et ai. have used a modified version of the physical model for solar radiation calculation
by Moser and Raschke (1983) to map the solar radiation in Brazil by use of METEOSAT data.
Validation is being made with the network of 22 pyranometers of the Brazilian meteorological
service. Results show standard errors of the order of 13%. A microwave radiative transfer
model is used by Mehrtens to derive weighting functions for precipitating clouds. An adjoint
formulation allows to solve the full equation of transfer including the phase function to include
scattering processes in the weighting functions. The results show that even below a precipitating
cloud (RR=lO mm/h) there is a contribution from the lowest layers and the ground at 85 Ghz.
Karlsson used monthly cloud cover statistics, derived from NOAA-AVHRR data, to validate
cloud cover information generated from the HIRLAM forecasting model both with and without
initial cloudiness states. When initial model cloudiness is set to zero, a considerable spin-up
time is required in order to generate realistic cloudiness fields. When 6-hour HIRLAM cloud
parameters are used as initial states, the model spin-up is drastically reduced; modelled and
observed cloudiness amounts are similar whereas some spatial discrepancies remain.
Chen et ai. study water vapor distribution obtained from ECHAM atmospheric GCM and
compare the simulation with satellite observations of total precipitable water from SSM/I and
upper tropospheric humidity from TOVS. In general, the model simulation agrees well with
satellite observed climatological mean, seasonal variation and interannual variation of moisture.
Cloud liquid water and water vapor are the two important atmospheric error sources for the
retrieval of sea-ice concentration and ice type/age with passive microwaves from satellites. Ch.
Oelke modelled these effects using a radiative transfer model and a high number of radiosonde
ascents from Antarctica and compared them with observed concentration changes in SSM/I
data.
Burford created a I-D model to investigate sublimation of snowfall profiles and particle spectral
evolution in the atmosphere. By assuming a Marshall Palmer type distribution and using the
diffusion equation, the effects of varying the temperature and humidity fields over a 1 km fall
depth were investigated. Most surprising results included large mass losses at relatively high
temperatures and low subsaturation values. The Sahara dust intrusion in the atmosphere and
the deposition in the mixed-layer of the Mediterranean Sea is studied by N. Kubilay et al.
607
somewhat different precipitation pattern than today's and a similar planetary albedo, except
for the polar regions (that lack a permanent ice sheet).
Development of reliable models for microwave emission and scattering from terrain, i.e. soil,
vegetation, snow, forest, etc., is one of the important problems of microwave remote sensing.
The simple case of scattering by a thin dielectric strip was examined by Arslan. Extinction
cross sections were conducted for certain dielectric constants and strip dimensions corresponding
to the parameters of vegetation elements.
Schroder and Hense applied inverse modelling, concerning different parameterizations of the
horizontal energy transports in atmosphere and ocean, to validate simple Energy Balance Models. Up to now two different diffusive approaches for the transports and one including some
transport velocity were examined by estimating coarse patterns of the free parameters of each
parameterization from net radiation data at the top of the atmosphere. First results suggest
the parameterizations (models) are of similar quality.
Models can be used to interpret remote sensing images. In the case study by Li et aI., the
two-layer finite depth model is used to simulate the oceanic internal wave propagation over
the continental shelf of United States imaged by Airborne High Resolution Synthetic Aperture
Radar in 1991. The results agree well with coincident oceanographic in-situ measurements.
Today a big effort is devoted to calibrate models with available measured data or to use models
to help explain processes in the atmosphere-ocean-cryosphere.
Pereira et ai. have used a modified version of the physical model for solar radiation calculation
by Moser and Raschke (1983) to map the solar radiation in Brazil by use of METEOSAT data.
Validation is being made with the network of 22 pyranometers of the Brazilian meteorological
service. Results show standard errors of the order of 13%. A microwave radiative transfer
model is used by Mehrtens to derive weighting functions for precipitating clouds. An adjoint
formulation allows to solve the full equation of transfer including the phase function to include
scattering processes in the weighting functions. The results show that even below a precipitating
cloud (RR=lO mm/h) there is a contribution from the lowest layers and the ground at 85 Ghz.
Karlsson used monthly cloud cover statistics, derived from NOAA-AVHRR data, to validate
cloud cover information generated from the HIRLAM forecasting model both with and without
initial cloudiness states. When initial model cloudiness is set to zero, a considerable spin-up
time is required in order to generate realistic cloudiness fields. When 6-hour HIRLAM cloud
parameters are used as initial states, the model spin-up is drastically reduced; modelled and
observed cloudiness amounts are similar whereas some spatial discrepancies remain.
Chen et ai. study water vapor distribution obtained from ECHAM atmospheric GCM and
compare the simulation with satellite observations of total precipitable water from SSM/I and
upper tropospheric humidity from TOVS. In general, the model simulation agrees well with
satellite observed climatological mean, seasonal variation and interannual variation of moisture.
Cloud liquid water and water vapor are the two important atmospheric error sources for the
retrieval of sea-ice concentration and ice type/age with passive microwaves from satellites. Ch.
Oelke modelled these effects using a radiative transfer model and a high number of radiosonde
ascents from Antarctica and compared them with observed concentration changes in SSM/I
data.
Burford created a I-D model to investigate sublimation of snowfall profiles and particle spectral
evolution in the atmosphere. By assuming a Marshall Palmer type distribution and using the
diffusion equation, the effects of varying the temperature and humidity fields over a 1 km fall
depth were investigated. Most surprising results included large mass losses at relatively high
temperatures and low subsaturation values. The Sahara dust intrusion in the atmosphere and
the deposition in the mixed-layer of the Mediterranean Sea is studied by N. Kubilay et al.